Project description:
Our final project involved the design of a fully functional, multi-purpose digital thermometer. This was our attempt at producing a portable device that could be widely used for a variety of different purposes. For example, think of the many situations where the precise measurement of temperature is of high importance. Temperature control and monitoring is important in homes for the comfort of its occupants… it is important for gardeners who want to carefully monitor the atmospheric conditions within a greenhouse… it is important in ensuring the correct operation of various electronic devices where many components may have a sensitive dependence on temperature.
LM34
Our final project involved the design of a fully functional, multi-purpose digital thermometer. This was our attempt at producing a portable device that could be widely used for a variety of different purposes. For example, think of the many situations where the precise measurement of temperature is of high importance. Temperature control and monitoring is important in homes for the comfort of its occupants… it is important for gardeners who want to carefully monitor the atmospheric conditions within a greenhouse… it is important in ensuring the correct operation of various electronic devices where many components may have a sensitive dependence on temperature.
LM34
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; <<Digital Thermometer>> ; Alan Nawoj, Donald Chai ; EE 476 - FINAL PROJECT ; *Description* ; Temperature range: 0F - 300F ; Aref = 4.096 V ; LM 34 --> 10 mV / 1 degree F ; PortC = LCD display ; PortD = pushbuttons ; PortB = LEDs ; Only 1 pushbutton can be pressed at a given time ;------------------------------ .nolist .include "8535def.inc" .list ;***************** ;REGISTERS: .def save = r1 .def reload = r2 .def lcdstat = r3 .def TXchar = r4 .def isneg = r14 ;says if we're below 32 F .def temp = r16 .def timeout = r17 .def timeout2= r18 .def LCDcharpos=r19 ;***************** ;Program constants: .equ lcdrs = PC6 ;LCD rs pin connected to PC6 .equ lcdrw = PC5 ;LCD r/w pin connected to PC5 .equ lcde = PC4 ;LCD e pin connected to PC4 ;***************** ;BUTTONS: ;DC - you might think we could simply store currbtn in SRAM as our state, ; as SRAM is plentiful. this reduces code size by ALOT. .equ toggle = ~(1<<7); toggle between temp scales .equ decmin = ~(1<<6); dec. minimum alarm temp .equ incmin = ~(1<<5); inc. minimum alarm temp .equ decmax = ~(1<<4); dec. maximum alarm temp .equ incmax = ~(1<<3); inc. maximum alarm temp .equ dispmin= ~(1<<2); display the minimum temp recorded .equ dispmax= ~(1<<1); display the maximum temp recorded ;-------------------------------------- .cseg .org $0000 ;8535 vector table rjmp RESET;reset entry vector reti reti reti reti reti reti;TIMER1A interrupt reti reti rjmp TIMER0 reti reti reti reti reti reti reti ;---------------------------------------------- RESET:;ALWAYS setup a stack pointer ldi temp, LOW(RAMEND);setup stack pointer out SPL, temp ldi temp, HIGH(RAMEND) out SPH, temp ;PortD is all inputs (pushbuttons) clr temp out DDRD, temp ser temp out PortD, temp ser temp out DDRB, temp; make PortB all outputs (LEDs) clr temp out PortB, temp ;setup timer0 as a 1ms delay ldi temp, 255-62 mov reload, temp ldi temp, 3 out TCCR0, temp ldi temp, exp2(TOIE0); timer 0 overflow interrupt enable out TIMSK, temp ;set up analog converter to read channel zero (read temperature as voltage) ldi temp, 0 out ADMUX, temp clr LCDcharpos clr timeout2 ;clear timeout2 to read pushbuttons ldi temp, 'F' sts (scale), temp ;default scale is Fahrenheit ldi temp, 0 sts (state), temp ;zero state (start) ldi temp, LOW(605) sts (mintemp), temp ; initialize MIN alarm temp. to 60.5°F ldi temp, HIGH(605) sts (mintemp+1), temp ldi temp, LOW(802) sts (maxtemp), temp ; initialize MAX alarm temp. to 80.2°F ldi temp, HIGH(802) sts (maxtemp+1), temp clr temp sts (hitemp), temp ; initialize MAX ($0000) sts (hitemp+1), temp ser temp sts (lotemp), temp ; initialize MIN ($FFFF) sts (lotemp+1), temp clr temp sts (flashcnt), temp sei rcall lcdinit rcall lcdclr ;------------------------------------ ; ******** MAIN PROGRAM LOOP ******** MAIN: tst timeout2 brne MAIN ;-------------- rcall ButtonActionListener;call this every 50mS (get button state) ldi timeout2, 50 rcall MeasureTemp; read in the current temp... rcall UpdateExtremes; update the measured HI/LO temps rcall lcdclr ; clear the LCD clr LCDcharpos; rcall UpdateSettings rcall ConvertTemp; convert temp value to appropriate scale... rcall DisplayTemp; display the temp. rcall DisplayScale; display °[F, C, K, or R] rcall CheckAlarm rjmp MAIN ;---------------------------------------------- .cseg MaxalarmMsg: .db "Max Temp:", 0 MinalarmMsg: .db "Min Temp:", 0 HotMsg: .db " HOT!", 0 ColdMsg: .db " COLD", 0 HiMsg: .db "HI: ", 0 LoMsg: .db "LO: ", 0 ;---------------------------------------------- ;@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ ; PROCEDURES: ;@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ ;********************************************************* UpdateExtremes: ; compares current temperature with the stored max and min temperatures ; updates them in SRAM [hitemp or lotemp] (if necessary) ;LOCALS: .def currL = r5 .def currH = r6 .def hiL = r7 .def hiH = r8 .def loL = r9 .def loH = r10 ;------------------------------- .dseg currtemp: .byte 2; the current temperature hitemp: .byte 2; the highest temp recorded by the thermometer lotemp: .byte 2; the lowest temp recorded by the thermometer ;------------------------------- .cseg push currL; save registers push currH push hiL push hiH push loL push loH lds currL, (currtemp); load values into registers lds currH, (currtemp+1) lds hiL, (hitemp) lds hiH, (hitemp+1) lds loL, (lotemp) lds loH, (lotemp+1) cp currL, hiL cpc currH, hiH brsh updatehigh; currtemp > hitemp cp loL, currL cpc loH, currH brsh updatelow; currtemp < lotemp rjmp updateexit updatehigh: sts (hitemp), currL sts (hitemp+1), currH rjmp updateexit updatelow: sts (lotemp), currL sts (lotemp+1), currH updateexit: pop loH; restore registers pop loL pop hiH pop hiL pop currH pop currL ret ; ENDP ;**************** ;********************************************************** CheckAlarm: ; compares current temperature with stored alarm temps (has alarm threshold been reached?) ; if alarm threshold reached...FLASH LEDs!!!! .def maxL = r6; ALARM max temp .def maxH = r7 .def minL = r8; ALARM min temp .def minH = r9 .def currL = r10; current temp .def currH = r11 .def flashcnt = r20 ;------------------------------- .dseg flashcnt: .byte 1; counter for flashing messages ;------------------------------- .cseg push currL; save registers push currH push maxL push maxH push minL push minH push flashcnt lds currL, (currtemp); load values into registers lds currH, (currtemp+1) lds maxL, (maxtemp) lds maxH, (maxtemp+1) lds minL, (mintemp) lds minH, (mintemp+1) lds flashcnt, (flashcnt) ser temp out PortB, temp; turn off LEDs cp currL, maxL cpc currH, maxH brsh toohot ; currtemp > maxtemp cp minL, currL cpc minH, currH brsh toocold ; currtemp < mintemp rjmp alarmexit toohot: ldi temp, (1<<6) out PortB, temp; turn on LED[6] mov temp, flashcnt andi temp, 2; display every 16 * 50 ms = ~1sec breq alarmexit ldi ZL, LOW(HotMsg<<1) ldi ZH, HIGH(HotMsg<<1) rcall lcdputflashstr rjmp alarmexit toocold: ldi temp, (1<<7); turn on LED[7] out PortB, temp mov temp, flashcnt andi temp, 2; display every 16 * 50 ms = ~1sec breq alarmexit ldi ZL, LOW(ColdMsg<<1) ldi ZH, HIGH(ColdMsg<<1) rcall lcdputflashstr alarmexit: inc flashcnt sts (flashcnt), flashcnt pop flashcnt pop minH; restore registers pop minL pop maxH pop maxL pop currH pop currL ret ; ENDP ;**************** ;****************************************************************** UpdateSettings: ; updates stored alarm temperatures if necessary --> (ALARM UPDATE) ; NOTE: if update alarm button is PRESSED: inc/dec by 1 ; if update alarm button is HELD: inc/dec by 5 ; if toggle button was pushed, update that --------> (SCALE UPDATE) ; NOTE: only toggle scale on a button release ;LOCALS: ;r20s don't conflict. first I use state to detect which state, and ;then iff state is in btnreleased, use scale .def state = r28 .def scale = r20 .def button = r21 .def maxL = r24; ALARM max temp .def maxH = r25 .def minL = r26; ALARM min temp .def minH = r27 .def UStemp = r5 ;---------------------- .dseg maxtemp: .byte 2; ALARM HI/LO temps... mintemp: .byte 2 scale: .byte 1;'F', 'C', 'K', 'R' ;---------------------- .cseg push state push button push scale push maxL push maxH push minL push minH lds state, (state) ; get state (0=start, 1=push, 2=stillp, 3=held, 4=rel) lds button, (button) lds maxL, (maxtemp) ; get alarm max value lds maxH, (maxtemp+1) lds minL, (mintemp) ; get alarm min value lds minH, (mintemp+1) cpi state, 2 brlo USjmpexit ;if state == 0 or state == 1, no action brne USbtnheld ;if state != 2... see if it's held/released instead... breq USbtnpush USjmpexit: rjmp USexit ;button pushed (state = 2) USbtnpush: ;** button is PRESSED ** USp0: cpi button, toggle ;NOTE: Don't do anything if holding down toggle. ;update ALARM MIN (if necessary)... USp1: cpi button, decmin brne USp2 sbiw minL, 1 ; decrease ALARM MIN by .1° (every 50 ms if held) rjmp MinPrompt; display min alarm text USp2: cpi button, incmin brne USp3 adiw minL, 1 ; increase ALARM MIN by .1° (every 50 ms if held) rjmp MinPrompt ;update ALARM MAX (if necessary)... USp3: cpi button, decmax brne USp4 sbiw maxL, 1 ; decrease ALARM MAX by .1° (every 50 ms if held) rjmp MaxPrompt; display max alarm text USp4: cpi button, incmax brne USp5 adiw maxL, 1 ; increase ALARM MAX by .1° (every 50 ms if held) rjmp MaxPrompt ;display the MIN recorded temp value (if necessary)... USp5: cpi button, dispmin brne USp6 lds UStemp, (lotemp) sts (disptemp), ustemp lds ustemp, (lotemp+1) sts (disptemp+1), ustemp ldi ZL, LOW(lomsg<<1) ldi ZH, HIGH(lomsg<<1) rcall lcdputflashstr ;display the MAX recorded temp value (if necessary)... USp6: cpi button, dispmax brne USjmpexit lds ustemp, (hitemp) sts (disptemp), ustemp lds ustemp, (hitemp+1) sts (disptemp+1), ustemp ldi ZL, LOW(himsg<<1) ldi ZH, HIGH(himsg<<1) rcall lcdputflashstr rjmp USexit ;button either held or released (state = 3 or 4)... USbtnheld: cpi state, 3 brne USbtnreleased ; button is released... ;** button is HELD down ** USh0: cpi button, toggle ;NOTE: Don't do anything if holding down toggle. ;<<<<<change ALARM values 5 X faster>>>>> ;update ALARM MIN (if necessary)... USh1: cpi button, decmin brne USh2 sbiw minL, 5 ; decrease ALARM MIN by .5° (every 50 ms if held) rjmp MinPrompt; display min alarm text USh2: cpi button, incmin brne USh3 adiw minL, 5 ; increase ALARM MIN by .5° (every 50 ms if held) rjmp MinPrompt ;update ALARM MAX (if necessary)... USh3: cpi button, decmax brne USh4 sbiw maxL, 5 ; decrease ALARM MAX by .5° (every 50 ms if held) rjmp MaxPrompt; display max alarm text USh4: cpi button, incmax brne USh5 adiw maxL, 5 ; increase ALARM MAX by .5° (every 50 ms if held) rjmp MaxPrompt; display max alarm text USh5: cpi button, dispmin brne USh6 lds ustemp, (lotemp) sts (disptemp), ustemp lds ustemp, (lotemp+1) sts (disptemp+1), ustemp ldi ZL, LOW(lomsg<<1) ldi ZH, HIGH(lomsg<<1) rcall lcdputflashstr USh6: cpi button, dispmax brne USexit lds ustemp, (hitemp) sts (disptemp), ustemp lds ustemp, (hitemp+1) sts (disptemp+1), ustemp ldi ZL, LOW(himsg<<1) ldi ZH, HIGH(himsg<<1) rcall lcdputflashstr rjmp USexit ; button released (state = 4) USbtnreleased: cpi button, toggle brne USexit ; EXIT... ;toggle the scale... lds scale, (scale) cpi scale, 'F' brne UStogC ldi scale, 'C' rjmp USstoretog UStogC: cpi scale, 'C' brne UStogR ldi scale, 'R' rjmp USstoretog UStogR: cpi scale, 'R' brne UStogK ldi scale, 'K' rjmp USstoretog UStogK: ldi scale, 'F' USstoretog: sts (scale), scale USexit: sts (maxtemp), maxL ; update ALARM temps in SRAM sts (maxtemp+1), maxH sts (mintemp), minL sts (mintemp+1), minH pop minH pop minL pop maxH pop maxL pop scale pop button pop state ret MinPrompt: ; display min alarm text ;if out of range, put it in range ;if (min<0) min=0 ;if (min>2048) min = 2048 clr UStemp cp minL, UStemp cpc minH, UStemp brge skipzerol clr minL clr minH skipzerol: clr UStemp cp minL, UStemp ldi temp, HIGH(2048) cpc minH, temp brlt skipmaxl clr minL ldi minH, HIGH(2048) skipmaxl: ldi ZL, LOW(MinalarmMsg<<1) ldi ZH, HIGH(MinalarmMsg<<1) rcall lcdputflashstr sts (disptemp), minL sts (disptemp+1), minH rjmp USexit MaxPrompt: ; display max alarm text ;if out of range, put it in range ;if (max<0) max=0 ;if (max>2048) max = 2048 clr UStemp cp maxL, UStemp cpc maxH, UStemp brge skipzeroh clr maxL clr maxH skipzeroh: clr UStemp cp maxL, UStemp ldi temp, HIGH(2048) cpc maxH, temp brlt skipmaxh clr maxL ldi maxH, HIGH(2048) skipmaxh: ldi ZL, LOW(MaxalarmMsg<<1) ldi ZH, HIGH(MaxalarmMsg<<1) rcall lcdputflashstr sts (disptemp), maxL sts (disptemp+1), maxH rjmp USexit ; ENDP ;**************** ;********************************************************* MeasureTemp: ; reads a value from the ADC and converts it to millivolts ; each mV = .1 deg F ; each bit increment of the ADC = 2 mV ;----------------- ;LOCALS: .def analo = r21 .def anahi = r20 ;----------------- push anahi push analo ;start A to D conversion (get a voltage) -- Aref = 2.048 V swait: ldi temp, 0b11100101 ;free run out ADCSR, temp await: in temp, ADCSR ;wait for A to D done andi temp, 0b01000000 ;by checking ADSC bit brne await ;this bit is cleared by the AtoD hardware in AnaLo, ADCL ;read the voltage in AnaHi, ADCH lsl analo ; multiply by 2 to get # of mV rol anahi sts (currtemp), analo; store the current temp value into SRAM sts (currtemp+1), anahi ;by default, display the current temperature sts (disptemp), analo sts (disptemp+1), anahi pop analo pop anahi ret ; ENDP ;**************** ;********************************************************** ConvertTemp: ; converts a temperature in mV (or Fahrenheit) from disptemp ; into a specified temperature scale and puts it back in ; .def scale = r20 .def tempL = r26 .def tempH = r27 .def temp1 = r24 .def temp2 = r25 .def countL = r28; will hold the quotient .def countH = r29 ;----------------------- .dseg disptemp: .byte 2 ;----------------------- .cseg push scale push tempL push tempH push temp1 push temp2 lds scale, (scale) lds tempL, (disptemp) lds tempH, (disptemp+1) clr isneg ;assume positive cpi scale, 'F' breq convertexit ; if Fahrenheit, don't change.... cpi scale, 'C' breq converttoC ; convert to °C cpi scale, 'K' breq converttoC ; if °K, first do the converttoC code... ;converttoR default: ldi temp1, LOW(4600) ldi temp2, HIGH(4600) add tempL, temp1 adc tempH, temp2 ; °R = °F + 460 cpi scale, 'R' breq convertexit ; if Rankine, exit... converttoC: ldi temp1, LOW(320) ldi temp2, HIGH(320) sub tempL, temp1; °F - 32 sbc tempH, temp2 mov temp, tempH andi temp, 0x80 breq Cnotneg ; check to see if °F < 32... ;Kelvin is never negative, but toggle isneg flag anyway ser temp mov isneg, temp cpi scale, 'K' breq Cnotneg ;get two's complement (1's complement + 1) ... restore # to positive com tempL com tempH adiw tempL, 1 Cnotneg: mov temp1, tempL; keep a copy of the temp (temp2:temp1 = °F - 32) mov temp2, tempH clc lsl tempL rol tempH clc lsl tempL rol tempH add tempL, temp1; 5 * (°F -32) adc tempH, temp2 ; ----- divide by 9 ------- (fast enough for our purposes) clr countL clr countH ; Y register div9: sbiw XL, 9 brcs divend adiw YL, 1 ; increment count (quotient) rjmp div9 divend: nop ; tempH:tempL holds 5/9 * (°F - 32) mov tempL, countL mov tempH, countH ; --------------------------- cpi scale, 'K' breq converttoK;convert to °K.... °K = °C + 273 rjmp convertexit;else exit with °C... converttoK: ldi temp1, LOW(2730) ldi temp2, HIGH(2730) add tempL, temp1 adc tempH, temp2;°K = °C + 273 tst isneg breq convertexit ldi temp1, LOW(7280) ;compensate for funny problems ldi temp2, HIGH(7280) ;with negative numbers sub tempL, temp1 sbc tempH, temp2;°K = °C + 273 clr isneg ;clear it so we don't display a - sign convertexit: sts (disptemp), tempL sts (disptemp+1), tempH pop temp2 pop temp1 pop tempH pop tempL pop scale ret ; ENDP ;**************** ;************************************************************ DisplayTemp: ; displays temperature in disptemp as «xxx.x°» (no scale here) .def tempL = r20 .def tempH = r21 lds tempL, (disptemp) lds tempH, (disptemp+1) rcall Bin2ASC ldi YL, LOW(ASCIItemp) ldi YH, HIGH(ASCIItemp) rcall lcdputRAMstr ret ; ENDP ;**************** ;*********************************************** DisplayScale: ; displays temperature scale as F, C, K, T ldi temp, 223;degree symbol, ° mov TXchar, temp rcall TXputC lds TXchar, (scale) rcall TXputC ret ;ENDP ;**************** ;************************************************ ButtonActionListener: ; gets called every 50 mS ; polls the button and does debouncing (internally) ; stores the (internal) state ;LOCALS: .def state = r21 .def count = r22 .def lastbtn = r15 .def currbtn = r20 ;---------------------- .dseg state: .byte 1 button: .byte 1 count: .byte 1 ;---------------------- .cseg push state push count push lastbtn push currbtn lds state, (state) lds lastbtn, (button) lds count, (count) ; Stored Machine States: ; 0--> 000=start ; 1--> 001=push detected ; 2--> 010=same button pressed ; 3--> 011=button is held (if pushed for 2s) ; 4--> 100=button is released (use for toggle button) ; ;switch (state) { ;case START: BALstart: cpi state, 0 brne BALpushed ;*state = START in currbtn, PinD ;in button, PinD cpi currbtn, 0xFF ;if (button==0xFF) break (no press) breq BALexit sts (button), currbtn;else store button ldi state, 0x01 ;state = PUSHED; sts (state), state rjmp BALexit ;break ;case PUSHED: BALpushed: cpi state, 1 brne BALstillpush ; *state = PUSHED in currbtn, PinD ;read the current button press (if any) ;use an AND here in case multiple buttons are/were pressed. and lastbtn, currbtn;check to see if same button is still pushed cp currbtn, lastbtn brne BALnotsame ;if (yes) ldi state, 0x02 ; state = STILLPUSH; sts (state), state clr count ; count = 0; (count how long button pressed) sts (count), count rjmp BALexit ;break ;case STILLPUSH: BALstillpush: cpi state, 2 brne BALheld ; *state = STILLPUSHED in currbtn, PinD and lastbtn, currbtn cp currbtn, lastbtn brne BALreleased ;if (button = same) inc count ; count ++; sts (count), count cpi count, 20 ;NOTE ---> 20 * 50ms = 1 sec brne BALexit ;if (count = 1 sec) ldi state, 0x03 ; state = held; sts (state), state rjmp BALexit ;case HELD: BALheld: cpi state, 3 brne BALnotsame in currbtn, PinD and lastbtn, currbtn cp currbtn, lastbtn brne BALreleased rjmp BALexit ; case RELEASED: BALreleased: ldi state, 4 sts (state), state rjmp BALexit BALnotsame: clr state; *state = START (reset the state) sts (state), state BALexit: pop currbtn pop lastbtn pop count pop state ret ;************************************************************** ; -------- TIMER0 ISR -------- ;************************************************************** ;Timer0 ISR decrements timeout TIMER0: in save, SREG out TCNT0, reload; keeps clock ticking at 1 ms dec timeout ; subtract another ms dec timeout2 out SREG, save reti ;back to background tasks ;************************************************************** ;************************************************************** Bin2ASC: ;NOTE: Compute temperature with base unit of .1 degrees (any scale) ;convert binary temp value to decimal and store in RAM .def temp = r20 .def power10L = r21 .def power10H = r22 .def degsL = r5; temp to display .def degsH = r6 ;----------------------- .dseg ASCIItemp: .byte 6; temp in ASCII (ready for display) ;----------------------- .cseg lds degsL, (disptemp); load the temp to display lds degsH, (disptemp+1) ldi power10L, LOW(1000) ldi power10H, HIGH(1000) clr temp ; temp will count each place value digit thousands: sub degsL, power10L sbc degsH, power10H brcs hundreds inc temp ; * temp actually holds the 100's temp. digit * rjmp thousands hundreds: add degsL, power10L ; restore the number adc degsH, power10H subi temp, -'0' sts (ASCIItemp), temp; put ASCII value of thousands digit into SRAM tst isneg ; see if number is negative..... breq __hundreds ldi temp, '-' sts (ASCIItemp), temp __hundreds: ldi power10L, LOW(100) ldi power10H, HIGH(100) clr temp _hundreds: sub degsL, power10L sbc degsH, power10H; subtract 100 from the temp value brcs tens ; dvdh:dvdL is less than 100, so goto tens.... inc temp ; * temp holds the 10's digit * rjmp _hundreds tens: add degsL, power10L adc degsH, power10H; restore the number (make it positive again) subi temp, -'0'; convert 10's digit to ASCII sts (ASCIItemp+1), temp; store 10's digit into RAM ldi power10L, 10 clr temp ; reset digit counter _tens: sub degsL, power10L brcs ones inc temp ; * temp holds the 1's digit * rjmp _tens ones: add degsL, power10L; restore the number back to positive (now holds tenths digit) subi temp, -'0'; convert ones digit to ASCII sts (ASCIItemp+2), temp; store 1's digit into RAM ldi temp, '.' sts (ASCIItemp+3), temp; store decimal point into RAM mov temp, degsL subi temp, -'0' ; convert tenth's digit to ASCII sts (ASCIItemp+4), temp; store tenths digit into RAM clr temp sts (ASCIItemp+5), temp; zero terminate ret ;============================================== ; Extra LCD functions ;============================================== ; NOTE: Expects register Y to hold the address in SRAM ; Y = char* lcdputRAMstr: nextc: ld TXchar, Y+ ; get next character from flash tst TXchar ; ...reach terminator byte yet? breq end1 ; ...if so, then get 4 digits rcall TXputC rjmp nextc ; get more characters... end1: ret ;============================================== ; NOTE: Expects register Z to hold the address in flash ; Z = char* lcdputflashstr: nextfc: lpm adiw ZL, 1 mov TXchar, r0 tst TXchar ; ...reach terminator byte yet? breq endf1 ; ...if so, then get 4 digits rcall TXputC rjmp nextfc ; get more characters... endf1: ret ;============================================== ;Character transfer routines TXputC: push temp cpi LCDcharpos, 8 ; addressing changes at char #8! brne writechar ; at char 8, fix the addressing ldi temp, 0xC0 ; set address to last 8 chars (start at $40) rcall lcdcmd writechar: mov temp, TXchar rcall lcdput ; displays character to LCD inc LCDcharpos pop temp ret ;************************************************** .include "lcdc.asm" |
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;**** MODIFIED LCD CODE --- uses Port C for LCD display **** ;=================================== ; *** LCD support routines *** ;=================================== ;Clear entire LCD and delay for a bit .equ LCDPort = PortC .equ DataDir = DDRC .equ InputPin = PINC lcdclr: ldi temp,1 ;Clear LCD command rcall lcdcmd ldi timeout,3 ;Delay 3 mS for clear command rcall delay ret ;================================================ ;Initialize LCD module lcdinit: ; cbi PORTB,0 ;Turn on LED 0 ldi temp,0 ;Setup port pins out LCDPort,temp ;Pull all pins low ldi temp,0xff ;All pins are outputs out DataDir,temp ldi timeout,15 ;Wait at least 15 mS at power up rcall delay ; LCD specs call for 3 repetitions as follows: ;first rep ldi temp,3 ;Function set out LCDPort,temp ;to 8-bit mode nop ;nop is data setup time sbi LCDPort,lcde ;Toggle enable line nop cbi LCDPort,lcde ldi timeout,15 ;Wait at least 15 mS rcall delay ;second rep ldi temp,3 ;Function set out LCDPort,temp nop sbi LCDPort,lcde ;Toggle enable line nop cbi LCDPort,lcde ldi timeout,15 ;Wait at least 15 ms rcall delay ;third rep ldi temp,3 ;Function set out LCDPort,temp nop sbi LCDPort,lcde ;Toggle enable line nop cbi LCDPort,lcde ldi timeout,15 ;Wait at least 15 ms rcall delay ;Now change to 4-wire interface mode ldi temp,2 ;Function set, 4 wire databus out LCDPort,temp nop sbi LCDPort,lcde ;Toggle enable line nop cbi LCDPort,lcde ; Finally, at this point, ; the normal 4 wire command routine (lcdcmd) can be used ldi temp,0b00100000;Function set, 4 wire, 1 line, 5x7 font rcall lcdcmd ldi temp,0b00001100;Display on, no cursor, no blink rcall lcdcmd ldi temp,0b00000110;Address increment, no scrolling rcall lcdcmd ; sbi PORTB,0 ;Turn off LED 0 ret ;============================================ ;Wait for LCD to go unbusy lcdwait: ;cbi PORTB,1 ;Turn on LED 1 ldi temp,0xF0 ;Make 4 data lines inputs out DataDir,temp sbi LCDPort,lcdrw ;Set r/w pin to read cbi LCDPort,lcdrs ;Set register select to command waitloop: sbi LCDPort,lcde ;Toggle enable line nop cbi LCDPort,lcde in lcdstat,InputPin ;Read busy flag ;Read, and ignore lower nibble sbi LCDPort,lcde ;Toggle enable line nop cbi LCDPort,lcde sbrc lcdstat,3 ;Loop until done rjmp waitloop ; sbi PORTB,1 ;Turn off LED 1 ret ;============================================= ;Send command in temp to LCD lcdcmd: push temp ;Save character rcall lcdwait ldi temp,0xFF ;Make all port D pins outputs out DataDir,temp pop temp ;Get character back push temp ;Save another copy swap temp ;Get upper nibble andi temp,0x0F ;Strip off upper bits out LCDPort,temp ;Put on port nop ;wait for data setup time sbi LCDPort,lcde ;Toggle enable line nop cbi LCDPort,lcde pop temp ;Recall character andi temp,0x0F ;Strip off upper bits out LCDPort,temp ;Put on port nop sbi LCDPort,lcde ;Toggle enable line nop cbi LCDPort,lcde ret ;============================================= ;Send character data in temp to LCD lcdput: push temp ;Save character rcall lcdwait ldi temp,0xFF ;Make all port D pins outputs out DataDir,temp pop temp ;Get character back push temp ;Save another copy swap temp ;Get upper nibble andi temp,0x0F ;Strip off upper bits out LCDPort,temp ;Put on port sbi LCDPort,lcdrs ;Register select set for data nop sbi LCDPort,lcde ;Toggle enable line nop cbi LCDPort,lcde pop temp ;Recall character andi temp,0x0F ;Strip off upper bits out LCDPort,temp ;Put on port sbi LCDPort,lcdrs ;Register select set for data nop sbi LCDPort,lcde ;Toggle enable line nop cbi LCDPort,lcde ret ;============================================= ;Subroutine waits for time equal to value in register timeout ;the register 'timeout' should be loaded before the call delay: tst timeout brne delay ret ; ---------------- (end of program) ------------------ |