by Michael Brown of Instant Net Solutions www.KillerPCs.net
Code:
;--------------------------------------------------------------------------------------------- ; HEADER: ;--------------------------------------------------------------------------------------------- LIST P=16f84a RADIX DEC INCLUDE "p16f84a.inc" __CONFIG _CP_OFF & _WDT_OFF & _XT_OSC & _PWRTE_ON ; This program and the code/routines contained within are Copyright 2001,2003 by michael brown. It may ; not be used for commercial purposes without written consent from the Copyright holder (me). It ; is free for personal use as long as this Copyright message is kept intact. If commercial ; usage is desired, please contact michael brown via e-mail at n5qmg@amsat.org to make licensing ; arrangements. I'm not trying to be a greedy jerk, but I have to eat too. ;-) ; ; 73's de N5QMG ;--------------------------------------------------------------------------------------------- #define Clock_Freq 4000000 #include "wait.mac" ;--------------------------------------------------------------------------------------------- ; EQUATES: ;--------------------------------------------------------------------------------------------- RS equ 0 ;LCD's pin 4 should be connected to PORTB.0 RW equ 1 ;LCD's pin 5 should be connected to PORTB.1 EN equ 2 ;LCD's pin 6 should be connected to PORTB.2 #define LCD_PORT PORTB ;LCD_PORT implies use of bits 4-7 for data lines to LCD #define LCD_RS LCD_PORT, RS #define LCD_RW LCD_PORT, RW #define LCD_EN LCD_PORT, EN #define LCD_DAT7 LCD_PORT, 7 #define LCD_DAT6 LCD_PORT, 6 #define LCD_DAT5 LCD_PORT, 5 #define LCD_DAT4 LCD_PORT, 4 #define YEL_LED PORTA, 0 #define RED_LED PORTA, 1 #define INTSCOPE PORTA, 2 #define MAIN_SCOPE PORTA, 3 #define ONE_WIRE PORTA, 4 ;Dallas 1-wire bus MAX_DEVICES equ 4 ;Maximum number of 1-wire devices to find STARTOFRAM equ 0x0C ;First Usable RAM Location for 16f84 ENDOFRAM equ 0x4F ;Last Usable RAM Location for 16f84 ; ; General Purpose Temp Storage ; cblock STARTOFRAM OneWireByte SOURCE DEST TEMP0 TEMP1 TEMP2 tempone temptwo ; ; ISR Register Save Areas ; ;INT_FLAGS ;W_TEMP ;STATUS_TEMP ;FSR_TEMP ; ; ISR Loop Control ; ;LoopCntH ;LoopCntL ; ; Variables Relating to LCD Control ; CursorRow ; Current Cursor Position CursorCol AbsAddr ; Absolute cursor position (start address of CursorRow + CursorCol) SrcRowNum ; Source Row Number DestRowNum ; Destination Row Number SrcCharAddr ; DDRAM address in LCD DestCharAddr ; DDRAM address in LCD RowLoopCtr ; For Scrolling the screen CharLoopCtr ; Same as above LCD_Data TEMPX ; ; Work areas ; rombit_idx bits ctr_1wire curr_discrep last_discrep done_flag return_value ; One-Wire work area work0 ; CRC (8 bits) work1 ; Serial # (48 bits) work2 ; " work3 ; " work4 ; " work5 ; " work6 ; " work7 ; Family Code (8 bits) ;Sensor 0 Storage ts00 ts01 ts02 ts03 ts04 ts05 ts06 ts07 ;Sensor 1 Storage ts10 ts11 ts12 ts13 ts14 ts15 ts16 ts17 ;Sensor 2 Storage ts20 ts21 ts22 ts23 ts24 ts25 ts26 ts27 ;Sensor 3 Storage ts30 ts31 ts32 ts33 ts34 ts35 ts36 ts37 endc ;--------------------------------------------------------------------------------------------- ; START: ;--------------------------------------------------------------------------------------------- org 0x000 goto Start org 0x004 ; movwf W_TEMP ;Save everything ; swapf STATUS, W ; movwf STATUS_TEMP ; movfw FSR ; movwf FSR_TEMP ; ; Interrupt handler right here ; ; bsf INTSCOPE ;Mark start of interrupt routine ; bcf INTSCOPE ;Mark end of interrupt routine (for timing) ; ; Restore everything and return ; ;IntExit ; movfw FSR_TEMP ; movwf FSR ; swapf STATUS_TEMP, W ; movwf STATUS ; swapf W_TEMP, F ; swapf W_TEMP, W retfie ;------------------------------------------------------------- ;Store_Bit -- take bit A (bits.1) and store into work0..work7 ; at bit offset rombit_idx (1 relative) ; Entry: ; bits - contains 2 bits read from 1 wire bus bits.1 is the one to store ; rombit_idx - contains one relative bit offset from rom work area (work0..work7) ; of bit to store ; Exit: ; bits.1 -> work0..work7(rombit_idx) ;------------------------------------------------------------- Store_Bit call SetupFSR ;convert rombit_idx to something we can use ;Determine if we need to set a bit (1) or clear a bit (0) movlw HIGH SetWorkBit movwf PCLATH rrf bits, W ;get bit.1 value right justified into W andlw b'00000001' ;maintain sanity addwf PCL, F ;quick test for 0 or 1 goto ClrWorkBit ;must be 0 (clr bit) SetWorkBit ;must be 1 (set bit) clrc rlf TEMP2, W ;get bit position * 2 (0, 2, 4 .. 14) addwf PCL, F ;bump PC, turn bit on then return bsf INDF, 7 return bsf INDF, 6 return bsf INDF, 5 return bsf INDF, 4 return bsf INDF, 3 return bsf INDF, 2 return bsf INDF, 1 return bsf INDF, 0 return ClrWorkBit movlw HIGH ClrWorkBit movwf PCLATH clrc rlf TEMP2, W ;get bit position * 2 (0, 2, 4 .. 14) addwf PCL, F ;bump PC and turn it off then return bcf INDF, 7 return bcf INDF, 6 return bcf INDF, 5 return bcf INDF, 4 return bcf INDF, 3 return bcf INDF, 2 return bcf INDF, 1 return bcf INDF, 0 return ;------------------------------------------------------------- ;GetWorkBit -- ; at bit offset rombit_idx (1 relative) ; Entry: ; rombit_idx - contains one relative bit offset from rom work area (work0..work7) ; of bit to retrieve value of ; Exit: ; work0..work7(rombit_idx) -> W ;-------------------------------------------------------------- GetWorkBit call SetupFSR ;point to the bit in question movlw HIGH GetWorkBit movwf PCLATH clrc rlf TEMP2, W ;get bit position * 2 into w addwf TEMP2, W ;compute w = bit offset * 3 (0, 3, 6 ...) addwf PCL, F ;bump PC to jump to appropriate test ;Bit 0 btfss INDF, 7 ;Is bit set(1) retlw d'0' ; No, return 0 retlw d'1' ; Yes, return 1 ;Bit 1 btfss INDF, 6 ;Is bit set(1) retlw d'0' ; No, return 0 retlw d'1' ; Yes, return 1 ;Bit 2 btfss INDF, 5 ;Is bit set(1) retlw d'0' ; No, return 0 retlw d'1' ; Yes, return 1 ;Bit 3 btfss INDF, 4 ;Is bit set(1) retlw d'0' ; No, return 0 retlw d'1' ; Yes, return 1 ;Bit 4 btfss INDF, 3 ;Is bit set(1) retlw d'0' ; No, return 0 retlw d'1' ; Yes, return 1 ;Bit 5 btfss INDF, 2 ;Is bit set(1) retlw d'0' ; No, return 0 retlw d'1' ; Yes, return 1 ;Bit 6 btfss INDF, 1 ;Is bit set(1) retlw d'0' ; No, return 0 retlw d'1' ; Yes, return 1 ;Bit 7 btfss INDF, 0 ;Is bit set(1) retlw d'0' ; No, return 0 retlw d'1' ; Yes, return 1 ;--------------------------------------------------------------------- ;Lookup_TS -- Return address of start of 8 byte entry within TS table ; Entry: ; W contains slot number within TS table (0,1,2, or 3) ; Exit: ; W contains address of beginning of slot pointed to by W ;--------------------------------------------------------------------- Lookup_TS andlw b'00000011' addwf PCL, F retlw ts00 retlw ts10 retlw ts20 retlw ts30 ;--------------------------------------------------------------------------------------------- ; ; lookup_row - Lookup ddram address of beginning of row for LCD ; ;--------------------------------------------------------------------------------------------- lookup_row addwf PCL, F ; bump PC by zero relative row number retlw 0x00 ; start of row 0 retlw 0x40 ; row 1 retlw 0x14 ; row 2 retlw 0x54 ; row 3 ;---------------------------------------------------------------------------------------- ; SetupFSR -- Point FSR at byte within work area determined by rombit_idx ; Entry: ; rombit_idx contians bit number (one relative) we need to get to ; Exit: ; FSR - pointing at byte within work0..work7 ; TEMP1 - zero relative byte offset (0,1,..7) ; TEMP2 - zero relative(0,1,..7) bit offset within byte ;---------------------------------------------------------------------------------------- SetupFSR ;Setup FSR, TEMP1(byte offset), and TEMP2(bit offset) decf rombit_idx, W ;convert index to 0 relative sublw d'63' ;form compliment of rombit_idw 0-63->63-0 movwf TEMP1 ; and temp byte offset area andlw b'00000111' ;strip off byte offset leaving bit offset only movwf TEMP2 ; and save into temp bit offset area clrc ;right justify the byte offset in TEMP1 rrf TEMP1, F ; by right shifting clrc ; and stripping 3 LSB's rrf TEMP1, F clrc rrf TEMP1, F ;Get FSR pointing at appropriate byte in work area (work0, work1 ...) movlw work0 ;Point FSR at beginning of work area movwf FSR movfw TEMP1 ;get byte offset (0 relative) addwf FSR, F ; point FSR straight at it return ;--------------------------------------------------------------------------------------------- ; ; Main level code begins here ; ;--------------------------------------------------------------------------------------------- Start bsf STATUS, RP0 ;Switch to Bank 1 movlw b'00000000' ;Define I/O on Port B (all outputs) movwf TRISB & 0x07F movlw b'00000' ;Define I/O on Port A (all outputs) movwf TRISA & 0x07F bcf STATUS, RP0 ;Back to Bank 0 clrf PORTA clrf PORTB Main ; Waste a couple of seconds between itterations Wait 100 Millisecs, 0 Wait 100 Millisecs, 0 Wait 100 Millisecs, 0 Wait 100 Millisecs, 0 Wait 100 Millisecs, 0 Wait 100 Millisecs, 0 Wait 100 Millisecs, 0 Wait 100 Millisecs, 0 Wait 100 Millisecs, 0 Wait 100 Millisecs, 0 Wait 100 Millisecs, 0 Wait 100 Millisecs, 0 Wait 100 Millisecs, 0 Wait 100 Millisecs, 0 Wait 100 Millisecs, 0 Wait 100 Millisecs, 0 Wait 100 Millisecs, 0 Wait 100 Millisecs, 0 Wait 100 Millisecs, 0 Wait 100 Millisecs, 0 call LCD_Init ;Initialize the LCD movlw 'I' ;Display Init message call LCD_Txt movlw 'n' call LCD_Txt movlw 'i' call LCD_Txt movlw 't' call LCD_Txt movlw 'i' call LCD_Txt movlw 'a' call LCD_Txt movlw 'l' call LCD_Txt movlw 'i' call LCD_Txt movlw 'z' call LCD_Txt movlw 'e' call LCD_Txt movlw 'd' call LCD_Txt movlw ' ' ;Display Version call LCD_Txt movlw 'V' call LCD_Txt movlw 'e' call LCD_Txt movlw 'r' call LCD_Txt movlw '.' call LCD_Txt movlw ' ' call LCD_Txt movlw '0' call LCD_Txt movlw '.' call LCD_Txt movlw '1' call LCD_Txt movlw 0x03 ;position to bottem row movwf CursorRow movlw 0x13 ;position to last column movwf CursorCol call Search_1Wire_init _search_next ; movlw 'a' ; call LCD_Print call Search_1Wire ;Initiate a search ; movlw 'b' ; call LCD_Print btfss return_value, 0 ;See if we found anything goto _search_done ;Nope, we are done ; movlw 'c' ; call LCD_Print movlw work0 ;get address of work area movwf SOURCE ;make it the source for block move movlw HIGH Lookup_TS movwf PCLATH movfw ctr_1wire ;get device count call Lookup_TS ;get address of its entry movwf DEST ;set as destination for block move call Block_Move ;copy the work area off to storage call Print_Work_Area incf ctr_1wire, F ;count the one just found movlw MAX_DEVICES xorwf ctr_1wire, W btfss STATUS, Z ;is it 4 devices found yet goto _search_next ; No, try for another _search_done ; movlw 'X' ; call LCD_Print goto Main Print_Work_Area movfw work0 call LCD_Hex movlw ':' call LCD_Print movfw work1 call LCD_Hex movfw work2 call LCD_Hex movfw work3 call LCD_Hex movfw work4 call LCD_Hex movfw work5 call LCD_Hex movfw work6 call LCD_Hex movlw ':' call LCD_Print movfw work7 call LCD_Hex movlw 0x13 ;position to last column so next byte starts on new line movwf CursorCol return ;------------------------------------------------------------------- ; ; Search the Dallas 1-Wire Bus ; ;------------------------------------------------------------------- Search_1Wire_init clrf ctr_1wire ;init device counter(effectively clears table) clrf work0 ;clear the work area to zeros clrf work1 clrf work2 clrf work3 clrf work4 clrf work5 clrf work6 clrf work7 clrf last_discrep ;init the bit position of last descrepancy clrf done_flag ;set status to not done return Search_1Wire clrf return_value ;set return flag to false btfss done_flag,0 ;Are we done yet? goto Do_reset ; No, start a search clrf done_flag ; Yes, init this for next time??? goto Wrapup ; and get on out of here Do_reset call Reset_1wire clrf rombit_idx ;set rom bit index to 1 incf rombit_idx, F clrf curr_discrep ;set descrepancy marker to 0 movlw h'f0' ;send search rom movwf OneWireByte call Sendbyte_1wire ; command to devices bsf MAIN_SCOPE bcf MAIN_SCOPE Get_2bits call Readbit_1wire ;read bit a from bus and movwf bits ; save it clrc ;clear the carry flag rlf bits, F ;shift bit A over to the left call Readbit_1wire ;read bit B from bus and iorwf bits, F ; save it movlw HIGH lookup_1x movwf PCLATH movfw bits lookup_1x addwf PCL, F ;decode the bits read goto bits_00 ;collision detected goto bits_01 ;0 read goto bits_10 ;1 read goto bits_11 ;nobody there bits_00 ;collision detected ;Does rombit_idx = last_discrep ; movlw '0' ; call LCD_Print movfw rombit_idx xorwf last_discrep, W btfss STATUS, Z ;Does rombit_idx = last_discrep goto _chknxt ; No, check other stuff movlw b'10' ; Yes, pretend we read a 1 movwf bits call Store_Bit ;Store a 1 into work area goto ack_bus _chknxt movfw last_discrep ;get current bit position subwf rombit_idx, W ;compare to last discrepancy position ;is rombit_idx > last_discrep btfss STATUS, C goto _chknx2 ; No, movlw b'01' ; Yes, pretend we read a 0 movwf bits call Store_Bit ;set discrepancy marker to rombit_idx movfw rombit_idx movwf curr_discrep goto ack_bus _chknx2 ;does rombits(rombit_idx) = 0 ? call GetWorkBit ;get bit located at work(rombit_idx) movwf TEMP0 ; and save movlw HIGH lookup_2x movwf PCLATH movfw TEMP0 lookup_2x addwf PCL, F ;quik test for 0 or 1 goto _zero ; was 0 _one ; was 1 movlw b'10' ; Pretend we read a 1 movwf bits goto ack_bus _zero movlw b'01' ; Pretend we read a 0 movwf bits ;set discrepancy marker to rombit_idx movfw rombit_idx movwf curr_discrep goto ack_bus bits_01 ;0 received ; movlw '1' ; call LCD_Print goto _storit bits_10 ;1 received ; movlw '2' ; call LCD_Print _storit call Store_Bit ;Save it into work area at rombit_idx offset ; Send rombit(rombit_idx) to 1-wire bus ack_bus ; call GetWorkBit clrc ;clear the carry flag and rrf bits, W ; get bit A into W call Sendbit_1wire ;send bit A to wire ; Increment rombit_idx incf rombit_idx, F ;bump pointer to next location ; Is rombit_idx > 64? movfw rombit_idx ;see if index > 64 sublw d'65' ; (i.e. = 65) btfss STATUS, Z goto Get_2bits ;if not, loop back for more ;set last discrepancy to descrepancy marker movfw curr_discrep movwf last_discrep ;is last discrepancy = 0? btfsc STATUS, Z incf done_flag, F ;yes, set done flag movlw d'1' ;either way, set return value to true movwf return_value goto Wrapup bits_11 ;nothing answered on the bus movlw 'D' call LCD_Print movlw 'e' call LCD_Print movlw 'a' call LCD_Print movlw 'd' call LCD_Print movlw 'B' call LCD_Print movlw 'e' call LCD_Print movlw 'e' call LCD_Print movlw 'f' call LCD_Print clrf last_discrep goto Wrapup Wrapup return ;--------------------------------------------------------------------- ;Reset the one wire bus ;--------------------------------------------------------------------- Reset_1wire bcf ONE_WIRE ;Pull it low Wait 480 Microsecs, 0 ;Hold it till they are reset bsf ONE_WIRE ;Let it idle back up ; ;*** suppose to check for ack from devices here, but why?? I'm leaving it out for now ; Wait 500 Microsecs, 0 return ;--------------------------------------------------------------------- ;Send bytes and bits on the one wire bus ; BYTE -- Send a byte from OneWireByte to the one wire bus ; bit -- Send bits, 1 to the one wire bus ;--------------------------------------------------------------------- Sendbyte_1wire movlw d'8' movwf TEMP0 ; bsf MAIN_SCOPE ; bcf MAIN_SCOPE _send_1w_lp clrf TEMP1 ;Clear work area bcf TEMP1, 0 ;Assume sending 0 clrc ;Fill new bits with 0 rrf OneWireByte, F ;Load CARRY with bit to send btfsc STATUS, C ;See what we are sending bsf TEMP1, 0 ; must be a 1 movfw TEMP1 ;Load up the bit and call Sendbit_1wire ; send it out decfsz TEMP0, F ;Is it 8 bits yet goto _send_1w_lp ; not yet return Sendbit_1wire movwf TEMP1 bcf ONE_WIRE ;Pull it low btfsc TEMP1, 0 bsf ONE_WIRE ;end of low pulse if bit was a 1 Wait 58 Microsecs,0 ; (Tslot + Trec) - Tlow1 bsf ONE_WIRE ;end of low pulse if 0 (1 no change) Wait 1 Microsecs,4 ; Trec return ;--------------------------------------------------------------------- ;Receive bytes and bits from the one wire bus ; BYTE -- Read a byte from the one wire and stick into OneWireByte ; bit -- Read a bit sticking it into bits, 1 ;--------------------------------------------------------------------- Readbyte_1wire movlw d'8' movwf TEMP0 _read_1w_lp call Readbit_1wire movwf TEMP1 ;Save the bit read clrc ;Assume bit is 0 btfsc TEMP1, 0 ;Check bit setc ; its a 1 rrf OneWireByte, F ;Rotate bit into IO area decfsz TEMP0, F ;Is it 8 bits yet goto _read_1w_lp ; not yet movfw OneWireByte ; yes, return with byte read in W return ; Readbit_1wire bcf ONE_WIRE ;Pull it low and nop bsf ONE_WIRE ; release for a clock pulse clrf TEMP1 ;Assume incomming bit is 0 Wait 12 Microsecs, 0 ;Give device time to respond btfsc ONE_WIRE ;What are we receiving? bsf TEMP1, 0 ; must be a 1 Wait 47 Microsecs, 0 ;Wait out the rest of the cycle movfw TEMP1 return ;--------------------------------------------------------------------- ;Block_Move -- Move 8 Bytes from SOURCE to DEST ; Entry: ; SOURCE should be pointing at place to move from ; DEST should be pointing at destination place to store block ; Exit: ; SOURCE ,DEST, TEMP0, TEMP1, FSR will be destroyed. However, ; the data will be moved ;-D ;--------------------------------------------------------------------- Block_Move movlw d'8' movwf TEMP0 _move_lp movfw SOURCE ;Set up source pointer movwf FSR movfw INDF ;get the byte movwf TEMP1 ; and save it movfw DEST ;Set up destination pointer movwf FSR movfw TEMP1 ;pick up saved byte movwf INDF ; and store it (now it is moved to destination) incf SOURCE, F ;adjust pointers incf DEST, F decfsz TEMP0, F goto _move_lp return ;--------------------------------------------------------------------------------------------- ; ; LCD_Print - Print a character to the LCD w/proper scrolling and wrapping ; Code is setup for a 4 * 20 LCD Display ; ;--------------------------------------------------------------------------------------------- LCD_Print movwf TEMPX incf CursorCol, F ;Bump the cursor movfw CursorCol ;Load it xorlw 0x14 ;Is it running off the right side of the screen btfss STATUS, Z goto noscroll ;No, go on and print it ; bsf MAIN_SCOPE call scroll_scr ;Yes, scroll the display clrf CursorCol ;Set cursor to beginning of line ; bcf MAIN_SCOPE noscroll movlw HIGH lookup_row movwf PCLATH movfw CursorRow ;Get current row into W call lookup_row ;Convert to start address of row addwf CursorCol, W ;Add in the column position movwf AbsAddr ;Store absolute address iorlw b'10000000' ; convert ABS Address to lcd command to set DDRAM address call LCD_Cmd ;Set DDRAM address movfw TEMPX ;Load the character received and goto LCD_Txt ; display it ;--------------------------------------------------------------------------------------------- ; ; scroll_scr - Scroll Screen by moving data up a line at a time and then ; filling the bottom row with blanks. ; ;--------------------------------------------------------------------------------------------- scroll_scr movlw 0x03 ; Move three rows total 1->0, 2->1, 3->2 movwf RowLoopCtr ; clrf DestRowNum ; Destination starts at row 0 movlw 0x01 ; Source row starts at row 1 movwf SrcRowNum move_row movlw HIGH lookup_row movwf PCLATH movf DestRowNum, W ; Get destination row number and call lookup_row ; convert to a char address movwf DestCharAddr ; and save it movlw HIGH lookup_row movwf PCLATH movf SrcRowNum, W ; Get source row number and call lookup_row ; convert to a char address movwf SrcCharAddr ; and save it movlw 0x14 ; twenty chars per line movwf CharLoopCtr move_chars ; read the source character movf SrcCharAddr, W ; Load DDRAM address into W ; call LCD_ReadRam ; Fetch the character stored there iorlw b'10000000' ;Turn on the high bit (Set DDRAM Address) call LCD_Cmd ;Write the command to set the address call LCD_In ;Read the DDRAM value at current position movwf LCD_Data ; and save it ;if bottom row move a space to it while we are here movf SrcRowNum,W ; See which row we are on xorlw 0x03 ; Is it the bottom one btfss STATUS, Z goto wrtdest ; No, just write the destination location ;have to reposition the cursor since it insists on moving itself after a read movf SrcCharAddr, W ; Load DDRAM address into W iorlw b'10000000' ; make into a command to set address call LCD_Cmd ; issue the command movlw ' ' ; Load up a space character call LCD_Txt ; and clear the character in the bottom row ;write to destination address wrtdest movf DestCharAddr, W ; Load Destination DDRAM address iorlw b'10000000' ; make into a command to set address call LCD_Cmd ; issue the command movf LCD_Data, W ; Get the saved character call LCD_Txt ; Write character to destination address incf SrcCharAddr, F incf DestCharAddr, F decfsz CharLoopCtr, F goto move_chars row_done incf DestRowNum, F ; Point to next row incf SrcRowNum, F ; Same thing decfsz RowLoopCtr, F ; Decrement loop counter and goto move_row ; move next row return ;--------------------------------------------------------------------------------------------- ; ; LCD_ReadRam - Return character stored at LCD DDRAM Location ; ;--------------------------------------------------------------------------------------------- LCD_ReadRam ; movwf TEMP3 ;Save the address iorlw b'10000000' ;Turn on the high bit (Set DDRAM Address) call LCD_Cmd ;Write the command to set the address call LCD_In ;Read the DDRAM value at current position return ;--------------------------------------------------------------------------------------------- ; LCD_Txt - Write ASCII byte in W to LCD ; ;--------------------------------------------------------------------------------------------- LCD_Txt movwf TEMP1 ;Store w for LCD_Out call LCD_BF ;Get the busy flag andlw b'10000000' btfss STATUS, Z ;Is busy flag set? goto $ - 3 ; yes. Re-test busy flag. bsf LCD_RS ;This is DATA. goto LCD_Out ;Execute part of LCD_Cmd ;--------------------------------------------------------------------------------------------- ; LCD_Cmd ROM: 12 words RAM: TEMP0, TEMP1 ;--------------------------------------------------------------------------------------------- LCD_Cmd movwf TEMP1 ;Store w call LCD_BF ;Get the busy flag andlw b'10000000' btfss STATUS, Z ;Is busy flag set? goto $ - 3 ; Yes. Re-test busy flag. bcf LCD_RS ;This is a COMMAND. LCD_Out bcf LCD_RW ;This is a WRITE. movf TEMP1, w ;Restore w. call LCD_Nbl ;Output the upper four bits of W. swapf TEMP1, w ;Swap nybbles (and put result in W). call LCD_Nbl ;Output the lower four bits of W. return ;Done--Return. ;---------------------------------------------------------------------------------------------- ; ; LCD_In - Return byte stored in CGRAM at currently addressed location (cursor position) ; ;---------------------------------------------------------------------------------------------- LCD_In call LCD_BF ;Get the busy flag andlw b'10000000' btfss STATUS, Z ;Is busy flag set? goto LCD_In ; Yes. Re-test busy flag. bsf LCD_RS ;This is DATA operation. bsf LCD_RW ;This is a READ. bsf STATUS, RP0 ;Select Bank 1. bsf TRISB & 0x07F, 4 ;Make ports input bsf TRISB & 0x07F, 5 bsf TRISB & 0x07F, 6 bsf TRISB & 0x07F, 7 bcf STATUS, RP0 ;Bank 0 please bsf LCD_EN ;Clock out the RS and RW bits. movf LCD_PORT, w ;Get, andlw b'11110000' ; mask, and movwf TEMP0 ; store the upper nybble into a temp area bcf LCD_EN ;Clock in the upper nybble bsf LCD_EN ;Clock in the lower nybble movf LCD_PORT, w ;Get and andlw b'11110000' ; mask the lower nybble bcf LCD_EN swapf TEMP0, f ;Flip the temp area around backwards and iorwf TEMP0, f ; OR in the lower nybble to the upper half of temp swapf TEMP0, w ;Repair and load the byte into w. return ;Done -- return. ;--------------------------------------------------------------------------------------------- ; ; LCD_Hex - Take byte in W and LCD_Print it in HEX ; ;--------------------------------------------------------------------------------------------- LCD_Hex movwf TEMP2 ;Store w swapf TEMP2, w ;Get upper nybble of w andlw b'00001111' call LCD_Hex1 ;Convert upper nybble to ASCII call LCD_Print ;Output ASCII on LCD display movf TEMP2, w ;Get lower nybble of w andlw b'00001111' call LCD_Hex1 ;Conver lower nybble to ASCII call LCD_Print ;Output ASCII on LCD display return ;Done--return. LCD_Hex1 addlw 0xF6 ;This routine converts a number in w to an btfsc STATUS, C ;ASCII hex number. Result in w. addlw 0x07 addlw 0x3A return ;--------------------------------------------------------------------------------------------- ; ; LCD_Nbl - Writes one nibble contained in upper half of W to LCD ; ;--------------------------------------------------------------------------------------------- LCD_Nbl bsf STATUS, RP0 ;Make LCD_PORT.4-7 Outputs bcf TRISB & 0x07F, 4 bcf TRISB & 0x07F, 5 bcf TRISB & 0x07F, 6 bcf TRISB & 0x07F, 7 bcf STATUS, RP0 bcf LCD_RW ;This is a WRITE command. bsf LCD_EN ;Clock out RS and RW. iorlw b'00001111' ;Write the upper four bits in W to the upper andwf LCD_PORT, f ; four bits in LCD_PORT. andlw b'11110000' iorwf LCD_PORT, f bcf LCD_EN ;Clock out the four data bits. return ;Done--Return. ;--------------------------------------------------------------------------------------------- ; ; LCD_BF - Do a busy flag read of the LCD returning in W': BF A6 A5 A4 A3 A2 A1 A0 ; ;--------------------------------------------------------------------------------------------- LCD_BF bcf LCD_RS ;This is a DATA operation. bsf LCD_RW ;This is a READ command. bsf STATUS, RP0 ;Select Bank 1. bsf TRISB & 0x07F, 4 ;Make ports input bsf TRISB & 0x07F, 5 bsf TRISB & 0x07F, 6 bsf TRISB & 0x07F, 7 bcf STATUS, RP0 bsf LCD_EN ;Clock out the RS and RW bits. movf LCD_PORT, w ;Get, andlw b'11110000' ; mask, and movwf TEMP0 ; store the upper nybble into a temp area bcf LCD_EN ;Bring enable pin low after getting data bsf LCD_EN ;Clock in the lower nybble movf LCD_PORT, w ;Get and andlw b'11110000' ; mask the lower nybble bcf LCD_EN swapf TEMP0, f ;Flip the temp area around backwards and iorwf TEMP0, f ; OR in the lower nybble to the upper half of temp swapf TEMP0, w ;Repair and load the byte into w. return ;Done -- return. ;--------------------------------------------------------------------------------------------- ; ; LCD_Init - That pretty much says it all ; ;--------------------------------------------------------------------------------------------- LCD_Init bcf LCD_RS ;The following will write to the HD44780's IR. Wait 10 Millisecs, 0 ; ;Grab display per recommended way by setting to eight bit mode 3 times ; movlw b'00111000' ;Function set call LCD_Nbl Wait 50 Microsecs, 0 ;Wait 50us movlw b'00111000' ;Function set call LCD_Nbl Wait 50 Microsecs, 0 ;Wait 50us movlw b'00111000' ;Function set call LCD_Nbl Wait 50 Microsecs, 0 ;Wait 50us ; ;Now that we have its attention, set it to nibble mode and initialize ; movlw b'00101000' ;Function Set -- 0 0 1 DL N F X X (nibble mode, 2lines, 5x7 font) call LCD_Cmd movlw b'00000001' ;Clear Display -- 0 0 0 0 0 0 0 1 call LCD_Cmd Wait 1650 Microsecs, 0 ;Wait 1.65ms movlw b'00000110' ;Entry Mode Set -- 0 0 0 0 0 1 ID S (increment, no shifting) call LCD_Cmd movlw b'00001100' ;Display Control -- 0 0 0 0 1 D C B (display on, no cursor, no blink) call LCD_Cmd return #include "delay.asm" end+
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file: /Techref/microchip/ibuttonsearch.htm, 44KB, , updated: 2013/1/11 13:09, local time: 2024/8/14 20:40,
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Ashley Roll has put together a really nice little unit here. Leave off the MAX232 and keep these handy for the few times you need true RS232! |
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