AN2599/D - NXP Semiconductors
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1. break RRR RR KR RRR RR RR RR RR RK RR RK RK ee e e x else if asm LinState Receiving ASR SWSCIDR Shift RxPin in to Data register variable BRCLR 1 PTA RLBL8 BSET 7 SWSCIDR BRA REND1 RLBL8 BCLR 7 SWSCIDR REND1 Shifted one Keep updating the timer to catch the next bit until all 8 are in SWSCIDR asm code above if BitCount lt 6 AddBitTime BitCount else Whole byte is in TSC1 0x48 set for input capture on falling edge FrameBuffer ByteCount SWSCIDR Save data in buffer BitCount 0 ByteCount if first byte and checkSleep set if checkSleep 1 amp amp ByteCount 1 if FrameBuffer 0 0x00 amp amp Id SLEEP got a sleep command LINSleep 1 If LIN sleep command set the flag LinState Idle ByteCount 0 BitCount 0 Reset process and wait for next break checkSleep 0 reset since check complete If all bytes are received else if ByteCount gt MessageCountTbl MessageIndex amp OxF Dummy is the index for the checksum 24 Generic LIN Driver for MC68HC908QY4 For More Information On This Product Go to www freescale com Freescale Semiconductor Inc AN2599 D Appendix LiNdriver c check how many messages data bytes the frame has Dummy MessageCountTbl MessageIndex amp OxF 1 asm PSHA CLRA CLC LDX Du2. 5 3 ae ip zm ig 47kQ 100 kag 1kQ MN 100 nF v MONITOR 5 12 MODE FRESET o _ 4 e 3 13 70 27 kas IRO B 5 V DEBUG 9 PUSH BUTTON c S1 WI 91V 7 8 47 Kad ZENER me Vsup INH io E e B7 MC68HC908QY4 B3 o LIN gt gt LIN MC3339 mx 16M Rx B5 3 J3 WAKE cc Be 4 T ME 14 v v 5 OSCILLATOR MODUL DEBUG osc1 vA NANI NA 10kQ J5 2 E 4 lkQ 1kQ 1kQ lkQ GND a e P Figure 1 MC68HC908QY4 Schematic rn Cyclone and MultiLink are registered trademarks of P amp E Microcomputer Systems Inc 2 Generic LIN Driver for MC68HC908QY4 For More Information On This Product Go to www freescale com Freescale Semiconductor Inc CodeWarrior Project AN2599 D CodeWarrior Project As mentioned this driver is included in the LIN Kits demo software which can be downloaded free of charge from the Motorola LIN website The driver comes as a Metrowerks CodeWarrior 3 0 project Sample mcp The project structure can be seen in Figure 2 i amp y Include B Tx Confia h B LiNdriver h 1 amp 3 Sources B slave c B vector c 13 Driver source B StartO8 c B MCB8HCS08QY4 C B LiNdriver c B LiNapi c B LiNmsa c a Prim AB hcO8qy4 prm Libs ansi lib Figure 2 CodeWarrior Project Structur
3. ByteCount 0 BitCount 0 RRRKKKKKKKKKAEKEKK END of send only new msgs else ignore this message LinState Idle TSC1 0x48 Set for input capture on falling edge ByteCount 0 end of checking for sleep ID BRK RRR KR RR ke RR heck RRR RRR deck RR ke kk ee e ke e ke ke ke x x else if LinState Sending switch BitCount case 0 Has not started sending yet BitCount TxPIN 0 SWSCIDR FrameBuffer ByteCount AddBitTime break Start bit Load byte to transmit case 9 Has sent all bits in the byte SWSCIDRB is used to store the read value from the LINbus for biterror checking asm Shift Rx pin in to SoftwareSCIDataRegBackup for BitError checking ASR SWSCIDRB BRCLR 1 PTA S9LBL8 BSET 7 SWSCIDRB BRA S9END1 S9LBL8 BCLR 7 SWSCIDRB S9ENDI1 TxPIN 1 Stopbit AddBitTimeH check for Bit Error e g when someone has messed with FrameBuffer if SWSCIDRB FrameBuffer ByteCount BitERROR 1 BitERROR2 1 Set 2 biterror flags 22 Generic LIN Driver for MC68HC908QY4 For More Information On This Product Go to www freescale com Freescale Semiconductor Inc AN2599 D Appendix LiNdriver c BitCount 0 ByteCount Add msg status After data sent from node its status is changed from LIN MSG UPDATED or LIN MSG OVERRUN to LIN MSG OK From
4. 2 freescale semiconductor AN2599 D For More Information On This Product Go to www freescale com
5. Go to www freescale com Freescale Semiconductor Inc AN2599 D developer to balance cost performance and other MCU features for a specific application These numbers show the memory usage for the LIN Kit application Table 3 Driver Performance Metrics Driver Code Resource Required Version Pe foeni Stack eve RAM Bytes ROM Bytes Bytes QY QT bit banged MIN 24 8 per 8 byte 536 4 3 per msg 22 drivers N msg S AN2503 D MAX 9 836 3 per msg 22 E er e ona k 32 412 per 8 byte 1103 driver drivers Y msg 487 API 35 AN2599 D 3 a ENIS Boe 19 1 per 8 byte 1130 a drivers r msg driver API ic U AN2575 p2 9 11 LINQL4 ASM N Sees PRES 172 7 S LINQL4 C N 12 120 20 0 8 per 8 byte msg 4 m 32 838 driver PROP Y 12 per 8 byte msg 420 API m 1 AN2503 D driver assumptions MIN external OSC 9600 bps no SLEEP mode no parity check no bit error checking MAX internal OSC 19200 bps SLEEP parity checking and bit error checking enabled Each also has 7 messages defined using 26 bytes of RAM 2 AN2575 D memory usage data comes from LINO8 driver manual for EY16 Generic LIN Driver for MC68HC908QYA4 For More Information On This Product Go to www freescale com Freescale Semiconductor Inc AN2599 D LIN Driver Features and Performance Comparison Table 4 Driver Performance Metrics No of CPU U
6. LIN MSG OK to LIN MSG NOCHANGE From LIN MSG NODATA or LIN MSG NOCHANGE it will stay the same if ByteCount gt MessageCountTbl MessageIndex amp OxF if LinMsgStatus MessageIndex LIN MSG UPDATED LinMsgStatus MessageIndex LIN MSG OVERRUN LinMsgStatus MessageIndex LIN MSG OK else if LinMsgStatus MessageIndex amp LIN MSG OK 0 LinMsgStatus MessageIndex LIN MSG NOCHANGE end msg status If all bytes are sent or BitError detected abort transmission if ByteCount MessageCountTbl MessageIndex amp OxF BitERROR2 1 LinState Idle Back to waiting for Id again BitERROR2 0 Reset bit error flag TSC1 0x48 Set to IC on falling edge break default In the middle of sending asm ASR SWSCIDRB save the active state for Bit ERROR check BRCLR 1 PTA SLBL8 BSET 7 SWSCIDRB BRA SEND1 SLBLS8 BCLR 7 SWSCIDRB SEND1 Shift Rx pin in to SoftSCIDataRegBackup BRCLR 0 SWSCIDR LBL1 BSET xBIT xPOR BRA END LBL1 BCLR xBIT xPOR END ASR SWSCIDR AddBitTime PSHA LDA TCH1L ADD BitTimeL STA TCH1L LDA TCH1H Generic LIN Driver for MC68BHC908QY4 23 For More Information On This Product Go to www freescale com Freescale Semiconductor Inc AN2599 D ADC BitTimeH STA CH1H LDA TCH1L STA CHIL PULA BitCount
7. Product Go to www freescale com LIN Communication Driver Software Overview Freescale Semiconductor Inc AN2599 D LIN Communication LIN information is sent on the LIN bus in the form of message frames Message frames can be of selectable length but they always have the same format A message frame has from 0 to 8 bytes of data in addition to the 3 bytes of control and data security information Each message frame starts with the master sending out a synchronization break signal synchbreak field followed by a synchronization field and a message identifier field The slave then responds with the data field which can be from 0 to 8 bytes and then the checksum field The synchbreak field identifies the beginning of a new message frame and provides a regular opportunity for the slave to synchronize on the bus clock The synch field contains the information for the clock synchronization and is always 0x55 An acknowledgment procedure for a correctly received LIN message is not defined in the LIN protocol MESSAGE FRAME INTER FRAME HEADER RESPONSE A L LLL JI LT dI INI mE SYNCH SYNCH IDENT DATA DATA A DATA DATA CHECKSUM BREAK FIELD FIELD FIELD FIELD FIELD FIELD FIELD IN FRAME INTER BYTE RESPONSE SPACE SPACE Figure 3 LIN Message Frame The file LINdriver c contains the main functionality for running the driver All LIN communication activities are handled in t
8. change the transmission pin from the default setting PTB2 Ensure that the vectors _ Startup uses vector 0 and TimA1ISR uses vector 5 are set up correctly either in the vector c file or in a parameter file Don t forget to include the file LINdriver h in your application code file LIN Driver Configuration Transmission Pin Configuration Message File Configuration The driver configuration uses two files LINmsg c and Tx Config h which can be edited by the user For detailed information about the configuration files and how to use the driver see the user manual for the MC68HC908QYA driver which is included with the LIN Kits software installation Tx Config h contains the definition of the transmission pin that the LIN driver uses This file must be edited only if you want to change the transmission pin to a pin other than the default PTB2 There are four parameters TxPIN TxPIN DDR TxPORT and TXBIT that must be set They should be defined in symbolic format and must match each other All LIN message frames to be used by the slave node must be defined in the LINmsg c file Generic LIN Driver for MC68BHC908QY4 For More Information On This Product Go to www freescale com Message Buffers Arrays NOTE Freescale Semiconductor Inc AN2599 D LIN Driver Configuration Define one array for each message frame that either requires a response or must be received When defining it is good practice
9. 2503 D does not have an API or autobauding but offers more flexibility and modularity and requires less memory space AN2633 D describes a LIN driver for the QL4 LIN Kit board The main difference between the QY QT series and the QL series MCU is that the QL series uses a slave LIN interface controller SLIC module for handling LIN communication The SLIC module automates many LIN bus functions allowing more of the CPU and memory resources to be used for the user application Other SLIC module features include Automatic LIN frame synchronization e Autobauding up to and well exceeding LIN standard bus speeds LIN error detection LIN message handling Automatic checksum generation and verification for both types ID parity checking The performance data suggests that the QL4 and EY16 MCUS are better suited for CPU intensive applications such as motor control For simpler less time critical applications such as contact monitoring the QY4 should be sufficient MCU selection must be made by balancing cost and resource requirements of CPU and memory The following performance data compares various methods of implementing LIN communications with different hardware and software options All are based on using the same basic application found in the LIN Kits demonstration software modified to accommodate an 8 byte message This data allows the Generic LIN Driver for MC68HC908QYA4 15 For More Information On This Product
10. DATA RECEIVED 10 Generic LIN Driver for MC68HC908QY4 For More Information On This Product Go to www freescale com API Freescale Semiconductor Inc AN2599 D API The API that comes with the driver makes it easier to interface with the driver When using the API it is not necessary to know anything about the communications protocol This section describes the functions and constants used in the API For details about the functions see the user s manual for the MC68HC908QYA driver The manual is included in the LIN Kits software installation The API includes status constants that describe Status of the service calls such as sending or receiving Status of individual messages such as empty updated or overrun Table 1 LIN Service Call Status Constants Constant Description Value LIN OK Service call succeeded without any error 0x00 LIN INVALID ID jesse uc uda node but for the opposite 0x80 LIN NO ID Requested message ID is not defined for this node Ox7F LIN INVALID MODE Service could not be called in the current driver state 0x16 Table 2 LIN Message Status Constants Constant Description Value LIN MSG NODATA fitiaized or roce ye ONU LIN MSG OK Message data OK not overrun and not empty 0x10u LIN MSG NOCHANGE Message data has not changed since last read written 0x02u LIN MSG UPDATED Message data has been updated 0x20u LIN MSG OVERRUN Message da
11. Freescale Semiconductor Inc Application Note AN2599 D Rev 1 2 2004 Generic LIN Driver for MC68HC908Q Y4 By Jenny Felvus and Davor Bogavac Motorola East Kilbride Overview This application note describes a generic slave LIN driver that was developed for the MC68HC908QY4 microcontroller unit MCU It is the driver that comes with the LIN Kits software which is described in Motorola document AN2573 D The complete documentation and software for the LIN Kits evaluation board including this driver can be downloaded from the Motorola LIN website www motorola com semiconductors LIN LIN local interconnect network is a low cost communication protocol often used in automotive applications that do not require the bandwidth and versatility of CAN The LIN bus uses a single data wire and can communicate at speeds up to 20 kbps A LIN network has a single master and multiple slaves so no bus arbitration is required The driver was developed from the LIN Specification Package rev 1 3 and has been evaluated at both 9 6 kops and 19 2 kbps This LIN driver can handle auto baud detection up to 20 kbps and synchronizes automatically without pre trimming the on chip RC oscillator The driver can detect bit and checksum errors It comes with an API which is described in this document and enables easier use The driver uses bit banging a method that uses general purpose I O lines to emulate a serial port Transmission is done by
12. LA FrameBuffer Dummy i load Checksum in to the byte after last AddBitTime8 moved on to next sample point add 8 bit times TSC1 0x50 Output compare no pin action ByteCount 0 BitCount 0 added to make sure only new msgs are sent if defined as F Check if the message only should be sent if updated and the msg has been else if MessageCountTbl MessageIndex amp 0xF0 OxFO amp amp LinMsgStatus MessageIndex LIN MSG NOCHANGE amp amp LinMsgStatus MessageIndex LIN MSG NODATA LinState Sending NoRelevantID 0 reset NoRelevantId since has received a relevant id check how many messages the frame has e g the Id s byte count Dummy MessageCountTbl MessageIndex amp OxF 1 Loop from i 0 to the Id s byte count 1 l checksum for i20 i lt Dummy i Copy data to framebuffer FrameBuffer i MessagePointerTbl MessageIndex i asm Calculate checksum PSHA CLRA CLC LDX Dummy Sloop2 ADC FrameBuffer 1 X DBNZX Sloop2 ADC 0 Generic LIN Driver for MC68HC908QY4 21 For More Information On This Product Go to www freescale com Freescale Semiconductor Inc AN2599 D COMA STA i PULA FrameBuffer Dummy i load Checksum in to the byte after last databyte AddBitTime8 Sample 8 bit times ahead TSC1 0x50 Output compare no pin action
13. LIN_GetMsg LIN_PutMsg LIN_MsgStatus Freescale Semiconductor Inc AN2599 D API This function initializes the LIN driver and makes the driver ready to detect LIN communication Initialization of the driver includes Clearing error flags Clearing the sleep flag Resetting and starting the timer Setting the driver to be in Unsynchronized state LIN Init must be called before any other LIN API function is called It takes no parameters and returns nothing Usage example LIN Init This function is used for getting the data of the message with a certain ID and copying its data into a buffer The parameters for this function are the ID with parity of the message and a pointer to the buffer where to put the message data LIN GetMsg returns a status constant that describes whether the call was successful LIN OK LIN INVALID ID or LIN NO ID If the status is LIN OK the message data was copied into the buffer and the status of the message was changed to show that the message has been read If the status is not LIN OK no data was copied to the buffer Usage example status LIN GetMsg 0x99 MsgData This function is used for copying data to send from a buffer to the message data of the message with a certain ID The parameters for this function are the ID with parity of the message and a pointer to the buffer where the data to send can be found The function returns a status constant that indicates w
14. RRR RRR kk RK kk RR kk kk kk e ke e e x x else if LinState Idle case idle waiting for falling edge break pulse TCHOHBuff TCH1H Save IC value later used to calculate puls length in Possiblesynk TCHOLBuff TCH1L Save IC value later used to calculate puls length in Possiblesynk TSC1 ELSIA 1 TSC1 ELS1B 0 Set for rising edge int trig LinState PossibleSynk Switch state SyncFieldBits 0 RRR RK KR RK KR RK RK RR RR RRR e ke RR RK e x else if LinState PossibleSynk case PossibleSynk waiting for rising edge break pulse asm PSHA LDA TCH1L Check current timer SUB TCHOLBuff Subtract timer value saved in Idle state STA BreakL store difference in BreakL BHI 1b13 LDA TCH1H DECA BRA 1b133 1lb13 LDA TCH1H Calculate pulse length between falling and rising edge 1b133 SUB TCHOHBuff Subtract timer value saved in Idle state STA BreakH store difference in BreakH LDA TCH1L PULA Check if longer than 11 bit times BreakLimitH val found in Unsyncronized if BreakH gt BreakLimitH LinState Syncbreak It has found the syncbreak else if BreakH BreakLimitH amp amp BreakL gt BreakLimitL LinState Syncbreak If yes It has found the syncbreak else LinState Idle If No did not find syncbreak look again TSCl_ELS1A 0 26 Generic LIN Driver fo
15. TCHIL LDA TCH1H ADC BitClockReload8H STA TCH1H LDA TCH1L Generic LIN Driver for MC68BHC908QY4 For More Information On This Product Go to www freescale com 29 Freescale Semiconductor Inc AN2599 D STA TCH1L PULA AA kkk kk kkk RRR RR RR RK RR RR RRR RK de ke ke ke RK e e x This function adds 1 bit time void AddBitTime void asm PSHA LDA ADD STA LDA ADC STA LDA STA PULA Bi TC Bi TC BOR KR KK RR RR RR RR RK RRR RR kkk kk kk kk kk RK kk kk kkk e ke ke ke RK This function adds 1 5 bit times void AddBitTimeH void asm PSHA LDA TCH1L ADD HBitTimeL STA TCHIL LDA TCH1H ADC HBitTimeH STA TCH1H LDA TCHIL STA TCHIL PULA 30 Generic LIN Driver for MC68HC908QYA4 For More Information On This Product Go to www freescale com Freescale Semiconductor Inc AN2599 D Generic LIN Driver for MC68BHC908QY4 31 For More Information On This Product Go to www freescale com Freescale Semiconductor Inc How to Reach Us Home Page www freescale com E mail support freescale com USA Europe or Locations Not Listed Freescale Semiconductor Technical Information Center CH370 1300 N Alma School Road Chandler Arizona 85224 1 800 521 6274 or 1 480 768 2130 support freescale com Europe Middle East and Africa Freescale Halbleiter Deutschland GmbH Technical Information Center Schatzbogen 7 81829 Muen
16. age is only sent if it has been updated since it was last read written Example U8 volatile near MessageCountTbl 0x03 OxF5 0x19 This example shows that the message with ID 0xD8 in IdTbl above is 2 bytes long plus checksum and defined for sending Please remember that the order of the messages must be consistent in all previous tables All arrays except message buffers must be defined as described in the bullets above The data type U8 frequently used in the driver and its API is defined as an unsigned 8 bit number For this compiler U8 is defined as unsigned char Generic LIN Driver for MC68HC908QYA4 5 For More Information On This Product Go to www freescale com Freescale Semiconductor Inc AN2599 D Special Considerations The driver uses only timer channel 1 Using channel 0 for other application functions is permitted but modifying the timer modulus register is prohibited because the driver assumes that the overflow value of the timer is set to OxFFFF No interrupt service routine ISR is allowed except the one used by the LIN driver during communication This is because the Tx and Rx pins are software controlled and must have a predictable latency for the ISR response The OSCTRIM register can be set to any value but it is recommended that it be set to 0 This is to trim the oscillator to its maximum speed which guarantees the highest possible bus speed This setting enables the applicatio
17. age with ID 0x3C and with the first data byte 0x00 The driver will discover a sleep mode message and set the sleep flag LINSleep The method of putting the module in sleep mode is hardware design dependent and is therefore handled by the application code Generic LIN Driver for MC68HC908QY4 For More Information On This Product Go to www freescale com Freescale Semiconductor Inc AN2599 D LIN Driver Features and Performance Comparison LIN Driver Features and Performance Comparison On the Motorola LIN web site http motorola com LIN you can find several different LIN driver implementations for the MC68HC908QY4 and other MCUs This section will describe the difference between this driver and other LIN driver implementations specifically the LIN slave driver described in AN2503 D which is also a timer based driver The driver in this application note AN2599 D was designed to handle autobaud detection and have the ability to run a hardware pulse width modulator PWM on one timer channel The driver is capable of sending data with only 1 bit time between every data byte The autobaud detection would be required fora ROM device The hardware PWM is required if the application needs a jitter free PWM such as for backlight intensity control DC motor speed etc Additionally one difference between this driver and the AN2503 driver is that this one has an API which can make application development easier The driver in AN
18. ate Syncronised asm INC SyncFieldBits Increase SyncFieldBits by 1 when SyncFieldBits 2 or 3 RRR RK KKK RR RK RK RK RK KK e ke e ke RK Generic LIN Driver for MC68HC908QY4 27 For More Information On This Product Go to www freescale com Freescale Semiconductor Inc AN2599 D else if LinState Syncronised AddBitTimeH Add 1 5 bit time TSC1 0x50 Output compare no pin action LinState Receiveld BitCount 0 Id 0 RRR k KKK RK RK de ke RK ek ke e e ke e ke else if LinState ReceivingWFS WFS WaitForStartbit AddBitTimeH Add 1 5 bit time TSC1 0x50 Output compare no pin action LinState Receiving BRK RRR KR RR KR RR RR RR RK RK ke ke RK e e x else if LinState Unsyncronized Unsyncronized state Untrimmed RC Osc BitCount BitCount var used to keep falling edge IC count if BitCount gt SyncBitCount Now it knows how long 2bit times are BreakLimitH BreakH BreakLimitL BreakL asm PSHA PSHX LDX BreakH LDA BreakL ASLA ROLX multiply by 2 ASLA ROLX multiply by 2 so X A has now 2bit times x 4 ADD BreakL STA BreakLimitL BreakLimitL has now the LSB of 10 bit times TXA ADC BreakH STA BreakLimitH BreakLimitH has now the MSB of 10 bit times LSR BreakH ROR BreakL divide by 2 to get 1 bit time LDA BreakLimitL ADD BreakL STA BreakLimitL B
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20. d Next Synchronized state is entered to wait for the start bit of the ID byte The timer changes to output compare 1 5 bit times later with no pin action and the driver enters ReceivelD state Generic LIN Driver for MC68HC908QYA4 For More Information On This Product Go to www freescale com 6 ReceivelD 7a ReceivingWFS Receiving 7b Sending Freescale Semiconductor Inc AN2599 D LIN Communication In ReceivelD state all 8 bits of the ID are caught and the ID is checked to determine what kind of ID it is If this ID is a sleep ID the sleep flag is set e lf this ID is not defined for this node the driver returns to Idle state Ifthe ID is relevant the routine must determine whether the ID instructs the slave to either receive or send Recall that the send when updated option indicates that the ID should be ignored unless its message data has been updated since the last time it was sent If the ID is for receiving the timer is changed to input capture on a falling edge The driver enters ReceivingWFS state and waits for the start bit of the first byte Then in Receiving state the received data byte is stored in a temporary buffer Only the 8 data bits in the byte field should be saved not the start and stop bits After each received byte there is a check to see whether all bytes are received If not ReceivingWFS is entered again to catch the start bit in the next byte The driver will switch bet
21. e The LIN driver consists of five files LINdriver c contains the main driver code LINapi c contains all the driver API functions LiNmsg c where all LIN message frames are defined LiNdriver h header file for the driver Tx Config h header file containing the transmission pin definitions The driver also requires these standard files and libraries start08 c MC68HC908QYA h MC68HC908QY4 c ansi lib vector c defines the interrupt vectors needed for the project hc08qy4 prm defines memory locations ROM and RAM in the MCU Metrowerks and CodeWarrior are registered trademarks of Metrowerks Inc a wholly owned subsidiary of Motorola Inc Generic LIN Driver for MC68HC908QY4 3 For More Information On This Product Go to www freescale com Freescale Semiconductor Inc AN2599 D How to Use the Driver The easiest way to begin developing a new application is to use the sample project that comes with the LIN Kits demo board To do this simply replace the slave c file from the LIN Kits sample application with your own application code You can also begin developing by creating a new project in a CodeWarrior development environment and adding the five LIN driver files from the sample application When creating a new application you must First define the messages that you want to use in the LINmsg c file as described in LIN Driver Configuration In the header file Tx Config h you can
22. er State State Exp Revision Revision 1 4 Functions LIN908QY4 Driver History Use the RCS command log to display revision history information ROR KKK RK k k k RRR KK RR heck k k KR KR ck k k RRR RR RR k k k k k k k k RR k k RRR RR RR k k RR kk k k k RR k k kk k k KR k k Includes include lt MC68HC9080Y4 h gt include LINdriver h include Tx Config h pragma DATA SEG SHORT DATA ZEROPAGE 18 Generic LIN Driver for MC68HC908QYA4 For More Information On This Product Go to www freescale com x C 0 vola vola vola vola vola vola vola vola vola vola vola vola U8 vola tile near tile near tile near tile near tile near tile near tile near tile near tile near tile near tile near tile near Freescale Semiconductor Inc AN2599 D Appendix LINdriver c Global Variables TCHOLBuff TCHOHBuff BreakH BreakL BreakLimitH BreakLimitL BitTimeH BitTimeL HBitTimeH HBitTimeL LinState MessageIndex SyncFieldBits tile BitCount ByteCount SWSCIDR SWSCIDRB Id FrameBuffer 9 FrameTimeOut NoRelevantID BitClockReload8H BitClockReload8L checkSleep volatile LINERRORSTR LinERROR Look in the header file to see what this is Prototypes void AddBitTime8 void void AddBitTimeH void void AddBitTime void BORK OR RK RR KR RRR KR RK RR heck kkk
23. he timer channel 1 ISR TimA1ISR Timer channel 1 is configured for input capture so when activity on the LIN bus is detected there is an interrupt and TimA1ISR is entered In TimA1ISR the driver goes through several states The flow of these states is described in TimA1ISR States and illustrated in Figure 4 Unsynchronized Idle PossibleSync SyncBreak Synchronized ReceivelD Either a ReceivingWFS then Receiving OR b Sending D Ord 0 mc Generic LIN Driver for MC68HC908QYA4 7 For More Information On This Product Go to www freescale com Freescale Semiconductor Inc AN2599 D TimA1ISR States 1 Unsynchronized 2 Idle 3 PossibleSync 4 SyncBreak 5 Synchronized This section describes the different states that the driver enters when in TimA1ISR The driver is initially in Unsynchronized state where the LIN bus is sampled The timer is used to measure the time between two falling edges and to calculate how long one bit time is The bit time value is saved each time that it is calculated to be shorter than the previous time This procedure is repeated a certain number of times The number of repetitions defined by the constant SyncBitCount should be set large enough so that at least two falling edges in the synch field are detected Worst case would be if measurement begins just before the ID byte In this case three edges would appear in every byte Adding the ID byte checksum byte and max
24. hether the call was successful LIN OK or not LIN INVALID ID or LIN NO ID When the message data has been updated the message status will be changed to show that the message has been written The call itself does not send any data on the LIN bus however the next time the master requests this ID the updated data will be sent Usage example status LIN PutMsg 0x1A MsgData The function returns the current status of the specified message It takes the message ID as a parameter If the ID is not defined the function will return LIN NO ID Usage example msgstatus LIN MsgStatus 0x1A Generic LIN Driver for MC68HC908QYA4 13 For More Information On This Product Go to www freescale com Freescale Semiconductor Inc AN2599 D LIN_GotoRun LIN_Wakeup Error Handling Sleep Mode This function changes the current driver state from SLEEP to RUN by clearing the LINSleep flag If the driver state is RUN LINSleep 0 the function does nothing It takes no parameters and returns nothing Note This function should be called before calling LIN Wakeup Usage example LIN GotoRun This function issues the LIN wake up signal which consists of eight dominant bits including start bit followed by at least four recessive bits including the stop bit and a recessive pause No wake up signal is sent if the driver is in SLEEP state the LINSleep flag is set because the LIN GotoRun function should have been cal
25. imum number of data bytes equals 10 bytes In that case SyncBitCount must be set to 3 edges x 10 bytes 3 1 synchbreak edge and 2 synch byte edges 33 So after repeating the sampling 33 times and always keeping the shortest time the accurate time corresponding to two bit times should have been calculated After synchronizing the driver enters Idle state In this state the timer will trigger on the input capture of a falling edge In Idle state the timer value is saved and the timer changes to trigger on a rising edge Then the driver enters PossibleSync state The saved timer value is used in PossibleSync to calculate the pulse length between a falling and a rising edge and to check if the pulse length is longer than 11 bit times If the pulse length is longer than 11 bit times a valid synchbreak is found Therefore the timer is changed to trigger on a falling edge and the driver enters SyncBreak state If no synchbreak was found the pulse length is not longer than 11 bit times the driver returns to Idle state to wait for a synchbreak In SyncBreak state several bit times are calculated for later use The synchronization field which is characterized by five falling edges within eight bit times the data 0x55 inside a byte field is used To calculate and save bit time x 8 start at the synchronization field s first falling edge and count four edges From this calculation bit time and bit time x 1 5 can be calculated and save
26. inState Idle TSC1 0x48 Set for input capture on falling edge NoRelevantID Count how many Ids sent out but NOT relevant to this node ByteCount 0 Check if master or slave task Id is relevant for this node and is a To Receive Id else if MessageCountTbl MessageIndex amp 0xF0 0x10 LinState ReceivingWFS TSC1 0x48 Set for input capture on falling edge NoRelevantID 0 reset NoRelevantId since has received a relevant id ByteCount 0 BitCount 0 else if MessageCountTbl MessageIndex amp 0xF0 0 Id is relevant for this node and is a To Send Id LinState Sending NoRelevantID 0 reset NoRelevantId since has received a relevant id check how many messages the frame has e g the Id s byte count Dummy MessageCountTbl MessageIndex amp OxF 1 Loop from i 0 to the Id s byte count 1 l checksum for i20 i lt Dummy i MessageCountTbl MessageIndex amp OxF 1 Copy data to framebuffer FrameBuffer i MessagePointerTbl MessageIndex i 20 Generic LIN Driver for MC68HC908QYA4 For More Information On This Product Go to www freescale com databyte ignore updated Freescale Semiconductor Inc AN2599 D Appendix LlINdriver c asm Calculate checksum PSHA CLRA CLC LDX Dummy Sloop ADC FrameBuffer 1 X DBNZX Sloop ADC 0 COMA STA i PU
27. kk kk k k kk k k k k k k k k k k k k k k k k k k RR k k ck k k k k k k ckckckckck ck ck k k k RR k k ck ck kk kk ee ek interrupt void TimAlISR void U8 if Dummy i LinState Receiveld asm Shift Rx into Id variable ASR Id BRCLR 1 PTA LBL8 BSET 7 Id BRA END1 LBL8 BCLR 7 Id ENDI1 Finished shifting one Keep updating the timer to catch the next bit until all 8 are in Id asm code above if BitCount 6 AddB Bitc else itTime ount got the whole Id checkSleep 0 Generic LIN Driver for MC68HC9080Y4 19 For More Information On This Product Go to www freescale com Freescale Semiconductor Inc AN2599 D if Id SLEEP sleep defined in LINdriver h should be 0x80 checkSleep 1 Set flag to make sure checking if first databyte is 0x00 LinState ReceivingWFS TSC1 0x48 Set for input capture on falling edge NoRelevantID 0 reset NoRelevantId since has received a relevant id ByteCount 0 else LINSleep 0 stay awake BitCount 0 Reset BitCount and MessageIndex MessagelIndex OxFF for i 0 i lt No of Ids i loop through identifier table to check if Id exist in the table i e is relevant to this node if Id IdTbl i MessageIndex i If found save away index if MessageIndex OxFF Found no id for this node keep waiting L
28. led before To wake up the LIN bus the bus signal is held low for 8 bit times then set high again After waiting at least 4 bit times can be up to 64 bit times there should be a synchbreak and communication should resume The driver will resume from Idle state The function takes no parameters There are two possible return values either LIN OK the wake up signal was successfully sent or LIN INVALID MODE the driver state is SLEEP Usage example status LIN Wakeup The driver detects two types of errors in the LIN message bit errors and checksum errors A bit error is detected when a recessive bit is sent and a dominant bit is detected on the bus This indicates that the bus is controlled by another node or is shorted to GND In either case the transmission is aborted and the BitERROR flag is set The receiving node will calculate the checksum by doing a modulo 256 sum of the message data bits This checksum must match the received checksum If not the message is corrupt and the receiving node will set the ChecksumERROR flag and ignore the received data The error flags are single bit field values that are set by the driver setto 1 and cleared by the application code set to 0 The flags are global and can be polled in the application to check whether there is an error during send or receive The LIN protocol version 1 3 includes a sleep mode which reduces system power consumption The global SLEEP command is a mess
29. mmy loop Calculate checksum ADC FrameBuffer 1 X DBNZX loop ADC 0 COMA STA l PULA if i FrameBuffer Dummy If calculated Checksum received checksum Load data to variables for i 0 i lt Dummy i MessagePointerTbl MessageIndex i FrameBuffer il else LinState Idle ByteCount 0 BitCount 0 Reset process and wait for next break ChecksumERROR 1 Error Set ChecksumERROR flag Added msg status set appropriate status for received message After message received at node status is changed to LIN MSG UPDATED if previously it was in LIN MSG NODATA LIN MSG OK or LIN MSG NOCHANGE If it was in LIN MSG UPDATED it is changed to LIN MSG OVERRUN If it was in LIN MSG OVERRUN it will stay the same if LinMsgStatus MessageIndex LIN MSG OK LinMsgStatus MessageIndex LIN MSG NODATA LinMsgStatus MessageIndex LIN MSG NOCHANGE LinMsgStatus MessageIndex LIN MSG UPDATED else LinMsgStatus MessageIndex LIN MSG OVERRUN end msg status add End if all bytes received else All bytes are not received yet Generic LIN Driver for MC68HC9080Y4 25 For More Information On This Product Go to www freescale com Freescale Semiconductor Inc AN2599 D LinState ReceivingWFS Switch state to catch the next expected start bit BRK RR KR RK KR RR RR
30. ms any and all liability including without limitation consequential or incidental damages Typical parameters which may be provided in Freescale Semiconductor data sheets and or specifications can and do vary in different applications and actual performance may vary over time All operating parameters including Typicals must be validated for each customer application by customer s technical experts Freescale Semiconductor does not convey any license under its patent rights nor the rights of others Freescale Semiconductor products are not designed intended or authorized for use as components in systems intended for surgical implant into the body or other applications intended to support or sustain life or for any other application in which the failure of the Freescale Semiconductor product could create a situation where personal injury or death may occur Should Buyer purchase or use Freescale Semiconductor products for any such unintended or unauthorized application Buyer shall indemnify and hold Freescale Semiconductor and its officers employees subsidiaries affiliates and distributors harmless against all claims costs damages and expenses and reasonable attorney fees arising out of directly or indirectly any claim of personal injury or death associated with such unintended or unauthorized use even if such claim alleges that Freescale Semiconductor was negligent regarding the design or manufacture of the part e LF
31. n to take full advantage of the auto baud detection feature Manipulating the Tx pin outside of the driver will most likely cause a bit error and aborted transmission Special care should be taken when using read modify write instruction sequences such as LDA STA instruction combinations on the port that contains the Tx pin because this could write the wrong value if a LIN interrupt occurs between the two instructions Either disable interrupt while using read modify write not recommended or use instructions that you know will compile to BSET or BCLR The Rx pin PTA1 is hardware protected from manipulation because it is set as an input capture If using MONOS tools for debugging do not manipulate pin PTAO because that would disturb communication with the tool When updating send or receive variables larger than 8 bits in an 8 bit MCU special considerations must be taken to guarantee atomic operation The normal approach is to inhibit interrupts while updating the 8 bit variable This approach can be used but it is highly recommended to update only one variable at a time Also the interrupt should be enabled between the updates Observing these recommendations ensures that communication timing will not be disturbed When updating 8 bits or less atomic operation at the frame levelis guaranteed because frame data is copied to from the frame buffer inside the ISR Generic LIN Driver for MC68HC908QYA4 For More Information On This
32. or receive a regular LIN bus frame of maximum length containing 8 bytes of data 124 bits The required LIN message budget of 4096 is also taken into account For Reference T frame 9615 bps 18 055 ms T frame 19230 bps 9 028 ms For received data command messages 0x55 data and checksum used for worst case ISR load EY16 CPU usage information was measured based on 4 9152 MHz CPU frequency then recalculated for a 3 2 MHz CPU frequency Generic LIN Driver for MC68HC908QYA4 17 For More Information On This Product Go to www freescale com Freescale Semiconductor Inc AN2599 D References Motorola See the Motorola website http motorola com semiconductors and the Motorola LIN website http motorola com LIN for these documents MC68HC908QY QT Data Sheet Motorola MC68HC908QY4 D AN2503 D Slave LIN Driver for the MC68HC908QT QY MCU AN2633 D LIN Drivers for SLIC Module on the MC68HC908QL4 AN2573 D LIN Kits LIN Evaluation Boards AN2575 D MC68HC908EY16 ESCI LIN Drivers Other References LIN Specification Package Rev 1 3 Dec 12 2002 LINO8 Driver User s Manual Rev 1 1 March 13 2001 Appendix LINdriver c BORK RRR RR RK kk kk kk kk kk heck RR kk ke k k k k k k RK k k k k k k k k k RRR RR k k k k k k k RRR RR RR ck ck ck ck k k ck RR RR RRR RR RK RR k k Copyright C 2004 Motorola Inc All Rights Reserved Filename SRCSfile LINdriver c v Author SAuthor r57404 Locker SLock
33. r MC68HC908QY4 For More Information On This Product Go to www freescale com Freescale Semiconductor Inc AN2599 D Appendix LiNdriver c TSC1 ELS1B 1 Set for falling edge int trig RRR RRR KR RK deck RR RR kk e e ke de ke ke e e x Case Syncbreak Start at syncfield first falling edge count 4 edges and calculate and save Bit time Bit time x 1 5 and x 8 else if LinState Syncbreak if SyncFieldBits 0 TCHOHBuff TCH1H save away timer values TCHOLBuff TCH1L else if SyncFieldBits 4 now calculate how long time has passed asm PSHA LDA TCH1L SUB TCHOLBuff subtract saved timer value from new timer value STA BreakL difference TCHIL TCHOLBuff is stored in BreakL BHI lblsb5 Branch if Higher LDA TCH1H DECA BRA lblsb55 lblsb5 LDA TCH1H lblsb55 SUB TCHOHBuff Calculate time between 4 falling edges STA BreakH MOV BreakH BitClockReload8H MOV BreakL BitClockReload8L save 8 x bit time value LSR BreakH ROR BreakL LSR BreakH ROR BreakL LSR BreakH ROR BreakL BreakL BreakH gt gt 3 ie 8 LDA TCH1L Read needed not to stall TCH1 IC MOV BreakH BitTimeH MOV BreakL BitTimeL save bit time value LSR BreakH ROR BreakL divide by 2 to get 1 2 bit time LDA BitTimeL ADD BreakL STA HBitTimeL LDA BitTimeH ADC BreakH STA HBitTimeH Calculate 1 5 x Bit time value and save in HBitTimeL H PULA LinSt
34. reakLimitL 11 bit times LSB LDA BreakLimitH ADC BreakH STA BreakLimitH BreakLimitH 11 bit times MSB PULX PULA LinState Idle Ready to look for SyncBreak if SyncFieldBits 0 Loop to save away current timer values TCHOHBuff TCH1H Start by saving away timer values TCHOLBuff TCH1L 28 Generic LIN Driver for MC68HC908QYA4 For More Information On This Product Go to www freescale com Freescale Semiconductor Inc SyncFieldBits AN2599 D Appendix LiNdriver c Calculate how long time has passed to find out the time between 2 falling edges else if SyncFieldBits 1 asm PSHA PSHH PSHX LDA TCH1L SUB TCHOLBuff TAX BHI lblusi LDA TCH1H DECA BRA lblus2 lblus1 LDA TCH1H lblus2 SUB TCHOHBuff PSHA PULH CPHX BreakH BCC endus STX BreakL PSHH PULA STA BreakH endus LDA TCH1L PULX PULH PULA Dummy TSC1 CH1IF SyncFieldBits 0 TS C1 0 read timer Calculate time between 2 falling edges Compare to previously captured value Branch if value in memory is bigger store if lower release TCH1L H Read byte and reset CH1F in case of a pending interrupt ROR KR kkk kkk kk kkk kkk kk RR kkk kk kk kk kk kk kk kk kkk kk ke ke kk This function adds 8 bit times void AddBitTime8 void asm PSHA LDA TCH1L ADD BitClockReload8L STA
35. sage Ve Std Interrupts LINBus CPU Speed ed API Msg Frame Speed MHz 2 8 byte msg Average Peak QY QT bit banged 9 615 Pos fe drivers N 111 Rx 193 us DUE 29 rx AN2503 D 19 230 Pe 40 tx d o F QY QT bit banged 9 615 sh nn drivers Y 97 Rx i 272 us DB 38 rx AN2599 D 19 230 44 tx EY16 ESCI 9 615 e Ee drivers 3 2 9 APO og N 12 39 us n calculated 4 rx ul AN2575 D 19 230 7 tx 0 3 rx LINQL4 ASM 2015 0 2 tx N 34 us AN2633 D 0 5 rx 19 230 0 5 tx 0 4 rx o LINQL4 C BB 0 4 tx N 2 3 2 61 us O AN2633 D 0 8 rx 19 230 08 tx 0 8 rx LINQL4 API 85 0 8 tx Y 123 us AN2633 D 1 6 rx T9209 1 7 tx A 9 CPU usage represents the time spent in the communication ISR s vs time spent doing other tasks API functions and handling performed outside of the ISR s is not counted against this metric Average value is reported as a percentage of times but is still a function of CPU speed as LIN communications is asynchronous to CPU operations CPU usage numbers are approximate Peak time represents the longest single interrupt which must be processed From LINO8 Driver User s Manual CPU performance is calculated as L T active T frame 100 where Lis the CPU load in percent T active is the amount of CPU time expended in executing the driver code during T frame T frame is the amount of time required to transmit
36. software toggling the data line in the proper sequence Reception is done by using the output compare function to periodically sample the bus state NOTE With the exception of mask set errata documents if any other Motorola document contains information that conflicts with the information in the device data sheet the data sheet should be considered to have the most current and correct data This product incorporates SuperFlash technology licensed from SST lto 2 freescale For More Information On This Product semiconductor Go to www freescale com Freescale Semiconductor Inc 2004 All rights reserved Freescale Semiconductor Inc AN2599 D Hardware The LIN Kits demo board consists of an MC68HC908QY4 MCU and a LIN interface The LIN interface consists of an MC33399 LIN transceiver and a 5 V regulator LT1121 chip The board can be programmed using either the RS 232 MONOS interface or a Cyclone MultiLink tool The user may choose which GPIO port is used as the LIN transmit pin but the default configuration is port B pin 2 PTB2 The LIN receive pin must be port A pin 1 PTA1 because this is the timer channel 1 pin The board requires one jumper J3 for running an application and three jumpers J2 J4 and J5 if using the RS 232 MONOS interface to program debug The jumper J2 is not required when using a MultiLink Cyclone tool to program Vpat gt Paral e 8 LT1121 1 e 5V b d
37. ta has not been read and was overwritten 0x04u Generic LIN Driver for MC68BHC908QY4 For More Information On This Product Go to www freescale com 11 AN2599 D LIN Message Status Flow Previous Status LIN MSG OK LIN MSG NOCHANG LIN MSG NODATA E LIN MSG UPDATED Freescale Semiconductor Inc The message status is stored in the table called LinMsgStatus When the LIN driver is initialized all messages have the status LIN MSG NODATA Message status will change when the message is being sent received or Figure 5 illustrates the change of status after PutMsg is called or a message is received at a node New Status PutMsg is called OR A message is received at the node LIN MSG UPDATED LIN MSG OVERRUN LIN MSG OVERRUN Previous Status IN MSG OVERRUN stays the same Figure 5 Status Change After PutMsg is Called Figure 6 illustrates the change of status after GetMsg is called or data is sent from a node New Status LIN MSG OK LIN MSG UPDATED LIN MSG OVERRUN LIN MSG NODATA GetMsg is called OR Data is sent from the node LIN MSG NODATA LIN MSG NOCHANGE LIN MSG OK stays the same gt LIN MSG NOCHANGE Figure 6 Status Change After GetMsg is Called Generic LIN Driver for MC68HC908QYA4 For More Information On This Product Go to www freescale com API Functions LIN_Init
38. to include the frame ID in the name for example MessageOxID where ID is the message identifier in hexadecimal with the parity bits included The data field can be 2 4 or 8 bytes long The array size should equal the number of data bytes for example U8 volatile MessageOxD8 2 After all messages that will be recognized by the node have been defined you must include them in a number of arrays The order of the messages must be consistent in all arrays The following three arrays are required MessagePointerTbl Consists of pointers to all message buffers defined according to Message Buffers Example U8 volatile MessagePointerTbl Message0xD8 Message0x99 IdTbl Contains all IDs relevant to this node It is very important that the ID includes the parity bits The order of the messages must be the same as in MessagePointerTbl and MessageCountTbI Example U8 const near IdTbl 0xD8 0x99 MessageCountTbI Defines the length in bytes of the message data for each message and shows whether the message should be sent or received by the slave The least significant half byte LSHB is the number of data bytes in the frame plus the checksum For example for Message0x20 4 then LSHB 5 The most significant half byte MSHB should be set to 1 for master tasks slave receiving or 0 for slave tasks slave sending It could also be set to F send when updated which means that the mess
39. ween these two states until all bytes are received When all bytes are received the checksum is calculated and compared with the received checksum to see whether the received data is correct If not the ChecksumERROR flag is set If all data is correct the data is saved in the message buffer the message status is updated and the driver returns to Idle state If the ID is for sending or if the ID is defined for send when updated and the message is updated the message data and a calculation of the checksum will be copied to a frame buffer In Sending state all data bytes are sent including start and stop bits Bit errors are dealt with if needed the message status is updated and the driver finally returns to Idle state where it waits for a synchbreak and a new ID Generic LIN Driver for MC68HC908QYA4 9 For More Information On This Product Go to www freescale com Freescale Semiconductor Inc AN2599 D START TimA 1ISR CALCULATE BIT TIME Y WIATING FOR FALLING EDGE BREAK PULSE WAITING FOR RISING EDGE BREAK PULSE FOUND SYNCHBREAK NO YES Y CALCULATE BIT TIMES FOR LATER USE WAIT FOR START BIT OF ID BYTE Y UPDATED YES Figure 4 Interrupt Flow Chart CONFIGURED FOR SEND WHEN UPDATED YES WAIT FOR START BIT Y RECEIVE ONE BYTE YES ALL
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