; FILE: Digital_clock.asm ; AUTH: Dhaminda Siriwardena ; DATE: 2nd May 2005 ; DESC: A Digital Clock ; NOTE: Tested on PIC16F84-04/P. list p=16F84 radix hex ;---------------------------------------------------------------------- ; cpu equates (memory map) tmr0 equ 0x01 pcl equ 0x02 status equ 0x03 portA equ 0x05 portB equ 0x06 intcon equ 0x0b ;----- User defined memory locations counter1 equ 0x10 ; Incrementing counter lower 8 bits counter2 equ 0x10 ; Incrementing counter higher 8 bits freqLow equ 0x12 freqHigh equ 0x13 FreqDelay equ 0x14 ClockMode equ 0x15 ; 0x03 for normal 0x01 or 0x02 for edit mode. 0x01 for minute edit and 0x02 for hour edit digit equ 0x16 delay equ 0x17 MinTicks equ 0x18 SecTicks equ 0x19 status_Temp equ 0x1a ; Interrupt temp storage W_temp equ 0x1b ; Interrupt temp storage ;----- CPU extended registers option_reg equ 0x81 trisa equ 0x85 trisb equ 0x86 ;Flags of STATUS file C equ 0 DC equ 1 Z equ 2 ;File types W equ 0 F equ 1 ;---------------------------------------------------------------------- org 0x000 goto start ; Start program ;---------------------------------------------------------------------- org 0x04 int_service_routine ; Do Interrupt service movwf W_temp ; Copy W to TEMP register, movf status, W ; Swap status to be saved into W movwf status_Temp ; Save status to STATUS_TEMP register ; Interrupt Service Routine btfss intcon,2 ; Check for Timer 0 overflow flag goto no_INT Timer0_Overflow ; Service Timer 0 overflow INT movfw intcon andlw b'11100000' ; Clear Time 0 INT Flag iorlw b'00100000' ; Reset Timer0 INT movwf intcon movlw 0x82 ;Load time with 0xFF - 0x82 = 7D movwf tmr0 ;Load time with value incf digit,F ; Point to next digit for the next call movfw delay btfss status,Z ; Check if delay is zero. If zero do not decf it decf delay,F ; Decrease delay counter when TMR0 overflows ;Change Counter value decfsz FreqDelay,F ; Do delay for seconds timming. goto no_INT ; If not complete service next interrupt movlw 0xf9 ; Set counter to divide by 125 insted of 250 so to divide by 2 movwf FreqDelay movfw ClockMode xorlw 0x03 ; Check if both bits are ON btfss status,Z ; If ON then stop Sec count display goto CountSecs ; Skip to next section movfw SecTicks ; Seconds blink LED status xorlw 0x10 ; Invert current status movwf SecTicks CountSecs decfsz MinTicks,F ; Count up to 60 Seconds for a minute goto CheckEditButton movfw ClockMode ; Check operation status xorlw 0x03 ; Check if both bits are ON btfsc status,Z ; If ON then stop Clock call Clock_Counter SkipClockCount movfw freqLow ; Copy frequency count to output for display movwf counter1 movfw freqHigh movwf counter2 movlw 0xf9 ; Set counter to divide by 125 insted of 250 so to divide by 2 movwf FreqDelay movlw 0x3c ; Set 60 for 60Sec = 1 Min movwf MinTicks ; Check for Edit mode switch on Port B CheckEditButton btfsc portB,7 ; Check bit 7 status goto no_INT decf ClockMode,W ; Set clock in edit mode andlw 0x03 btfsc status,Z ; check if state is 00 movlw 0x03 ; Then revert to 0x03 for all ON movwf ClockMode xorlw 0x03 ; Check for Operational mode btfss status,Z goto SetPortA4Input ; Set port A to input banksel trisa ; Set Port A RA4 as an output clrf trisa ; port A is output banksel portA goto IntComplete SetPortA4Input banksel trisa ; Set Port A RA4 as an input movlw 0x10 ; Set RA4 as as input movwf trisa ; port A is output banksel portA bsf portA,4 ; Clear data in port A bit 4 IntComplete movlw 0x00 ; Clear Port B movf portB,W ; Read Port B and then clear RBIF flag ; End of Interrupt Service Routine no_INT movf status_Temp, W ; Swap nibbles in STATUS_TEMP register and place result into W movwf status ; Move W into STATUS register ; (sets bank to original state) movf W_temp,W ; move W_TEMP and place result in W retfie ; Return from interrput ;End of Interrup service routine ;---------------------------------------------------------------------- start clrwdt ; clear watchdog timer ; bit 7: RBPU: PORTB Pull-up Enable bit ; 1 = PORTB pull-ups are disabled ; 0 = PORTB pull-ups are enabled (by individual port latch values) ; bit 6: INTEDG: Interrupt Edge Select bit ; 1 = Interrupt on rising edge of RB0/INT pin ; 0 = Interrupt on falling edge of RB0/INT pin ; bit 5: T0CS: TMR0 Clock Source Select bit ; 1 = Transition on RA4/T0CKI pin ; 0 = Internal instruction cycle clock (CLKOUT) ; bit 4: T0SE: TMR0 Source Edge Select bit ; 1 = Increment on high-to-low transition on RA4/T0CKI pin ; 0 = Increment on low-to-high transition on RA4/T0CKI pin ; bit 3: PSA: Prescaler Assignment bit ; 1 = Prescaler assigned to the WDT ; 0 = Prescaler assigned to TMR0 ; bit 2-0: PS2:PS0: Prescaler Rate Select bits ; ; Bit Value TMR0 Rate WDT Rate ; ------------------------------------ ; 000 1 : 2 1 : 1 ; 001 1 : 4 1 : 2 ; 010 1 : 8 1 : 4 ; 011 1 : 16 1 : 8 ; 100 1 : 32 1 : 16 ; 101 1 : 64 1 : 32 ; 110 1 : 128 1 : 64 ; 111 1 : 256 1 : 128 movlw b'11010100' ; assign prescaler, internal clock and divide by 256 banksel option_reg movwf option_reg banksel tmr0 ; Set Tmr0 to initial value movlw 0x82 ;Load time with 130 (255 - 125). Divide movwf tmr0 ;Load time with value banksel trisb ; Configure Port Direction registers movlw 0x10 ; Set RA4 as as input movwf trisa ; port A is output movlw 0x80 ; set w = 0 movwf trisb ; port B is output banksel portB movlw 0x03 ; Switch all digits ON movwf ClockMode ; Set clock on normal run mode clrf freqLow clrf counter1 ; Set counter1 to zero clrf SecTicks clrf digit movlw 0x12 ; Set statup value to 12 O'clock movwf freqHigh movwf counter2 ; ; Freq = 1 Mhz Prescaler = 16 counter = 125 ; Ref Freq = 1/(32*125) = 250 ; 250 / 250 (Software) = 1Hz movlw 0xfa ; Set counter to 250 movwf FreqDelay movlw 0x3c ; Set 60 for 60Sec = 1 Min movwf MinTicks ; INTCON register ; bit 7: GIE: Global Interrupt Enable bit ; 1 = Enables all un-masked interrupts ; 0 = Disables all interrupts ; Note: For the operation of the interrupt structure, please refer ; bit 6: EEIE: EE Write Complete Interrupt Enable bit ; 1 = Enables the EE write complete interrupt ; 0 = Disables the EE write complete interrupt ; bit 5: T0IE: TMR0 Overflow Interrupt Enable bit ; 1 = Enables the TMR0 interrupt ; 0 = Disables the TMR0 interrupt ; bit 4: INTE: RB0/INT Interrupt Enable bit ; 1 = Enables the RB0/INT interrupt ; 0 = Disables the RB0/INT interrupt ; bit 3: RBIE: RB Port Change Interrupt Enable bit ; 1 = Enables the RB port change interrupt ; 0 = Disables the RB port change interrupt ; bit 2: T0IF: TMR0 overflow interrupt flag bit ; 1 = TMR0 has overflowed (must be cleared in software) ; 0 = TMR0 did not overflow ; bit 1: INTF: RB0/INT Interrupt Flag bit ; 1 = The RB0/INT interrupt occurred ; 0 = The RB0/INT interrupt did not occur ; bit 0: RBIF: RB Port Change Interrupt Flag bit ; 1 = When at least one of the RB7:RB4 pins changed state (must ; 0 = None of the RB7:RB4 pins have changed state banksel intcon ; Change bank movlw b'10100000' ; Set Interrupt on level for TMR0 overflow interrupt flag movwf intcon ; Update INTCON Register loop call ShowTime ; Display Time movfw ClockMode ; Get clock mode xorlw 0x03 ; If ClockMode is 0x03 then the Zero falg is set after XOR btfss status,Z ; If ClockMode is 0x03 then loop Else edit goto ClockEdit goto loop ; Enless loop ClockEdit btfss ClockMode,0 ; Check miniute edit flag goto CheckHour ; 0x02 for Hour bcf status,Z ; Clear Zero movfw portA ; Read Port A to check port A bit 4 input andlw 0x10 ; Check only PortA bit4 ON status btfss status,Z ; Skip if Bit 4 set ON goto loop ;Increase Mins incf freqLow,F ; Increase Low byte movfw freqLow ; Get Low nibble andlw 0x0f bcf status,DC ; Clear DC flag sublw 0x09 ; Miniute low digit btfsc status,DC ; Check nibble carry goto MinEditComplete ; All OK do Min edit delay movfw freqLow ; Update Low nibble andlw 0xf0 addlw 0x10 ; Increase High nibble by one movwf freqLow swapf freqLow,W ; Swap nibbles bcf status,DC sublw 0x05 ; Check for 60 min range btfss status,DC clrf freqLow ; If 60 is reached then clear to zero MinEditComplete ; Display Freq values and display while delay movfw freqLow movwf counter1 movfw freqHigh movwf counter2 Call SetupTimeDelay ; Call delay with display goto loop ; Done with Min edit CheckHour bcf status,Z ; Clear Zero movfw portA ; Read Port A to check port A bit 4 input andlw 0x10 ; Check only PortA bit4 btfss status,Z goto loop ; If nothing then get back to main loop ;Increase Hours incf freqHigh,F ; Increase hours movfw freqHigh ; Select Low nibble of hour andlw 0x0f bcf status,DC sublw 0x09 ; Check for up 9 count on low nibble btfsc status,DC ; If not then done with this nibble goto HourEditComplete movfw freqHigh ; Increase high nibble by one andlw 0xf0 addlw 0x10 movwf freqHigh HourEditComplete Call checkHours ; Check Hour 24 format movfw freqLow ; Get a copy of the frequency movwf counter1 movfw freqHigh movwf counter2 Call SetupTimeDelay ; Delay with display goto loop ; Get back to main loop ;--------------------------------------------------------------------------------- ; 16 bit Counter Clock_Counter incf freqLow,F ; Increase Low byte movfw freqLow andlw 0x0f bcf status,DC sublw 0x09 ; Miniute low digit btfsc status,DC goto no_nibble_carry movfw freqLow andlw 0xf0 addlw 0x10 movwf freqLow swapf freqLow,W bcf status,DC sublw 0x05 ; Miniute high digit btfsc status,DC goto no_nibble_carry clrf freqLow incf freqHigh,F movfw freqHigh andlw 0x0f bcf status,DC sublw 0x09 ; Hour low digit btfsc status,DC goto checkHours movfw freqHigh andlw 0xf0 addlw 0x10 movwf freqHigh checkHours movfw freqHigh bcf status,C ; Check for 24 hour format sublw 0x23 ; Check for 24 hour clock format btfsc status,C goto no_nibble_carry movlw 0x00 ; Set hour to '1' movwf freqHigh no_nibble_carry return ;---------------------------------------------------------------------- ; Display value in 7 segments ShowTime movfw digit ; Get digit number andlw 0x03 ;Select bit 0 and 1 addwf pcl,F ; Increament program counter goto Digit1 goto Digit2 goto Digit3 goto Digit4 ;Display Min Digit 1 Digit1 movfw counter1 call display ; Get display pattern in WREG btfss ClockMode,0 ; Check Minute display state movlw 0x00 movwf portB movfw SecTicks iorlw b'11101110' ; Select Digit 4 andlw b'11111110' movwf portA ; Send to portA return ;Display Min Digit 2 Digit2 swapf counter1,W call display ; Get display pattern in WREG btfss ClockMode,0 ; Check Minute display state movlw 0x00 movwf portB movfw SecTicks iorlw b'11101101' ; Select Digit 3 andlw b'11111101' movwf portA ; Send to portA return ;Display Hour Digit 1 Digit3 movfw counter2 call display ; Get display pattern in WREG btfss ClockMode,1 ; Check Minute display state movlw 0x00 movwf portB movfw SecTicks iorlw b'11101011' ; Select Digit 2 andlw b'11111011' movwf portA ; Send to portA return ;Display Hour Digit 2 Digit4 swapf counter2,W andlw 0x0f btfss status,Z call display ; Get display pattern in WREG btfss ClockMode,1 ; Check Minute display state movlw 0x00 movwf portB ; Send to portB movfw SecTicks iorlw b'11100111' ; Select Digit 1 andlw b'11110111' movwf portA ; Send to portA return ;---------------------------------------------------------------------- ; converts the value in number to a 7 segment value ; Value passed in W Register ; ; Seven segment connections from Port B ; ; RB1 ; -------- ; | | ; RB2 | | RB0 ; | | ; -------- ; | RB3 | ; RB4 | | RB6 ; | | ; -------- ; RB5 ; ;----------------------------------------------------------------------; ; display andlw 0x0f ; Get lower nibble only addwf pcl,F ; Increament program counter retlw 0x77 ; 0 retlw 0x41 ; 1 retlw 0x3b ; 2 retlw 0x6b ; 3 retlw 0x4d ; 4 retlw 0x6e ; 5 retlw 0x7e ; 6 retlw 0x43 ; 7 retlw 0x7f ; 8 retlw 0xcf ; 9 retlw 0x5f ; A retlw 0x7c ; B retlw 0x36 ; C retlw 0x79 ; D retlw 0x3e ; E retlw 0x1e ; F retlw 0x08 ; - ;---------------------------------------------------------------------- ; Time Setup delay ; ; SetupTimeDelay movlw 0x7d ; Set Approx 1/5sec delay movwf delay ; Update delay to be changed by TMR0 INT DelayLoop call ShowTime ; Spend time displaying Time bcf status,Z movfw delay ; Check delay counter decremented by TMR0 INT btfss status,Z goto DelayLoop ; If not then repeat counter return end ;---------------------------------------------------------------------- ; at burn time, select: ; memory uprotected ; watchdog timer disabled ; standard crystal (4 MHz) ; power-up timer on