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Development of a low power hand-held device in a low

1. Using BGA packages is compelling when designing for small size as well as performance but the problematic assembly and complex rout ing increases costs as well as development and prototyping time Thus using QFN QFP and SO packages prioritized after size and availability seems to be a better choice 4 2 Interconnections Components must be connected to create a working system For this purpose there are several data busses amp bus protocols available The ColdFire MCF5249 10 has dedicated bus hardware for several protocols I C SPI PS IEC958 UART BDM and a system bus It also has hardware support for the IDE protocol and a SDRAM controller both using the system bus 4 2 1 TC Inter IC The PC protocol uses a two wire serial bus for low speed com munications which is most suitable for controlling peripheral de 2See chapter 4 4 3 PCB design conclusion 4 2 Interconnections 23 vices 27 This protocol is very common for this purpose and is implemented in the Wolfson WM8750L audio codec 16 and the Phillips TEA5764HN radio tuner 29 It is also used by the Cy press CY7C68301B USB to ATA bridge 13 to communicate with it s configuration EEPROM The ColdFire MCF5249 10 has one dedicated I C and one shared I C SPI bus interface The first solution was to use I C for the radio and SPI for the audio codec but this was changed to I C only with minor hardware modifications due to existing software support for P
2. Some players on the market such as the iPod Shuffle does not have a GUI this is not acceptable on a player with several gigabytes of music Almost all players on the market today feature colour displays As it turned out it was not easy to find colour displays in small volumes Eventually a 2 5 inch TFT supporting up to 262 144 colours was found The display manufactured by a Chinese com pany Tianma was not well documented the data sheet 20 was very incomplete However the datasheet for the controller IC used 21 was available on the Internet From these two datasheets the conclusion was drawn that the TFT was easy to connect to the processor through its external sys tem bus without any extra glue logic 3 7 Power supplies The player should run on batteries according to the requirements in section 1 5 Batteries are not capable of delivering constant voltages For example the voltage of a lithium polymer cell varies from about 2 7 V discharged to about 4 23 V fully charged 14 Since stable voltages at 3 3 V and 1 8 V are needed no matter what the current battery voltage is there is need for voltage regulators For high efficiency these regulators should be of switching DC DC type At first there was some hope of being able to use a power man agement unit PMU from Philips Semiconductors It had multiple individually adjustable voltages outputs However using this PMU was not going to be possible since the smallest orderi
3. converts 16 bit writes to two 8 bit writes and since address 0 A0 is missing the address incrementation remains unseen Writing is only allowed on even addresses for 16 bit words Thus using the TFT interface in the connected way works without any problems SDRAM Synchronous dynamic RAM The ColdFire MCF5249 has a built in SDRAM controller 10 which shares address and data pins with the system bus Control pins are 4 2 Interconnections 25 dedicated for this purpose and only the bus clock BCLK is shared though no other component uses the bus clock in this design This is used to connect the SDRAM component in the design IDE Integrated drive electronics The CPU also has dedicated hardware for IDE interfacing This interface also shares address amp data pins with the system bus and uses dedicated control pins A problem with this is that adding a hard drive in addition the the flash SDRAM and TFT already on the system bus will add excessive load and compromise signal integrity As a solution to this the ColdFire MCF5249 10 includes a buffer enable 1 pin BU FEN1 Unfortunately this pin is intended to drive a buffer situated after the SDRAM and before the flash The buffer enable 2 pin BU FEN2 intended for IDE buffering does not exist on the QFP package variant posing a troublesome problem Trying to work around this problem several solutions were con sidered the most prominent solution was to use a GPIO pin as buff
4. this option seems better than the 3 2 USB interface 13 PortalPlayer The ColdFire processor does not come with an on chip USB 2 0 PHY but neither does the PortalPlayer The loss in size of the design needing an external audio codec for the ColdFire is compensated by not needing to pay any fees for SDKs 3 2 USB interface 3 2 1 FTDI Chip FT245R amp FT232R The FT245R amp FT232R chips from Future Technology Devices In ternational Ltd FTDI 11 are made to be easy to use The FT245R is a USB to parallel FIFO interface and the FT232R is a USB to serial UART interface with optional clock generator output The simplicity of these chips however is their weakest side There is no support for USB Mass Storage Class 3 2 2 Philips ISP1582 According to the datasheet 12 the ISP1582 USB 2 0 controller from Philips Semiconductors fully complies with Universal Serial Bus Specification Rev 2 0 supporting data transfer at high speed 480Mbit s and full speed 12Mbit s It connects through a parallel buss interface hence it could be connected to the processor through the external system bus This would also require some external logic for address decoding 3 2 3 Cypress EZ USB AT2LP The AT2LP from Cypress Semiconductor is a fully featured USB 2 0 to ATA bridge supporting the USB 2 0 Mass Storage Class It is a fixed function ATA controller that needs no special firmware to function The chip is able to set its data pins to
5. ability to do post manufacturing changes considering of course that this board would not have hard size constrains that a final encapsulated version would have In hind sight using a 4 layer PCB for this project would have been more time efficient and resulted in a higher quality board The current design led to some very poor signal routing as a consequence of the large number of signals needing high performance A few signals were even routed by additional wires to save time and effort in trying to route them on the PCB Layers Price dm 1 48 75 2 61 25 4 164 00 6 205 00 Table 4 1 PCB technology prices 8PCBs can be modified by cutting the copper traces and soldering wires to the correct connections this cannot be done on the internal layers of 4 or 6 layer PCBs Prices taken from Beta LAYOUT Ltd website 26 30 Chapter 4 Hardware design Chapter 5 Software In this chapter the software used any problems that may have arisen and their solutions will described 5 1 Firmware Embedded systems are rarely compromized of purely hardware This is mostly because in comparison with reusing configurable ASIPs or programmable ICs like MCUs DSPs and CPUs designing pure hardware ASICs is a time consuming and costly ordeal Thus soft ware is used to implement functionality at a faster and more cost effective way This software may more or less be transparent to the user of t
6. among others decoders for MP3 and WMA The SDK also comes with a C compiler E mail correspondence with a SigmaTel representative showed that the SDK license comes with a one time fee of 12 000 and that SigmaTel do not support customers using third party software such as the GNU C compiler for Motorola DSP56k The SigmaTel D Major pros and cons can be reviewed in table 3 1 Pros Cons Much integrated hardware allowing Very expensive SDK for small designs No support from manufacturer Good interfacing possibilities if one does not buy the SDK Table 3 1 SigmaTel D Major pros and cons PHY Physical Layer is the lowest level of the implementation ie the hardware The codec contains the digital to analog converter and headphone amplifier 3 1 Audio processor 11 3 1 4 Freescale ColdFire MCF5249 The ColdFire MCF5249 from Freescale Inc 8 is MCU based on the Motorola 68000 architecture The MCF5249 is a variable instruction length RISC processor that incorporates a MAC unit which makes it suitable for signal processing It also have good interfacing possibilities thanks to the C Philips IIS PS and its external parallel system bus The MCF5249 doesn t have any internal audio codecs but thanks to the I S bus it is easy to interface external codecs According to 8 the MCF5249 is capable of decoding a MP3 file at frequencies as low as 20 MHz using only the on chip SRAM But since the file to be
7. decoded needs to be stored there is still need for an external memory Thanks to the system bus this should not imply any significant problems Freescale 8 also states that the power dissipation is less than 1 3 mW MHz That means that MP3 decoding consumes about 26 mW To be added to this value is power dissipation in the audio codec Freescale technical support works well they normally answers inquiries within 48 hours The MCF5249 is available in two different packages 160 pin BGA or 144 pin QFP See figure 3 1 for physical differences between the two package options The QFP package is missing some of the pins those pin are used for example in the flash media interface For a more specific specification of what pins are missing see the datasheet 10 Software There is a free firmware for the SCF5249 based iRiver MP3 play ers called Rockbox 9 According to 8 SCF5249 is a MCF5249 manufactured by Samsung rather than Motorola Rockbox is released under the GNU General Public License GPL In short terms this means that the source code of the Rockbox project can be freely used and modified The full license text can be found in Appendix A The Rockbox project website 9 states that the Rockbox firmware have functions for reading and writing a FAT32 filesystem They 3Since external memory is needed always this does not need to be accounted for when comparing the processors As defined by FSF Free as in speech
8. distortion or THD is a measurement of the extent of that distortion 8 Chapter 2 Audio coding amp sound quality The THD is defined as the sum of the powers of the harmonics above the fundamental frequency to the power of the fundamental THD gt harmonics powers fundamental frequency power or as Pardo Prat al pe THD Pi The THD is usually expressed in dB A meaningful measurement must include the number of harmonics included and should include other information about the test conditions For more information about THD see 3 Chapter 3 Component selection In this chapter the process of selecting components will be presented The choices made are presented and which facts those choices were made upon 3 1 Audio processor To get the most possible flexibility out of the audio player in terms of supported file formats and upgrade possibilities there should not be any specific hardware decoder encoder Instead they should be software based This leads to a number of choices In principle any DSP or MCU with enough capacity to encode and decode compressed audio data in real time would suffice A few different alternatives have been studied 3 1 1 Philips Nexperia The Philips Nexperia series of multimedia processors covers almost everything regarding audio and video decoding 4 Unfortunately it was hard to get any specific details about their line of audio DSPs without signing Philips NDA A
9. lossless formats FLAC among others 2 2 Lossy coding Lossy encoding algorithms discards data to gain good compression rates In opposite to lossless coding the original data cannot be perfectly restored from the compressed data Since good compression rates are possible to get lossy coding are often used in audio coding The basic idea is to try to avoid coding sound that are outside of what can be heard by the human ear Examples of lossy audio formats are MP3 Ogg Vorbis and AAC Kagerin Karlsson 2006 5 6 Chapter 2 Audio coding amp sound quality 2 2 1 MP3 MPEG 1 Layer 3 MP3 is the most commonly used lossy audio format today The MP3 format uses technology patented by Fraunhof Group and Thomson Inc The distributors of every MP3 encoder and decoder have to pay a compulsory license fee to be allowed to use those patented tech nologies This is to be considered when developing a DAP Not only manufacturers of encoders and decoders have to pay fees Artists record companies and so on also have to pay fees to be allowed to distribute material coded in the MP3 format The MP3 format is a part of the MPEG 1 standard There are specifications of how the encoder should encode the signal as well as how the decoder should decode it 2 2 2 Ogg Vorbis There have been forces in the Free Software community to develop a format that should be as least as good as MP3 but it should be free to use in any manner Ogg Vorbis was
10. program normally reads commands interactively when run you must cause it when started running for such interactive use in the most ordinary way to print or display an announcement including an appropriate copyright notice and a notice that there is no warranty or else saying that you provide a warranty and that users may redistribute the program under these conditions and telling the user how to view a copy of this License Exception if the Program itself is interactive but does not normally print such an announcement your work based on the Program is not required to print an announcement These requirements apply to the modified work as a whole If identifiable sections of that work are not derived from the Program and can be reasonably considered independent and separate works in themselves then this License and its terms do not apply to those Sections when you distribute them as separate works But when you distribute the same sections as part of a whole which is a work based on the Program the distribution of the whole must be on the terms of this License whose permissions for other licensees extend to the entire whole and thus to each and every part regardless of who wrote it Thus it is not the intent of this section to claim rights or contest your rights to work written entirely by you rather the intent is to exercise the right to control the distribution of derivative or collective works based on the Program In ad
11. to be that format Ogg Vorbis is a patent and royalty free audio compression format developed by the Xiph org Foundation Since the format is royalty free nobody has to pay anything to use the format or to implement encoders and decoders The Ogg Vorbis format does not specify how to encode an Ogg Vorbis stream The specification only tells how to implement the decoder All streams that can be correctly decoded in such a decoder are to be considered as Ogg Vorbis streams This gives the opportunity to let encoders use any technique to encode the stream In this way the format isn t stuck with a technique if better techniques arise as would be the case with MP3 Decoding an Ogg Vorbis stream is more demanding than MP3 decoding in terms of computing time But at the other hand the Ogg Vorbis format have a lower transparancy The transparancy is a measure of the bit rate needed so that the human ear cannot hear the difference between the decoded signal and the original uncom pressed signal 2 3 Sound quality In this section the methods of measuring sound quality will be dis cussed Focus will be on two measurements that have been chosen since they are the most common 2 3 Sound quality T 2 3 1 SNR Signal to noise ratio The signal to noise ratio is a term of the power ratio between a signal meaningful information and the background noise The SNR is defined as I na SNR Zr Since many signals have a very wide dynamic rang
12. 3 It should include an RDS capable FM tuner 1 6 Topics covered There are seven chapters including this introduction and one ap pendix Main topics dealt with are Chapter 2 Will give some basics about audio coding and sound quality Chapter 3 Presentation of the component selection Chapter 4 Here the hardware design procedure will be presented Chapter 5 Presentation of the software integration Chapter 6 Will give a summary of problems and mishaps during the project Chapter 7 Summary of the project results and suggestions of fu ture work to improve the player Appendix A The full GNU General Public License text Chapter 1 Introduction Chapter 2 Audio coding amp sound quality This chapter covers the basics in audio coding It s not going to be a detailed guide on how to code audio data but rather a short intro duction to different coding techniques This is to have a basic idea of what the device should be doing For a more detailed introduction to audio coding see 1 This chapter will also be a brief introduction to measures of sound quality 2 1 Lossless coding Lossless coding is one principle of audio coding Lossless compres sion algorithms produce compressed data that can be decoded to output that is identical to the original according to 2 Due to the complexity of audio it is hard to get good compression rates using lossless coding For use in audio applications there are a couple of
13. C 4 2 2 SPI Serial peripheral interface SPI is a faster alternative to C using three wires plus chip selects 10 4 2 3 TS Inter IC sound Philips IIS TS I is a special protocol for audio transfers 28 This is supported by both the ColdFire MCF5249 10 and the Wolfson WM8750L 16 and was thus used without much debate Both com ponents also claim support for the Sony EIAJ protocol using the same bus hardware but there is no obvious reason to use the EIAJ protocol instead A design choice to note is that the audio codec was chosen to act as as bus master The audio sample rate timings are then handled by the audio codec rather than the CPU 4 2 4 IEC958 IECO958 is also known as S PDIF and is also an audio transfer pro tocol but is intended for digital transfers to other devices rather than for direct DAC ADC communication like IS This is not used since there is no component that supports this interface IS is used instead 4 2 5 UART Universal asynchronous receiver transmitter The UART protocol is commonly found in the form of RS232 PC COM port Since this hardware was available it was connected to a RS232 physical interface intended for debugging 24 Chapter 4 Hardware design 4 2 6 System bus The ColdFire MCF5249 CPU system bus is a large bus using 16 data pins 23 address pins plus control pins read write R W Output enable OE and chip selects CS It features programmable chip selects wait s
14. DM BGA BSD CODEC CPU DAC DAP DC DSP EEPROM FAT32 FM FSF GCC GDB GNU GPIO GPL GUI HDD PC PS IC IDE IEC IEEE LCD LED Advanced audio coding audio compression standard Analog to digital converter Advanced RISC machine processor family Application specific IC Application specific processor AT Attachment also known as IDE Background debug mode debug protocol Ball grid array chip package Berkeley software distribution software licence Coder decoder Central processing unit Digital to analog converter Digital audio player Direct current Digital signal processor Electronically erasable programmable read only memory File allocation table 32 bit version data storage format Frequency modulation Free software foundation GNU Compiler Collection GNU Project Debugger GNU s not Unix collection of software General purpose input output General public licence software licence Graphical user interface Hard disk drive Inter IC communication protocol Inter IC sound communication protocol Integrated circuit Integrated drive electronics communication protocol International electrotechnical commission standardization group Institute of electrical and electronics engineers inc standardization group Liquid crystal display monitor technology Light emitting diode xiii m68k MCU mil MP3 MPEG NAND NDA PCB PHY PMU QFN QFP RAM RDS RISC RMS RS232 SDK SDRAM SNR SO
15. Development of a low power hand held device in a low budget manner Master thesis in Electronic Systems by Anders Kagerin Michael Karlsson LiTH ISY EX 06 3797 SE Link ping 18 March 2006 Development of a low power hand held device in a low budget manner Master thesis in Electronic Systems by Anders Kagerin Michael Karlsson LiTH ISY EX 06 3797 SE Supervisor Kent Palmkvist Department of Electrical Engineering Link pings Universitet Examiner Kent Palmkvist Department of Electrical Engineering Link pings Universitet Link ping 18 March 2006 Datum Sa inu Avdelning Institution Date 5 LJ KA Division Department A A 2 Institutionen f r Systemteknik 18 March 2006 Nos uns 581 83 LINKOPING LINK PINGS UNIVERSITET SWEDEN Spr k Rapporttyp ISBN Language Report category SOME I ISRN Svenska Swedish Licentiatavhandling I X Engelska English X Examensarbete LiTH ISY EX 06 3797 SE C uppsats Serietitel och serienummer D uppsats Title of series numbering vrig rapport URL till elektronisk version URL to electronic version http www es isy liu se http www diva portal org liu Development of a low power hand held device in a low budget manner 1tle F rfattare Anders Kagerin Michael Karlsson Author Sammanfattning Abstract xi i The market o
16. General Public License instead You can apply it to your programs too When we speak of free software we are referring to freedom not price Our General Public Licenses are designed to make sure that you have the freedom to distribute copies of free software and charge for this service if you wish that you receive source code or can get it if you want it that you can change the software or use pieces of it in new free programs and that you know you can do these things To protect your rights we need to make restrictions that forbid anyone to deny you these rights or to ask you to surrender the rights These restrictions translate to certain responsibilities for you if you distribute copies of the software or if you modify it For example if you distribute copies of such a program whether gratis or for a fee you must give the recipients all the rights that you have You must make sure that they too receive or can get the Kagerin Karlsson 2006 47 48 Appendix A GNU General Public License Source code And you must show them these terms so they know their rights We protect your rights with two steps 1 copyright the software and 2 offer you this license which gives you legal permission to copy distribute and or modify the software Also for each author s protection and ours we want to make certain that everyone understands that there is no warranty for this free software If the software is modified by some
17. RS AND OR OTHER PARTIES PROVIDE THE PROGRAM AS IS WITHOUT WARRANTY OF ANY KIND EITHER EXPRESSED OR IMPLIED INCLUDING BUT NOT LIMITED TO THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU SHOULD THE PROGRAM PROVE DEFECTIVE YOU ASSUME THE COST OF ALL NECESSARY SERVICING REPAIR OR CORRECTION 12 IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING WILL ANY COPYRIGHT HOLDER OR ANY OTHER PARTY WHO MAY MODIFY AND OR REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE BE LIABLE TO YOU FOR DAMAGES INCLUDING ANY GENERAL SPECIAL INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE PROGRAM INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES END OF TERMS AND CONDITIONS 565 UN x Ro 2 LINK PING UNIVERSITY IK ELECTRONIC PRESS 5 S gt Nas y 2 13 19 L 37 HN LINK PINGS UNIVERSITET Copyright The publishers will keep this document online on the Internet or its possible replacement for a period of 25 years from the date of publication barring exceptional circumstances The online avail ability of the document implies a permanent permission for anyon
18. SoC SPI SRAM TFT THD UART USB Motorola 68000 processor family Micro controller unit Mili inch 1000th of an inch MPEG I Layer 3 audio compression standard Motion picture encoding group Not and logical operations Non disclosure agreement Printed circuit board Physical layer Power management unit Quad footprint no lead chip package Quad footprint chip package Random access memory Radio data system data protocol for radio Reduced instruction set computer processor category Root mean square mathematical formulae Recommended standard 232 communication protocol Software development kit Synchronous dynamic RAM Signal to noise ratio Small outline chip package System on chip Serial peripheral interface communication protocol Static RAM Thin film transistor monitor technology Total harmonic distortion Universal asynchronous receiver transmitter communication protocol Universal serial bus communication protocol xiv Contents 1 Introduction 11 Background 12 Purpose 13 Realisation 1 4 Limitation 1 5 Requirements 1 6 Topics covered 2 Audio coding amp sound quality 2 1 Lossless coding 2244 Keiner eier heilen 22 Lossy coding aes ee a 2 2 1 MP3 MPEG 1Layer3 222 Ogg Vorbis nase xx RR RES 2 3 Sound quality Ji eas ee ht ee baue 84 2 3 1 SNR Signal to noise ratio 2 3 2 THD Total Harmonic Distort
19. The development tools used for this project consisted of a set of GPL d software After that flash cannot be accessed without disabling IDE 34 Chapter 5 Software 5 2 1 GCC Binutils The GNU Compiler Collection GCC includes front ends for C C Objective C Fortran Java and Ada as well as libraries for these languages The GCC compiler generates assembler code from a high level language source code Since assembler code cannot be executed directly on the target processor it needs to be assembled into a processor specific binary code Binutils is a set of tools to make binary executables It contains the assembler to generate the binary code that can be run on the target processor To have support for the m68k architecture and the ColdFire MCF5249 these tools had to be compiled with m68k support This was fairly easy and worked as described in the installation instruc tions on the Rockbox web page 9 Both GCC and Binutils is part of the GNU Project and can be downloaded from the GNU Project web site 30 5 2 2 GDB Debugging software can be a very time consuming and nerve wreck ing ordeal To be able to debug a complex program such as a full firmware one must have some kind of tool This is where the GNU Project Debugger GDB comes in handy GDB is a debugging tool that lets the user load their program and enter breakpoints examine memory contents single step the program and many more features The GDB uti
20. Vorbis 168 kbps 532 mW Table 7 1 Power consumption meassurements 7 2 Future work There are a number of possible improvements to be done in the future In this section some of the possible improvements are pre sented 7 2 1 Hardware Improvements of the hardware is mainly concentrated to PCB size and power consumption Low power SDRAM Since Micron did not send the low power SDRAM that was prefered it was necessary to use an ordinary SDRAM to get the hardware working This is far from optimal from a power consumption point of view Once the low power SDRAM arrives it can replace the current one on the PCB This will make the player run at significantly less power consumption Power supplies Significantly more than halfway through the project Texas Instru ments released a power management unit similar to the one made by Philips mentioned in section 3 7 This should be a suitable re placement for some of the ICs used and would have saved space on the PCB 7 2 Future work 43 PCB size The main thing to improve is the PCB Currently the PCB is quite large due to a number of reasons e A two layer PCB were used e Full sized electromechanical components IDE connector BDM connector were used e Extra debugging functionality RS232 were added to the PCB e The PCB have other superfluous components as well By removing the debugging connectors and the superfluous com ponents the PCB size can be re
21. an flash even though there is a need for a tiny boot flash memory Hence a HDD was chosen for storage and a small flash memory as boot memory 3 4 2 RAM When using a HDD as storage media the HDD should not have to be powered on at all times Therefore some kind of RAM to buffer the files to allow the HDD to spin down is needed To get high performance the software should run from a high speed memory such as RAM rather than from flash According to the MCF5249 data sheet 10 the internal RAM of the processor is no greater than a total of 96 kB This is far less than enough for this application especially when using a HDD SRAMs are expensive in large sizes and since the MCF5249 have a built in SDRAM controller it would be intuitive to use a cheaper SDRAM The MT48LC8M16A2 2 Meg x 16 x 4 banks module from Mi cron was selected since the Philips retailer that contact already was established with also was a Micron retailer and provided free samples 3 5 FM tuner Currently there are just two decent FM tuners with RDS capability available at the market The TEA5764 from Philips Semiconductors and the Si4701 from Silicon Laboratories 19 However the Si4701 is covered by a NDA that is not compatible with the use of open source software Hence the Philips tuner TEA5764 was to be used 18 Chapter 3 Component selection 3 6 Display Sound is not everything The player must have some sort of graph ical user interface GUI
22. d this License would be to refrain entirely from distribution of the Program If any portion of this section is held invalid or unenforceable under any particular circumstance the balance of the section is intended to apply and the section as a whole is intended to apply in other circumstances It is not the purpose of this section to induce you to infringe any patents or other property right claims or to contest validity of any such claims this section has the sole purpose of protecting the integrity of the free software distribution system which is implemented by public license practices Many people have made generous contributions to the wide range of software distributed through that system in reliance on consistent application of that system it is up to the author donor to decide if he or she is willing to distribute software through any other system and a licensee cannot impose that choice This section is intended to make thoroughly clear what is believed to be a consequence of the rest of this License 8 If the distribution and or use of the Program is restricted in certain countries either by patents or by copyrighted interfaces the original copyright holder who places the Program under this License may add an explicit geographical distribution limitation excluding those countries so that distribution is permitted only in or among countries not thus excluded In such case this License incorporates the limitation as if written
23. dition mere aggregation of another work not based on the Program with the Program or with a work based on the Program on a volume of a storage or distribution medium does not bring the other work under the scope of this License 3 You may copy and distribute the Program or a work based on it under Section 2 in object code or executable form under the terms of Sections 1 and 2 above provided that you also do one of the following a Accompany it with the complete corresponding machine readable Source code which must be distributed under the terms of Sections 1 and 2 above on a medium customarily used for software interchange or b Accompany it with a written offer valid for at least three years to give any third party for a charge no more than your 50 Appendix A GNU General Public License cost of physically performing source distribution a complete machine readable copy of the corresponding source code to be distributed under the terms of Sections 1 and 2 above on a medium customarily used for software interchange or c Accompany it with the information you received as to the offer to distribute corresponding source code This alternative is allowed only for noncommercial distribution and only if you received the program in object code or executable form with such an offer in accord with Subsection b above The source code for a work means the preferred form of the work for making modifications to it For an executab
24. duced by a fair amount Using a four layer PCB will decrease the PCB size even more since a higher component density is achievable when signals can be routed on the inner layers of the PCB 7 2 2 Software There is still som unimplemented features in the software such as a driver for the radio tuner and recording feature in the WM8750L driver Also the battery charger control is not implemented Sup port for the USB mode is implemented but is untested Other things to do includes improvements of the GUI and much optimization of the software codecs Optimization of the codecs will reduce power consumption even more since it will allow for the processor to run in a lower frequency for greater periods of time For instance decoupling capacitors that might be unnecessary 44 Chapter 7 Results and future work Bibliography CO 00 N CO 10 11 12 13 14 15 Bosi M et al Introduction to digital audio coding and standards 2005 Dordrecht Xiph org Foundation http www xiph org September 2005 L wenborg P Mixed Signal Processing Systems Second edition 2006 Link ping Royal Philips Semiconductors http www semiconductors philips com September 2005 PortalPlayer Inc http www portalplayer com September 2005 SigmaTel Inc http www sigmatel com September 2005 SigmaTel Inc Product Data Sheet STMP35xx 2004 Freescale Inc http www freescale com September 2005 R
25. e SNR is usu ally expressed in terms of the logarithmic decibel scale Pa na Asi na SNR dB 1010g 0 Z 2010g 0 Aem noise noise P is average power and A is RMS amplitude Important to note is that signal and noise power are measured only within the system bandwidth SNR measures the ratio between noise and an arbitrary signal on the channel not necessarily the most powerful signal possible Hence measuring SNR requires the selection of a representative signal SNR is usually taken to indicate an average signal to noise ra tio It is possible that instantaneous SNR values are considerably different Higher signal to noise is better i e cleaner sound For more information about the SNR measurement see 3 2 3 2 THD Total Harmonic Distortion The defining properties of any linear and time invariant system are of course linearity and time invariance e Linearity means that the relationship between the input and the output of the system satisfies the scaling and superposition properties e Time invariance means that whether an input is applied to the system now or t seconds from now the output will be iden tical except a time delay of that t seconds In most cases the ideal transfer function is linear and time invariant However the real life system is not ideal Whenever the signal passes through the non linear system additional content is added at the harmonics of the original frequencies The total harmonic
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27. e as a data buffer in hard disk based players 16 Chapter 3 Component selection requirements the hard disk drive option requires a more advanced power management 100 00 4 Flash 10 00 1 00 4 Hard disk 0 10 4 0 01 T T T gt 1995 2000 2005 Figure 3 2 Price MB trends 18 1 000 000 4 100 000 10 000 Flash 1 000 100 Hard disk 10 4 256MB 4GB 64GB TB Figure 3 3 Total system costs as a function of total storage space 18 As seen in figure 3 2 HDDs have always been much cheaper per megabyte than flash based memories and they still are It is clear from the chart in figure 3 3 that HDDs have a floor price Small capacity flash memories are cheap the cross over appear at approx imately 256 MB Since the MP3 players of today usually have at least 512 MB or 1GB of storage space everything less than this would be unacceptable 3 5 FM tuner 17 Since the processor has no support of booting directly of aHDD it needs some kind of boot memory preferably a flash memory for the ability to upgrade the bootloader It then seems like there are two possible solutions to the storage space issue either one large flash memory or a HDD for storage space with a tiny flash based boot memory Conclusion HDDs have the benefit of being much more cost effective than flash memories Since at least 1 GB of storage space is wanted HDDs will be cheaper th
28. e is reached at the battery After that the voltage is kept constant until the charging current reaches about 6 7 percent of the initial current 3 9 Bluetooth AirLogic Co Ltd 23 is a manufacturer of bluetooth devices They have a couple of interesting bluetooth ICs A try to establish contact with their sales office was done but resulted in no response Due to this it was decided to go without bluetooth since bluetooth connectivity was not a requirement and since too little time for the implementation of this feature was available 20 Chapter 3 Component selection Chapter 4 Hardware design In this chapter steps taken in the hardware design process will be de scribed Also an account of the design choices made and the underlying facts will be given 4 1 Component packages When the main components have been selected the task of assem bly begins with the choice of packages Here several factors which affect the choice of package for each component must be taken into account Some of the most important factors when choosing pack ages are availability package type physical size performance and functionality 4 1 1 BGA Ball grid array Many of the components were available in BGA packages These packages are surface mounted small of high performance and usu ally have a lot of pins allowing more functionality The downside with BGA is the assembly requirements BGA packages do not have physical pins but solder
29. er enable Though this would be impossible since the system bus would have to be exclusive to the IDE when active and this is very hard to achieve and almost impossible to guarantee For exam ple a soft reset interrupt or exception could leave this pin active which would cause a bus collide on the first read when booting the system bus is also used when running the firmware since it is stored in SDRAM at runtime These problems may be avoidable by using the internal SRAM for all interrupt amp exception handlers but would require a lot of work fitting the code into the SRAM and making sure no code is executed from SDRAM accidentally Thus the most transparent solution was to add some glue logic in this case an OR gate The gate performs or on buffer enable 1 BUFENI and a GPIO pin that defaults to high at reset the output is used as the new buffer enable At boot this would lock the buffer enable high disabling the buffer and when the GPIO is driven low the buffer would follow buffer enable 1 BUF ENT This only poses one restriction even if buffer enable 1 BUFEN1 is configured to follow the IDE signals it always follows chip select 0 C SO Thus the flash must not be read when the IDE buffer is active since that would cause a bus collision This is not a severe problem since the flash is only used at boot uploading all executable code to SDRAM before starting IDE transfers 26 Chapter 4 Hardware design 4 2 7 BDM Backg
30. ers Physical size primarily depends on the routing and component requirements To reduce board size components can be mounted on both sides of a PCB as well as using multiple layers to reduce routing space Minimum trace and drilling sizes also have an influence on board size but are more important when fulfilling component requirements Minimum trace size defines the smallest signal separation and width this must be small enough to fit the smallest pin pitch needed A small trace width can be benficial when minimizing board size but most benefit is gained from the simplified routing process This makes a small trace width a sought after feature Drill size has similar properties to trace width usually minimum drill sizes are far smaller than hole mounted component requirements but they are still relatively large in comparison to trace widths This com plicates routing since drill holes are used for vias Depending on number of layers and component layout vias can quickly amount large quantities of drill holes increasing cost and board size Using multiple layers can decrease board size lessen routing ef fort and provide better electrical properties 2 layer PCBs are a nessecity when designing for almost anything but the simplest cir cuits They also allow for components to be placed on the bottom side of the board 4 and 6 layer PCBs are also available and are a very interesting alternative to 2 layer but come at increasing costs As d
31. f portable digital audio players DAPs have literally exploded the last couple of years Other markets has grown as well PDAs GPS receivers mobile phones and so on This resulted in more advanced ICs and SoCs becoming publically available eliminating the need for in house ASICs thus enableing smaller actors to enter the markets This thesis explores the possibilities of developing a low power hand held device on a very limited budget and strict time scale This thesis report also covers all the steps taken in the development procedure Nyckelord Keyword Embedded Hand held Device Codec Decoder MP3 Ogg WMA FLAC Develop ment Hardware Software Abstract The market of portable digital audio players DAPs have literally exploded the last couple of years Other markets has grown as well PDAs GPS receivers mobile phones and so on This resulted in more advanced ICs and SoCs becoming publically available elimi nating the need for in house ASICs thus enableing smaller actors to enter the markets This thesis explores the possibilities of developing a low power hand held device on a very limited budget and strict time scale This thesis report also covers all the steps taken in the develop ment procedure Keywords Embedded Hand held Device Codec Decoder MP3 Ogg WMA FLAC Development Hardware Software Kagerin Karlsson 2006 vii viii Acknowledgements We would like to thank our supervisor a
32. g the Program is not restricted and the output from the Program is covered only if its contents constitute a work based on the Program independent of having been made by running the Program Whether that is true depends on what the Program does 1 You may copy and distribute verbatim copies of the Program s Source code as you receive it in any medium provided that you conspicuously and appropriately publish on each copy an appropriate copyright notice and disclaimer of warranty keep intact all the notices that refer to this License and to the absence of any warranty and give any other recipients of the Program a copy of this License along with the Program You may charge a fee for the physical act of transferring a copy and you may at your option offer warranty protection in exchange for a fee 49 2 You may modify your copy or copies of the Program or any portion of it thus forming a work based on the Program and copy and distribute such modifications or work under the terms of Section 1 above provided that you also meet all of these conditions a You must cause the modified files to carry prominent notices stating that you changed the files and the date of any change b You must cause any work that you distribute or publish that in whole or in part contains or is derived from the Program or any part thereof to be licensed as a whole at no charge to all third parties under the terms of this License c If the modified
33. ground debug mode 26 4 2 8 GPIO General purpose input output 26 4 3 Peripheral components 26 4 3 1 Passive components ss 26 4 3 2 Active components 445 4 eh coe oe 4 27 4 3 3 Electro mechanical components 27 4A iim pu prep qm 27 4 4 1 Cost vs Functionality 28 44 2 PCB manufacturers iii 28 44 3 Conclusion 242 24 pesa o dus 29 5 Software 31 och EE ur a ae deh 31 SLL OCHO a s a s e s s oe Ah oe de 32 51 2 Bootloader xu zes da s suy re ROG A 33 5 2 Development environment 33 5 221 GCC amp Binutils 54a bx Ye X 34 5 22 GDB eio bu oe over rue 34 5 2 3 BDM sofiware _ a 34 Contents 6 Problems and mishaps 37 6 1 Manufacturers 2 2 2 oo oo 37 62 Development iui RS malet A 39 7 Results and future work 41 7 1 Resulis u o n 41 7 1 1 Power consumption capa 85 4 41 7 2 Future work on 42 7 2 1 Hardware ss 42 1 2 2 SoftWare se i dox doo e b Ue xx e vg 43 A GNU General Public License 47 xviii Contents Chapter 1 Introduction This text is written as a master of science final thesis at Linkopings Uni versitet by Anders Kagerin and Michael Karlsson with Kent Palmkvist as supervisor and examiner The document is written in IATEX in 2006 In this first chapter some background about embedded systems SoCs and their availability will be given Also some main questions this pro
34. he system and is therefore generally refered to as firmware The solution chosen for this project as described in chapter 3 1 was to use a MCU and implement needed functionality in software This software would have implemented a lot of features some of which are e User interface e Audio encoding amp decoding e File management e Power management e Peripheral control Hard disk drive TFT LCD monitor Audio codec Radio tuner Kagerin Karlsson 2006 31 32 Chapter 5 Software USB interface Push button interface Battery monitor amp charger Implementing all this functionality would be too time consuming so it was decided that existing software should be used as much as possible When using existing software care has to be taken due to copyright and licensing limitations Although there are licenses that allow for relatively unhindered use The most notable sources of software are the growing commu nities of users and developers working on free and open source software These communities develop software for almost all pur poses and provide the source code through licences such as GPL or BSD licenses 5 1 1 Rockbox Since there was an existing free firmware known as Rockbox See Software section in chapter 3 1 4 already ported to the MCF5249 MCU this was a perfect choice Rockbox consists of an operating system and an application layer The operating system layer implements a cooperative multithreding ker
35. heir respective services AirLogic Co Ltd AirLogic Co Ltd 23 did not respond to e mail inquiries This is also mentioned in Chapter 3 9 The reason for this is unknown and it was not followed up later due to loss of interest in their product offering Silicon Laboratories Inc SiLabs 19 had very appealing products but unfortunately they re quired a NDA to be signed see chapter 3 5 This is problematic since an NDA will conflict with the requirements of the GNU GPL software license thus prohibit distribution of any software source or binary Kagerin Karlsson 2006 3T 38 Chapter 6 Problems and mishaps SigmaTel Inc SigmaTel 6 was originally a target of interest due to their D Major chipset See chapter 3 1 3 but it was clarified that their SDK costs 12 000 and that they do not support third party SDKs This pro hibited further development for this chipset Royal Philips Semiconductors Philips Semiconductors 4 has a wide range of high quality prod ucts one of these being a PMU Unfortunately this PMU is factory configured and thus Philips requires a minimum order of 500 000 pieces This is far too many for the PMU to be a viable option in this project Philips also provided a FM radio chip This chip was acquired uneventfully but problems were encountered when acquiring the spe cial varicap diodes that were specified as peripheral requirements These were not possible to acquire from normal supplier
36. high impedance thus enabling it to share the IDE data bus with a processor or micro controller For more information about the AT2LP chip see the datasheet 13 3 2 4 Conclusion The FTDI chips are easy to use but since they do not support USB Mass Storage Class they cannot be used in this design 14 Chapter 3 Component selection Both the ISP1582 from Philips and the AT2LP from Cypress can be used both chips support USB 2 0 high speed and full speed The ISP1582 does not directly support USB Mass Storage Class but since it fully complies with USB 2 0 the Mass Storage Class can be implemented in software however since the AT2LP already supports Mass Storage Class this will be the chip of choice This allows development to be concentrated on other tasks since there is no need to implement the Mass Storage Class 3 3 Audio codec Since the chosen processor does not offer an on chip audio codec there is a need for an external codec One of the most important things to consider not to say the most important thing when choosing a codec is sound quality However some tradeoffs may be done for example in a portable device the power consumption is an important factor One other important thing is the interface The ColdFire sup ports different standards for audio interfacing so this should not be a problem 3 3 1 Wolfson WM8750L Wolfson Microelectronics plc is a United Kingdom based man ufacturer known for its high qualit
37. ilips UDA1380 The Philips UDA1380 codec is commonly used in many MP3 players on the market 9 The datasheet 17 states values for the SNR and THD of the codec these are almost identical to the values of the WMS750L codec According to the datasheet the minimum power consumption during playback is a little more than 10 mW The supply voltage must be in the range 2 4 3 6 volts 3 3 3 Conclusion The Wolfson WMS750L will be the codec of choice The WM8750L was able to generate all common sample rates from USB clock rates This allows the use of only one external clock circuit since the codec and CPU then can be run at the same frequencies as the USB chip 3 4 External memory There will always be a need for an external memory in these types of applications Sometimes there is only need for some storage space sometimes there might be need of some kind of extra RAM 3 4 1 File storage The file storage media needs to be large in terms of storage space since the device should be able to store a lot of music There are basically three different options available memory card flash mem ory or a hard disk drive As a matter of fact memory cards are flash based so it should be enough to compare general flash memories to HDDs The memory card and flash memory options are still limited in storage size The hard disk drive option allows for much greater storage space but instead it requires more power Due to the power 6For exampl
38. in the body of this License 9 The Free Software Foundation may publish revised and or new versions of the General Public License from time to time Such new versions will be similar in spirit to the present version but may differ in detail to address new problems or concerns Each version is given a distinguishing version number If the Program Specifies a version number of this License which applies to it and any later version you have the option of following the terms and conditions either of that version or of any later version published by the Free Software Foundation If the Program does not specify a version number of this License you may choose any version ever published by the Free Software Foundation 10 If you wish to incorporate parts of the Program into other free programs whose distribution conditions are different write to the author 52 Appendix A GNU General Public License to ask for permission For software which is copyrighted by the Free Software Foundation write to the Free Software Foundation we sometimes make exceptions for this Dur decision will be guided by the two goals of preserving the free status of all derivatives of our free software and of promoting the sharing and reuse of software generally NO WARRANTY 11 BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE THERE IS NO WARRANTY FOR THE PROGRAM TO THE EXTENT PERMITTED BY APPLICABLE LAW EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDE
39. ion 3 Component selection 3 1 Audio processor 2 0 0 0 ee ee 3 1 1 Philips Nexperia e eses es 3 1 2 PortalPlayer uuu 2 422584 I 3 1 3 SigmaTel D Major STMP35xx 3 1 4 Freescale ColdFire MCF5249 3 1 5 Conclusion eo se ses rss rss ss 4 3 2 USB interface yor 8 21 FTDI Chip FT245R amp FT232R 244 244 3 2 2 Philips ISP1582 3 23 224 232 Y oh Ka 3 23 Cypress EZ USB AT2LP 3 2 4 Conclusion siriani 3 3 Audio codec asia LAN A 3 3 1 Wolfson WM8750L 3 3 2 Philips UDA1380 Kagerin Karlsson 2006 XV xvi Contents 3 3 3 Conclusion 2 Lue susanne 15 3 4 External memory 2 52253 E ex an ed 15 3 4 1 Pile storage oir ie e Rom Ro Rowe 15 342 TAM i a A ren 17 35 FM tuner ow gas oS a Eee a e 17 3 6 Display som ee ere Q qas e Le a 18 3 7 Power supplieS oo isa rss en ow 18 3 8 Battery charger 2 22224 rs s 19 3 9 Bluetooth Loa om lid Ra A 19 4 Hardware design 21 4 1 Component packages o 21 4 1 1 BGA Ball grid array ok x siste 21 4 1 2 QFP amp SO Quad footprint amp Small outline 22 4 1 3 QFN Quad footprint no lead 22 4 1 4 Conclusi n soe say pene 22 4 2 Interconnections _ md ko ei 22 4 2 1 PC nemi ops ratas bas ds 22 4 2 2 SPI Serial peripheral interface 23 4 2 3 PPS Inter IC sound sra ra 20 424 ECOS Lo moe 4 AE 23 A MW RE eee et 23 4 2 6 System bus ium ira 24 4 2 7 BDM Back
40. is power can be disabled for all other circuits when the player is in an off state and still react to events on the power button 4 3 3 Electro mechanical components Some components are needed for physical properties as well as elec trical mainly push buttons and connectors Push buttons are used for user interaction power play stop etc connectors are plenti ful and come in many forms power RS232 USB stereo plug IDE BDM etc 4 4 PCB design Selecting a PCB for the mounting of the components was a straight forward decision The only viable alternative to PCBs are pro totyping boards and those are mostly intended for hole mounted components Even though there are surface mount capable proto typing boards finding one capable of mounting the many different footprints needed seemed impossible The majority of components chosen for this design were not available as hole mounted rendering these boards useless for this project There are cutting edge tech nologies that provide alternatives to PCBs such as using conductive weave for fabric boards 25 and conductive ink 24 none of these are practical for this project or readily available 28 Chapter 4 Hardware design 4 4 1 Cost vs Functionality Even if all PCBs are based on the same manufacturing technology they are very configurable Functionality and cost wise the most interesting parameters are board size minimum trace drilling sizes and number of lay
41. iscussed in chapter 4 1 4 Component packages conclusion the use of BGA packages was omitted largely based on the difficulty of mounting them thus using more than 2 layers was not mandatory 4 4 2 PCB manufacturers There are several PCB manufacturers available from these Beta LAYOUT Ltd was selected because of their low costs and high performance PCB boards Their website 26 specifies their technol ogy limits to 6mil 0 15mm minimum trace gap width and mini mum drill size to 12mil 0 3mm This satisfies the estimated trace 5Vias are used to route a signal from one layer to another 6Also known as double sided PCBs 7On a single layer PCB signals can not cross paths without extra components using two layers theoretically allows arbitrary routing though trace drilling sizes provide a natural limit 4 4 PCB design 29 width minimum of 8mil 0 2mm and provides drill sizes that are far smaller than required 4 4 3 Conclusion To reach a conclusion the pricing of PCB layers according to table 4 1 were studied As can be seen the price increases steeply from 2 to 4 layers thus making 4 layer PCBs rather expensive though the decrease in size that results from an increase of layers must be taken into account A decrease in size of 5096 seems very unlikely Thus the pricing can still be considered to be over 100 making the price difference noticeable After much thought a 2 layer PCB was selected due to pricing and the
42. ject seeks to answer will be formulated and topics covered will be described 1 1 Background The use of digital audio and its distributions over the Internet have become more and more common the last years This have made the market of portable digital audio players DAPs literally explode Other markets has grown as well PDAs GPS receivers mo bile phones and so on This resulted in more advanced ICs and SoCs becoming publically available eliminating the need for in house ASICs thus enableing smaller actors to enter the markets However the development effort can still be very large even through the use of highly integrated systems Many design fea tures need to be decided upon and many development tasks are time exhausting 1 2 Purpose Considering the availability of ICs and SoCs would it be possible to develop a small low power hand held device on a very limited budget and time scale The purpose of this thesis is to try to develop an embedded sys tem on a low budget and in that way evaluate the possibillities of Kagerin Karlsson 2006 1 2 Chapter 1 Introduction doing so on a low budget and a very limited time scale Different kinds of problems may occur while developing such a system because of the low budget These problems has to be con sidered too Things as power consumption power management and energy saving needs to be considered during the development as well Is it possible to get a fully func
43. le work complete source code means all the source code for all modules it contains plus any associated interface definition files plus the scripts used to control compilation and installation of the executable However as a Special exception the source code distributed need not include anything that is normally distributed in either source or binary form with the major components compiler kernel and so on of the operating system on which the executable runs unless that component itself accompanies the executable If distribution of executable or object code is made by offering access to copy from a designated place then offering equivalent access to copy the source code from the same place counts as distribution of the source code even though third parties are not compelled to copy the source along with the object code 4 You may not copy modify sublicense or distribute the Program except as expressly provided under this License Any attempt otherwise to copy modify sublicense or distribute the Program is void and will automatically terminate your rights under this License However parties who have received copies or rights from you under this License will not have their licenses terminated so long as such parties remain in full compliance 5 You are not required to accept this License since you have not signed it However nothing else grants you permission to modify or distribute the Program or its derivative works The
44. lity is a part of the GNU Project and can be down loaded from the project web site 30 5 2 3 BDM software The BDM has been mentioned earlier in section 4 2 7 To be able to use all the features of the BDM interface some software was needed There are a set of proprietary software for this purpose but there also is a set of tools that indeed is free software This set of tools included a utility to flash the boot memory through the processor and more important it included a device driver making GDB working over the BDM protocol The install procedure of this toolset was not as easy as it seamed at first However lots of help was given from one of the leading developers in the Rockbox development team Also a set of useful 5 2 Development environment 35 scripts were retrieved from him that helped setting up the debugging environment The set of BDM tools is available from SourceForge 31 36 Chapter 5 Software Chapter 6 Problems and mishaps This chapter will briefly give an account of the problems and mishaps experienced during the project 6 1 Manufacturers Problems encountered with manufacturers were not that many most manufacturers were very professional and accommodating though unfortunately there were some mishaps It must be made clear that tough the following text may reflect negatively upon the manufac turers at hand these were isolated experiences and do not represent a comprehensive review of t
45. ly no severe problems were encountered Components Some issues with hardware was encountered in a late stage of de velopment The Wolfson WM8750L codec and ColdFire MCF5249L had some compatibility problems due to clock speeds and protocol configurations over I S see chapter 5 1 1 This was solved by finding the correct configuration parameters through careful reading of the datasheets and using the trial amp error methodology Other issues with components were difficulties during soldering The ColdFire MCU s pins were very easily bent even when nudging the chip into place on the PCB The Wolfson codec was very difficult to solder due to it s very small size and the pin design of the QFN package The QFN packages required a very sharp soldering tip which are inherently harder to solder with and the leadless pins inhibit the solder to flow out and make a good connection with the PCB This was overcome with perseverance and the use of various tools such as a microscope PCB layout As mentioned in chapter 4 4 3 the design choice to use a 2 layer PCB is in hind sight not the best when dealing with routing re quirements of this complexity Routing the large system bus to the many components using it proved time consuming and required some elaborate solutions rarely being electrically optimal Using a 4 layer PCB would have been more time efficient but would have been more expensive so this is still not a clear cut choice The routing
46. nd examiner Kent Palmkvist and all the staff at ISY for all the help and support they have pro vided We would also like to thank our families and our friends who have proof read this thesis Finally we would like to thank all the Rockbox developers espe cially Linus Feltzing Nielsen for all the help on getting the develop ment environment working Last but not least we want to pay our tribute to the open source community Kagerin Karlsson 2006 ix Nomenclature Most of the reoccurring abbreviations and symbols are described here Notation In this thesis kilobytes kB means 1024 bytes megabytes MB means 1024 1024 bytes and so on Signals are written as SIG or should the signal be used as active low SIG Symbols Js Sample frequency fak CPU frequency fous System bus frequency Via Vee Supply voltages Terminology Active low The associated function is performed when it is logical 0 Bootloader A program that loads and executes the operating system Codec In the context of hardware refers to CODEC for digital analog conversion In the context of software refers to a program that encode or decode compressed audio data Driver A collection of routines for hardware control and abstraction Firmware Software in embedded systems Operating system The main software that handles hardware and programs Kagerin Karlsson 2006 xi xii Abbreviations AAC ADC ARM ASIC ASIP ATA B
47. nel with message passing ability drivers for hardware and dy namic CPU frequency control The application layer implements functionality that does not directly depend on hardware implemen tation only on the functionality it presents Applications may for example be a GUI or audio encoding decoding From studying the Rockbox source it was concluded that the iRiver H100 was the most similar target to this projects hardware design though many modifications were still needed GPIO configuration and pin mapping Even though there are large similarities between the system designed and the Rockbox target almost no GPIO pins were used for the same purpose This meant all usage of GPIO pins had to be modified to match this project s design Wolfson WM8750L Since no Rockbox target utilized a Wolfson WM8750L compatible IC a driver had to be written from scratch This driver handles 1As defined by FSF Free as in speech not beer often referred to as open source 5 2 Development environment 33 configuration power management and runtime operation of the IC Changes were also made in the code outside of the driver like PC amp TS setup on the MCF5249 and extended feature support A lot of issues were experienced with the hardware during devel opment the most notable was getting S communication to work properly This was finally solved using oscilloscope probing and con figuration experimentation The conclusion from this i
48. ng volume was about half a million pieces Since no other comparable PMU was available on the market at the time it was dicided to use separate DC DC converters for the different required supply voltages The DC DC converters chosen were TPS62005 TPS61031 and TPS61061 all from Texas Instru ments They were chosen mainly because of their availability they were all available as free samples from Texas Instruments web page 22 and because they have the right properties One major concern for the TPS61031 was to make sure it was capable of delivering enough current to power the HDD during spin up The TPS61031 is capable of delivering up to 1A at 3 3V so there is no problem driving the HDD at any time 3 8 Battery charger 19 For more detailed information about these ICs see the Texas Instruments web site 22 3 8 Battery charger There are many battery charger ICs available on the market most of them do not differ much from each other Where they differ is mainly on how the charging monitoring works temperature moni toring and so on They may also differ in what battery types they are capable of charging The BQ24023 from Texas Instruments is a simple lithium poly mer battery charger with no temperature monitoring This was chosen because it was one of the most basic chargers available and the current leakage in its off state was almost none The charging sequence used is to apply a constant current until the charged voltag
49. not beer often referred to as open Source 12 Chapter 3 Component selection 14mm QFP 10 mm BGA 10 mm 14 mm Figure 3 1 Physical size differences between BGA and QFP packages also claim that they have a multi codec architecture supporting de coding of among others MP3 Ogg Vorbis and FLAC It is also stated that the Rockbox firmware have a simple thread handler and fully functional memory management This should be a solid code base to get started from With this solution no codecs need to be implemented nor any existing ported Thus the software coding part will consist more of device driver programming for the choosen peripheral devices The ColdFire MCF5249 pros and cons are summarized in table 3 2 Pros Cons Good support from manufacturer Needs many external components Existing open source software Good interfacing possibilities Easy to receive sample chips Table 3 2 ColdFire MCF5249 pros and cons 3 1 5 Conclusion The SigmaTel chip offers small designs because of the integrated components such as USB 2 0 PHY and power management units However their SDK fee of 12 000 makes it impossible to use their chip in a low budget design The most lucrative option seems to be the ColdFire MCF5249 microcontroller from Freescale Inc Offering good support fast de liveries of samples and an existing open source DAP firmware even though it is not from Freescale
50. ockbox Project http www rockbox org September 2005 Motorola Freescale Inc MCF5249 ColdFire Integrated Micro processor Users s Manual 2003 Future Technology Devices International Ltd http www ftdichip com September 2005 Royal Philips Semiconductors SP1582 Hi Speed Universal Se rial Bus peripheral controller 2005 Cypress Semiconductor Corp EZ USB AT2LPTM USB 2 0 to ATA ATAPI Bridge 2005 Wikipedia The free encyclopedia http www wikipedia org October 2005 High Quality Low Voltage Audio http www rane com hilovolt htm September 2005 Kagerin Karlsson 2006 45 46 Bibliography 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 3l 32 Wolfson Microelectronics plc WM8750L Stereo CODEC for Portable Audio Applications 2005 Royal Philips Semiconductors UDA1380 Stereo audio coder decoder for MD CD and MP3 2004 Handy J Semico Research Flash Memory vs Hard Disk Drives Which Will Win June 6 2005 Silicon Laboratories http www silabs com September 2005 Tianma Microelectronics Co Ltd Specification for LCD mod ule TM0276ANFWG 2004 Renesas HD66789 528 channel One chip Driver for Amor phous TFT Panels with 262 144 color display RAM Power Supply Circuit and Gate Circuit 2003 Texas Instruments http www ti com October 2005 AirLogic Co Ltd http www airlogic co kr October 2005 Conductive Circui
51. one else and passed on we want its recipients to know that what they have is not the original so that any problems introduced by others will not reflect on the original authors reputations Finally any free program is threatened constantly by software patents We wish to avoid the danger that redistributors of a free program will individually obtain patent licenses in effect making the program proprietary To prevent this we have made it clear that any patent must be licensed for everyone s free use or not licensed at all The precise terms and conditions for copying distribution and modification follow GNU GENERAL PUBLIC LICENSE TERMS AND CONDITIONS FOR COPYING DISTRIBUTION AND MODIFICATION 0 This License applies to any program or other work which contains a notice placed by the copyright holder saying it may be distributed under the terms of this General Public License The Program below refers to any such program or work and a work based on the Program means either the Program or any derivative work under copyright law that is to say a work containing the Program or a portion of it either verbatim or with modifications and or translated into another language Hereinafter translation is included without limitation in the term modification Each licensee is addressed as you Activities other than copying distribution and modification are not covered by this License they are outside its scope The act of runnin
52. owing up and chip manufactures that did not reply to requests However it have been proven that it is indeed possible for just two persons to develop a complete working DAP in just 20 weeks and on a very limited budget The player is capable of playing a number of audio formats Ogg Vorbis and MP3 beeing two of them Open source software is the key to the success It saved a lot of time since it was not necessary to develop an firmware from scratch even though many task were to be done to get a functional firmware 7 1 1 Power consumption The power consumption of the resulting player was measured for some different music files Ogg Vorbis and MP3 files in different bit rates In table 7 1 the results from the measurements are summarized According to these figures an approximate battery life of about 16 hours can expected Note that the hard drive power consumption Approximated with a 2000mAh Li pol battery Kagerin Karlsson 2006 41 42 Chapter 7 Results and future work is not taken into account in these figures About 30 less battery life can be expected when taking the hard drive into account There was no disk drive of the right type available so no real measurements could be done Average power consumption for the hard drive were approximated out of figures at the Hitachi web site 32 Format Bit rate Power consumption MP3 128 kbps 486 mW MP3 160 kbps 493 mW Ogg Vorbis 141 kbps 508 mW Ogg
53. pads arranged in grids under the package thus the package cannot be soldered with a sol dering iron This grid also makes routing complex requiring 4 or more layers and very small vias situated between the footprint pads on the PCB These vias often referred to as micro vias are rare and expensive to manufacture 1BGA packaged chips have to be factory mounted or mounted through the use of ovens or other elaborate heating devices Kagerin Karlsson 2006 21 22 Chapter 4 Hardware design 4 1 2 QFP SO Quad footprint amp Small outline QFP and SO packages are available for almost all components and are the most common alternative to BGA when a high pin count is needed The pins are arranged along the sides of the package SO uses two sides and QFP all four making them fairly easy to solder and route depending on the pin spacing pitch These are larger than BGA equivalents and therefore usually are functionality reduced to lessen the number of pins They may also be slower than their BGA counterparts 4 1 3 QFN Quad footprint no lead The QFN package is a blend between BGA and QFP package types QFN packages use solder pads instead of pins but these are arranged along the sides of the package This makes them fairly small and possible to solder using a soldering iron These packages are not as common as QFP and are not avail able with as many pins but are much more compact than QFP equivalents 4 1 4 Conclusion
54. problems were solved by routing long performance undemanding connections using wires soldered to vias This method was also used to modify the board when the change from SPI to PC was definite see chapter 4 2 1 and 4 2 2 1Providing Finagle s law is proven Anything that can go wrong will 40 Chapter 6 Problems and mishaps A true design error was made when placing the connectors for the TFT monitor Even though the positioning was meticulously done the two connectors did not line up with the monitor s This was most likely due to a miscalculation or a simple offset direction mishap which could have been caught by printing out the PCB board layout in real size on paper and visually comparing connections Software Software bugs are probably the most common problems by far Fortunately these are often minor and simple to fix though find ing them can be a daunting task Some of the problems encoun tered were spelling mistakes misconfiguration of hardware or other absent minded blunders Chapter 7 Results and future work This chapter presents the results of this thesis as well as some sugges tions of how to further improve the device 7 1 Results A device that fulfilled all the requirements were implemented How ever the additional goals were not fulfilled because of chips showing up too late and due to the strict timeline Some problems was experienced during the project such as com ponents never sh
55. round debug mode The BDM protocol is intended for debugging but is also used for pro gramming software to the system flash This protocol is very useful for development allowing code to be uploaded to RAM and de bugged during runtime remotely on a PC The Freescale MCF5249 10 allows single stepping breakpoints etc for precise code amp data debugging 4 2 8 GPIO General purpose input output Protocols not supported by the CPU can be implemented in software and use GPIO pins as configurable busses Additional protocols amp busses were not needed since all connected components had dedi cated hardware for these purposes This left GPIO pins for simple input output signals which is their ideal usage There were quite many signals that needed to be connected in this way battery charge control power management USB detection amp bridge control push button inputs and LED outputs to name a few Since GPIO pins often are shared with dedicated logic these pins may exhibit random behaviour after reset This meant short circuits and unwanted activity had to be taken into account until these pins had been configured properly Only a handful of the GPIO pins had defined reset behaviour requiring careful planning of signal assignment 4 3 Peripheral components The component selection process results in a handful of primary components but these are rarely sufficient for a working system Most components require peripheral component
56. s and thus were ordered as samples from Philips itself This was followed by a long delivery time inhibiting incorporation of the FM radio chip Micron Technology Inc Micron is a SDRAM vendor and was requested for samples See chapter 3 4 2 of a low power chip but due to a company reorga nization delivery was severely delayed This forced the search for a temporary alternative and SDRAM chips that were physical and functional equivalents were found Unfortunately these chips were not electrically equivalent specifically they were not low power and will therefore have a negative affect on the power consumption Cypress Semiconductor Corp Cypress was requested for samples of a USB chip see chapter 3 2 3 though their sample arrived too late to be incorporated into the system This functionality was therefore temporarily left out but should be easily included in future development Tianma Microelectronics Co Ltd Tianma is a LCD monitor manufacturer A sample monitor was ac quired See chapter 3 6 from this manufacturer but unfortunately the datasheet 20 was far from complete The only available datasheet 6 2 Development 39 lacked important information and was unclear on electrical proper ties Fortunately a datasheet for the LCD controller IC 21 incor porated into the monitor was available and proved very useful 6 2 Development Developing a product without encountering problems is impossible fortunate
57. s for purposes such as power supply filtering analog signal processing and input sources 4 3 1 Passive components A lot of components are simple resistors capacitors inductors and diodes These are used mostly for power supply filtering but have many other uses such as pull up down on signals to prevent unin tended operation and signal processing voltage dividers filters and 3Short circuits appears when two outputs are driving the same signal to dif ferent levels also a signal not driven may float to invalid voltages causing large current flows at input gates 4Some GPIO output clock signals which are for example not suitable for power management 4 4 PCB design 27 feed back circuitry Diodes are quite useful for voltage regulation and current rectifiers but also for cosmetic and user interface pur poses in the form of LEDs 4 3 2 Active components Often more complex components than passive are needed such as logic gates or discreet devices like transistors Logic gates are useful as glue logic or for simple functionality such as de bouncing push buttons and bistable latches multivibrators Transistors are suit able for controlling power supplies or very simple digital signal op erations In this project a bistable latch is used for power supply on off control and is directly connected to the battery power This latch consists of two cross connected NAND gates with inputs from a power button and CPU Using th
58. se actions are prohibited by law if you do not accept this License Therefore by modifying or distributing the Program or any work based on the Program you indicate your acceptance of this License to do so and all its terms and conditions for copying distributing or modifying the Program or works based on it 6 Each time you redistribute the Program or any work based on the Program the recipient automatically receives a license from the original licensor to copy distribute or modify the Program subject to these terms and conditions You may not impose any further restrictions on the recipients exercise of the rights granted herein You are not responsible for enforcing compliance by third parties to this License 7T If as a consequence of a court judgment or allegation of patent 51 infringement or for any other reason not limited to patent issues conditions are imposed on you whether by court order agreement or otherwise that contradict the conditions of this License they do not excuse you from the conditions of this License If you cannot distribute so as to satisfy simultaneously your obligations under this License and any other pertinent obligations then as a consequence you may not distribute the Program at all For example if a patent license would not permit royalty free redistribution of the Program by all those who receive copies directly or indirectly through you then the only way you could satisfy both it an
59. ssue was that the MCF5249 User Manual 10 lacked important information about the I S interface when used in slave mode TFT monitor It was found that the TFT monitor used the same controller IC as the monitor used by iRiver s H300 player Though this player was not officially supported by Rockbox at the time development was underway and a driver for the controller IC had already been written Unfortunately Rockbox s GUI was not originally intended for colour monitors thus uses only simple foreground background colour schemes This leaves room for ample visual improvements but still give a perfectly functional interface 5 1 2 Bootloader The original Rockbox bootloader was designed to boot from the flash memory initialize basic hardware functions and load the firmware from HDD to the SDRAM and execute it from there As mentioned in section 4 2 6 it is not possible with this hard ware to access the flash and the IDE at the same time Hence there was need for some other way to boot the firmware than the original bootloader The basic idea with the new bootloader is to boot from the flash memory load a program that resides in the flash into the SRAM and execute that program Thereafter that program will enable the IDE and load the firmware from the HDD to the SDRAM and execute it from there 5 2 Development environment To successfully develop such a complex system as this there is need for some kind of development environment
60. t this point that did not seem to be necessary since there were many others options regarding DSPs 3 1 2 PortalPlayer The PortalPlayer website 5 states that the PortalPlayer chip fea tures dual ARM7 microprocessors with a zero wait state memory architecture delivering an equivalent of a 160 MHz ARMT According to 5 the chip has connectivity options for USB 2 0 Kagerin Karlsson 2006 9 10 Chapter 3 Component selection PHY and FireWire IEEE 1934a This does not mean that the chip has an on chip USB 2 0 PHY just that it can interface to one A feature that the chip does have on chip is a codec This codec is built upon technology from Wolfson Microelectronics Wolfson is known to build high quality audio codecs that can deliver high SNR The PortalPlayer series of audio processors is used in the iPod players from Apple 3 1 3 SigmaTel D Major STMP35xx The D Major from SigmaTel is a series of audio SoCs The STMP35xx have an integrated USB 2 0 PHY battery charger 18 bits channel audio codec and more For a more complete summary of features see 6 The DSP core in the Sigma Tel STMP35xx is a Motorola DSP56004 core with a filter coprocessor for FIR and IIR filters The DSP core is specified to run at as most 75 6 MHz at Vag gt 1 92 V According to the data sheet 7 power dissipation is about 80 mW when running at 36 MHz typical MP3 decoding in power save mode Software SigmaTel supply a massive SDK with
61. tates and bus termination It supports 16 and 8 bit port size but can only address 16 bit due to lack of address 0 A0 pin 10 Chip select 0 The CPU itself uses the system bus and chip select 0 for boot pur poses so it has to be connected to a boot memory in this case a Flash memory Chip select 1 The chip select 1 pin is unconfigured at start up and is connected the the TFT screen The TFT screen does not have a compatible bus interface 21 instead it uses separate read RD and write WR pins This usually results in the usage of so called glue logic but in this case additional address pins could be used as control pins The TFT interface does not trigger events without an active chip select so unrelated activity of address pins is harmless For this solution address 1 A1 is connected to the 1 bit address on the TFT interface RS address 2 42 is connected to read RD and read write R W is connected to write WR Effec tively this enables reads and writes using special memory addresses Using Base address 0x2 or Base address 0x6 for writes and Base address or Base address 0x4 for reads Writing or reading from these addresses in any other way results in unknown operation or read of invalid data Another problem with the TFT interface is that it is 8 bit and requires two consecutive read or write operations to the same ad dress since it internally has 16 bit registers Fortunately the CPU
62. tional device in less than 40 man weeks What are the main difficulties in developing a system like this 1 3 Realisation The development of an embedded device involves many tasks these are usually divided into hardware vs software Hardware tasks include architecture planning selection and evaluation of ICs and PCB layout Software tasks include architecture design implemen tation and testing All of these tasks are highly interdependent where design deci sions and tradeoffs have to be made based on several factors such as size performance power compatibility and project resources 1 4 Limitation This thesis will focus on developing a working prototype Many optimizations will be done but due to time limitations many opti mizations are left outside of this thesis 1 5 Requirements The basic requirements of the system is the following Requirement 1 It should be able to run on a battery Requirement 2 It should be able to start a program from a none volatile memory Requirement 3 It should be able to output audio to earphones Requirement 4 It should have a display Requirement 5 The software should be upgradeable Requirement 6 It should be able to decode at least two common lossy audio format 1 6 Topics covered 3 Except for the basics requirements some goals are set these are Goal 1 It should be able to act as a USB 2 0 mass storage device Goal 2 It should have Bluetooth connectivity Goal
63. ts Inc http www conductivecircuits com January 2006 Post O et al MIT Media Laboratory E broidery Design and fabrication of textile based computing May 9 2000 Beta LAYOUT Ltd http www pcb pool com October 2005 Royal Philips Semiconductors The I C bus specification 2000 Royal Philips Semiconductors The P S bus specification 1996 Royal Philips Semiconductors TEA5764HN FM radio RDS 2005 The GNU Operating System http www gnu org January 2006 SourceForge net http www sf net November 2005 Hitachi Global Storage Technologies http www hitachigst com portal site en January 2006 Appendix A GNU General Public License GNU GENERAL PUBLIC LICENSE Version 2 June 1991 Copyright C 1989 1991 Free Software Foundation Inc 59 Temple Place Suite 330 Boston MA 02111 1307 USA Everyone is permitted to copy and distribute verbatim copies of this license document but changing it is not allowed Preamble The licenses for most software are designed to take away your freedom to share and change it By contrast the GNU General Public License is intended to guarantee your freedom to share and change free software to make sure the software is free for all its users This General Public License applies to most of the Free Software Foundation s software and to any other program whose authors commit to using it Some other Free Software Foundation software is covered by the GNU Library
64. v teknisk och administrativ art Upphovsman nens ideella r tt innefattar r tt att bli n mnd som upphovsman i den omfattning som god sed kr ver vid anv ndning av dokumentet p ovan beskrivna s tt samt skydd mot att dokumentet ndras eller pre senteras i sadan form eller i s dant sammanhang som r kr nkande f r upphovsmannens litter ra eller konstn rliga anseende eller ege nart F r ytterligare information om Link ping University Elec tronic Press se f rlagets hemsida http www ep liu se 2006 Anders Kagerin Michael Karlsson Kagerin Karlsson 2006 53
65. y audio codecs 15 Offering a 24bits channel DAC with a possibility to automatically over sample the signal by a interpolation factor of 64 or 128 it can deliver a SNR of 98 dB A and a THD of 84 dB at 48 kHz according to 16 The codec have an internal headphone driver supporting capless mode of operation eliminating the need for external DC decoupling capacitors at the output All parts of the codec can be shut down while not in use to reduce power consumption When running at lowest power settings Vag 1 8V the codec consumes only 7 mW while still delivering a SNR of 90 dB A The WM8750L has a feature that Wolfson calls USB Mode When running in this mode the codec is capable of generating all common sample rates from a USB application clock frequency For a more specific list of these sample rates se the data sheet 16 The USB Mode supports fag of 12 MHz to 24 MHz these are common USB application clock rates 5Some amplifiers needs DC decoupling capacitors to work 3 4 External memory 15 Wolfson provides the possibility to order free samples from their website However it was not possible to order samples of the WM8750L After being in contact with a Wolfson sales office they said that the WMS750L where exclusive to some of their customers However they had another chip the WM8973 that was identical When the sample chips arrived both the WM8750L and the WM8973 were included for some unknown reason 3 3 2 Ph

Development of a low power hand-held device in a low

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