TITLE "humi.asm" List P=PIC16F684, R=DEC INCLUDE "p16f684.inc" errorlevel -311 SCL_sensor EQU 4 SDA_sensor EQU 5 SCL_disp EQU 2 ; Clock line setup SDA_disp EQU 1 ; Data line setup CORR EQU 6832 + 186 ; correction const for pressure D1 EQU 4010 ; correction const for TEMP C2 EQU 5871300 ; correction const for HUMI C1_1 EQU 14939840 ; -"- C1_2 EQU 15939840 ; -"- ; SHT15 interface adr command r/w #define STATUS_REG_W 0x06 ; 000 0011 0 #define STATUS_REG_R 0x07 ; 000 0011 1 #define MEASURE_TEMP 0x03 ; 000 0001 1 #define MEASURE_HUMI 0x05 ; 000 0010 1 #define RESET 0x1e ; 000 1111 0 ; data segment CBLOCK 0x20 del, cnt, tmp:4 ; local variables bar:2, temp:2, humi:3 ; storage for pressure/temp/humidity humi_lin:4, i, dataIO, ACK ENDC ; code segment __CONFIG _FCMEN_OFF & _IESO_OFF & _BOD_OFF & _CPD_OFF & _CP_OFF & _MCLRE_OFF & _PWRTE_ON & _WDT_OFF & _INTRC_OSC_NOCLKOUT ORG 0 goto start ORG 4 retfie msg1 ; first message to display addwf PCL, f dt "mmHg", 0 msg2 ; second message to display addwf PCL, f dt "C RH:", 0 start bcf STATUS, RP0 ; switch to BANK 0 clrf PORTA ; initialize PORT A clrf PORTC ; initialize PORT C movlw 0x07 movwf CMCON0 ; comparators OFF bsf STATUS, RP0 ; switch to BANK 1 ; ADC and ports configuration clrf TRISA ^ 0x80 ; configure PORTA for output bsf TRISA ^ 0x80, SDA_sensor movlw b'011100' movwf TRISC ^ 0x80 movlw b'10000000' movwf ANSEL ^ 0x80 ; configure RC3 as analog input movlw b'00100000' ; 250 KHz oscillator movwf OSCCON ^ 0x80 movlw b'01110000' ; set ADC Frc clock movwf ADCON1 ^ 0x80 bcf STATUS, RP0 ; back to BANK 0 movlw b'00011101' movwf ADCON0 ; left justify, Vdd Vref, AN7, On movlw 100 movwf del call delay call soft_reset_SHT15 movlw 'P' ; clear display call writeLCD loop movlw 250 movwf del call delay ; 250 msec delay call get_BARO call get_TEMP call get_HUMI call writeMSG goto loop ; endless loop ;//////////////////////////////////// procedures ; _____ ________ ; DATA: |_______| ; ___ ___ ; SCK : ___| |___| |______ start_SHT15 ; start condition for SHT15 movlw 0x85 ; setup FSR to point to TRISA movwf FSR bsf INDF, SDA_sensor ; start with SDA=1 and SCL=0 bcf PORTA, SCL_sensor nop ; delay slot bsf PORTA, SCL_sensor ; set clock high bcf PORTA, SDA_sensor bcf INDF, SDA_sensor ; set dala low nop bcf PORTA, SCL_sensor goto $+1 ; 5 us delay goto $+1 nop bsf PORTA, SCL_sensor ; set clock high nop bsf INDF, SDA_sensor nop bcf PORTA, SCL_sensor return ; _____________________________________________________ ________ ; DATA: |_______| ; _ _ _ _ _ _ _ _ _ ___ ___ ; SCK : __| |__| |__| |__| |__| |__| |__| |__| |__| |______| |___| |______ reset_SHT15 ; reset sensor interface movlw 0x85 ; setup FSR to point to TRISA movwf FSR movlw 9 movwf cnt bsf PORTA, SCL_sensor nop bcf PORTA, SCL_sensor decfsz cnt, f goto $-4 call start_SHT15 return soft_reset_SHT15 call reset_SHT15 movlw RESET movwf dataIO call write_SHT15 return write_SHT15 ; write byte to SHT15 bsf INDF, SDA_sensor ; make sure that DATA=1 and CLK=0 bcf PORTA, SCL_sensor movlw 8 movwf cnt ; bits counter w_loop bcf PORTA, SDA_sensor ; preset 0 on data line rlf dataIO, f ; get the rightmost data bit btfsc STATUS, C bsf INDF, SDA_sensor btfss STATUS, C bcf INDF, SDA_sensor ; now the data bit is on the data bus bsf PORTA, SCL_sensor ; raise clock up goto $+1 ; short delay goto $+1 nop bcf PORTA, SCL_sensor ; ... and low decfsz cnt, f goto w_loop ; repeat this 8 times bsf INDF, SDA_sensor ; release the data line goto $+1 ; let slave respond for ACK goto $+1 goto $+1 bsf PORTA, SCL_sensor ; clock up goto $+1 ; slave responds OK (hopefully) bcf PORTA, SCL_sensor ; clock down return read_SHT15 ; read byte from SHT15 bsf INDF, SDA_sensor ; make sure that DATA=1 and CLK=0 bcf PORTA, SCL_sensor movlw 8 movwf cnt ; bits counter r_loop bsf PORTA, SCL_sensor ; clock up bcf STATUS, C btfsc PORTA, SDA_sensor bsf STATUS, C ; C = data bit bcf PORTA, SCL_sensor ; clock down rlf dataIO, f ; insert it into the data byte decfsz cnt, f goto r_loop ; repeat this 8 times movf ACK, f ; set Z flag bcf PORTA, SDA_sensor btfsc STATUS, Z bcf INDF, SDA_sensor ; ACK signal bsf PORTA, SCL_sensor ; clock up goto $+1 goto $+1 nop bcf PORTA, SCL_sensor ; clock down bsf INDF, SDA_sensor ; release the data line return get_TEMP ; measure TEMP call start_SHT15 movlw MEASURE_TEMP movwf dataIO call write_SHT15 ; send command (dataIO) btfsc PORTA, SDA_sensor ; wait for the end of measurement goto $-1 clrf ACK ; send ACK after reading the first byte call read_SHT15 movf dataIO, w ; MSB movwf temp+1 incf ACK, f ; ignore the checksum call read_SHT15 movf dataIO, w movwf temp ; LSB movlw LOW D1 ; correct temp subwf temp, f btfss STATUS, C decf temp+1, f movlw HIGH D1 subwf temp+1, f return get_HUMI ; measure relative humidity call start_SHT15 movlw MEASURE_HUMI movwf dataIO call write_SHT15 ; send command (dataIO) btfsc PORTA, SDA_sensor ; wait for the end of measurement goto $-1 clrf ACK ; send ACK after reading the first byte call read_SHT15 movf dataIO, w ; MSB movwf humi+1 incf ACK, f ; ignore the checksum call read_SHT15 movf dataIO, w movwf humi ; LSB call process_humi return get_BARO ; measure atmospheric pressure bsf ADCON0, GO ; start ADC operation btfsc ADCON0, GO ; and wait for its completion goto $-1 movf ADRESH, w ; get high 8 bits of ADC movwf bar ; multiply bar by 6 clrf bar+1 rlf bar, f ; bar *= 2 rlf bar+1, f bcf bar, 0 addwf bar, f ; bar *= 3 btfsc STATUS, C incf bar+1, f rlf bar, f ; bar *= 6 rlf bar+1, f bcf bar, 0 movlw low CORR ; add corr constant addwf bar, f btfsc STATUS, C incf bar+1, f movlw high CORR ; bar = pressure*10 addwf bar+1, f ; (max 4 decimal digits) movlw 5 ; rounding off to 3 digits addwf bar, f btfsc STATUS, C incf bar+1, f return process_humi movlw 0xF0 ; STEP1 - linearization (second-order curve) andwf humi, f ; zero 4 lsb's clrf tmp+3 movlw LOW C2 ; computing tmp = 5871300 - 4096·SO_RH movwf tmp ; 24-bit subtraction movf humi, w ; however, LSB(subtrahend)=0, so only sublw HIGH C2 ; 2 higher-order bytes of C2 are affected movwf tmp+1 movf humi+1, w btfss STATUS, C addlw 1 ; won't lead to overflow sublw UPPER C2 movwf tmp+2 movf humi, w ; adding 16·SO_RH to tmp addwf tmp, f ; 24-bit operation movf humi+1, w ; however humi is only a 16-bit value btfsc STATUS, C addlw 1 ; won't lead to overflow since humi+1 addwf tmp+1, f ; has 4 leading zeros btfsc STATUS, C incf tmp+2, f movf humi+1, w ; humi and humi+2 = SO_RH addwf humi, f swapf humi, w movwf humi movwf humi+2 clrf humi_lin ; computing humi_lin = tmp·SO_RH clrf humi_lin+1 ; 24-bit x 8-bit multiplication clrf humi_lin+2 ; initialize the result with 0 clrf humi_lin+3 movlw 8 ; counter for the # of iterations movwf cnt mul_tmp ; unsigned multiplication rrf humi, f ; put lsb(multiplier) into C btfss STATUS, C goto shift_tmp ; jump to shifting tmp movf tmp, w ; add current tmp to humi_lin addwf humi_lin, f ; 32-bit operation movf tmp+1, w btfsc STATUS, C incfsz tmp+1, w addwf humi_lin+1, f movf tmp+2, w btfsc STATUS, C incfsz tmp+2, w addwf humi_lin+2, f movf tmp+3, w btfsc STATUS, C addlw 1 addwf humi_lin+3, f shift_tmp bcf STATUS, C rlf tmp, f ; shift tmp to the left for the rlf tmp+1, f ; next iteration rlf tmp+2, f rlf tmp+3, f decfsz cnt, f goto mul_tmp movf humi+1, w ; special cases xorlw 0xA0 andlw 0x10 ; bit Z is set of humi=160 or 176 clrf tmp ; in this case tmp=1 btfss STATUS, Z ; otherwise, tmp=0 incf tmp, f movlw LOW C1_1 ; subtract C1 btfsc tmp, 0 movlw LOW C1_2 subwf humi_lin, f ; this is a 32-bit operation but we use movlw HIGH C1_1 ; the fact that the MSB of C1 is 0 btfsc tmp, 0 movlw HIGH C1_2 btfss STATUS, C ; none of the bytes of C1 is 0xFF addlw 1 ; no overflow here! subwf humi_lin+1, f movlw UPPER C1_1 btfsc tmp, 0 movlw UPPER C1_2 btfss STATUS, C addlw 1 ; no overflow here! subwf humi_lin+2, f btfss STATUS, C decf humi_lin+3, f movlw LOW 2500 ; STEP2: temperature compensation subwf temp, w ; compute tmp+2:tmp+1 = temp - 2500 movwf tmp+1 movwf humi ; we do not need humi any more movlw HIGH 2500 btfss STATUS, C addlw 1 subwf temp+1, w movwf tmp+2 movwf humi+1 ; humi+1:humi = temp - 2500 clrf tmp clrf tmp+3 btfss tmp+2, 7 ; temp - 2500 < 0? goto proceed2 ; no - proceed decf tmp+3, f ; sign extend tmp (tmp+3 was 0 before) comf humi, f ; humi = |temp - 2500| comf humi+1, f incf humi, f btfsc STATUS, Z incf humi+1, f proceed2 rlf tmp+2, w ; C = sign bit of tmp+2 rrf tmp+2, f ; tmp = (temp-2500)/2 rrf tmp+1, f ; signed division! movlw 8 ; counter for the # of iterations movwf cnt addwf humi+2, f ; temp+3 = SO_RH + 8 mul_tmp2 ; updating humi_lin rrf humi+2, f ; put lsb into C btfss STATUS, C goto shift_tmp2 ; jump to shifting tmp movf tmp+1, w ; add current tmp to humi_lin addwf humi_lin+1, f ; 32-bit operation movf tmp+2, w ; but LSB(tmp)=0 so only 24 high-order btfsc STATUS, C ; are involved into the operaton incfsz tmp+2, w addwf humi_lin+2, f movf tmp+3, w btfsc STATUS, C addlw 1 addwf humi_lin+3, f shift_tmp2 bcf STATUS, C rlf tmp+1, f ; shift tmp to the left for the rlf tmp+2, f ; next iteration rlf tmp+3, f ; again, only 3 higher-order bytes decfsz cnt, f ; need to be shifted goto mul_tmp2 movlw 0xF0 ; load 10240 or 61440 into WREG andwf humi+1, w ; bit Z is set if |temp-2500| < 4096 movlw HIGH 10240 btfss STATUS, Z movlw HIGH 61440 ; w = MSB(correction const) subwf humi_lin+1, f ; subtract correction const from humi_lin clrw ; this is a 32-bit operation btfss STATUS, C ; but the constant is 16-bit only addlw 1 ; and LSB(const)=0 subwf humi_lin+2, f clrw btfss STATUS, C addlw 1 ; no overflow here! subwf humi_lin+3, f return ;//////////////////////////////////// getDigit32 clrf cnt incf cnt, f movf tmp, w ; 32-bit subtraction of the value in tmp subwf humi_lin, f ; from humi_lin movf tmp+1, w btfss STATUS, C incfsz tmp+1, w subwf humi_lin+1, f movf tmp+2, w btfss STATUS, C incfsz tmp+2, w subwf humi_lin+2, f movf tmp+3, w btfss STATUS, C incfsz tmp+3, w subwf humi_lin+3, f btfsc STATUS, C goto getDigit32+1 movf tmp, w ; 32-bit addition of the value in tmp addwf humi_lin, f ; to humi_lin movf tmp+1, w btfsc STATUS, C incfsz tmp+1, w addwf humi_lin+1, f movf tmp+2, w btfsc STATUS, C incfsz tmp+2, w addwf humi_lin+2, f movf tmp+3, w btfsc STATUS, C incfsz tmp+3, w addwf humi_lin+3, f decf cnt, w ; return digit in WREG addlw 48 ; ASCII conversion return getDigit16 clrf cnt incf cnt, f movf tmp+2, w ; 16-bit subtraction of tmp+3:tmp+2 subwf tmp, f ; from tmp+1:tmp movf tmp+3, w btfss STATUS, C incfsz tmp+3, w subwf tmp+1, f btfsc STATUS, C goto getDigit16+1 movf tmp+2, w ; 16-bit addition of tmp+3:tmp+2 addwf tmp, f ; to tmp+1:tmp movf tmp+3, w btfsc STATUS, C incfsz tmp+3, w addwf tmp+1, f decf cnt, w ; return digit in WREG addlw 48 ; ASCII conversion return ;*******************LCD interface writeMSG ; output of the top row (msg1) movlw b'10000001' ; clear display call writeLCD movlw ':' call writeLCD movf bar, w ;********** output pressure movwf tmp movf bar+1, w movwf tmp+1 movlw LOW 1000 movwf tmp+2 movlw HIGH 1000 movwf tmp+3 call getDigit16 call writeLCD ; first digit movlw LOW 100 movwf tmp+2 clrf tmp+3 call getDigit16 call writeLCD ; second digit movlw LOW 10 movwf tmp+2 clrf tmp+3 call getDigit16 call writeLCD ; third digit clrf i L1 movf i, w call msg1 ; get the next char iorlw 0 ; end of string? btfsc STATUS, Z goto L2 ; YES - jump out of the loop call writeLCD ; NO - send it to LCD incf i, f ; update the char index goto L1 L2 movlw 0xC0 call writeLCD ; move the cursor to the second line clrf i ; clear the index of the second string ; output the bottom row movlw 'T' call writeLCD movlw ':' call writeLCD movlw '+' ; temp sign btfss temp+1, 7 goto $+7 comf temp, f ; compute |temp| comf temp+1, f incf temp, f btfsc STATUS, C incf temp+1, f movlw '-' call writeLCD movf temp, w ; *******************output TEMP movwf tmp movf temp+1, w movwf tmp+1 movlw 5 ; round-off temp to 1 digit after addwf tmp, f ; the decimal point btfsc STATUS, C incf tmp+1, f movlw LOW 1000 movwf tmp+2 movlw HIGH 1000 movwf tmp+3 call getDigit16 sublw 48 btfsc STATUS, Z goto $+3 ; drop the leading 0 sublw 48 ; restore digit call writeLCD ; first digit movlw 100 movwf tmp+2 clrf tmp+3 call getDigit16 call writeLCD ; second digit movlw 46 call writeLCD ; decimal point movlw 10 movwf tmp+2 clrf tmp+3 call getDigit16 ; third digit call writeLCD ; output msg2 L3 movf i, w call msg2 ; get the next char iorlw 0 ; end of string? btfsc STATUS, Z goto L4 ; YES - jump out of the loop call writeLCD ; NO - send it to LCD incf i, f ; update the char index goto L3 L4 ; *************output humidity clrf tmp ; load 10^8 into tmp movlw LOW 390625 ; this is 10^8 / 256 movwf tmp+1 movlw HIGH 390625 movwf tmp+2 movlw UPPER 390625 movwf tmp+3 call getDigit32 sublw 57 ; the first digit is at least 10 btfsc STATUS, C ; if humi exceeds 99% goto $+6 ; in this case we just show 99 movlw 57 ; ASCII(9) call writeLCD ; output 99% movlw 57 call writeLCD goto humi_end sublw 57 ; restore the first digit btfss STATUS, Z ; don't show the leading 0 call writeLCD ; first digit movlw 128 movwf tmp movlw LOW 39062 ; this is 10^7 / 256 movwf tmp+1 movlw HIGH 39062 movwf tmp+2 movlw UPPER 39062 movwf tmp+3 call getDigit32 call writeLCD ; second digit humi_end movlw '%' call writeLCD ; percentage sign return writeLCD ; write byte in W to the LCD line movwf dataIO movlw b'111001' andwf PORTC, f movlw 0x87 ; setup FSR to point to TRISC movwf FSR bsf INDF, SCL_disp ; make sure that clock is high movlw 8 movwf cnt ; bits counter w_LCD_loop btfss PORTC, SCL_disp ; wait for release of the clock line goto $-1 bcf INDF, SCL_disp ; set clock low rlf dataIO, f ; get the rightmost data bit btfss STATUS, C bcf INDF, SDA_disp btfsc STATUS, C bsf INDF, SDA_disp ; now the data bit is on the line goto $+1 ; short delay bsf INDF, SCL_disp ; raise clock up movlw 6 ; a 20 usec delay addlw -1 btfss STATUS, Z goto $-2 decfsz cnt, f goto w_LCD_loop ; repeat this 8 times return delay ; a delay for del milliseconds movlw 200 sublw 1 ; this loop takes 5us*200 = 1ms sublw 0 ; for PIC @ 4 Mhz btfss STATUS, Z goto $-3 decfsz del, f goto delay return end