TITLE "ADT75A.asm" ; -55 - 120C thermometer List P=PIC16F628a, R=DEC ; with ADT75A sensor INCLUDE "p16f628a.inc" SCL EQU 7 ; Clock line setup SDA EQU 6 ; Data line setup ; data segment in BANK 0 CBLOCK 0x20 tempRQ, d, tmp, cnt, tint:2 ; local variables w_save, stat_save, pc_save ; ISR variables point, scale, button, sign ; decimal point flag err_i2c, dataIO, ACK_NAK ; I2C interface vars hundreds, units, tens, fract ; vars for BCD conversion bcd:4 ; BCD representation of TEMP temp:2 ; storage for temp measurement conv:2, temp2:2, convTime ; storage for C -> F conversion divTMP ; used in div5 procedure ENDC ; code segment PAGE __CONFIG _CP_OFF & _DATA_CP_OFF & _LVP_OFF & _BOREN_OFF & _MCLRE_OFF & _PWRTE_ON & _WDT_OFF & _INTOSC_OSC_NOCLKOUT ORG 0 goto main ORG 4 ; ISR movwf w_save ; save W reg swapf STATUS, w ; save stat reg without movwf stat_save ; changing flags movf PCLATH, w movwf pc_save bcf INTCON, 2 ; clear TMR0 INT flag call displayDigit ; <45 mksec movf tint, f ; tint-- (in 16-bit) btfsc STATUS, Z ; lower(tint) == 0 ? decf tint+1, f decf tint, f movf tint, w ; check if tint == 0 (in 16-bit) iorwf tint+1, w btfss STATUS, Z ; time to read temp ? goto task2 ; NO - get to the next task task1 ; request new temp conversion bsf tint+1, 2 ; restore the temp interval cntr call getTemp1 ; request TEMP in one-shot mode incf tempRQ, f movlw 15 movwf convTime ; resetup 60ms delay for TEMP conversion goto ISR_end task2 btfss tempRQ, 0 ; new temp requested? goto task3 ; NO - get to the next task decf convTime, f btfss STATUS, Z ; is conversion ready? goto task3 ; not yet - continue call getTemp2 ; get TEMP call bin2bcd ; convert it into BCD (<1 msec) goto ISR_end task3 ; check the C/F button status btfss PORTA, 5 goto $+3 clrf button ; button is not pressed - continue goto ISR_end btfsc button, 0 ; button debouncing: goto ISR_end ; button was pressed and not released bsf button, 0 ; button is just pressed movf scale, w ; toggle the C/F status sublw 1 movwf scale ; scale = 1 - scale addlw 10 ; W = 10 or 11 to display C/F movwf bcd ; setup the scale letter code call bin2bcd ; according to the scale (C/F) ISR_end movf pc_save, w ; restore PCLATH movwf PCLATH swapf stat_save, w ; get orig flags in STATUS movwf STATUS swapf w_save, f ; restore the original W swapf w_save, w retfie encode7seg ; set up 7-seg digit codes andlw 0x0F addwf PCL, f retlw b'00111111' ; digit 0 pgfedcba retlw b'00000110' ; digit 1 retlw b'01011011' ; digit 2 retlw b'01001111' ; digit 3 retlw b'01100110' ; digit 4 retlw b'01101101' ; digit 5 retlw b'01111101' ; digit 6 retlw b'00000111' ; digit 7 retlw b'01111111' ; digit 8 retlw b'01101111' ; digit 9 retlw b'00111001' ; letter C retlw b'01110001' ; letter F retlw b'01000000' ; the - sign retlw b'00000000' ; blank retlw b'00001000' retlw b'00001000' main ; main code bcf STATUS, RP0 ; activate BANK 0 clrf PORTA ; initialize PORT A clrf PORTB ; initialize PORT B movlw 0x07 movwf CMCON ; comparators OFF bsf STATUS, RP0 ; change to BANK 1 movlw b'10000011' ; TMR0 1:16 prescaler and movwf OPTION_REG^0x80 ; falling edge INT setup movlw b'00100000' movwf TRISA ^ 0x80 ; enable RA<7:4> for input clrf TRISB ^ 0x80 ; enable output on PORTB bcf STATUS, RP0 ; back to BANK 0 clrf tint ; INITIALIZATION clrf tint+1 ; setup temp reading interval (4sec) bsf tint+1, 2 ; set tint = 1024 clrf scale ; scale: 0=C 1=F clrf point ; decimal point flag clrf temp clrf temp+1 movlw 1 movwf d ; d is the digit code (0 - 3) movlw 0x0D ; initialize BCD array with blanks movwf bcd+3 movwf bcd+2 movwf bcd+1 movlw 0x0A movwf bcd ; setup ADT75A one-shot mode call start_I2C movlw b'10010000' ; address byte movwf dataIO call write_I2C ; send address byte movlw 1 movwf dataIO ; config pointer call write_I2C movlw b'00100000' movwf dataIO call write_I2C call stop_I2C movlw b'10100000' ; enable TMR0 interrupts movwf INTCON goto $ ; infinite loop ; procedures start_I2C ; start setup for I2C interface movlw 0x85 ; setup FSR to point to TRISA movwf FSR movlw b'00111111' andwf PORTA, f bsf INDF, SDA ; pull high SDA and SCL bsf INDF, SCL goto $+1 ; delay slot bcf INDF, SDA ; set data low nop ; wait for slave to detect it bcf INDF, SCL ; set clock low return stop_I2C ; stop setup for I2C interface movlw b'00111111' andwf PORTA, f bcf INDF, SCL ; make sure that clock and data bcf INDF, SDA ; lines are low goto $+1 bsf INDF, SCL ; release clock line goto $+1 bsf INDF, SDA ; release data line return write_I2C ; write byte to I2C line movlw b'00111111' andwf PORTA, f bcf INDF, SCL ; make sure that clock is low clrf err_i2c ; start with no error movlw 8 movwf cnt ; bits counter w_loop bcf INDF, SDA ; start w. data bit low rlf dataIO, f ; get the rightmost data bit btfss STATUS, C bcf INDF, SDA ; now the data bit is on the line btfsc STATUS, C bsf INDF, SDA goto $+1 bsf INDF, SCL ; raise clock up goto $+1 bcf INDF, SCL ; ... and low decfsz cnt, f goto w_loop ; repeat this 8 times goto $+1 bsf INDF, SDA ; check ACK from slave goto $+1 ; let slave respond bsf INDF, SCL ; clock up btfsc PORTA, SDA ; check the ACK from slave incf err_i2c, f ; no ACK (error) bcf INDF, SCL ; clock down return read_I2C ; read byte from I2C line movlw b'00111111' andwf PORTA, f bcf INDF, SCL ; make sure that clock is low movlw 8 movwf cnt ; bits counter r_loop bcf INDF, SCL ; set clock low for long enough goto $+1 bsf INDF, SCL ; set clock high bcf STATUS, C btfsc PORTA, SDA bsf STATUS, C ; C = data bit rlf dataIO, f ; insert it into the data byte decfsz cnt, f goto r_loop ; repeat this 8 times bcf INDF, SCL ; sending the ACK/NAK to slave bsf INDF, SDA movf ACK_NAK, f ; the NAK signal btfsc STATUS, Z bcf INDF, SDA ; the ACK signal goto $+1 bsf INDF, SCL ; raise clock up goto $+1 bcf INDF, SCL ; ... and low nop bsf INDF, SDA ; release the data line return getTemp1 ; request TEMP conversion call start_I2C movlw b'10010000' ; address byte movwf dataIO call write_I2C ; send address byte movlw 4 movwf dataIO ; one-shot register call write_I2C call stop_I2C return getTemp2 ; read TEMP from sensor ; call start_I2C ; movlw b'10010000' ; address byte/W ; movwf dataIO ; call write_I2C ; send address byte ; movlw 4 ; movwf dataIO ; one-shot register pointer ; call write_I2C call start_I2C movlw b'10010001' ; address byte/R movwf dataIO call write_I2C ; send address byte clrf ACK_NAK call read_I2C ; get TEMP high order byte movf dataIO, w movwf temp+1 incf ACK_NAK, f ; setup to send NAK signal call read_I2C ; get TEMP low order byte movf dataIO, w movwf temp call stop_I2C movlw 4 ; shift temp 4 bits to the right movwf cnt ; multiply the sign bit bcf STATUS, C btfsc temp+1, 7 bsf STATUS, C rrf temp+1, f rrf temp, f decfsz cnt, f goto $-6 return bin2bcd ; convert tempAve into BCD repres. clrf sign clrf point movf temp, w ; preserve the original temp value movwf conv ; by copying it to conv for movf temp+1, w ; further processing movwf conv+1 btfsc scale, 0 ; scale == C? call convert ; convert C to F btfss conv+1, 7 ; temp < 0 ? goto frac ; NO - proceed movlw 0xFF ; convert temp to a positive xorwf conv+1, f ; value in the 2's complement system xorwf conv, f movlw 1 addwf conv, f btfsc STATUS, C incf conv+1, f movlw 12 ; the "-" sign code movwf bcd+3 incf sign, f ; negative sign flag frac movf conv, w andlw 0x0F movwf fract ; fraction as int bcf STATUS, C rlf fract, f rlf fract, f addwf fract, f ; tmp = fraction*5 rrf fract, f bcf STATUS, C rrf fract, f bcf STATUS, C rrf fract, f btfsc STATUS, C incf fract, f ; rounding off rrf conv+1, f ; fetching the integer part rrf conv, f ; it all fits in 8 bits rrf conv+1, f rrf conv, f rrf conv+1, f rrf conv, f rrf conv+1, f rrf conv, w ; the int part of temp is in W clrf hundreds clrf tens clrf units dig2 ; processing hundreds incf hundreds, f addlw -100 btfsc STATUS, C goto dig2 decf hundreds, f addlw 100 dig1 ; processing tens incf tens, f addlw -10 btfsc STATUS, C goto dig1 decf tens, f addlw 10 movwf units ; processing units ; packing the digits in BCD btfss sign, 0 ; temp < 0 ? goto positive ; NO - positive number processing movf tens, f btfss STATUS, Z ; tens == 0 ? goto nofrac ; NO - drop the fraction movf units, w ; -10 < temp < 0 movwf bcd+2 ; display units and fraction movf fract, w movwf bcd+1 bsf point, 7 ; raise the decimal point flag return nofrac movf tens, w ; pack tens and units movwf bcd+2 movf units, w movwf bcd+1 return positive movf hundreds, f ; hundreds == 0 ? btfsc STATUS, Z goto nohundreds movf hundreds, w ; display a 3-digit number movwf bcd+3 movf tens, w movwf bcd+2 movf units, w movwf bcd+1 return nohundreds movf tens, w btfsc STATUS, Z movlw 13 ; blank code movwf bcd+3 ; display one or two-digit number movf units, w ; and fraction movwf bcd+2 movf fract, w movwf bcd+1 bsf point, 7 return displayDigit ; display digit at position d movlw 0xF0 andwf PORTA, f ; shut down all digits btfss d, 0 goto check2 ; leftmost digit movf bcd+3, w call encode7seg ; w = segment code goto lightIt check2 btfss d, 1 ; middle number digit goto check3 movf bcd+2, w call encode7seg addwf point, w goto lightIt check3 btfss d, 2 ; rightmost number digit goto check4 movf bcd+1, w call encode7seg goto lightIt check4 movf bcd, w ; C/F LED call encode7seg lightIt movwf PORTB movf d, w iorwf PORTA, f bcf STATUS, C rlf d, f ; next d in cyclic order movlw 1 btfsc d, 4 movwf d return convert ; convert C into F movf temp, w ; input: temp; output: conv movwf temp2 ; save original temp in temp2 movf temp+1, w movwf temp2+1 btfss temp+1, 7 goto absolute movlw 0xFF ; complement temp2 if temp < 0 xorwf temp2+1, f xorwf temp2, f movlw 1 addwf temp2, f btfsc STATUS, C incf temp2+1, f absolute movf temp2, w movwf tmp movf temp2+1, w ; w:tmp contain the orig. temp2 bcf STATUS, C rlf temp2, f rlf temp2+1, f rlf temp2, f rlf temp2+1, f rlf temp2, f rlf temp2+1, f ; now temp2 is 8*temp2 addwf temp2+1, f movf tmp, w ; tmp = old temp2 addwf temp2, f btfsc STATUS, C incf temp2+1, f ; now temp2 = temp2*9 movf temp2+1, w ; w = first dividend call div5 movwf tmp ; tmp = q1 movwf conv+1 ; byte conv+1 is ready bcf STATUS, C rlf tmp, f ; tmp = q1*2 rlf tmp, f ; tmp = q1*4 addwf tmp, w ; w = q1*5 subwf temp2+1, w ; w = r1 movwf tmp swapf tmp, f swapf temp2, w ; w = left nibble of temp andlw 0x0F addwf tmp, w ; w = second dividend movwf temp2+1 ; save it call div5 ; w = q2 movwf tmp swapf tmp, w movwf conv ; left nibble of conv is ready swapf conv, w ; w = q2 again bcf STATUS, C rlf tmp, f ; tmp = q2*2 rlf tmp, f ; tmp = q2*4 addwf tmp, w ; w = q2*5 subwf temp2+1, w ; w = r2 movwf tmp swapf tmp, f movf temp2, w andlw 0x0F addwf tmp, w ; w = third dividend movwf temp2 ; save it call div5 addwf conv, f ; conv is ready movwf tmp bcf STATUS, C rlf tmp, f ; tmp = q3*2 rlf tmp, f ; tmp = q3*4 addwf tmp, w ; w = q3*5 subwf temp2, f ; temp = r3 incf temp2, f btfss temp2, 2 goto compl movlw 1 ; rounding off addwf conv, f btfsc STATUS, C ; now conv (2 bytes) equals incf conv+1, f ; 9*temp / 5 compl btfss temp+1, 7 ; was temp (in C) negative? goto add32 ; NO - proceed adding 32 movlw 0xFF xorwf conv+1, f ; YES - complement temp2 xorwf conv, f movlw 1 addwf conv, f btfsc STATUS, C incf conv+1, f add32 movlw 2 ; adding 32 to the result addwf conv+1, f ; to complete the conversion return div5 movwf divTMP ; save W movlw high divTable movwf PCLATH ; PCLATH = table segment movf divTMP, w ; restore original W addlw low divTable ; w = table offset btfsc STATUS, C ; correct PCLATH incf PCLATH, f ; (if needed) movwf PCL ; jump to the table entry divTable dt 0, 0, 0, 0, 0, 1, 1, 1 dt 1, 1, 2, 2, 2, 2, 2, 3 dt 3, 3, 3, 3, 4, 4, 4, 4 dt 4, 5, 5, 5, 5, 5, 6, 6 dt 6, 6, 6, 7, 7, 7, 7, 7 dt 8, 8, 8, 8, 8, 9, 9, 9 dt 9, 9, 10, 10, 10, 10, 10, 11 dt 11, 11, 11, 11, 12, 12, 12, 12 dt 12, 13, 13, 13, 13, 13, 14, 14 dt 14, 14, 14, 15, 15, 15, 15, 15 dt 16, 16, 16, 16, 16, 17, 17, 17 dt 17, 17, 18, 18, 18, 18, 18, 19 dt 19, 19, 19, 19, 20, 20, 20, 20 dt 20, 21, 21, 21, 21, 21, 22, 22 dt 22, 22, 22, 23, 23, 23, 23, 23 dt 24, 24, 24, 24, 24, 25, 25, 25 dt 25, 25, 26, 26, 26, 26, 26, 27 dt 27, 27, 27, 27, 28, 28, 28, 28 dt 28, 29, 29, 29, 29, 29, 30, 30 dt 30, 30, 30, 31, 31, 31, 31, 31 dt 32, 32, 32, 32, 32, 33, 33, 33 dt 33, 33, 34, 34, 34, 34, 34, 35 dt 35, 35, 35, 35, 36, 36, 36, 36 dt 36, 37, 37, 37, 37, 37, 38, 38 dt 38, 38, 38, 39, 39, 39, 39, 39 dt 40, 40, 40, 40, 40, 41, 41, 41 dt 41, 41, 42, 42, 42, 42, 42, 43 dt 43, 43, 43, 43, 44, 44, 44, 44 dt 44, 45, 45, 45, 45, 45, 46, 46 dt 46, 46, 46, 47, 47, 47, 47, 47 dt 48, 48, 48, 48, 48, 49, 49, 49 dt 49, 49, 50, 50, 50, 50, 50, 51 end