AN541

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00014 IF (CPU==1654) (CPU==1655) 000001FF 00015 _RESVEC EQU 01FFH ;16c54 start address 00016 ENDIF 00017 00018 IF CPU==1656 00019 _RESVEC EQU 03FFH ;16C56 start address 00020 ENDIF 00021 00022 IF CPU==1657 00023 _RESVEC EQU 07FFH ;16C57 start address 00024 ENDIF 00025 00026 ;*** Reset Vector ******************************************* 00027 01FF 00028 ORG _RESVEC ; 01FF 00029 RESVEC ; 01FF 0A0B 00030 GOTO INIT ; 00031 00032 ;*********************************************************** 00033 00034 ;*********************************************************** 00035 ;* Macros to set/clear/branch/skip on bits 00036 ;* These macros define and use synthetic bit labels 00037 ;* Bit labels contain the address and bit of a location 00038 ;* 00039 ;********************************************************************** 00040 ;* Usage Description 00041 ;* ----------------------- --------------------- 00042 ;* BIT label,bit,file ;Define a bit label 00043 ;* SEB label ;set bit using bit label 00044 ;* CLB label ;clear bit using bit label 00045 ;* SKBS label ;SKIP on bit set 00046 ;* SKBC label ;SKIP on bit clear 00047 ;* BBS label,address ;BRANCH on bit set 00048 ;* BBC label,address ;BRANCH on bit clear 00049 ;* CBS label,address ;CALL on bit set 00050 ;* CBC label,address ;CALL on bit clear 00051 ;* 00052 ;********************************************************************** 00053 00054 BIT MACRO label,bit,file ;Define a bit label 00055 label EQU file<<8 bit ;(macro) 00056 ENDM ; 00057

00058 SEB MACRO label ;Set bit 00059 BSF label>>8,label &7 ;(macro) 00060 ENDM ; 00061 00062 CLB MACRO label ;Clear bit 00063 BCF label>>8,label &7 ;(macro) 00064 ENDM ; 00065 00066 SKBS MACRO label ;Skip on bit set 00067 BTFSS label>>8,label &7 ;(macro) 00068 ENDM 00069 00070 SKBC MACRO label ;Skip on bit clear 00071 BTFSC label>>8,label &7 ;(macro) 00072 ENDM 00073 00074 BBS MACRO label,address ;Branch on bit set 00075 BTFSC label>>8,label &7 ;(macro) 00076 GOTO address ;(macro) 00077 ENDM ; 00078 00079 BBC MACRO label,address ;Branch on bit clear 00080 BTFSS label>>8,label &7 ;(macro) 00081 GOTO address ;(macro) 00082 ENDM 00083 00084 CBS MACRO label,address ;Call on bit set 00085 CALL label>>8,label &7 ;(macro) 00086 ENDM ; 00087 00088 CBC MACRO label,address ;Call on bit clear 00089 CALL label>>8,label &7 ;(macro) 00090 ENDM 00091 00092 00093 ;For Assembler portability 00094 00000000 00095 W EQU 0 ;For file,w 00000000 00096 w EQU 0 ;For file,w 00000001 00097 F EQU 1 ;For file,f 00000001 00098 f EQU 1 ;For file,f 00099 00100 ;******************************************************************* 00101 ;* REGISTER DECLARATIONS

00102 ;******************************************************************* 00103 00104 0000 00105 ORG 0 ;ORG for register declarations 00106 0000 00107 ind RES 1 ;0=pseudo-reg 0 for in direct (FSR) 0001 00108 TMR0 RES 1 ;1=real time counter 0002 00109 PC RES 1 ;2=PC 0003 00110 STATUS RES 1 ;3=status reg 00111 00112 ;* Status reg bits 00113 00114 BIT B_C,0,STATUS ;Carry 00000300 M B_C EQU STATUS<<8 0 ;(macro) 00115 BIT B_DC,1,STATUS ;Half carry 00000301 M B_DC EQU STATUS<<8 1 ;(macro) 00116 BIT B_Z,2,STATUS ;Zero 00000302 M B_Z EQU STATUS<<8 2 ;(macro) 00117 BIT B_PD,3,STATUS ;Power down 00000303 M B_PD EQU STATUS<<8 3 ;(macro) 00118 BIT B_TO,4,STATUS ;Timeout 00000304 M B_TO EQU STATUS<<8 4 ;(macro) 00119 BIT B_PA0,5,STATUS ;Page select (56/57 only) 00000305 M B_PA0 EQU STATUS<<8 5 ;(macro) 00120 BIT B_PA1,6,STATUS ;Page select (56/57 only) 00000306 M B_PA1 EQU STATUS< ;(macro) 00121 BIT B_PA2,7,STATUS ;GP flag 00000307 M B_PA2 EQU STATUS<<8 7 ;(macro) 00122 0004 00123 FSR RES 1 ;4=file select reg 0-4 =indirect address 0005 00124 PORTA RES 1 ;5=port A I/O register (4 bits) 0006 00125 PORTB RES 1 ;6=port B I/O register 00126 00127 IF (CPU==1655) (CPU==1657) 00128 PORTC RES 1 ;7=I/O port C on 16C54/56 only 00129 ENDIF 00130 00131 ;registers used by this code 00132 0007 00133 I2CFLG RES 1 ;I2C flag reg 00134 ;--i2c flags------------------------------------------------- 00135 BIT B_RD,0,I2CFLG ;Flag: 1=read 00000700 M B_RD EQU I2CFLG<<8 0 ;(macro) 00136 BIT B_UA,1,I2CFLG ;Flag: 0=reading unit address

00000701 M B_UA EQU I2CFLG<<8 1 ;(macro) 00137 BIT B_SA,2,I2CFLG ;Flag: 1=reading subabbress 00000702 M B_SA EQU I2CFLG<<8 2 ;(macro) 00138 BIT B_ID,3,I2CFLG ;Flag: 1=reading id 00000703 M B_ID EQU I2CFLG<<8 3 ;(macro) 00139 ;------------------------------------------------------------ 0008 00140 I2CREG RES 1 ;I2C I/O register 0009 00141 I2CSUBA RES 1 ;Subaddress 000A 00142 I2CBITS RES 1 ;I2C xmit bit counter 00143 00144 00145 ;********************************************************************** 00146 ;* 8 Pseudo registers accessed by sub-addresses 1-8 00147 ;* (address 0 accesses the ID string) 00148 ;* these are read-write registers 00149 ;********************************************************************** 00150 00151 0000000B 00152 I2CR0 EQU $ ;Sub-address 8 000B 00153 RES 1 ;8 pseudo registers 00154 0000000C 00155 I2CR1 EQU $ ;Sub-address 1 000C 00156 RES 1 00157 0000000D 00158 I2CR2 EQU $ ;Sub-address 2 000D 00159 RES 1 00160 0000000E 00161 I2CR3 EQU $ ;Sub-address 3 000E 00162 RES 1 00163 0000000F 00164 I2CR4 EQU $ ;Sub-address 4 000F 00165 RES 1 00166 00000010 00167 I2CR5 EQU $ ;Sub-address 5 0010 00168 RES 1 00169 00000011 00170 I2CR6 EQU $ ;Sub-address 6 0011 00171 RES 1 00172 00000012 00173 I2CR7 EQU $ ;Sub-address 7 0012 00174 RES 1 00175 00176 ;Constants used by program 00177

000000D6 00178 DEVICE_ADDRESS EQU 0D6H ;I2C device address (device_address+1 = read) 00179 00180 ;************************************************************** 00181 ;** PORTA DEFINITIONS 00182 ;** I2C interface uses PORTA 00183 ;** note SDA goes to A0 for code efficiency 00184 ;** 00185 ;*************************************************************** 00186 00187 000000F7 00188 TAREAD EQU B 11110111 ;TRISA register for SDA read 000000F6 00189 TAWRITE EQU B 11110110 ;TRISA register for SDA write 000000F7 00190 TAINIT EQU TAREAD ;Initial TRISA value 00191 00192 BIT B_SDA,0,PORTA ;I2C SDA (data) This must be bit 0! 00000500 M B_SDA EQU PORTA<<8 0 ;(macro) 00193 BIT B_SCL,1,PORTA ;I2C SCL (clock) 00000501 M B_SCL EQU PORTA<<8 1 ;(macro) 00194 ;spare B_???,2,PORTA ;not used 00195 ;spare B_???,3,PORTA ;not used 00196 00197 ;************************************************************** 00198 ;** 00199 ;** Port B definition (Parallel out) 00200 ;** 00201 ;**************************************************************** 00000000 00202 TBINIT EQU B 00000000 ;Port B tris (all output) 000000FF 00203 PBINIT EQU B 11111111 ;Port B init 00204 00205 00206 ;********************************************************************** 00207 ;* Macros to contain user POLL loop code. 00208 ;* These are implemented as macros to allow ease of modification, 00209 ;* especially in real-time applications. The functions could be coded 00210 ;* as in-line code or as subroutines depending on ROM/time tradeoffs. 00211 ;* 00212 ;* USER_MAIN: Decision or code to perform at idle time 00213 ;* 00214 ;* USER_Q: Quick code for use during transfer - max 8 Ês for 00215 ;* full I2C Spec. More than 4s may result in I2C 00216 ;* retries (at full spec speed. 00217 ;* 00218 ;* USER_MSG: Code to execute at receipt of I2C command. 00219 ;*

00220 ;********************************************************************** 00221 00222 USER_MAIN MACRO 00223 ;*** This would be user code for idle loop 00224 ENDM 00225 00226 USER_Q MACRO 00227 ;*** This would be quick user code 00228 ENDM 00229 00230 USER_MSG MACRO 00231 ;*** This would be user code to process a message 00232 ENDM 00233 00234 USER_RECV MACRO 00235 ;*** This would be user code to process a received byte 00236 ;*** example code sends sub-address 0 to port b 00237 BBC B_ID,_NXI_notid ;Channel 0! Bit set if INITIAL address was 0 00238 MOVFW I2CREG ;get received byte 00239 MOVWF PORTB ;and write it on portb 00240 GOTO IN_CONT 00241 _NXI_notid 00242 ENDM 00243 00244 USER_XMIT MACRO 00245 ;*** This would be user code to prepare an output byte 00246 ;*** example code sends id string to output 00247 BBC B_ID,_NXO_notid ;Channel 0! Bit set if INITIAL address was 0 00248 CALL GETID ;get next byte from ID channel 00249 GOTO OUT_CONT ;and send it 00250 _NXO_notid 00251 ENDM 00252 00253 ;******************************************************************* 00254 ; START OF CODE 00255 ;******************************************************************* 0000 00256 ORG 0 00257 ;******************************************************************* 00258 ;* Device ID Table (must be at start) 00259 ;* TABLE FOR UNIT ID returns next char in W 00260 ;******************************************************************* 0000 00261 GETID 0000 0209 00262 MOVFW I2CSUBA ;W=I2CSUBA 0001 0E07 00263 ANDLW 07H ;Limit to 8 locations

0002 01E2 00264 ADDWF PC,F 00265 00266 ;********************************************************************** 00267 ;* Device ID text: read starting at sub-address 0 00268 ;********************************************************************** 00269 0003 0850 00270 RETLW P 0004 0849 00271 RETLW I 0005 0843 00272 RETLW C 0006 0849 00273 RETLW I 0007 0832 00274 RETLW 2 0008 0843 00275 RETLW C 0009 0800 00276 RETLW 0 000A 0800 00277 RETLW 0 00278 00279 00280 ;********************************************************************** 00281 ;* I2C Device routines 00282 ;* 00283 ;* Enable must be HIGH, else state goes to 0 00284 ;* write is to me, read is from me. 00285 ;* 00286 ;* <============== first byte / subsequent writes =====> <end> 00287 ;* 00288 ;* SDA -- X-----X-----X-----X-----X-----X-----X-----X---X------ -- 00289 ;* ---X-----X-----X-----X-----X-----X-----X-----X---X****** -- 00290 ;* (bit) s 7 6 5 4 3 2 1 0 ackout 00291 ;* SCL ----- -- -- -- -- -- -- -- -- 00292 ;* -- -- -- -- -- -- -- -- -- 00293 ;* 00294 ;* STATE: 0 1 2 3 2 3 2 3 2 3 2 3 2 3 2 3 2 4 5 6 2 3 0 00295 ;* 00296 ;* <============== subsequant reads ===================> 00297 ;* 00298 ;* SDA X-----X-----X-----X-----X-----X-----X-----X----X------X----- 00299 ;* --X-----X-----X-----X-----X-----X-----X-----X----X******X----- 00300 ;* (bit)ack 7 6 5 4 3 2 1 0 ackin 00301 ;* SCL -- -- -- -- -- -- -- -- -- -- -- 00302 ;* -- -- -- -- -- -- -- -- -- -- 00303 ;* 00304 ;* STATE: 7 8 7 8 7 8 7 8 7 8 7 8 7 8 7 8 9 A 7 8 00305 ;* 00306 ;* <============== Final READ =========================> 00307 ;*

00308 ;* SDA X-----X-----X-----X-----X-----X-----X-----X----X- ** ------- 00309 ;* --X-----X-----X-----X-----X-----X-----X-----X----X* -- 00310 ;* (bit)ack 7 6 5 4 3 2 1 0 ackin 00311 ;* SCL -- -- -- -- -- -- -- -- -- --------- 00312 ;* -- -- -- -- -- -- -- -- -- 00313 ;* 00314 ;* STATE: 7 8 7 8 7 8 7 8 7 8 7 8 7 8 7 8 9 A 0 0 00315 ;* 00316 ;* STATE B is an ignore bit state for non-addressed bits 00317 ;* STATE C indicates last sample had ENA low on rising 00318 ;* edge of ENA, DATA LOW = low voltage, DATA&CLOCK low = RESET 00319 ;***************************************************************** 00320 00321 ;I2C interface uses PORTA 00322 ;note SDA must be on PORTA,0 for code efficiency 00323 00324 ;***************************************************************** 00325 ;** INIT 00326 ;** Hardware reset entry point 00327 ;** 00328 ;***************************************************************** 000B 00329 INIT ;Power-on entry 00330 00331 ;***************************************************************** 00332 ;** RESET 00333 ;** software reset entry point 00334 ;** 00335 ;***************************************************************** 000B 00336 RESET ;Soft reset 00337 000B 0CF7 00338 MOVLW TAINIT ;Init ports 000C 0005 00339 TRIS PORTA 000D 0C00 00340 MOVLW TBINIT 000E 0006 00341 TRIS PORTB 000F 0CFF 00342 MOVLW PBINIT 0010 0026 00343 MOVWF PORTB 00344 00345 ;***************************************************************** 00346 ; Main wait loop while idle. POLL loop should be called here 00347 ; 00348 ;***************************************************************** 00349 0011 00350 I2CWAIT 0011 0004 00351 CLRWDT ;Clear watchdog timer

00352 CLB B_UA ;Init state flags 0012 0427 M BCF B_UA>>8,B_UA&7 ;(macro) 00353 CLB B_SA ;Init state flags 0013 0447 M BCF B_SA>>8,B_SA&7 ;(macro) 00354 CLB B_RD ;Init state flags 0014 0407 M BCF B_RD>>8,B_RD&7 ;(macro) 00355 0015 00356 loop1 0015 0004 00357 CLRWDT ;Clear watchdog timer 00358 00359 USER_MAIN ;Call user code while in idle state M ;*** This would be user code for idle loop 00360 00361 SKBC B_SDA ;Wait for SDA&SCL=H 0016 0605 M BTFSC B_SDA>>8,B_SDA&7 ;(macro) 0017 00362 loop2 00363 SKBS B_SCL ; 0017 0725 M BTFSS B_SCL>>8,B_SCL&7 ;(macro) 0018 0A15 00364 GOTO loop1 ; No longer valid to wait for start! 00365 0019 0004 00366 CLRWDT ;Clear watchdog timer 00367 00368 USER_MAIN ;Call user code while in idle state M ;*** This would be user code for idle loop 00369 00370 ;** wait for start ** 00371 SKBC B_SCL ;Clock has dropped 001A 0625 M BTFSC B_SCL>>8,B_SCL&7 ;(macro) 00372 SKBC B_SDA ;Data dropped... Start! 001B 0605 M BTFSC B_SDA>>8,B_SDA&7 ;(macro) 001C 0A17 00373 GOTO loop2 00374 00375 ;** START RECEIVED! --- wait for first bit! 001D 00376 loop3 00377 BBS B_SDA,I2CWAIT ;Data raised before clock dropped -- abort 001D 0605 M BTFSC B_SDA>>8,B_SDA&7 ;(macro) 001E 0A11 M GOTO I2CWAIT ;(macro) 00378 BBS B_SCL,loop3 ;Wait for clock low 001F 0625 M BTFSC B_SCL>>8,B_SCL&7 ;(macro) 0020 0A1D M GOTO loop3 ;(macro) 00379 00380 0021 00381 NEXTBYTE 0021 0004 00382 CLRWDT ;Clear watchdog timer

0022 0C01 00383 MOVLW 1 ;Init receive byte so bit falls off at end! 0023 0028 00384 MOVWF I2CREG 00385 00386 ;*Shift bits! external poll may be executed during low clock cycle only! 00387 ;*ENABLE line is checked for loss of enable ONLY during HIGH CLOCK 00388 00389 ;*** CLOCK IS LOW -- DATA MAY CHANGE HERE 00390 ;*** We have at least 4 Ês before any change can occur 00391 0024 00392 loop4 00393 USER_Q M ;*** This would be quick user code 0024 00394 loop4a 00395 BBC B_SCL,loop4A ;Wait for clock high 0024 0725 M BTFSS B_SCL>>8,B_SCL&7 ;(macro) 0025 0A24 M GOTO loop4a ;(macro) 00396 00397 ;*** CLOCK IS HIGH -- SHIFT BIT - then watch for chang e 0026 0305 00398 RRF PORTA,W ;Move RA0 into C 0027 0368 00399 RLF I2CREG,F ;Shift in bit 0028 0603 00400 SKPNC ;Skip if not done 0029 0A36 00401 GOTO ACK_I2C ;Acknowledge byte 00402 002A 0608 00403 BTFSC I2CREG,0 ;Skip if data bit was 0 002B 0A31 00404 GOTO ii_1 ;This bit was set 002C 00405 ii_0 00406 BBC B_SCL,loop4 ;Wait for clock low 002C 0725 M BTFSS B_SCL>>8,B_SCL&7 ;(macro) 002D 0A24 M GOTO loop4 ;(macro) 00407 SKBS B_SDA ;Data low-high == stop 002E 0705 M BTFSS B_SDA>>8,B_SDA&7 ;(macro) 002F 0A2C 00408 GOTO ii_0 0030 00409 I2CSTOP 00410 USER_MSG ;process completed message! M ;*** This would be user code to process a message 0030 0A11 00411 GOTO I2CWAIT ;back to main loop 00412 00413 ii_1 BBC B_SDA,I2CWAIT ;Data high-low == start 0031 0705 M BTFSS B_SDA>>8,B_SDA&7 ;(macro) 0032 0A11 M GOTO I2CWAIT ;(macro) 00414 BBC B_SCL,loop4 ;Wait for clock low 0033 0725 M BTFSS B_SCL>>8,B_SCL&7 ;(macro) 0034 0A24 M GOTO loop4 ;(macro)

0035 0A31 00415 GOTO ii_1 00416 0036 00417 ACK_I2C 00418 BBC B_UA,ACK_UA ;Not addressed - check unit address 0036 0727 M BTFSS B_UA>>8,B_UA&7 ;(macro) 0037 0A8B M GOTO ACK_UA ;(macro) 00419 BBS B_SA,ACK_SA ;Reading secondary address 0038 0647 M BTFSC B_SA>>8,B_SA&7 ;(macro) 0039 0A97 M GOTO ACK_SA ;(macro) 00420 00421 ;**** 00422 ;** Do what must be done with new data bytes here (before ACKloop) 00423 ;** Don t ack if byte can t be processed! 00424 ;**** 00425 ;-------- 00426 00427 USER_RECV M ;*** This would be user code to process a received byte M ;*** example code sends sub-address 0 to port b M BBC B_ID,_NXI_notid ;Channel 0! Bit set if INITIAL address was 0 003A 0767 M BTFSS B_ID>>8,B_ID&7 ;(macro) 003B 0A3F M GOTO _NXI_notid ;(macro) 003C 0208 M MOVFW I2CREG ;get received byte 003D 0026 M MOVWF PORTB ;and write it on portb 003E 0A47 M GOTO IN_CONT 003F M _NXI_notid 00428 003F 0C07 00429 MOVLW 07H ;Register count 0040 0169 00430 ANDWF I2CSUBA,f ;Limit register count 0041 0C0B 00431 MOVLW I2CR0 ;Pseudo-registers 0042 01C9 00432 ADDWF I2CSUBA,W ;Offset from buffer start 0043 02A9 00433 INCF I2CSUBA, F ;Next sub-address 0044 0024 00434 MOVWF FSR ;Indirect address 0045 0208 00435 MOVFW I2CREG 0046 0020 00436 MOVWF ind ;Put data into register 00437 0047 00438 IN_CONT ;continue point for intercepted bytes 00439 0047 00440 ACKloop 00441 BBS B_SCL,ACKloop ;Wait for clock low 0047 0625 M BTFSC B_SCL>>8,B_SCL&7 ;(macro) 0048 0A47 M GOTO ACKloop ;(macro) 00442 00443 CLB B_SDA ;Set ACK

0049 0405 M BCF B_SDA>>8,B_SDA&7 ;(macro) 004A 0CF6 00444 MOVLW TAWRITE 004B 0005 00445 TRIS PORTA 00446 CLB B_SDA ;Set ACK (just in case docs are wrong) 004C 0405 M BCF B_SDA>>8,B_SDA &7 ;(macro) 00447 00448 004D 00449 ACKloop2 00450 USER_Q M ;*** This would be quick user code 00451 BBC B_SCL,ACKloop2 ;Wait for clock high 004D 0725 M BTFSS B_SCL>>8,B_SCL&7 ;(macro) 004E 0A4D M GOTO ACKloop2 ;(macro) 00452 004F 00453 ACKloop3 00454 USER_Q M ;*** This would be quick user code 00455 BBS B_SCL,ACKloop3 ;Wait for clock low 004F 0625 M BTFSC B_SCL>>8,B_SCL&7 ;(macro) 0050 0A4F M GOTO ACKloop3 ;(macro) 00456 0051 0CF7 00457 MOVLW TAREAD ;End ACK 0052 0005 00458 TRIS PORTA 00459 00460 BBC B_RD,NEXTBYTE ;Skip if read (we were acking address only) 0053 0707 M BTFSS B_RD>>8,B_RD&7 ;(macro) 0054 0A21 M GOTO NEXTBYTE ;(macro) 00461 00462 00463 ;********************************************************************* 00464 ; I2C Readback (I2C read request) 00465 ; Application specific code to get bytes to send may be added here. 00466 ; This routine gets data from location pointed to by I2CSUBA and 00467 ; sends it to I2C. Subsequent reads get sequential addresses. This 00468 ; version AND s the register # with 7 to limit to 8 registers (for 00469 ; speed). Thiscould be modified to do a comparison to an Absolute 00470 ; number. 00471 ;********************************************************************* 00472 0055 00473 NEXTOUT 00474 00475 ;*** <<< PUT NEXT BYTE INTO I2CREG HERE NOW! >>> *** 00476 00477 USER_XMIT

M ;*** This would be user code to prepare an output byte M ;*** example code sends id string to output M BBC B_ID,_NXO_notid ;Channel 0! Bit set if INITIAL address was 0 0055 0767 M BTFSS B_ID>>8,B_ID&7 ;(macro) 0056 0A59 M GOTO _NXO_notid ;(macro) 0057 0900 M CALL GETID ;get next byte from ID channel 0058 0A60 M GOTO OUT_CONT ;and send it 0059 M _NXO_notid 00478 0059 0C07 00479 MOVLW 07H ;Register count 005A 0169 00480 ANDWF I2CSUBA,f ;Limit register count 005B 0C0B 00481 MOVLW I2CR0 ;Pseudo-registers 005C 01C9 00482 ADDWF I2CSUBA,W ;Offset from buffer start 005D 02A9 00483 INCF I2CSUBA, F ;Next sub-address 005E 0024 00484 MOVWF FSR ;Indirect address 005F 0200 00485 MOVFW ind ;Get data from register 00486 0060 00487 OUT_CONT 0060 0028 00488 MOVWF I2CREG 00489 ;-- add code here to init I2CREG! when B_ID is clear! 0061 0C08 00490 MOVLW 8 ;Bit counter 0062 002A 00491 MOVWF I2CBITS 00492 00493 ;** OUT bits! -- external poll may be executed during low clock cycle, 00494 ; but may also be executed during high cycle if necessary. 00495 00496 ;* ENABLE line is checked for loss of enable ONLY during HIGH CLOCK 00497 00498 ;*** CLOCK IS LOW -- CHANGE DATA HERE FIRST! 00499 00500 ;*** loop 1: data was 1 0063 00501 iiout_loop_1 0063 0368 00502 RLF I2CREG,F ;Shift data out, MSB first 0064 0603 00503 SKPNC ;1->0: change 0065 0A79 00504 GOTO iiout_1 ;Output another 1! 00505 CLB B_SDA ;Output 0 0066 0405 M BCF B_SDA>>8,B_SDA&7 ;(macro) 0067 0CF6 00506 MOVLW TAWRITE 0068 0005 00507 TRIS PORTA 00508 CLB B_SDA ;Set data (just in case docs are wrong) 0069 0405 M BCF B_SDA>>8,B_SDA&7 ;(macro) 00509 006A 00510 iiout_0 006A 0004 00511 CLRWDT ;Clear watchdog timer

00512 00513 USER_Q M ;*** This would be quick user code 00514 006B 00515 iiout_loop_02 00516 BBC B_SCL,iiOUT_loop_02 ;Wait for clock high 006B 0725 M BTFSS B_SCL>>8,B_SCL&7 ;(macro) 006C 0A6B M GOTO iiout_loop_02 ;(macro) 00517 00518 USER_Q M ;*** This would be quick user code 00519 006D 00520 iiout_loop_03 00521 BBS B_SCL,iiOUT_loop_03 ;Wait for clock low 006D 0625 M BTFSC B_SCL>>8,B_SCL&7 ;(macro) 006E 0A6D M GOTO iiout_loop_03 ;(macro) 00522 006F 02EA 00523 DECFSZ I2CBITS, F ;Count bits 0070 0A74 00524 GOTO iiout_loop_0 ;Loop for last bit 0 0071 0CF7 00525 MOVLW TAREAD ;Done with last bit 0... Set to 1 for ACK 0072 0005 00526 TRIS PORTA 0073 0A80 00527 GOTO iiout_ack ;Get ACK 00528 0074 00529 iiout_loop_0 0074 0368 00530 RLF I2CREG,F ;Shift data out, MSB first 0075 0703 00531 SKPC ;0->1: change 0076 0A6A 00532 GOTO iiout_0 ;Output another 0! 00533 0077 0CF7 00534 MOVLW TAREAD ;Set to 1 0078 0005 00535 TRIS PORTA 00536 0079 00537 iiout_1 0079 0004 00538 CLRWDT ;Clear watchdog timer 00539 00540 00541 USER_Q M ;*** This would be quick user code 00542 007A 00543 iiout_loop_12 00544 BBC B_SCL,iiOUT_loop_12 ;Wait for clock high 007A 0725 M BTFSS B_SCL>>8,B_SCL&7 ;(macro) 007B 0A7A M GOTO iiout_loop_12 ;(macro) 00545 00546

00547 USER_Q M ;*** This would be quick user code 00548 007C 00549 iiout_loop_13 00550 BBS B_SCL,iiOUT_loop_13 ;Wait for clock low 007C 0625 M BTFSC B_SCL>>8,B_SCL&7 ;(macro) 007D 0A7C M GOTO iiout_loop_13 ;(macro) 00551 007E 02EA 00552 DECFSZ I2CBITS, F ;Count bits 007F 0A63 00553 GOTO iiout_loop_1 ;Loop for last bit 1 00554 00555 0080 00556 iiout_ack ;Get acknowledge 0080 02A9 00557 INCF I2CSUBA, F ;Next sub-address 00558 0081 00559 iiout_loop_a2 00560 BBC B_SCL,iiOUT_loop_a2 ;Wait for clock high 0081 0725 M BTFSS B_SCL>>8,B_SCL&7 ;(macro) 0082 0A81 M GOTO iiout_loop_a2 ;(macro) 00561 00562 BBS B_SDA,I2CWAIT ;No ACK --- wait for restart! 0083 0605 M BTFSC B_SDA>>8,B_SDA&7 ;(macro) 0084 0A11 M GOTO I2CWAIT ;(macro) 00563 00564 ;-- prepare next character here! 00565 0085 00566 iiout_loop_a3 00567 BBC B_SCL,NEXTOUT ;Wait for clock low - output next char! 0085 0725 M BTFSS B_SCL>>8,B_SCL&7 ;(macro) 0086 0A55 M GOTO NEXTOUT ;(macro) 00568 00569 BBS B_SDA,iiOUT_loop_a3 ;Watch out for new start condition! 0087 0605 M BTFSC B_SDA>>8,B_SDA&7 ;(macro) 0088 0A85 M GOTO iiout_loop_a3 ;(macro) 0089 0A11 00570 GOTO I2CWAIT ;Stop received! 008A 00571 USER_READ ;user code to process data sent 00572 008A 0A11 00573 GOTO I2CWAIT 00574 00575 00576 ;********************************************************************** 00577 ;* Unit address received - check for valid address 00578 ;* 00579 ;**********************************************************************

008B 00580 ACK_UA 00581 SEB B_UA ;Flag unit address received 008B 0527 M BSF B_UA>>8,B_UA&7 ;(macro) 008C 0608 00582 BTFSC I2CREG,0 ;Skip if data coming in 00583 SEB B_RD ;Flag - reading from slave 008D 0507 M BSF B_RD>>8,B_RD&7 ;(macro) 008E 0208 00584 MOVF I2CREG,W ;Get address 008F 0EFE 00585 ANDLW 0FEH ;Mask direction flage before compare 0090 0FD6 00586 XORLW DEVICE_ADDRESS ;Device address 0091 0743 0A11 00587 BNZ I2CWAIT ;Not for me! (skip rest of message) 00588 BBS B_RD,ACKloop ;Read - no secondary address 0093 0607 M BTFSC B_RD>>8,B_RD&7 ;(macro) 0094 0A47 M GOTO ACKloop ;(macro) 00589 SEB B_SA ;Next is secondary address 0095 0547 M BSF B_SA>>8,B_SA&7 ;(macro) 0096 0A47 00590 GOTO ACKloop ;Yes! ACK address and continue! 00591 00592 ;********************************************************************** 00593 ;* Secondary address received - stow it! 00594 ;* SA = 0 is converted to 128 to facilitate ID read 00595 ;********************************************************************** 0097 00596 ACK_SA 00597 CLB B_SA ;Flag second address received 0097 0447 M BCF B_SA>>8,B_SA&7 ;(macro) 00598 CLB B_ID 0098 0467 M BCF B_ID>>8,B_ID&7 ;(macro) 0099 0208 00599 MOVFW I2CREG ;Get subaddress 009A 0643 00600 SKPNZ ;Not 0 00601 SEB B_ID ;Flag - id area selected 009B 0567 M BSF B_ID>>8,B_ID&7 ;(macro) 009C 0029 00602 MOVWF I2CSUBA ;Set subaddress 009D 0A47 00603 GOTO ACKloop 00604 00605 00606 END MEMORY USAGE MAP ( X = Used, - = Unused) 0000 : XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX 0040 : XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX 0080 : XXXXXXXXXXXXXXXX XXXXXXXXXXXXXX-- ---------------- ---------------- 01C0 : ---------------- ---------------- ---------------- ---------------X All other memory blocks unused. Program Memory Words Used: 159 Program Memory Words Free: 353 Errors : 0

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