Microcontrollers ApNote AP2922
Contents
1. TXIE 0 bi dl LDLC 8 L LTransmit data frames Lidentifier Standard CAN MO 11 bit ID LMO number Table 3 3 Local variables Type Corresp Task input parameter ee char char 1 29 bit ID 0 11 bit ID oop pi o long dir unsigned P4 holds specified DIR bit char 1 transmit data frames 0 receive data frames char txie unsigned holds specified TXIE bit char 1 transmit interrupts enabled 0 transmit interrupts disabled rxie unsigned holds specified RXIE bit char 1 receive interrupts enabled 0 receive interrupts disabled int dummy_idptr unsigned is loaded with id_ptr_16x i 1 in the procedure int which is the Lower Arbitration Register Used to load this register Semiconductor Group 11 of 33 AP2922 05 97 SIEMENS C CAN Driver Routines for the C166 family Additional Information Before being able to transmit or receive any frame the message objects that are going to be used must be configured which is done with this procedure Only message object numbers between 1 and 15 are accepted The procedure has to be called for each message object separately The procedure performs the following actions e Check if the specified message object is valid number between 1 and 15 e Load the Upper Arbitration Register and the Lower Arbitration Register with the specified identifier value e Load the Messag2. The example programs are all following the same structure The parts that are important for the use of the CAN driver routines are now discussed Please note that the target of the example programs is not to execute an ingenious program but to show how to work with the CAN driver routines 12 2 define statements The example programs use some constants for a better overview The following table describes the most important constants Semiconductor Group 26 of 33 AP2922 05 97 SIEMENS C CAN Driver Routines for the C166 family Table 12 2 Constants used in the example programs Defined constant Meaning in the example program MY_IEN_B Used to generally enable 1 or disable 0 interrupt to the CPU via the bit IEN in the PSW register C_VALUE Used to enable the interrupt from the CAN module CPU side and set it to a certain interrupt priority level This constant will be used to load the XPOIC register If XPOIC contains 0 the CAN module interrupt is disabled Used to specify the input parameter P1 of procedure init_can 16x Used to specify the input parameter P2 of procedure init_can_16x Used to specify the input parameter P3 of procedure init_can_16x el Used to specify the input parameter P4 of procedure init_can_ 16x Used to specify the input parameter P2 of procedure def_mo_16x Used to specify the input paramet
3. execute some application specific code 13 Hints concerning the Interrupt Service Routine CISR16X1 C 13 1 Overview CISR16X1 C is an example for a CAN interrupt service routine Using the interrupts of the CAN module will increase the performance of your application because the CPU load is significantly reduced Furthermore your application will be able to react on CAN bus traffic much faster than it would be able to without using the CAN module interrupt Please note that the use of this interrupt service routine depends on the use of the example program EXI_16X1 C In other words To be able to use the interrupt service routine the following conditions must be fulfilled e The global interrupt enable bit IEN in register PSW of the microcontroller must be set to 1 in the main program e The CAN interrupt CPU side must be enabled by loading the XPOIC X Peripheral 0 Interrupt Control register with an appropriate value e g 0x444 for priority level 1 e CAN interrupts CAN controller side must be enabled by setting the Interrupt Enable bit IE in the Control Register of the CAN module to 1 when initializing the CAN module using init_can_16x Also select if you want to select Status Change Interrupts set SIE to 1 and or Error Interrupts set EIE to 1 e For the enabling of message object specific interrupts the respective bit fields TXIE for transmit interrupts and or RXIE for receive interrupts must
4. 33 AP2922 05 97 SIEMENS C CAN Driver Routines for the C166 family Table 6 3 Local variables Type Corresp Task input parameter mo15 db _ptr unsigned P1 is loaded with the address of the first element pee eae of the 8 byte array to be filled with the data bytes of the specified MO mo15 _id_ ptr unsigned P2 is loaded with the address of the long variable long to be filled with the hexadecimal value of MO 15 char to be filled with the data length code of MO 15 dummy _dbptr unsigned is loaded with dbO_ptr_16x 15 in the char procedure This is where the data will be copied from Gi funs char _ loop variable Additional Information This procedure is used to read the data bytes the data length code and the identifier of message object 15 and copy them into a user specific 8 byte data buffer a user specific char variable and a user specific long variable Usually it will be called after the software has detected that new data has been written into message object 15 using the function check_mo_16x see below Whenever using message object 15 please have in mind that message object 15 is double buffered This is why the input variables for this procedures have the index 1 The main program could have the same variables with index 2 as well as shown in the example program for these driver procedures For example if the software has detected that a new data frame has been stored into the messag
5. Semiconductor Group 13 of 33 AP2922 05 97 SIEMENS C CAN Driver Routines for the C166 family Table 4 3 Local variables Type Corresp Task Input parameter char upl_data_ptr unsigned P2 is loaded with the address of the first element char of the 8 byte array filled with the data to be sent dummy_dbptr unsigned is loaded with dbO_ptr_16x nr in the char procedure This is where the data will be copied ins char_ loop variable Additional Information Before being able to transmit any data frame the message object s data bytes have to be loaded at least once which can be done with this procedure Please note that as MO 15 cannot be transmitted its data bytes cannot be loaded with this procedure Only message object numbers between 1 and 14 are accepted The procedure has to be called for each message object separately The procedure performs the following actions Check if the specified message object is valid number between 1 and 14 Set CPUUPD and NEWDAT in the Message Control Register of the specified message object to indicate that the CPU is actually working on the message object s data Copy data bytes from the upload buffer specified in input parameter P2 to the data bytes of the message object specified in input parameter P1 Reset CPUUPD in the Message Control Register to enable transmission of the message object Semiconductor Group 14 of 33 AP2922 05 97 SIEMENS C CAN Driver
6. be enabled in the Message Control Register of the respective message when configuring a message using def_mo_ 16x e The interrupt service routine has to be linked to the main program having access to the CAN library CAN16X1 LIB The CAN interrupt service routine has been compiled and tested with the BSO Tasking compiler C166 Slight changes may be necessary to compile it with an other compiler for the C166 family The contents of the CAN interrupt service routine is now discussed Again please note that the target of this example interrupt service routine is to show a general example how to work with the CAN driver routines using the CAN module interrupt Semiconductor Group 30 of 33 AP2922 05 97 SIEMENS C CAN Driver Routines for the C166 family 13 2 Contents of the CAN interrupt service routine The routine starts with two include statements to include the register definitions of the used microcontroller and additionally to include the register declarations for the general CAN control registers After that the CAN driver routines are declared as external in the example programs This avoids warnings created by your compiler when compiling the interrupt service routine The interrupt service routine uses the following local variables Table 13 1 Local variables of the example interrupt service routine Name Ty _ Task S O char CAN module EF014 char CAN module char 15 buffer char object 2 char
7. not using the interrupt service routine If the identifier of the new data frame matches the test identifier the software will then read the data bytes and write them into mo15_ db_buf 0 Additionally the identifier and the data length code of the data frame that had been written into message object 15 will be read and stored into the respective variables mo15_id 0 and mo15_dlc1 0 This will also release the momentarily accessed MO15 buffer After that message object 14 is configured as a message object to transmit data frames with the same identifier as the frame from message object 15 and the same data length code as well Message object 14 is then loaded with the data bytes just read from message object 15 and is transmitted Therefore this section initiates the return of exactly the same data frame by message object 14 as was just read from message object 15 In a similar way remote frames received by message object 15 if message object 15 is configured for the reception of remote frames could be read the identifier could be evaluated by the CPU and the corresponding data frame could be sent in return if necessary Should both buffers of message object 15 have been allocated containing new data the interrupt service routine will not yet be left because the Interrupt Register is still Ox014 The message object 15 interrupt section will be entered again now accessing the other buffer of message object 15 There
8. received by the CANalyzer If you press the a key on your CANalyzer once a data frame which matches with the test identifier for message object 15 in your node will be sent Therefore your node returns this message Press a a second time and another message with the same identifier will be sent different dlc and data and returned The third time you press a a data frame which does not match with the test identifier for message object 15 will be sent You will see that your node performs a correct software acceptance filtering and will not return this message Pressing a for the 4 time will start this message series over again Note The CANalyzer configuration files were created with the software version that works together with the PCMCIA CANalyzer card Problems might occur using the files with other software designed to work with other hardware Semiconductor Group 33 of 33 AP2922 05 97
9. 15_16x If new data has been written into message object 15 the function will return 1 and the software will then read the new data bytes into the message object 15 data buffer 1 Additionally the identifier and the data length code of the data frame that had been written into message object 15 will be read and stored into the respective variables mo15_id1 and mo15 dic1 After that message object 14 is configured as a message object to transmit data frames with the same identifier as the frame from message object 15 and the same data length code as well Message object 14 is then loaded with the data bytes just read from message object 15 and is transmitted Therefore section 3 initiates the return of exactly the same data frame by message object 14 as was just read from message object 15 In a similar way remote frames received by message object 15 if message object 15 is configured for the reception of remote frames could be read the identifier could be evaluated by the CPU and the corresponding data frame could be sent in return if necessary Semiconductor Group 29 of 33 AP2922 05 97 SIEMENS C CAN Driver Routines for the C166 family Section 4 calls check_busoff_16x to check whether the CAN module has entered the bus off state or not If so the bus off recovery is initiated in check_busoff_16x itself bit INIT in the CAN module s control register is cleared Additionally the main program could
10. D and NEWDAT in the Message Control Register of MO 15 in order to release the momentarily accessed buffer of MO 15 Semiconductor Group 19 of 33 AP2922 05 97 SIEMENS C CAN Driver Routines for the C166 family 7 Routine 6 Send a Message Object Table 7 1 Procedure overview request transmission of one message object of the CAN module Input parameters P1 see below Name of C source file SNDMO16X C Table 7 2 Input parameters values unsigned 1 14 Specified MO will be transmitted message char Calling example send _mo_16x 4 LMO number Type Corresp Task Input parameter Table 7 3 Local variables unsigned holds specified message object char Semiconductor Group 20 of 33 AP2922 05 97 SIEMENS C CAN Driver Routines for the C166 family Additional Information This procedure transmits the specified message object If the message object was configured with DIR 1 then a data frame will be transmitted If the message object was configured with DIR 0 then a remote frame will be transmitted Please note that as MO 15 cannot be transmitted this procedure cannot be applied to MO 15 Please note that before being able to transmit any data frame the message object s data bytes have to be loaded at least once which can be done with the procedure Id_modata_16x Only message object numbers between 1 and 14 are accepted The procedure has to be called for each message object separat
11. Read out Message Object 15 Basic CAN Message Object 17 7 Routine 6 Send a Message Object ccceseeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeseeeeeeeeeeneees 20 8 Routine 7 Check a Message Object 1 14 for MEW data ccccceceeeeeeeeeeeeeeeeeeeeees 22 9 Routine 8 Check Message Object 15 for new data or new remote frame 24 10 Routine 9 Check for a Bus Off Situation in the CAN Module cccsssssseseeee 25 11 Hints concerning the CAN Library CAN16X1 LIB 0 cccccccessesssseeeeeeeeeeeeeneeeeeeees 26 12 Hints concerning the Example Programs ccceeeeeii iii ieee eee 26 13 Hints concerning the Interrupt Service Routine CISR16X1 C csseceeseesseeeeees 30 14 Hints concerning the Header File CREG_16X H ccceseeeeeeeeeeeeeeeeeeeeeeeeeeeeeees 33 15 Hints concerning the CANalyzer Configuration Files CFG sscseseeeeeee 33 AP2922 ApNote Revision History Actual Revision Rel 01 Previous Revision Page of Page of Subjects changes since last release actual Rel prev Rel Semiconductor Group 2 of 33 AP2922 05 97 SIEMENS C CAN Driver Routines for the C166 family 1 Introduction 1 1 Abstract This application note describes CAN protocol driver software routines for the members of the Siemens 16 bit microcontroller family C166 which are equipped with an on chip CAN module e g C167CR C164Cl Whilst every effort ha
12. Routines for the C166 family 5 Routine 4 Read the data bytes of a Message Object 1 14 Table 5 1 Procedure overview read the data bytes of one message object of the CAN module Input parameters P1 P2 see below Name of C source file RDMOD16X C Table 5 2 Input parameters bi lial A a values P1 of unsigned 1 14 Data bytes of specified MO will be read message char object P2 address ofa address user The 8 byte array whose start address 1 download specific 8 element is passed on to this procedure is filled data array 8 byte buffer with the data bytes of the specified MO Calling example rd_modata_16x Gownload data buf Laddress of first element of 8 byte data bytes of the spec message object 4 array which shall be filled with the LMO number Semiconductor Group 15 of 33 AP2922 05 97 SIEMENS C CAN Driver Routines for the C166 family Table 5 3 Local variables Type Corresp Task input parameter char downl_data_ptr unsigned is loaded with the address of the first element lt a of the 8 byte array to be filled with the data bytes of the specified MO pene leew tesa mules char This is where the data will be copied from i__ uns char_ _ loop variable loop variable dummy_char___ uns char __ used to temporarily store 8bitvalues Additional Information This procedure is used to read the data bytes of a certain message o
13. SIEMENS Microcontrollers ApNote AP2922 M additional file AP292201 EXE available C CAN Driver Routines for the C166 Family This application note describes CAN protocol driver software routines written in C for the members of the Siemens 16 bit microcontroller family C166 which are equipped with an on chip CAN module e g C167CR C164Cl Authors Axel Wolf SCI Cupertino ICD Dr Jens Barrenscheen HL MC PD 8 Semiconductor Group 05 97 Rel 01 SIEMENS C CAN Driver Routines for the C166 family TINT OGUCHION eaa A E EE TTT A E 3 Le We PADSUACL Gi scsscatsinsere Cosh e a a aar aar e a 3 1 2 CAN Driver Routines OVERVIEW s aiccsictsisdt ceded ce ce estadoteceleiedel ctesods cata tndic tacu baa habebadenaie 3 1 3 Files included in the CAN Driver ApNote cccceeeeeeeeeeeeeeeeeeeeeeeeeeeeeeenneaeeeeeeees 4 1 4 Global Variables used by the Driver ROutineS cccccccceeeeseeeeeceeeeeeeeeeeeeeeneeeeeeeeees 4 15 Notes concerning this APNGl x c ccc0 c titec chet navaa a eet aAa RAES 5 2 Routine 1 Initialization Procedure for the CAN MOdule ccccssssssseeeeeteeeeeeeeees 7 3 Routine 2 Configuring a Message Object of the CAN Module eseee 10 4 Routine 3 Load the data bytes of a Message ObjeCt cccecceesseeeeeeeeeeeeeeees 13 5 Routine 4 Read the data bytes of a Message Object 1 14 ccssesseeeeeeeeeeeeeenees 15 6 Routine 5
14. Use these templates if you configure other message objects to generate receive or transmit interrupts Semiconductor Group 32 of 33 AP2922 05 97 SIEMENS C CAN Driver Routines for the C166 family 14 Hints concerning the Header File CREG_16X H Via the define statements in this header file the global CAN control registers can be accessed by using the register names which represent the contents of a pointer pointing to the address of the respective register This header file is included into some of the CAN driver routine source files as well as into the CAN interrupt service routine example CISR16X1 C 15 Hints concerning the CANalyzer Configuration Files CFG EXS_16X1 CFG and EXX_16X1 CFG are two configuration files designed for the Vector Softing CANalyzer for Windows to act as an opposite CAN node to the one that works with the example program of the same name You the have a small CAN network made of the CANalyzer and your node Start the CANalyzer program and load the configuration file Start the measurement and then start your node by running the example program The CANalyzer now receives the data frames transmitted by message object 1 identifier 001 of your node As an answer the CANalyzer sends back a data frame with identifier 002 which will be received in message object 2 in your node The data will be copied into message object 3 and sent out in a data frame with identifier 003 which will again be
15. ariables used by the CAN driver routines can be found in table 3 These variables can not be accessed via the example programs though Semiconductor Group 4 of 33 AP2922 05 97 SIEMENS C CAN Driver Routines for the C166 family Table 1 3 Global variables used by the CAN driver routines Names Type Task S id_ptr_16x 16 unsigned int Field of 16 pointers only 1 15 are used to the Upper Arbitration Registers of the message objects 1 15 db0_ptr_16x 16 unsigned char Field of 16 pointers only 1 15 are used to the data byte 0 of the message objects 1 15 msg_ctril_ptr_16x 16 unsigned int Field of 16 pointers only 1 15 are used to the Message Control Registers of message objects 1 15 msg_conf_ptr_1l6x 16 unsigned char Field of 16 pointers only 1 15 are used to the Message Configuration Registers of message objects 1 15 dir_bit_16x 16 unsigned char Field of 16 chars only 1 15 are used which contain a copy of the direction bits of the message objects 1 15 xtd_bit_16x 16 unsigned char Field of 16 chars only 1 15 are used which contain a copy of the extend bits of the message objects 1 15 dic_16x 16 unsigned char Field of 16 chars only 1 15 are used which contain a copy of the data length code of the message objects 1 15 1 5 Notes concerning this ApNote Before using the CAN driver software please read the followi
16. bject and copy them into a user specific 8 byte data buffer Usually it will be called after the software has detected that new data has been written into a message object using the function check_mo_16x see below Please note that for MO 15 a separate procedure to read out this message object is available see below Only message object numbers between 1 and 14 are accepted The procedure has to be called for each message object separately The procedure performs the following actions e Check ifthe specified message object is valid number between 1 and 14 e Store the actual data length code of the new message into the global variable dic_167 nr e Clear INTPND and NEWDAT in the Message Control Register of the specified message object in order to allow a new message to be written into this message object during this procedure is running e Copy the data bytes their number is specified by the actual dic from the message object specified in input parameter P1 to the download buffer specified in input parameter P2 At the end the procedure is only left if NEWDAT has not been updated to 1 i e no new message has arrived for this message object during the execution of this procedure If NEWDAT has been set to 1 again the procedure is repeated In this way only the latest data bytes are returned Semiconductor Group 16 of 33 AP2922 05 97 SIEMENS C CAN Driver Routines for the C166 family 6 Routine 5 Read out Message Ob
17. ceived in MO 15 if this message object has been configured to receive remote frames DIR 1 If the result of this function is true most likely the procedure rd_mo15_ 16x will be called to read out MO 15 as shown in the example program This function performs the following actions e Check NEWDAT and RMTPND in the Message Control Register of MO 15 e Return 1 if one of these bits is set otherwise return O Semiconductor Group 24 of 33 AP2922 05 97 SIEMENS C CAN Driver Routines for the C166 family 10 Routine 9 Check for a Bus Off Situation in the CAN Module Table 10 1 Function overview check if a bus off situation has occurred in the CAN module Input parameters Returns o O 1 if CAN controller was in bus off state 0 otherwise Name of C source file CHKBO16X C Input parameters none Calling example if check_busoff_16x Table 9 2 Local variables Type Corresp Task Input parameter busoff_var ee holds value to be returned to main program char Additional Information This function checks if a bus off situation has occurred in the CAN module This function performs the following actions e Check if the BOFF bit in the Status Register has been set to 1 by the CAN controller e f BOFF is set this indicates a bus off situation To recover from the bus off the function resets the INIT bit in the Control Register e Return 1 if BOFF was set ot
18. d be used to store data char EXX_16X1 length code from second buffer of MO15 The variables mo15_db_buf2 8 mo15 id2 and mo15 dlc2 are currently not used by the example programs Nevertheless they are defined to show the double buffering of message object 15 See also section 9 12 5 Preparations for the main loop The general preparations for the main loop are the same in all three example programs First the CAN module is initialized by calling the routine can_init_16x Then message objects 1 2 3 and 15 are configured using the routine def_mo_16x After that the register XPOIC is loaded and the Bit IEN is set 12 6 The main loop Semiconductor Group 28 of 33 AP2922 05 97 SIEMENS C CAN Driver Routines for the C166 family The main loop is divided into 4 sections Between the sections a delay of 10 ms will be generated by calling the local routine delay which generates time delays between 1 ms and 26 ms using timer T4 of the microcontroller All example programs execute section 1 In example program EXI_16X1 C however the sections 2 3 and 4 are no longer in the example program itself but are all handled interrupt controlled by the interrupt service routine CISR16X C See section 13 for details In section 1 the data bytes of message object 1 which has been configured as a message object to transmit standard data frames with identifier O01 are loaded with the data store
19. d in the upload data buffer by using the procedure Id_modata_16x After that message object 1 is transmitted by calling send_mo_16x Finally to have different data bytes each time message object 1 is sent each byte of the upload data buffer is incremented by 1 Therefore section 1 initiates the transfer of a standard data frame with the identifier O01 and 8 different data bytes roughly every 40 ms In section 2 message object 2 which has been configured for the reception of standard data frames with the identifier O02y is checked for new data frames by calling check_mo_ 16x If new data has been written into message object 2 the function will return 1 and the software will then read the new data bytes into the download data buffer After that message object 3 which has been configured as a message object to transmit standard data frames with identifier O03 is loaded with the data bytes just read from message object 2 and is transmitted Therefore section 2 initiates the transfer of a standard data frame with the identifier O03 and the data bytes received in message object 2 each time new data is detected in message object 2 In section 3 the basic CAN feature of the CAN module is used Message object 15 which has been configured for the reception of standard data frames EXS_16X1 C extended data frames EXX_16X1 C with any identifier is checked for new data frames by calling check_mo
20. ded in the CAN driver ApNote Table 2 shows all the files that are part of this ApNote You will find them in the additional file AP292201 EXE Table 1 2 Files belonging to this ApNote Name Explanation CAN16X1 LIB CISR16X1 C EG_16X H CAN Library CAN driver routine library to be linked to your application programs See also section 11 Example programs Gives an idea of how to use the CAN driver routines in your application Just standard CAN 11 bit identifier messages are used in EXS_16X1 C standard and extended 29 bit messages are used in EXX_16X1 C Interrupts are evaluated when using EXI_16X1 C plus CAN interrupt service routine CISR16X1 C See section 12 for details CAN Interrupt service routine Can be used together with EXI_16X1 C to evaluate interrupts of the CAN module See section 13 for details Header File Include file for the declaration of the Control Registers of the CAN module Is included in some of the source files and in the CAN interrupt service routine see also section 14 CANalyzer Configuration files If you have a Windows based Vector Softing CANalyzer this configuration file is prepared to communicate with the example programs mentioned above EXS16X1 CFG works together with EXS_16X1 C and EXI_16X1 C EXX_16X1 CFG works together with EXX_16X1 C See section 15 for details 1 4 Global Variables used by the Driver Routines The global v
21. e DEFMO16X C Table 3 2 Input parameters Caa e a a values P1 unsigned 1 15 Specified message object MO will be i message char configured and can then be used for CAN object to be communication configured P2 eXTenD bit unsigned 0 e MO will be configured for standard CAN eel char 11 bit identifier 1 e Extended CAN 29 bit ID is selected P3 Message unsigned 0 3FFy Specified Identifier will be applied to the Identifier long std On message object The message object will the HEX code 1FFFFFFFy receive transmit message which carry this extended specified identifier e MO will be configured to transmit data frames and receive remote frames P4 DiRection bit unsigned 0 e MO will be configured to receive data char frames and transmit remote frames Specifies length of the data field on transmission of the MO Set to 0 for remote frames P5 Data Length unsigned Code of MO char to be configured TXIE bit unsigned 0 e MO will generate no transmit interrupts char 1 e MO will generate an interrupt on each successful transmission of a frame 0 i RXIE bit unsigned MO will generate no receive interrupts char MO will generate an interrupt on each Semiconductor Group 10 of 33 AP2922 05 97 successful reception of a frame SIEMENS C CAN Driver Routines for the C166 family Calling example def_mo 16x 4 0 0x123 1 8 0 O URXIE 0
22. e Control Register For transmit objects DIR 1 CPUUPD is set Therefore the message object can not yet be transmitted because its data bytes do not yet contain valid values Load the message object s data bytes before transmitting see next procedure For receive objects DIR 0 there s no CPUUPD field but this bit field is called MSGLST here Message Lost It will be reset by this procedure as no message has been lost so far Add the values specified for TXIE and RXIE to the Message Control Register e Load the Message Configuration Register with the values specified for DLC DIR and XTD Semiconductor Group 12 of 33 AP2922 05 97 SIEMENS C CAN Driver Routines for the C166 family 4 Routine 3 Load the data bytes of a Message Object Table 4 1 Procedure overview E oe Lae load the data bytes of one message object of the CAN module Input parameters P1 P2 see below Name of C source file LDMOD16X C Table 4 2 Input parameters ee e a values message char object address of address user The data bytes of the specified MO will be filled an upload specific 8 with the contents of the 8 byte array whose start data array 8 byte buffer address 1 element is passed on to this procedure Calling example ld_modata_16x upload_data_buf Laddress of first element of 8 byte 4 array previously filled with the L data to be sent out amp upload_data_buf 0 MO number
23. e object 15 using the procedure check_mo_16x the software could then call the rd_mo15_16x procedure with the variable set indexed 1 Before returning this procedure will release the momentarily accessed buffer The software could then immediately check message object 15 again for new data which is probably located in the other buffer If new data is detected here as well the software could read out this data again by using rd_mo15_16x but now with the variable set indexed 2 and now automatically accessing the other buffer Semiconductor Group 18 of 33 AP2922 05 97 SIEMENS C CAN Driver Routines for the C166 family The procedure performs the following actions The data length code of the new message is read from the momentarily accessed buffer and is stored into the user specific MO15 dlc variable and into the global variable dic_167 15 Please have in mind that the dic may be 0 if you have configured the MO 15 to receive remote frames The identifier of the new message is read from the momentarily accessed buffer is converted into hexadecimal format and is stored in the user specific MO15 identifier variable The data bytes of the new message their number is specified by the actual dic are read from the momentarily accessed buffer and are stored in the user specific MO15 data byte buffer Please have in mind that the data has to be ignored if you have configured MO 15 to receive remote frames Clear INTPND RMTPN
24. ely The procedure performs the following actions e Check if the specified message object is valid number between 1 and 14 e Set TXRQ in the Message Control Register of the specified message object to request the transmission of this message object Semiconductor Group 21 of 33 AP2922 05 97 SIEMENS C CAN Driver Routines for the C166 family 8 Routine 7 Check a Message Object 1 14 for new data Table 8 1 Function overview Task check if new data has been received in one message object of the CAN module Input parameters P1 see below 1 if new the specified message object contains new data 0 otherwise Table 8 2 Input parameters values unsigned 1 14 Specified MO will be checked for new data message char Calling example if check_mo_16x 4 LMO number Table 8 3 Local variables Type Corresp Task Input parameter holds specified message object char unsigned holds value to be returned to main program char Semiconductor Group 22 of 33 AP2922 05 97 SIEMENS C CAN Driver Routines for the C166 family Additional Information This function checks if new data has been written into the data bytes of the specified message object It will be applied to message objects that were configured with DIR 0 i e that they are able to receive data frames Please note that for MO 15 a separate function called check_mo15_16x is available If the result of
25. emens standalone CAN controller 81C92 CAN drivers for Siemens standalone CAN controllers 81C91 90 e The CAN driver routines in this ApNote use two different approaches of accessing the CAN registers For the general CAN control registers on the fly casting from near address to pointers is used The registers within the message objects however are accessed by proper pointer types e For best efficiency execute the driver routines in segment 0 of the memory first 64k code segment e Within the routines very often the pointers e g to the data bytes are copied into a local dummy pointer so that the original pointer remains untouched during the routine e g in a loop e The send_mo_16x procedure won t work without having defined a message object def_mo_16x AND having specified the data bytes with Id_mo_16x to prevent the transmission of invalid data Semiconductor Group 6 of 33 AP2922 05 97 SIEMENS C CAN Driver Routines for the C166 family 2 Routine 1 Initialization Procedure for the CAN Module Table 2 1 Procedure overview initialize the global registers of the CAN module Input parameters P1 P4 see below Name of C source file INCAN16X C Table 2 2 Input parameters ol ill bal al values P1 baud rate unsigned 50 125 Bit timing register will be loaded with the values Yrs 250 500 corresponding to the selected baud rate 1000 P2 EIE bit unsigned 0 e No error interrupts are generated
26. er P3 of procedure def_mo_16x Used to specify the input parameter P4 of procedure def_mo_ 16x E O 0 O O moe Used to specify the input parameter P5 of procedure def_mo_ 16x Used to specify the input parameter P6 of procedure def_mo_ 16x Used to specify the input parameter P7 of procedure def_mo_ 16x F S a v Gi a a E BIT ESB EL BIT x_XTD_BIT x_ID x DIR_BIT x_ DLC Bk BIT S E_BIT 12 3 Prototypes for the CAN driver routines After the define statements the CAN driver routines are declared as external in the example programs This avoids warnings created by your compiler when compiling your application program 12 4 Local variables of the example programs The example programs use different local variables described in the following table Semiconductor Group 27 of 33 AP2922 05 97 SIEMENS C CAN Driver Routines for the C166 family Table 12 3 Local variables of the example programs Names Type Used by _ Task char programs char programs the data bytes of message object 1 char EXX_16X1 message object 2 char EXX_16X1__ first buffer of MO15 15_db_buf2 8 unsigned EXS_16X1 could be used to store data char EXX_16X1 bytes from second buffer of MO15 long EXX_16X1 buffer of MO15 long EXX_16X1 from second buffer of MO15 char EXX_16X1 from first buffer of MO15 mol5_dicz2 unsigned EXS_16X1 coul
27. fore the data id and dlc from this buffer is written into mo15_ db_buf 1 mo15_id 1 and mo15 dlc1 1 Now also the second buffer of message object 15 is released and the interrupt service routine may be left if no other interrupt is pending and no new data has been written again into the other buffer of message object 15 Note The Interrupt service routine will not be left until both buffers of message object 15 are released Avoid the storage of too many messages coming close to each other into the Basic CAN message object 15 or giving the CAN interrupt service routine a priority which is too low to ensure proper functionality The section Message 2 interrupt will be entered if new data has been written into message object 2 earlier described as section 2 of main of the two example programs not using the interrupt service routine The software will read the new data bytes into the download data buffer After that message object 3 which has been configured as a message object to transmit standard data frames with identifier O03 is loaded with the data bytes just read from message object 2 and is transmitted Therefore this section initiates the transfer of a standard data frame with the identifier O03 and the data bytes received in message object 2 each time new data is detected in message object 2 The interrupt service routine contains templates for the handling of other message objects
28. from the 1 e Error interrupts are enabled P3 SIE bit unsigned 0 e No status interrupts are generated from the er char CAN module to the C16x CPU 1 e Status interrupts are enabled P4 IE bit unsigned 0 e Interrupt line from the CAN module to the cre char C16x CPU is disabled 1 e Calling example Interrupt line enabled init_can_16x 1000 0 0 1 CAN interrupts enabled Lno status interrupts Lno error interrupts LBaud rate 1 Mbit s Semiconductor Group 7 of 33 AP2922 05 97 SIEMENS C CAN Driver Routines for the C166 family Table 2 3 Local variables Type Corresp Task Input Ph Pos esecaT Beatle char pe pe errr char eerie holds status interrupt enable 1 disable 0 char unsigned P4 holds general CAN interrupt enable 1 char disable 0 unsigned eee eee variables char dummy_dbptr unsigned is loaded with dbO_ptr_16x i in the procedure char Used to reset all data bytes in all message objects Additional Information This will be the first procedure called in the main program The procedure performs the following actions e Set port pin P4 6 CAN TxD to output e Set port pin P4 5 CAN RxD to input e Load above mentioned pointers to the different registers of the on chip CAN module After the for loop the pointers are set as follows Table 2 4 Pointer Setting in procedure init_can_16x ical e Address object n id ape vee O Upper Arb
29. herwise return 0 Semiconductor Group 25 of 33 AP2922 05 97 SIEMENS C CAN Driver Routines for the C166 family 11 Hints concerning the CAN Library CAN16X1 LIB The file CAN16X1 LIB contains all CAN driver routines described in this application note It was created with the BSO Tasking archive utility ar166 A new class called CAN16X1LIB has been created for the library to be able to locate the CAN driver routines separately To use the CAN driver routines just link this library to your application programs At the beginning of your application programs you should declare the routines you want to use as external as shown in the example programs The source files of the CAN driver routines are also included in this application note Feel free to alter the source files and generate your own customized CAN library 12 Hints concerning the Example Programs 12 1 Overview There are three example programs included in this application note The following table shows the differences between the files Table 12 1 Differences between the example programs ee ee erupto used used used interrupts used Please note that EXI_16X1 C depends on the additional use of the interrupt service routine CISR16X1 C The CAN example programs have been compiled and tested with the BSO Tasking compiler C166 Slight changes may be necessary to compile them with an other compiler for the C166 family
30. itration Register of MO n msg_ ae ptr lex EFn6 Message Configuration Registers of message object n Please compare to the following figure Semiconductor Group 8 of 33 AP2922 05 97 SIEMENS C CAN Driver Routines for the C166 family Message Control Object Start Address Arbitration Msg Config Data 7 0 Reserved Figure 2 1 Message Object structure in the C167CR C164Cl e Clearthe arrays dir_bit_16x n xtd_bit_16x n dlc_16x n e Initialize the Bit Timing Register according to the specified baud rate e Set the Global Masks in a way that for message objects 1 14 each bit of the standard extended identifier of the incoming frame must match to store the message into the respective message object e Set the Mask of Last Message in a way that a messages which cannot be stored in message objects 1 14 are stored in message object 15 enable Basic CAN feature e Set all message objects to NOT VALID e Set all data bytes in all message objects to 0 e Set the user specified values for interrupt control bits EIE SIE IE in the Control Register EFOOw Semiconductor Group 9 of 33 AP2922 05 97 SIEMENS C CAN Driver Routines for the C166 family 3 Routine 2 Configuring a Message Object of the CAN Module Table 3 1 Procedure overview def _mo_16x Pl P2 P3 P4 P5 P6 P7 configure one message object of the CAN module Input parameters P1 P7 see below Name of C source fil
31. ject 15 Basic CAN Message Object Table 6 1 Procedure overview Procedure name rd_mo15_16x P1 P2 P3 read message object 15 of the CAN module Input parameters P1 P3 see below Name of C source file RDM1516X C Table 6 2 Input parameters T values P1 address ofa address user The 8 byte array whose start address 1 download specific 8 element is passed on to this procedure is filled data array 8 byte buffer with the data bytes of the MO 15 buffer which is momentarily accessed by the CPU P2 address of a address user The long variable whose address is passed on to download specific this procedure is filled with the hexadecimal identifier long value of the identifier stored in the Upper and variable variable Lower Arbitration Register of the MO 15 buffer which is momentarily accessed by the CPU P3 address of a address user The char variable whose address is passed on to download specific this procedure is filled with the data length code data length code variable byte of the MO 15 Message Configuration Register variable buffer which is momentarily accessed by the CPU Calling example rd_mo15_16x mo15_ data _buf1l amp mol15_id1 amp mo15_dilicl Laddress of MO 15 data length code variable Laddress of MO15 identifier variable Laddress of first element of 8 byte array which shall be filled with the data bytes of MO 15 amp mo15_data_buf1 0 Semiconductor Group 17 of
32. ng notes e The CAN example programs have been compiled and tested with the BSO Tasking compiler C166 To make compilations with other compilers easier the routines don t really use BSO Tasking specific code Still slight changes may be necessary to compile them with an other C166 family compiler e Inthe additional file AP292201 EXE you will find all the files discussed in this ApNote source files for the routines example programs interrupt service routine etc e At least in this first version of this ApNote the 16x CAN driver routines are written in a way that they can be easily ported to other C166 compilers or even to the 8 bit world to be used together with the Siemens 8 bit derivatives with integrated CAN module e g C505C C515C The routines are furthermore designed for easy handling of the CAN module by the user They do not claim to be optimized for small code generation or fast execution speed Semiconductor Group 5 of 33 AP2922 05 97 SIEMENS C CAN Driver Routines for the C166 family e Nevertheless the names of the driver procedures functions and all other files included in this ApNote contain the letters 16X to differentiate between the different CAN driver ApNotes that are available or planned for other Siemens CAN components Table 1 4 Differentiation between files belonging to different ApNotes Explanation CAN drivers for C166 family 500 CAN drivers for C500 family CAN drivers for Si
33. of MO15 long of MO15 char buffers of MO15 The whole interrupt service routine is made of a while loop The contents of the interrupt register is copied into the variable intid and the while loop is executed until the Interrupt Register is 0 which means all pending CAN interrupts have been correctly serviced Within the while loop the CAN module Status Register is copied into the variable status and is cleared afterwards Please note Reading the Status Register already clears a pending Status interrupt and the Interrupt Register is updated The rest of the interrupt service routine is a switch statement Depending on which interrupt is pending Status Change Interrupt Error Interrupt Message Object Interrupt the respective actions can be performed In all these sections you may insert application specific code Semiconductor Group 31 of 33 AP2922 05 97 SIEMENS C CAN Driver Routines for the C166 family The section Error Interrupts will be entered e g if the bus off bit has been set by the CAN module You will also find the recovery from bus off state there which was performed in section 4 of main of the two example programs not using the interrupt service routine The section Message 15 receive interrupt will be entered if new data has been written into message object 15 used as Basic CAN receive register earlier described as section 3 of main of the two example programs
34. s been made to ensure the accuracy of information contained in this application note the authors cannot be held responsible for any consequences arising from its use Please report comments suggestions for improvement etc to axel wolf sci siemens com For further information concerning the on chip CAN module on the C166 devices or the C166 microcontroller itself please refer to the document Description of the on chip CAN module and the respective derivative s User s Manual For further information concerning the CAN protocol Siemens CAN devices and additional CAN ApNotes please refer to http Awww sci siemens com can html For further information concerning Siemens Microcontrollers please refer to http Awww sci siemens com select the microcontrollers http Awww siemens de Semiconductor products products htm select the MC s 1 2 CAN Driver Routines Overview The following table shows an overview of the included CAN driver routines Table 1 1 Included driver routines Initialization routine for the CAN module Define a message object in the CAN module def_mo_16x Load the data bytes of a message object Check for new data or remote frame in message object 15 Check if a bus off situation has occurred and recover check_busoff_16x from bus off Semiconductor Group 3 of 33 AP2922 05 97 SIEMENS C CAN Driver Routines for the C166 family 1 3 Files inclu
35. this function is true most likely the procedure rd_modata_16x will be called to read out the new data as shown in the example program Only message object numbers between 1 and 14 are accepted The function has to be called for each message object separately This function performs the following actions e Check if the specified message object is valid number between 1 and 14 e Check NEWDAT in the Message Control Register of the specified message object e Return 1 if NEWDAT is set otherwise return 0 Semiconductor Group 23 of 33 AP2922 05 97 SIEMENS C CAN Driver Routines for the C166 family 9 Routine 8 Check Message Object 15 for new data or new remote frame Table 9 1 Function overview Function name check_mo15_16x Task check if new data or a new remote frame has been received in message object 15 of the CAN module Input parameters 1 if new the specified message object contains new data 0 otherwise Name of C source file CHM1516xX C Input parameters none Calling example if check_mo15 16x Table 9 2 Local variables Type Corresp Task Input parameter new_event_var unsigned Ee holds value to be returned to main program char Additional Information This function checks if new data has been written into the data bytes of MO 15 if this message object has been configured to receive data frames DIR 0 or if a new remote frame has been re
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