Bachelor Thesis
Contents
1. busid 2 sda 17 use GPIO 17 as sda scl 4 use GPIO 4 as scl udelay 3 use I2C speed of about 100 Hz timeout 0 sda od 0 should switch sth about open drain with this one scl od 0 and the following enabled not all devices are recognised gt set to 0 o for further explanations of parameters for the module see https github com kadamski i2c gpio param o attention Because of another native I2C bus on another pin header I2C bus 0 of the clkboard programme will be I2C bus 1 on the RPi I2C 1 of the programme will be I2C bus 2 on the RPi o asroot edit Makefile KDIR home pi lt build_directory gt in build directory make recommended test module with modprobe and i2c tools cp i2 gpio param ko lib modules lt version_number gt kernel drivers i2c add i2c gpio param to etc modules for autoload at boot edit as root 00000 using the kadamski module add bus via echo busid sda scl gt sys class i2c gpio add__bus remove bus via echo busid gt sys class i2c gpio remove_bus use GPIO numbers for sda and scl further options on https github com kadamski i2c gpio param e after successful test remove source files 28 9 Addendum 9 2 Setup for qemu compilation environment e instructions from http wiki debian org QemuUserEmulation e download Raspbian image from Raspberry Pi homepage http www raspberrypi org downloads or use image used to set up Raspberry Pi in the2. 1 4145 diff 1 5057 diff 1 8828 diff 1 2633 diff 1 4563 diff 1 9382 diff 1 3861 diff 1 5394 diff 1 4887 diff 1 5048 diff 1 5141 diff current I 0 6880 0 6748 0 6733 0 8016 0 7297 0 7475 0 7444 0 7276 0 7341 1 1880 1 1877 0 7547 0 7493 0 7639 0 7008 0 7536 0 7440 0 7853 0 7156 0 7332 0 7851 0 7627 0 7533 0 4423 0 7110 1 2619 0 7742 0 7635 0 7229 0 7562 0 9649 0 7073 0 7529 0 9414 0 6316 0 7282 0 9691 0 6930 0 7697 0 7443 0 7524 0 7571 tion test between Raspberry Pi and clockboards 1ca Measurement results of communi Table 2 1 31 9 Addendum VDD5 V before FET after FET 0 6078 diff 0 6067 diff 0 6032 diff 0 6028 diff 1 4605 diff 0 6016 diff 0 6000 diff 0 5984 diff 0 5974 diff 1 0001 diff 1 0011 diff 0 6038 diff 0 6038 diff 0 6008 diff 0 6006 diff 0 6024 diff 0 6026 diff 0 6026 diff 0 6144 diff 0 6127 diff 0 6115 diff 0 6119 diff 0 6146 diff 0 5529 diff 0 6124 diff 0 6102 diff 0 6132 diff 0 6134 diff 0 6130 diff 0 6131 diff 0 6134 diff 0 6088 diff 0 6096 diff 0 6075 diff 0 6075 diff 0 6074 diff 0 6057 diff 0 6091 diff 0 6073 diff 0 6070 diff 0 6092 diff 0 6084 diff current I 0 1057 0 1055 0 1049 0 1048 0 1051 0 1046 0 1043 0 1041 0 1039 0 1739 0 1741 0 1050 0 1050 0 1045 0 1044 0 1048 0 1048 0 1048 0 1068 0 1066 0 1064 0 1064 0 1069 0 0962 0 1065 0 1061 0 1066 0 1067 0 1066 0 1066 0 1067 0 1
3. 22 23 24 Reticle 2 3 6 45 ca 0 DI_VCCANA V VDDA V DI_VCC v Current probe before FET after FET current I before FET afterFET current I before FET afterFET current I 2 38 1 8062 1 8054 0 0180 1 8086 1 8034 1 5408 1 8106 1 8061 1 3293 2 79 1 8053 1 8039 0 0360 1 8094 1 8033 1 7825 1 8099 1 8091 2 45 1 8068 1 07 1 8087 1 8027 1 7513 1 8083 1 8077 2 32 1 8068 1 8058 0 0257 1 8091 1 8040 1 5097 1 8111 1 8100 2 32 all DI_voltages after FETs break down to almost 0 after few seconds 2 83 1 8088 1 8076 0 0308 1 8083 1 8055 1 8123 ne tes 2 9 1 8074 18104 oe 1 8073 1 8053 1 8115 1 8150 2 4 1 8080 1 8067 0 0333 1 8096 1 8062 1 8118 1 8060 1 7201 2 59 1 8080 1 8103 es 1 8093 1 8064 1 8108 13127 M 2 5 1 8083 1 8071 0 0308 1 8098 1 8068 1 8106 1 8089 0 4834 2 39 1 8109 1 8101 0 0206 1 8133 1 8059 2 1766 1 8133 13124 2 33 1 8107 1 8095 0 0308 1 8113 1 8050 1 8441 1 8114 1 8087 0 7860 2 3 1 8113 1 8113 always O 1 8138 1 8080 1 7075 1 8113 1 3105 DE 2 3 1 8146 1 8113 0 0829 1 8171 1 8080 2 6832 1 8154 1 8113 1 2196 2 33 1 8095 1 8094 ME 1 8109 1 8048 1 7953 1 8124 1 8102 2 31 1 8102 1 8090 0 0284 1 8097 1 8049 1 4301 1 8123 1 8115 2 33 1 8112 1 8106 0 0156 1 8121 1 8074 1 3733 1 8137 1 8112 2 38 1 8125 1 8110 0 0363 1 8127 1 8065 1 8311 1 8154 1 8108 1 3428 2 58 1 8120 1 312 0 0104 1 8135 1 8083 1 5259 1 8159 1 3170 63357 2 3 all DI_voltages after FETs break down to almost O after few seconds 2 31 1 8148 1 8131 0 0415
4. 0 5277 diff 1 0076 diff 0 9976 diff 0 5341 diff 0 5341 diff 0 5317 diff 0 5313 diff 0 5317 diff 0 5314 diff 0 5321 diff 0 5473 diff 0 5465 diff 0 5443 diff 0 5442 diff 0 5407 diff 0 5348 diff 0 5429 diff 0 5425 diff 0 5450 diff 0 5444 diff 0 5434 diff 0 5434 diff 0 5476 diff 0 5408 diff 0 5410 diff 0 5415 diff 0 5413 diff 0 5396 diff 0 5387 diff 0 5388 diff 0 5370 diff 0 5370 diff 0 5406 diff 0 5401 diff current I 0 2676 0 2675 0 2664 0 2661 0 2676 0 2669 0 2664 0 2642 0 2638 0 5038 0 4988 0 2670 0 2670 0 2658 0 2657 0 2658 0 2657 0 2660 0 2737 0 2732 0 2722 0 2721 0 2703 0 2674 0 2715 0 2712 0 2725 0 2722 0 2717 0 2717 0 2738 0 2704 0 2705 0 2707 0 2706 0 2698 0 2693 0 2694 0 2685 0 2685 0 2703 0 2701 test between Raspberry Pi and clockboards ication Measurement results of communi Table 2 2 32 Statement of Originality Erklarung I certify that this thesis and the research to which it refers are the product of my own work Any ideas or quotations from the work of other people published or otherwise are fully acknowledged in accordance with the standard referencing practices of the discipline Ich versichere dass ich diese Arbeit selbstandig verfasst und keine anderen als die angegebenen Quellen und Hilfsmittel verwendet habe Markus Hellenbrand Heidelberg 12 July 2013
5. 3 Execution of the integration Note that the I2C busses used in the clkboard programme are called I2C 0 and 12C 1 whereas the busses used on the Raspberry Pi are called I2C 1 and I2C 2 The reason for this is that the I2C 0 bus on the Raspberry Pi is the one on the P5 header which is not used 3 3 2 Configuration of the 1 wire bus for temperature readout As the operating system provides drivers for 1 wire and also for temperature readout via 1 wire the only thing that had to be done apart from loading the drivers was specifying the pin which is to be used in the corresponding kernel file This has already been taken care of when compiling the kernel To enable the drivers at boot time they have to be added to the etc modules file which is responsible for this action Cf step by step guide for details Before testing the 1 wire bus in the WSI system it was tested with a single DS18B20 temperature sensor which was soldered together according to its datasheet 31 and then connected to the corresponding GPIO pin There were no problems when testing the bus 3 3 3 Configuration of the GPIOs for HICANN reset and 1 8 V power supply The HICANN reset and power supply control interfaces require one GPIO pin each There is no operating system support for the required functions cf chapter 2 4 so they had to be implemented in the clkboard programme One possibility to access GPIO pins on the Raspberry Pi was found on the internet 21 and
6. Raspberry Pi Center Online Broadcom 2012 Cited 7 July 2013 http raspberrycenter de sites default files bcm2835 arm peripherals pdf 10 Price List Stamp9G20 taskit Online taskit GmbH 2012 Cited 7 July 2013 https ssl kundenserver de ssl taskit de xtc product_info php products_id 271 11 Raspberry Pi farnell Online Farnell 2007 2010 Cited 10 July 2013 http de farnell com raspberry pi 12 Raspberry Pi amazon Online Amazon 2013 Cited 10 July 2013 http www amazon de Raspberry Pi RBCA000 Mainboard 1176JZF S dp BOO8PT4GGC ref sr_1__1 278 4608845 2407944 ie UTF8 amp qid 1373470085 amp sr 8 1 amp keywords Raspberry Pi 13 sw wsiclkboard gitviz BrainScaleS Repository Online 2013 Cited 7 July 2013 https brainscales r kip uni heidelberg de projects sw wsiclkboard 22 8 List of references 14 12C bus specification and user manual nxp Online nxp Semiconductors 13 February 2012 Cited 7 July 2013 http www nxp com documents user_manual UM10204 pdf 15 iButton maximintegrated Online Maxim Integrated 7 April 2005 Cited 7 July 2013 http www maximintegrated com products ibutton ibuttons standard pdf 16 Downloads Raspberry Pi Online Raspberry Pi Foundation 9 February 2013 Cited 22 April 2013 http www raspberrypi org downloads 17 Main Page Ext Wiki Online Linux 21 June 2013 Cited 7 July 2013 https ext4 wiki kernel org inde
7. analyse imperfections in the WSI system setup but rather to check on communication between the Raspberry Pi and the system 28 Cf comments in table 1 The optimal values were defined in the context of the design of the system 17 5 Conclusion By successfully addressing every single reticle on the wafer it has been established that the integration of the Raspberry Pi into the WSI system was successful as well This means that the system is in the same state as before even better as it uses new hardware The decision to use a Raspberry Pi instead of the former taskit evaluation board turned out to be as expected a good idea The Raspberry Pi is faster smaller cost efficient and easy to handle As mentioned in chapter 2 2 there is also a huge Raspberry Pi community which was already to the benefit of the integration into the WSI system Using the kadamski I2C bit banging module very much facilitated adding a second bus to the required header It will also facilitate changes to the system in future as the busses can be added dynamically using almost every GPIO pin available A guide on how to do so is included in the addendum and can be found on the gitviz page as well It would have been worthwhile to further investigate the 400 kHz I2C clock and to fix the incorrect data transfer but there was no time to do so Nevertheless it seems that communication at high speed using 400 kHz is only a few steps away Achieving successful
8. that the hardware is supported by the operating system in an optimal way 7 The Raspberry Pi provides five headers Figure 6 Pin layout for the ribbon cable adapter on the clockboard This layout defines which pin with accessible pins They consist of 26 has do be Anlass er ante ale eight another eight seven and two pins programme function The blue circle is a drill hole and mostly act as GPIO pins Two of in the corner of the board 48 the headers are used as JTAG interfaces during the production of the board The header of main interest is the so called Pl header which is also the only header equipped with connectors Some of its pins are preconfigured two of them already in the way it is required by the clockboard layout cp figure 6 and 7 All of the pins can be used as GPIOs 21 In chapter 2 4 the required functionalities have been described already Figure 6 shows which pin has to provide which functionality From the Raspberry Pi github a Linux kernel for further configuration was cloned The clone directory was https github com raspberrypi linux git 22 14 Secure Shell Network protocol 1 Joint Test Action Group interface for debugging purposes 3 Execution of the integration Necessary adaptions take place in the bem2708 c file which contains information about the pin configuration In the cloned directory it can be found in the linux arch arm mach bem2708 subdirectory With regard to
9. 1 8140 1 8074 1 9204 1 8125 1 8099 2 35 1 8157 1 8146 0 0258 1 8130 1 8069 1 7984 1 8174 1 8168 3 02 1 8120 1 13 1 8115 1 8080 1 8135 1 8154 2 24 1 8120 1 8110 0 0233 1 8109 1 8080 1 8103 1 8090 2 36 1 8111 1 8134 ee 7 8097 1 8073 1 8120 1 8149 2 53 1 8097 1 8086 0 0257 1 8099 1 8047 1 5124 1 8109 1 8098 2 64 1 8120 1 8106 0 0339 1 8127 1 8049 2 2975 1 8130 1 8114 2 59 1 8113 1 8095 0 0437 1 8129 1 8050 2 3277 1 8138 1 8132 2 25 1 8112 1 8097 0 0385 1 8126 1 8059 1 9644 1 8108 1 8090 2 4 1 8126 1 8116 0 0231 1 8130 1 8063 1 9644 1 8150 1 8147 1 3 enabling FETs switches off half of the voltages VDD25 at ca 3 3 V almost no voltage behind FETs 2 27 1 8106 1 8105 Oooo 1 8117 1 8071 1 3567 1 8104 1 8106 25 1 8112 1 8102 0 0257 1 8112 1 8071 1 2089 1 8141 1 8134 2 46 1 8082 1 8090 0 0206 1 8090 1 8049 springt zw 1 1 8082 1 8073 2 46 OV before FETs and some values behind FETs for VBIAS VDD5 VDD12 and VDD25 vice versa 2 38 1 8060 1 8059 BEE 1 8059 1 8016 EDA 1 8056 1 8043 2 52 1 8075 1 8068 0 0181 1 8072 1 8015 1 6725 1 8091 1 8084 2 5 1 8087 1 3083 BORN 1 8084 1 8021 1 8561 1 8085 1 8094 2 52 1 8087 1 8077 0 0259 1 8070 1 8018 1 5518 1 8086 1 8080 2 96 1 8067 1 8066 BANET ANO 1 8029 1 7968 1 7952 1 8096 1 8100 2 44 1 8054 1 8043 0 0262 1 8055 1 7999 1 6431 1 8055 1 8049 2 49 1 8075 1 3078 oor 1 8073 1 8020 1 5518 1 8077 1 8082 2 43 all DI_voltages after FETs break down to almost O after few seconds 2 39 1 8084 1 8095 SO oeed 1 8086 1 8042 1 2776 1
10. 8086 1 510 eee 2 63 1 8091 1 8081 0 0257 1 8071 1 8035 ter 1 8098 1 8080 0 5475 2 66 1 8082 1 8089 Oe 1 8086 1 8028 1 7020 1 8093 1 8103 ee 2 44 1 8078 1 8061 0 0439 7 8096 1 8035 1 7931 1 8043 1 8019 0 6990 before FET VDD V after FET current I 1 8109 1 8057 1 5408 1 8110 1 8027 2 4472 1 8102 1 8048 1 6003 1 8101 1 8040 1 8117 1 8099 1 8056 1 2642 1 8080 1 8062 1 8109 1 8092 1 8102 1 8070 1 8107 1 8075 1 8133 1 8074 1 7231 1 8144 1 8077 1 8138 1 8105 0 9757 1 8146 1 8105 1 8117 1 8069 1 8104 1 8061 8 8126 1 8086 1 8148 1 8086 1 8132 1 8083 1 2817 1 8156 1 8099 ee 1 8144 1 8092 1 8109 1 8055 1 8112 1 8098 1 8125 1 8097 1 8118 1 8079 1 8127 1 8062 1 9045 1 8126 1 8063 1 8440 1 8131 1 8086 1 3297 1 8137 1 8077 1 7528 1 8119 1 8093 1 8116 1 8078 1 8090 1 8073 1 8067 1 8036 0 9123 1 8078 1 8030 1 4293 1 8090 1 8048 1 2476 1 8084 1 8038 1 3388 1 8052 1 8022 0 8824 1 8071 1 8026 1 3388 1 8087 1 8040 1 3693 1 8098 1 8069 1 8091 1 8047 1 8090 1 8044 1 3676 1 8097 1 8059 1 0941 VDD25 V before FET after FET 1 3761 diff 1 3496 diff 1 3466 diff 1 6033 diff 1 4594 diff 1 4950 diff 1 4887 diff 1 4553 diff 1 4682 diff 2 3759 diff 2 3754 diff 1 5094 diff 1 4986 diff 1 5278 diff 1 4016 diff 1 5072 diff 1 4880 diff 1 5706 diff 1 4311 diff 1 4664 diff 1 5702 diff 1 5253 diff 1 5066 diff 0 8847 diff 1 4219 diff 2 5238 diff 1 5485 diff 1 5269 diff 1 4458 diff 1 5124 diff 1 9299 diff
11. Pi 2 4 Interfaces the Raspberry Pi has to provide The performance of different tasks of the clkboard programme requires different interfaces to the WSI system which the Raspberry Pi has to provide These interfaces are two 12C busses one 1 wire bus and three GPIO busses so far cf figure 4 The GPIO busses pass the HICANN reset signal which resets all HICANNs to a certain standard configuration and the enabling signal for the external 1 8 V power supply The 1 wire bus is used for temperature readout One of the I2C busses accesses the microcontrollers which monitor the FET voltages cf figure 4 wafer 12C 0 to PICs and the clkboard Ethernet temperature sensors other one accesses the pcb programme HICANN reset powerboards for data readout cf figure 5 I2C 1 to PSB The separation of the two I2C busses was carried VDDA VDDOUT VDDA out because of security A ill power supply board printed circuit board considerations so it wi Figure 4 Schematic diagram of the interfaces between the Raspberry still be possible to Pi and the main pcb User access to the programme takes place switch off the voltages through Ethernet The different commands executable from within the programme require different interfaces to the WSI system if one of the busses is blocked completely due to for instance a defect of the adherent devices 5 13 In the following short overviews over the
12. functionality of the used interfaces are provided Inter Integrated Circuit 10 General Purpose Input Output 2 The WSI system emulating the human brain 2 4 1 Overview I2C Developed in the 1980s the I2C bus has evolved to one of the most frequently used busses in inter circuit communication Its architecture follows the master slave architecture which means that one master device controls several slave devices Slaves can never read or write data on their own The I2C bus is a two wire serial bus using one wire for the clock SCL and the other one for data SDA To start communication the master device sends a start signal in such a way that the data line switches from high potential high to low potential low while the clock line remains high cf figure 5 Switching SDA while SCL remains constant is only allowed for the start and stop signal For data transfer SDA has to remain unchanged while a clock pulse is being sent The stop signal works in the opposite way of the start signal Start sequence Stop sequence so SDA switches from low Ki a ra oh while SOL Seman high cf figure 5 Data SCL transfer takes place in SDA SCL between these two signals After the start signal the Figure 5 Schema of start and stop sequence for I2C master device sends the communication Only for these two signals SDA is switched while SCL remains constant Data transfer takes place in address of the device it w
13. given to the driver for instance via an ID table Once a driver recognises matching device names it will attach to the device and henceforth manage communication with this device 29 Activating the kadamski module so that it can be used is basically done in the same way as adding any c programme The module can be downloaded from https github com kadamski i2c gpio param 30 Afterwards it just has to be compiled and the result has to be moved to the kernel drivers directory Then it can be loaded automatically at boot time when the command to do so is added to the etc modules file When loading the module a default bus is being initialised In this case where the pins for the additional I2C bus are known from the beginning and where they are fixed and will not change the default bus and its pins can be specified before compiling As a consequence the module only has to be started and it is not necessary to remove the default bus and to add the correct bus Before testing the I2C busses within the WSI system both of them were tested with a chain of temperature sensors All sensors were recognised by the busses and the temperature values could be read 2 Modules included in the modprobe blacklist are prevented from being loaded automatically during the booting process 21 Cf chapter 4 for further information 22 As the developer s username is kadamski the module will be referred to as kadamski module in the following 12
14. of the system runs by a ribbon cable A further advantage of the Raspberry in comparison to the taskit board not listed in the table is its huge community providing support and many projects already carried out with the Raspberry Pi This often facilitates finding solutions for problems occurring when operating a Raspberry Pi 2 3 The Raspberry Pi s tasks in the system Enabling users to switch on and off the FETs for single reticles is only one task of the clkboard programme In fact the overall task of the programme is to provide an interface to the whole power supply chain which allows comprehensive monitoring and control Running on the Raspberry Pi it provides a handy interface which bundles all further interfaces necessary to manage the WSI system power supply and requires only Ethernet to be accessible 2 The WSI system emulating the human brain A future aim with regard to the WSI system and especially with regard to the clkboard programme and the Raspberry Pi is further automation One command should be enough to start the whole system monitoring should work independently from constant human supervision and above all it should react to certain critical values by itself as for instance to temperatures which surpass a certain threshold As the plans for the whole project include several WSI systems running in parallel large scale automation is absolutely necessary This can be further elaborated after the integration of the Raspberry
15. sr_1_1 ie UTF8 amp qid 1372256547 amp sr 8 1 amp keywords raspberry pi 50 Raspberry Pi SD Cards Database elinux Online 10 July 2013 Cited 10 July 2013 http elinux org RPi_SD_ cards 25 9 Addendum The addendum contains a step by step guide on how to set up the Raspberry Pi from scratch so that it can be used with the WSI system a guide on how to set up the compiling environment for the clkboard programme and the measurement results of the communication tests between the Raspberry Pi and the other parts of the WSI system 9 1 Step by step guide Get the Raspberry Pi up and running e get Linux running on the Raspberry Pi detailed procedure on http elinux org RPi_Easy_SD_Card_ Setup in German e get current Raspbian from http www raspberrypi org downloads e verify checksum and write image to SD card ext4 size of at least 4GB recommended the image alone needs about 2GB o run shalsum lt file gt on your zip file and compare to checksum from download page unzip lt file gt insert SD card get the card s partition number e g using df h unmount all SD partitions with umount dev lt partition_number gt O O O 0 write image to SD card make sure to write the correct file behind if make sure to insert the whole SD card not only one partition name for lt SD_card gt and make sure you do not insert the wrong device after of all data on this device will be lost 4M should suf
16. use of a 400 kHz clock would of course reduce a possible bottleneck and increase security A new feature accompanying the inclusion of the Raspberry Pi into the WSI system is the possibility of switching on the whole system with just one command Concerning this feature the most decisive addition is the GPIO pin accessing the 1 8 V power supply With the former power supply this would have been possible as well but it was not done so far because it would have taken too much time The use of the new 1 8 V power supplies being introduced with the new system will be maintained avoiding the necessity to buy more of the unhandy power supplies used so far because the new power supplies are designed by the Electronic Vision s group Furthermore now there is a detailed modularised and easy to follow workflow which allows changing present and adding further features to the Raspberry Pi and the clkboard programme Creating this workflow and the annexed guide is an important result of this thesis As it describes the complete Raspberry Pi setup it includes compiling the Raspberry Pi kernel which is important for further hardware changes and it also includes compiling the clkboard programme which is of course important for further software changes The workflow was tested several times partly also on different PCs so future developers can simply follow it even without basic knowledge 2 Cf 9 2 step by step guide 18 5 Conclusio
17. 059 0 1060 0 1057 0 1057 0 1056 0 1053 0 1059 0 1056 0 1056 0 1060 0 1058 DI_VCC33ANA V before FET after FET 3 3000 3 3000 3 3000 3 3000 3 3000 3 3000 3 3000 3 3000 3 3000 3 3000 3 3000 3 3000 3 3000 3 3000 3 3000 3 3000 3 3000 3 3000 3 3000 3 3000 3 3000 3 3000 3 3000 3 3000 3 3000 3 3000 3 3000 3 3000 3 3000 3 3000 3 3000 3 3000 0 0000 3 3000 3 3000 3 3000 3 3000 3 3000 3 3000 3 3000 3 3000 3 3000 3 3000 3 3000 3 3126 3 3107 3 3023 3 3116 3 3119 3 3167 3 3051 3 3123 3 3069 3 3105 3 3051 3 3099 3 3124 3 3079 3 3093 3 3089 3 3119 3 3180 3 3076 3 3200 3 3164 3 3099 3 3155 3 3110 3 3129 3 3150 3 3057 3 3163 current I 0 0575 VDDBUS V before FET after 1 2362 1 2358 1 2346 1 2353 1 2517 1 2362 1 2356 1 2353 1 2356 1 2379 1 2377 1 2374 1 2407 1 2363 1 2372 1 2370 1 2374 1 2374 1 2470 1 2480 1 2436 1 2441 1 2438 1 2717 1 2480 1 2485 1 2361 1 2375 1 2364 1 2369 1 2342 1 2335 1 2333 1 2350 1 2353 1 2467 1 2463 1 2359 1 2362 1 2355 1 2346 1 2348 FET current I 1 2351 0 3021 1 2352 1 2363 1 2364 1 2540 1 2395 1 2392 1 2348 1 2380 1 2375 1 2376 1 2374 0 or 0 24392 1 2374 1 2366 1 2371 1 2372 1 2378 1 2385 1 2458 1 2462 1 2459 1 2468 1 2466 1 2434 1 2477 1 2481 1 2365 0 1209 1 2361 zw 0 4 und 1 2373 1 2381 1 2350 0 3325 1 2335 1 2341 1 2339 1 2345 1 2463 1 2
18. 26 28 Corbet Jonathan The platform device API LWN Online 21 June 2011 Cited 7 July 2013 http lwn net Articles 448499 29 The Linux Kernel Drivers Linux Online Linux 2013 Cited 7 July 2013 http www linux org article view the linux kernel drivers 23 8 List of references 30 Adamski Krzysztof A kadamski i2c gpio param github Online April 2013 Cited 25 April 2013 https github com kadamski i2c gpio param 31 Datasheet DS18B20 farnell Online Maxim Integrated 2008 Cited 7 July 2013 http www farnell com datasheets 1647364 pdf 32 RCF deltavsoft Online Delta V Software 2013 Cited 10 July 2013 http www deltavsoft com doc ref_user_ guide Intro html rcf_user_guide Intro Wh atIsRcf 33 qemu qemu Online 26 June 2013 http wiki gemu org Main_ Page 34 BrainScaleS BrainScaleS Online 2011 Cited 7 July 2013 http brainscales kip uni heidelberg de 35 Chapman Seville Chapter 3 General Study Suggestions How To Study Physics Cambridge Addison Wesley Publishing Company 1949 36 Technische Daten Raspberry Pi Center Online Raspberry Pi Foundation 23 April 2012 Cited 7 July 2013 http raspberrycenter de handbuch technische daten 37 Technical details taskit Online taskit GmbH 2012 Cited 7 July 2013 http www taskit de en products stamp9g20 tech htm 38 Speicher Microcontroller Online Cited 7 July 2013 http www mikrocontr
19. 470 1 2361 1 2378 1 2375 1 2359 1 2361 VOH V 0 7116 0 7127 0 7064 0 7028 0 7055 0 7068 0 7064 0 0704 0 7064 0 7094 0 7083 0 7099 0 7066 0 7093 0 7094 0 7085 0 7100 0 7069 0 7091 0 7098 0 7072 0 7062 0 7060 0 7050 0 7064 0 7074 0 7078 0 7080 0 7059 0 7056 0 7039 0 7034 0 7024 0 7050 0 7075 0 6972 0 7033 0 7062 0 7049 0 7045 0 7090 0 7032 before FET afterFET current I 0 7118 0 7131 0 7086 0 7024 0 7088 0 7109 0 7080 0 7100 0 7061 0 7085 0 7082 0 7091 O or discrete 0 7099 0 0829 0 7111 0 7097 0 7101 0 7103 0 7115 0 7086 0 7085 0 7106 0 7065 0 7087 0 7053 0 7077 0 7069 0 7069 0 7091 VOL V before FET after FET 0 9035 0 9028 0 9025 0 9067 0 9042 0 9049 0 9040 0 9065 0 9039 0 9068 0 9055 0 9032 0 9059 0 9062 0 9056 0 9098 0 9068 0 9049 0 9046 0 9064 0 9061 0 9078 0 9073 0 9043 0 9064 0 9019 0 9005 0 9055 0 9057 0 9055 0 9063 0 9072 0 9062 0 9037 0 9025 0 9037 0 9053 0 9047 0 9025 0 9033 0 9048 0 9054 0 9050 0 9027 0 9028 0 9025 0 9048 0 9070 0 9064 0 9053 0 9040 0 9037 0 9030 0 9023 0 9023 0 9054 0 9041 0 9034 0 9050 0 9051 0 9042 0 9038 0 9041 0 9022 0 9029 0 9029 0 9028 0 9019 0 9018 0 9042 current I 0 0796 0 0829 VBIAS V before FET after FET 0 5353 diff 0 5350 diff 0 5327 diff 0 5322 diff 0 5352 diff 0 5338 diff 0 5327 diff 0 5283 diff
20. Faculty of Physics and Astronomy University of Heidelberg Bachelor Thesis in Physics submitted by Markus Hellenbrand born in Saarbr cken Germany July 2013 A Raspberry Pi controlling neuromorphic hardware This bachelor thesis was carried out by Markus Hellenbrand at the Kirchhoff Institute for Physics Ruprecht Karls University Heidelberg under the supervision of Prof Dr Karlheinz Meier A Raspberry Pi controlling neuromorphic hardware This thesis describes the integration of a Raspberry Pi a credit card sized single board computer into the Wafer Scale Integration WSI System of the BrainScaleS project The Raspberry Pi s task is to bundle all the interfaces necessary to manage the system s elaborate power supply into one single access easy to use interface To this purpose the Raspberry Pi replaced the former evaluation board responsible for power management taking over all of its tasks and in addition providing faster and cheaper hardware The integration took place in two main steps configuring the Raspberry Pi s hardware and adapting the control programme from the former board to the new hardware The results of this thesis are the successful integration of the Raspberry Pi into the WSI system which was proven by several communication tests between the Raspberry Pi and the rest of the system and an easy to follow step by step guide on how to set up Raspberry Pis to manage additional systems Ein Raspberr
21. OST US scar cats acta Steet cen scene nitel cpcnceacchantenileencne nenne ee neds cotta ta 30 Ill 1 Introduction What physicists strive to achieve is an understanding of nature or expressed in a more extensive way understanding the world So it is no wonder that sooner or later physicists would be trying to understand the process of understanding itself as an elementary part of human nature And the human brain which recently became the subject of one of the largest research projects of the European Union the Human Brain Project 1 is in turn elementary for human understanding The Electronic Vision s group s approach in Heidelberg 2 is to simulate neural information processing not on supercomputers in a digital manner as often done until today 3 but rather on analogue hardware 4 The special aspect of the Electronic Vision s approach is Wafer Scale Integration WSI This term describes producing the necessary circuits on a silicon wafer and not cutting the wafer to dies afterwards but interconnecting the circuits directly on the wafer via post processing 5 to enable the required data transfer rates coming along with large network simulations For the emulation of large network simulations quite an amount of energy is required 3 One of the advantages of the WSI approach as opposed to a digital approach on supercomputers is that far fewer energy is needed to simulate comparable brain information processing N
22. The second way to reduce the number of required inputs is to measure some of the voltages dropping over a FET by a differential amplifier and passing the amplifier s output to a PIC input pin cf figure 8 black lines For both of the methods the pin demand is reduced from two to one but to the detriment of less precise data 5 Regarding the incorrect data transfer at high I2C clock speeds it seems that the problem has its origins in the transfer of the values and not in the values themselves It 6 Cf table 1 for an explanation of the colours 27 This was not a part of this thesis which is why the results are not part of the addendum 16 4 Tests could be possible that a bit flip occurred due to too high speed which could explain the occurrence of exactly half of the actual value Unfortunately there was no time left to investigate this any further The next steps would be examining the I2C signal with an oscilloscope to identify the source of the error Additionally the speed of the I2C clock could be raised gradually to find the threshold above which the values are transferred incorrectly The explanations given for fluctuations or for negative values are only supposed to supply hints on what has to be taken into account when examining the measurement results They are not intended to sufficiently explain existent deviations from optimal values This is because it was not the purpose of the measurement to quantitatively
23. able advice the whole Electronic Vision s group for a friendly and helpful environment others whom I have unintentionally omitted from this list Thank you all 21 8 List of references Websites occurring in the list of references are listed the following way Side name site name possibly date of last actualisation date of last visit on the site address 1 Human Brain Project Human Brain Project Online Cited 7 July 2013 http www humanbrainproject eu 2 Electronic Vision s Electronic Vision s Online 14 May 2015 Cited 7 July 2013 http www kip uni heidelberg de cms groups vision home 3 In Brief Blue Brain Project Online 29 April 2013 Cited 7 July 2013 http bluebrain epfl ch page 56882 en html 4 The FACETS Neuromorphic Hardware Electronic Vision s Online 19 May 2011 Cited 7 July 2013 http www kip uni heidelberg de cms vision projects facets neuromorphic_hardware 5 Husman de Oliviera Dan et al et al FACETS Wafer Scale Integration WST Heidelberg Dresden s n 6 Gerstner Wulfram and Kistler Werner M Spiking Neuron Models Lausanne Cambridge University Press 2002 ISBN 0 521 81384 0 90 USD 7 Raspberry Pi Wikipedia Online 4 July 2013 Cited 7 July 2013 http en wikipedia org wiki Raspberry_ Pi 8 About Raspberry Pi Online Raspberry Pi Foundation 2012 Cited 7 July 2013 http www raspberrypi org about 9 BCM2835 ARM Peripherals
24. adapted to the specific needs of the Raspberry Pi in the WSI system Access takes place with the help of the operating system s memory device file Byte addresses passed to this file are mapped to physical memory addresses which allows direct manipulation of the GPIO pins via their memory addresses In one of the header files of the clkboard programme some macros were defined which use the GPIO pin number on the pin header on the Raspberry Pi to calculate the memory address for the pins If something in the programme will be changed later on it will have to be taken into account that the GPIO number cf Figure 6 has to be used not the continuous pin number beginning with 1 in the bottom left and ending with 26 in the top right 21 When compiling the kernel it has already been taken care of that the pins needed for HICANN reset and power supply switch will not be occupied by some Raspberry Pi internal functions 233 dev mem short description on http linux about com library cmd blemdl4_mem htm 42 13 3 Execution of the integration When initialising the pins the following happens e open memory device file dev mem e map addresses to physical memory e close memory device file e define pin as input using a macro defined in the HICANN reset header file pins have to be set always as input first due to pin register definition 21 e define pin as output After initialisation the pins can be used as output p
25. beforehand e resize image by dd if dev zero bs 1M count 2048 gt gt file img e grow filesystem by e losetup f file img e kpartx a dev loop0 e fsck dev mapper loop0p2 e resize2fs dev mapper loop0p2 e kpartx d dev loop0 e losetup d dev loop0 e mount file img somewhere offset from output of file file img 512 second partition e mount file img o loop offset 62914560 mnt tmp e install on host qemu qemu user static qemu user static e now update binfmts display should include qemu stuff e copy etc resolv conf to mnt tmp etc resolv conf for DNS support e now chroot mnt tmp should work e set proxy in chroot environment e export http_proxy http proxy kip uni heidelberg de e export https_proxy https proxy kip uni heidelberg de e in chroot install work stuff e to work on software e sudo mount 2013 usw usf img o loop offset 62914560 mnt tmp e sudo chroot mnt tmp 29 9 Addendum SVIGA sanjea e 10A vw oS lt vw oS lt VS 0 70 VO0 lt HOA snadqdqa 4u11N9 93e NIje9 0 Uaye anjen WOI SJaJJIP anjen 39uels sal UBAIS SYIGA Pue STGGA 134 Jaye Auo YNVEEIIN Id ZIaaA posnseaW zou quaWaINsealw jeNU313J41P Jo asnevaq painseaw anjen auo JUO JID Sada STaaA sane e sane e aaa DOA Id VeE T usIs Jle gagje Jo asueyo ajo UO enjon 4 y31y anjen JOYM F anjea zey F ed Ajysow suo nenpn jy ajqesapisuod Vvo lt Mo 00 sAemje aw BY 40 JSOW s
26. current kernel change default pin from 4 to 14 specified by ribbon cable layout as root edit lt build_directory gt arch arm mach bem2708 bem2708 c e change define W1_GPIO 4 to define W1_GPIO 14 e change define UARTO_DMA 15 14 to define UARTO_DMA 22 25 to avoid overwriting pin 14 needed for 1 wire in build directory make lasts about six hours if compiled on Raspberry Pi as root in build directory make modules lasts a few minutes on Raspberry Pi make modules_ install lasts a few minutes on Raspberry Pi move the new kernel image from arch arm boot Image to boot recommended rename new image to e g kernel_new img in boot as root edit config txt change kernel kernel img to kernel kernel_new img or add this line if not existing test booting with new kernel in case of success remove old kernel img enable I2C and 1 wire native I2C detailed procedure on http www gsurf de vorbereiten des raspberry pi auf i2c German o as root edit etc modprobe d raspi blacklist conf make blacklist i2c bcm2708 a comment 27 9 Addendum o as root edit etc modules add the following lines i2c bcm2708 ic2 dev wl gpio wil therm e additional I2C add Kadamski I2C module to add remove GPIO bit banged I2C busses o get the module via git clone https github com kadamski i2c gpio param git o default build directory i2c gpio param o edit lt build_directory gt i2c gpio param c
27. ds 2 2 2 Why to exchange the former board with a Raspberry Pi ccceee 3 2 3 The Raspberry Pi s tasks in the system cv eceea ne deeba dane ceeaaeened ics scenes 4 2 4 Interfaces the Raspberry Pi has to provide xie tees ces cig as manenn ee 5 2 4 Overview DE ee Ba iR 6 DA 2 Overview l wires erae ee ieda e shangsne tea Era a a r un diulirekerin teren 7 BR ON a E na LO E E E EEE EE AEE T 3 Execution of the integration a ee anne 8 3 1 Installation of the operating system Debian aaa aaa a ea 8 3 2 Preparation of the kernel for the clkboard programme uueenene 9 3 3 Configuration of the required interessant ea 11 3 3 1 Configuration of the I2C his na a a 11 3 3 2 Configuration of the 1 wire bus for temperature readout 13 3 3 3 Configuration of the GPIOs for HICANN reset and 1 8 V power supply 13 3 4 Compilation of the clkboard programme urenenenenenenenenenenenenenenenenenen 14 A Tests ara riDERiiniehtan 15 4 1 Examination of the DC Dissen een ae 15 4 2 Analysis of the PC Hessens 15 SB CONCIUSION near ara aaa EE E LA dare E EA E aatia E aeea aE Eaa bane 18 6 Outlook izanarena ee areas ans 20 7 Ackn wledgements u a ma 21 8 ELISE Ob TETETEN GES ea a a le E 22 9 Addendum i 22 22 22 Nee 26 9 1 Step by step guide Get the Raspberry Pi up and running 26 0 2 Setup for qemu compilation environment sauna ee 29 9 3 Measurement P
28. e based on different processor Figure 7 GPIO pin numbering on the Raspberry Pi P1 header 21 In this case the host processor is based on the x86 architectures which differ in their instruction sets architecture 23 24 whereas the target processor is based on the ARM architecture 25 16 Most basic operations a processor can execute 17 Developed by Intel Cf referenced documents for further information 18 ARM Advanced RISC Machine RISC Reduced Instruction Set Computing 10 3 Execution of the integration Building a cross compilation toolchain was the first approach to compiling the custom Linux kernel crosstool ng 26 promised to be an easy way to set up such a toolchain thus using this programme was the first try Following for instance the guide on http www kitware com blog home post 426 27 should have led to a toolchain ready to compile the kernel Unfortunately even after several attempts and consultation of as well as practical help by experienced programmers within the research group it was not possible to set up a working toolchain on the used host system Some host system modules caused dependency problems which could neither be resolved automatically by using apt get install nor manually by trying to install the modules one by one To avoid further unnecessary delay it was decided to continue compiling on the Raspberry Pi itself This option was not favoured in the first place as
29. e was updated at least ten times to identify fluctuations and a value lying in the middle of the fluctuations was noted down Therefore the fact that four digits were recorded does not imply that there is a high precision They were noted down in such a detail nevertheless because it was interesting to get an insight into the fluctuations and to obtain a distribution of current values for the more stable voltages As mentioned in chapter 3 3 1 some of the voltage values were transferred incorrectly when the I2C bus was driven by a 400 kHz clock For some of the values only half of their actual value was displayed If a clock of 100 kHz is used all values are transferred correctly 4 2 Analysis of the I2C measurement First and most important of all the results prove that the integration has been successful All reticles could be accessed switched on and off and their values could be obtained Six of the 48 reticles showed strange behaviour two of them being 23 Cf comments in tables 2 1 and 2 2 included in the addendum 15 4 Tests controlled by the same microcontroller The latter occurrence may indicate a problem with the PIC programming None of the problems were caused by the Raspberry Pi as could be shown by observing correct values for other reticles in between the errors as well as by repeatedly trying to read the faulty values again some time later on Quite a few current values of the voltage measurement showed mediu
30. environment 4 Remote Call Framework cross platform interprocess communication framework for C 32 14 4 Tests As the last part of the integration of the Raspberry Pi into the WSI system the complete functionality of the voltage control interface had to be tested To do so every single reticle s voltage and current values were measured The aim of the measurement was to prove whether the integration was successful if the communication works properly throughout the whole system and to get an overview over the values being applied and measured by the system itself In general it had to be proven that the system is in the same state as before only using new hardware 4 1 Examination of the I2C busses The results of the measurements can be found in the addendum and were obtained as follows All reticles were manually switched on using the clkboard programme and only one at a time throughout the whole measuring process Then first the value of a current probe attached to the cable running to the system from the power supply was measured Afterwards the values for the different voltages before and after the FETs as well as the current values calculated by the clkboard programme were measured The measures were not orientated towards obtaining precise values but only to get an overview over the reticles and to identify possibly defective elements Thus no statistical mean values or errors were calculated Nevertheless every valu
31. etup is with a smaller periphery which still provide all required interfaces and which are at the same time less expensive One of the best total 6 dsPIC33FJ128GP710 PIC T Field Effect Transistor 8 Central Processing Unit processor Figure 3 Raspberry Pi size as big as a credit card The header P1 is the one at This the very left equipped with pins header is used with the ribbon cable 2 The WSI system emulating the human brain packages is provided by the Raspberry Pi cf figure 3 originally designed by the Raspberry Pi Foundation to promote the teaching of basic computer science in schools 7 8 The table below lists some of the technical details of both of the boards and shows why a change is reasonable 9 10 11 12 Chip CPU Coprocessors GPU Memory Ethernet USB Power Supply Power Consumption Dimensions Price taskit Stamp9G20 with Evaluation board Atmel AT91SAM9G20 400 MHz ARM 64 MB SDRAM optional up to 128 MB 10 100 Mbit s Ethernet 3 3 V max 180 mW 20 cm x 13 cm x 4 5 cm 299 EUR 10 Raspberry Pi Model B Broadcom BCM2835 700 MHz ARM digital processing floating point unit Dual Core VideoCore IV Multimedia Co Processor 512 MB SDRAM 10 100 Mbit s Ethernet 5 V MicroUSB max 3 5 W 8 6 cm x 5 4 cm x 1 7 cm 40 EUR 12 cheaper than the former The communication between the Raspberry Pi and the rest
32. evertheless the whole system may consume up to 1000 W of energy if operated at full capacity 5 To control such a power and to control it for a system as sensitive as the present one an elaborate power management is indispensable This is implemented by using a single board computer running a programme which was written by Electronic Vision s member Maurice Giittler However the hardware of the board used so far is somewhat outdated today Exchanging the board for a Raspberry Pi and transferring the control programme clkboard to the new device is the topic of this bachelor thesis The thesis is written in a way which my former chemistry teacher always emphasised when talking about scientific texts It ought to be comprehensive enough for an interested and informed reader yet not an expert to understand it So I intend to realise a quote which is often falsely attributed to Albert Einstein whose name probably appears in the introduction of at least half of all bachelor theses ever written in physics The quote contains in a nutshell how I personally think physics should be conveyed Tf you can t explain it simply you don t understand it well enough The Raspberry Pi is a single board computer with the size of a credit card It was released in 2011 for the first time 8 2 Actually this was probably never said by Einstein but it rather is a simplification as well as a summary of quotes from Albert Einstein and Ernest R
33. fice if not try 1M sudo dd bs 4M if lt unzipped_ file gt of dev lt SD_card gt dd command does not give any processing information may seem frozen may take some minutes to finish card reader should blink while working o run sudo sync to flush write cash important to safely unmounts SD card e insert SD card into Raspberry Pi boot with screen adapted e first boot allows some configuration o make sure to expand file system to be able to use the complete card memory o configure at your convenience e get MAC address to be able to register Raspberry Pi in the KIP network o cat sys class net eth0 address o register in KIP network recommended host name raspeval xyz where xyz is the running number 26 9 Addendum prerequisites for I2C and 1 wire compile kernel with required settings o make sure gcc compiler is installed on RPi should be installed by default get kernel on RPi with git clone depth 1 https github com raspberrypi linux git recommended get kernel on desktop then copy to SD card or use scp default folder linux this is your build directory in build directory git checkout rpi 3 6 y make mrproper in build directory get config file from current kernel via zcat proc config gz gt config move the new config to your build directory if zcat was executed elsewhere as root edit config to enable additional I2C CONFIG _PC_GPIO m compiled as module 1 wire supported in
34. g or removing a potential These two tasks are exactly the two which the Raspberry Pi s GPIO pins are used for in the WSI system Using a GPIO pin only requires defining it as input or output pin and sometimes connecting it to a pull up resistor so that it does not need to be driven by the chip 9 In the WSI system the used GPIO pins are all defined as output pins One can be used to execute a HICANN reset if necessary another one switches the 1 8 V power supply on or off cf figure 4 11 Edge Signal switching from high to low falling edge or from low to high rising edge 12 A pull up resistor ensures that the pin potential logic level is driven towards a certain value determined by the pull up resistor and an external voltage supply This is necessary when devices connected to the chip require higher power than the chip is able to deliver 3 Execution of the integration This chapter describes the actual steps that were carried out to successfully integrate the Raspberry Pi into the WSI system A step by step guide of the setup for practical use can be found in the clkboard gitviz wiki and is also included in the addendum To comply with the WSI system requirements the following steps have to be carried out e setting up an operating system for the Raspberry Pi to be able to run the clkboard programme e adapting the pin layout of the Raspberry Pi GPIO header in the kernel to match the clockboard pin layout cp figu
35. header using a bit banging module developed by Krzysztof A 19 Bit banging describes the emulation of a hardware interface with the help of software and GPIO interfaces 11 3 Execution of the integration Adamski a developer from the Raspberry Pi community The Raspberry Pi even has a pull up resistor embedded for some pins 21 so that only for the added interface an external pull up resistor had to be soldered onto the clockboard For the first I2C bus only the corresponding drivers provided by the operating system have to be activated This happens by removing the drivers from the modprobe blacklist and adding them to the etc modules file so that they are loaded automatically when the Raspberry Pi is booted Cf step by step guide for details The Raspberry Pi I2C bus is capable of communicating with at least 400 kHz but unfortunately some of the voltage values were transferred incorrectly when using a 400 kHz clock To implement the second I2C interface the kadamski module mentioned above was used The addition of further I2C busses using the kadamski module is realised with the help of Linux s platform devices These provide methods to inform the kernel about hardware which it cannot detect on its own 28 The kadamski module works as an I2C bus driver so it provides a struct which the kernel is able to identify as device Platform device drivers recognise actual devices the device names of which match the ones
36. ill between these two signals Taken from http www robot communicate with so that Ben the other slaves will not be affected After the address has been sent communication will begin The master device can determine if it will write data to SDA to be read by the slave or if it will read data sent by the slave In order to confirm that the transfer of one byte of data has been successful the receiving device will send an acknowledgement signal to avoid data loss in case of unsuccessful communication 14 Typical clock frequencies for I2C communication are up to 100 kHz in standard mode up to 400 kHz in fast mode or even up to 3 4 MHz in high speed mode To transfer a single bit SDA switches to low or high depending on whether a 0 or a 1 is to be transferred and while SDA remains constant the bit is transferred by the clock switching from low to high and back to low again this is one clock pulse 14 The I2C communication can be observed on an oscilloscope by simply connecting the oscilloscope inputs with the two I2C lines During this thesis observations of the signals have been conducted to test if higher clock frequencies than 100 kHz can be used for communication and to look for communication errors These tests will be shortly discussed later on 2 The WSI system emulating the human brain 2 4 2 Overview 1 wire 1 wire busses in contrast to I2C busses use only one communication line The fact that no clock signal is tran
37. ilure or a system crash 18 After unpacking the downloaded Debian image it can be copied onto the SD card 19 Cf step by step guide for details of the SD card setup 13 http elinux org RPi_SD_ cards 50 3 Execution of the integration If connected to a monitor booting the Raspberry Pi with its new operating system for the first time should display a configuration menu In case of not using an extra monitor for the Raspberry Pi but using e g SSH instead the configuration menu can be accessed with the help of the command raspi config as root One should at least expand the file system on the SD card to be able to use all of its space Cf step by step guide for further properties 3 2 Preparation of the kernel for the clkboard programme The central unit of an operating system is its kernel which is situated between the user software and the hardware and manages access to the hardware The Debian Wheezy distribution is based on a Linux kernel which is maintained as open source l I l I ee ND PERS Wl As the kernel is responsible for managing m m 9 hardware access it also defines which ae pin is available for which functionality Si m 1 Therefore the kernel has to be HERNY RESET iir epa 2C configured in such a way that it fulfils 2 ENSOR PWR_SDA x u PIC SCL the requirements of the clockboard pin I l i Bag ee SDA wine E layout cf figure 6 This guarantees om NC
38. ins so they can pass a value 1 or 0 to adherent devices Apart from the initialisation there are two functions which access exactly the pins defined in the clockboard layout These two functions are integrated into the clkboard programme menu so they can be called using the predefined commands when the programme is running 3 4 Compilation of the clkboard programme Once the new functions for GPIO access have been defined and added to the menu file the programme had to be compiled for the Raspberry Pi From previous compilations for the taskit board it was known that the compiling and especially the linking takes some time mostly due to RCF libraries 32 used in the programme So the idea was again to use cross compiling although its setup would be a little tedious Unfortunately again as when trying to cross compile the kernel some errors occurred that could not be resolved immediately It took some fruitless effort until Eric M ller came up with a quite handy trick On the internet he ran into a way to emulate a Raspberry Pi on a host computer but in a way that emulates only the instruction set instead of the whole Raspberry Pi It is based on qemu a processor emulation programme 33 Using this method saved a lot of resources and made it possible to reduce compiling and linking time from at least 20 minutes on the Raspberry Pi to about five to ten minutes on a desktop PC Cf guide in the addendum for how to set up the qemu
39. it requires some time To lose as little time as possible the compilation was started to run over night As it turned out it takes about six hours to complete the kernel compilation on the Raspberry Pi itself Altogether compilation took place some three or four times during the work on the system so the solution of using the Raspberry Pi for compilation and running the compilation over night could be considered as reasonable afterwards 3 3 Configuration of the required interfaces In chapter 2 4 the tasks of the required interfaces were already discussed As stated there the following interfaces need to be configured e two I2C interfaces for access to the PICs and the powerboards e one 1 wire bus for temperature readout e one GPIO pin for the HICANN reset e two further GPIO pins one of them for the external 1 8 V power supply the other one not used yet The pins were already defined in the chapter above when the compilation of the kernel was executed so in the following only the necessary software adaptations are explained 3 3 1 Configuration of the I2C busses The Raspberry Pi provides two I2C interfaces ex factory where one of them is on the wrong header on header P5 which will not be used by the ribbon cable Of course one could change the cable and direct single pins to the other header but this would not be as handy and usable as a single plug for the cable So a second I2C interface was configured on the P1
40. ly sooner or later by proper insulation Another aspect which is already being dealt with is a possible redesign of the main pcb in such a way that it will be possible to directly measure all potentials before and after the HICANN FETs instead of using differential pairs or measuring the potential for adjacent FETs on a single line This will increase measurement stability Furthermore some automation could be introduced for example regarding measurements presently done by hand A suitable programme just needs to read the voltage values several times calculate a mean and a standard deviation to observe fluctuations and should possibly include some security functions to switch off FETs in case of high currents As stated in chapter 2 3 several automation processes with regard to starting stopping and monitoring the whole WSI system are also necessary and will be implemented The Raspberry Pi providing newer and faster hardware than the former taskit board offers solid conditions in this context What is needed above all also for other issues is time which is scarce Some of the issues at stake might be suitable for internships A second Raspberry Pi has been configured in the same way as the first one so it can be integrated into the first WSI system which is already running soon Then the taskit board will not be needed anymore in neither of the systems The second WSI system into which the Raspberry Pi has been integrated during this thesis
41. m to high fluctuations If so they were colour coded The voltages did not show high fluctuations but only the currents did This simply derives from low FET resistances These fluctuations probably arise from noise coupling into the signal as some parts of the system are not ideally insulated yet Furthermore the fluctuations seem to depend on the measurement conditions as the values were measured with far less fluctuations a few days later From the arrangement of the measured values in the table it becomes obvious that the fluctuations are voltage based and not reticle based as the fluctuations occur throughout voltage columns and not throughout reticle lines The reticles provided with error annotations will be investigated during work going beyond this thesis v1 m Cawreni Valles peine v2 calculated as negative derive from suboptimal NETEVE arii measurement points To of reticle 1 of reticle 2 measure all twelve voltages of a reticle two ae reticles per microcontroller 48 inputs would be required As one PIC provides only 32 inputs the total inputs Figure 8 Ways to reduce the number of required PIC inputs to needed for the monitoring measure the voltages dropping over the FETs Taken from the WSI of all voltages have to be aa reduced This is done by measuring the potential before the FETs only once for some voltages and thus retrieving only one potential for two reticles cf figure 8 grey lines
42. n as the guide was explicitly written in a way that not only experts but also beginners in this field can work with it The work on the Raspberry Pi itself allowed first insight into hardware programming and even a little more insight into the possibilities and the importance of using Linux in a scientific environment Getting to understand the WSI system at hardware level alone took quite a while and yet it was only possible to scratch the surface which shows the system s immense complexity Nevertheless it was very interesting and the work on this thesis was always challenging and most of all very instructive Figure 9 Comparison between the new and the old board Raspberry Pi on the left side with a ribbon cable running to one of the clockboards USB power supply and Ethernet cable former taskit board not connected anymore on the right clearly visible size difference 19 6 Outlook There are some features connected to the Raspberry Pi in the WSI system which can and will be improved in future Maybe the greatest issue is time as many possible starting points are known however the necessary manpower is not available The possibility of using a 400 kHz bus for the communication between the PICs on the main pcb and the Raspberry Pi is the most obvious aspect connected to the Raspberry Pi Second the noise coupling into the voltage signals which was observed during the communication test will be reduced permanent
43. njea uaamjeq sduunf vada VeE T vw OOT 0 an yedau s emje ysowje VNVIIA Id 9 3 Measurement results On these three pages the results of the communication test between the Raspberry Pi and the clockboards are presented In the first table the optimum values and the colour codes are listed The second and third table contain the results with corresponding colour coding It is obvious that fluctuations occur voltage dependent and not reticle dependent Some columns do not contain values but only the label diff This differential measurement of the corresponding voltages The voltage VDD12 which occurs in the WSI documentation is not yet connected and thus not measured For VCC33ANA only the values after the FETs are measured The values before the FETs are given 3 3 V for the current calculation which leads to negative current values indicates throughout the measurement The reticles which seem to be defective will be investigated at a later stage To obtain the values every reticle was switched on individually and the values were updated at least ten times As the measurements were not intended to deliver precision values no mean value was calculated but a value approximately in the middle of occurring fluctuations was noted down Table 1 Optimal current values for different voltages and explanation of colour codes 30 9 Addendum Hl PIC 1 10 11 12 13 14 15 17 21
44. oller net articles Speicher Flash ROM 39 Overview sdcard Online SD Association 2013 Cited 7 July 2013 https www sdcard org developers overview 40 The Linux Kernel Introduction Linux Online Linux 2013 Cited 7 July 2013 http www linux org article view the linux kernel introduction 41 Roch Benjamin Kernel computing Wikipedia Online 6 July 2013 Cited 7 July 2013 http en wikipedia org wiki Kernel_ 28computing 29 42 Haas Juergen Linux Unix command mem linux about Online 2013 Cited 7 July 2013 http linux about com library cmd blemdl4_mem htm 43 G ttler Maurice Konzeptoptimierung und Entwicklung einer hochintegrierten Leiterplatte Heidelberg Diploma Thesis 2010 http www kip uni heidelberg de Veroeffentlichungen details php id 2111 44 RPi Kernel Compilation elinux Online 24 June 2013 Cited 7 July 2013 http elinux org RPi_Kernel_ Compilation 45 Using the I2C bus robot electronics Online 30 May 2013 Cited 7 July 2013 http www robot electronics co uk acatalog I2C_Tutorial html 46 Giittler Maurice Verbal information 47 Miiller Eric Verbal information 24 8 List of references 48 Husman de Oliviera Dan Clockboard Layout layout diagram Heidelberg s n 2013 49 Raspberry Pi Amazon Online Raspberry Pi Foundation 2013 Cited 9 July 2013 http www amazon de Raspberry Pi RBCA000 Mainboard 1176JZF S dp BOO8PT4GGC ref
45. res 6 and 7 e configuring the interfaces used for the communication with the WSI system e adapting the clkboard programme from the taskit board to the Raspberry Pi This had to done only once which happened during the work on this thesis 3 1 Installation of the operating system Debian The clkboard programme is laid out to run on top of an operating system so installing one on the Raspberry Pi is the first thing to do The preferred system for this task is Debian as there is a distribution available which is optimised in particular for the Raspberry Pi It can be downloaded from http www raspberrypi org downloads 16 For this thesis the Wheezy 2013 02 09 distribution was used The operating system always runs from an SD card which was found to be reasonable during the development of the Raspberry Pi SD cards deliver high capacity are cheap and fast easily writable and easily changeable in case of damage The link provided below contains a table with reportedly working SD cards and read write speeds The size of the used card should amount to at least 4 GB as it will contain the operating system about 2 GB and should still provide some additional space The filesystem used for the first setup during the integration of the Raspberry Pi into the WSI system was ext4 17 It is recommended to continue working with ext4 or at least another journaling filesystem as journaling provides higher security in case of a power fa
46. sferred during communication requires the definition of another kind of consistent timing Similar to the I2C bus the 1 wire bus is based on the master slave principle so consistent timing is achieved by passing bits every time the master signal reaches a falling edge Transferring 0 or 1 is implemented by the use of different times during which the line is pulled to low potential Using only one line and thus a different communication protocol 1 wire does not reach communication speeds as high as I2C standard mode reaches up to about 16 kHz whereas overdrive mode may reach up to about 140 kHz 15 l wire is often used to monitor sensors such as temperature sensors which is exactly how it is used in the WSI system Overall there are six temperature sensors integrated into the central system main pcb plus clockboards and powerboards cf figure 2 so far four of them situated immediately under the wafer bracket cf figures 1 and 2 to measure the wafer temperatures during runtime and two more sensors outside of the bracket to measure room temperatures More temperature sensors can be found on the boards attached at a later stage but they are monitored in a different way 5 2 4 3 Overview GPIO General Purpose Input Output GPIO pins can be used as the name implies for many different purposes It is possible for instance to use GPIO pins for I2C or if programmed appropriately simply for switching a device on or off by applyin
47. the pin layouts shown in figure 6 and 7 the following changes have to be carried out e W1_GPIO 14 instead of W1_ GPIO 4 for 1 wire e UARTO_DMA 22 25 instead of UARTO_DMA 15 14 to avoid overwriting the 1 wire pin definition GPIO 0 and GPIO 1 are already correctly defined as I2C interface pins cf figure 7 Another aspect which does not concern pin definitions but which is a prerequisite for configuring the second I2C bus later on has to be taken care of at this point In the kernel s config file the CONFIG_I2C__GPIO option has to be set to CONFIG I2C GPIO m in the line already predefined This makes it possible to add the I2C module which will be responsible for the second I2C bus at a later stage When the pin layout and the CONFIG_I2C_GPIO option have been changed in the bcm2708 c file the kernel has to be compiled and moved to the boot directory so that the Raspberry Pi will use the new kernel and the new pins accordingly when it boots Cf step by step guide for details A common way to compile Linux kernels is cross compilation This allows compilation on a host system with much more processing power than the target system can provide Its realisation requires a system specific cross compilation toolchain which ensures that the executable files created on the host system are actually executable on the target system Such a toolchain is necessary because the host processor and the target processor ar
48. utherford The only quote found to be similar originates from How to study physics 1949 by Seville Chapman 35 When you understand it well enough you can explain it easily 2 The WSI system emulating the human brain Under a silver coloured bracket in the middle of the main board main printed circuit board main pcb there is the wafer as the heart of the WSI system cf figure 1 On the wafer there are 48 reticles each of them consisting 2 en ET chips which contain the neuron and synapse circuits EN her as actual electronic images of the biological system 5 In the human brain information processing takes place via electrical signals between the brain cells the neurons These electrical signals arise from potential differences between the inside and the outside of the neuron cells Surpassing a voltage threshold a neuron can emit a spike a voltage peak which will be transmitted to for instance other Figure 1 Wafer Scale Integrated WSI System The Wafer is situated under the silver coloured The currents driving the membrane bracket in the centre taken from BrainScaleS neurons or to muscle cells in the body potentials are controlled by channels homepage 34 which are regulated by each other s conductivity 6 The circuits of the HICANN chips now work in the same way Making use of transistors low voltage resistive area s exponential drain source current dependency on the drain source
49. voltage they cause the same conductance behaviour as membrane currents do To be able to achieve this they of course need a certain power supply which is controlled by the clkboard programme running on a single board computer 2 1 Basic technical setup of the WSI system The wafer mounted under the bracket in the middle of the main board is electrically connected to the surrounding periphery by flexible electrical contacts In the four corners of the main pcb powerboards and clockboards are installed They are essential for the power supply of the HICANN chips The remaining boards installed on the main pcb as well are FPGA boards necessary for communication with the WSI system cf figure 2 and 5 3 A reticle is the largest structure possible to manage during one production step of the wafer 5 4 High Input Count Analogue Neural Network 5 Field Programmable Gate Array Model From bottom Figure 2 of WSI system to Cooling fins wafer with bracket main composition top printed circuit board main pcb four FPGA boards The FETs necessary to gate the supply voltages are situated under the bracket in the middle the PICs are the 24 small black squares distributed in the corners of the main Taken the WSI documentation 5 pcb from 2 The WSI system emulating the human brain In order to function the HICANN chips need twelve different voltages Ten of them are generated on the powerboards the t
50. will be completed in the near future using the Raspberry Pi as power supply interface and together with the further systems to come will be bringing research closer to the understanding of the human brain 20 7 Acknowledgements At the end of this thesis I would like to express my gratitude to several people for their support in many different ways I could never have come this far without those supporting me and thus I would have never been able to reach the end of my studies in the field of physics This thesis as the conclusion of my studies seems a good place to write down my greatest thanks In random order I am deeply grateful to above all my parents and my grandparents for their love and understanding for always supporting me through word and deed and for their absolute encouragement for whatever I plan to do my brother my sister and my friends for being there for me and making the world a bright place every single day Professor Karlheinz Meier for admitting me into the research group and for leaving a lasting impression on me already in the first two semesters lectures on experimental physics Doctor Johannes Schemmel for being my second examinant Maurice G ttler for ever patient support and explanations during my bachelor thesis and my internship Eric Miller for frequent IT assistance and for presenting a solution to every problem possible Alexander Gorel for reading my bachelor thesis and giving valu
51. wo remaining are provided by an external supply as they may need high cannot supply From these power supplies the routed to the HICANN through the main pcb The monitoring of the currents which the powerboards voltages are chips voltages is conducted by 24 microcontrollers the of the microcontrollers monitoring the voltages of two situated on main pcb each reticles The circuits delivering the voltages contain FETs which are needed to switch the voltages on or off The FETs can either close the circuits to apply the voltages or open the circuits to disconnect the voltages There are measuring points before and after the FETs the values of which are monitored by the corresponding microprocessor If the values surpass a certain threshold the microcontroller switches the FETs off so that the reticles have no more voltages 5 The different voltages applied to each reticle can be switched on and off manually as well for instance when starting the system At this point the Raspberry Pi becomes relevant for the system 2 2 Why to exchange the former board with a Raspberry Pi When the first WSI system was set up two years ago the CPU module chosen to run the clkboard programme was a taskit Stamp9G20 The processor comes along with an evaluation board which provides interfaces necessary to communicate with the other parts of the WSI Today this somewhat outdated There are faster processors system hardware s
52. x php Main_ Page 18 Journal File System Linux Online Linux 2013 Cited 7 July 2013 http www linux org article view journal file system 19 RPi Easy SD Card Setup elinux Online 6 May 2013 Cited 7 July 2013 http elinux org RPi_Easy_SD_Card_Setup 20 About linux Online Linux Foundation 2012 Cited 10 July 2013 http www linuxfoundation org about 21 RPi Low Level Peripherals elinux Online 4 July 2013 Cited 7 July 2013 http elinux org RPi_Low level_ peripherals 22 Raspberry Pi Linux github Online April 2013 Cited 25 April 2013 https github com raspberrypi linux 23 Intel Architecture Software Developer s Manual Volume 1 Basic Architecture intel Online Intel 1997 Cited 9 July 2013 http download intel com design intarch manuals 24319001 pdf 24 Intel Architecture Software Developers Manual Volume 2 Instruction Set Reference intel Online Intel 1999 Cited 9 July 2013 http download intel com design intarch manuals 24319101 pdf 25 ARM Documentation arm Online ARM Holdings 2010 Cited 9 July 2013 http infocenter arm com help index jsp topic com arm doc set architecture index h tml 26 crosstool ng crosstool ng Online 24 April 2013 http crosstool ng org 27 Ibanez Luis and Maclean Andrew Cross Compiling for Raspberry Pi Kitware Blog Online 24 December 2012 Cited 7 July 2013 http www kitware com blog home post 4
53. y Pi kontrolliert neuromorphe Hardware Diese Bachelorarbeit beschreibt die Integration eines Raspberry Pi eines kreditkartengro en Einplatinencomputers in das Wafer Scale Integration System WSI des BrainScaleS Projektes Der Raspberry Pi b ndelt alle Schnittstellen die f r den Zugriff auf die umfangreiche Stromversorgung des Systems notwendig sind zu einer einzelnen einfach zu bedienenden Schnittstelle Dazu ersetzte der Raspberry Pi das zuvor f r die Stromversorgung zust ndige Evaluationsboard und bernahm all seine Aufgaben stellt zugleich jedoch leistungsf higere und preiswertere Hardware zur Verf gung Die Integration erfolgte in zwei wesentlichen Schritten Zun chst wurde die Hardware des Raspberry Pi konfiguriert damit anschlie end das Verwaltungsprogramm vom vorherigen Board an die neue Hardware angepasst werden konnte Die Ergebnisse dieser Arbeit sind die erfolgreiche Integration des Raspberry Pi in das WSI System die durch verschiedene Kommunikationstests zwischen dem Raspberry Pi und dem brigen System berpr ft wurde sowie eine praktische Schritt f r Schritt Anleitung zur Einrichtung von Raspberry Pis f r zuk nftige Systeme Table of contents T Introduction usa a ae de ented edie ede Navman Sechaba S Ea 1 2 The WSI system emulating the human brain cccseccceeeceeeeeeeeeeeeeeeeeeeeeeees 2 2 1 Basic technical setup of the WSI system sui2 hc accdsaonkdcorcrtgsteambaksteneetaande bentdecheuseeese
Download Pdf Manuals
Related Search