Registered Member #3546
Joined: Tue Dec 28 2010, 08:24AM
Location: Pittsburgh, PA
Posts: 18
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First project post, please don't be gentile...
This is a simple project I started after the mechanical failures of my persistence of vision propeller clock. I am sure I will get that working someday and have a post for that as well...
For this project I decided to use the PIC16F886 micro controller to run two two-digit seven-segment displays. Because this chip has only 28 pins, and about a third of them were needed for controlling the time and supplying the chip with power, I had to rely on the persistence of vision effect for this project. That being said what I did was use one set of seven pins connected to the corresponding inputs on the four displays, but I connected nMOS transistors on the grounds of each of the four pins. As the micro controller switches what is being displayed it switches which nMOS is in saturation, allowing me to control which display is on. When this is done fast enough it appears constant.
Besides dealing with that little mess I had to write code that kept track of time, allowed the user to change the time, allowed the user to set the alarm clock, and controlled if the alarm clock was turned on.
Parts:
1-PIC16F886
5-2N7000 MOSFETs
1-8ohm 2W speaker
2-MAN6750 seven segment displays
28-100ohm resistors
5-SPDT switches
1-audio jack
1-7805 regulator
2-ceramic filter capacitors (for the 7805)
If you want a circuit diagram I can probably put one together tomorrow sometime.
My future plans for this project involve adding a thermometer feature, that I have already started as seen here. I'm just running into problems getting the PIC to read the reference values as I am pretty sure the room temperature is not 98 Celsius. It has to be a simple coding error.
I think I would like to turn this into my first PCB endeavor. I am thinking of trying the acid etching first, if you have any tips on that throw me a pm. If I am to put anymore time into this I will also have to clean the code up as it is rather sloppy right now. Another idea I have is wiring the right most two digit display upside down so that I can use the decimal points as the colon of a clock. I know that you can get displays with the colon, but I'm cheap. I also seem to be having a problem with driving the speaker with an MP3 player but I attribute that to not having any fresh batteries for my MP3 player right now. It works great off my computer.
Oh one last thing I forgot to mention, it currently is running off the PIC's internal oscillator, which is amazing because it only loses about one minute per seventy-six minutes. I am looking into the best solution. I can either add code to add an extra minute every so often, I can adjust the frequency of the oscillator, I could learn how to add an external crystal, or I could create a wall power supply for it like the clocks you buy that would a square wave clock generator based off the oscillations in the AC voltage. The last would be the best solution as the power companies actually will adjust the frequency during none peak hours so that the frequency averages out to exactly 60 Hz over the course of each day.
This project is mostly for me proof of concept though. I hopefully by the end of this year will have created the world most dangerous alarm clock. Nixie clock with a plasma speaker anyone? Although I am not sure that the plasma speaker will be loud enough.
The source code is as follows... Let me warn you though that I only code in assembly, I find programming in assembly to be more of a challenge for my personal projects. I only ask that you please do not re-post my code elsewhere on the web without accreditation.
Mind you this code is rather sloppy right now, instead of using one set of code to control the display and time changing of both the actual time and the alarm time I copied the code and changed the variables. Also, the displaying function could use a rewrite, it is rather disgusting imo.
;Walter P Kerin
;Seven Segment Display Clock
#include <p16F886.inc>
__CONFIG _CONFIG1, _LVP_OFF & _FCMEN_OFF & _IESO_OFF & _BOR_OFF & _CPD_OFF & _CP_OFF & _MCLRE_OFF & _PWRTE_ON & _WDT_OFF & _INTRC_OSC_NOCLKOUT
__CONFIG _CONFIG2, _WRT_OFF & _BOR21V
cblock 0x20
ten
hundred
Seconds
MinuteOnes
MinuteTens
HourOnes
HourTens
digitkeep
AMinuteOnes
AMinuteTens
AHourOnes
AHourTens
Adigitkeep
ATest
endc
cblock 0x70
w_temp
STATUS_temp
endc
org h'00'
GOTO Start
org h'04'
GOTO ISR
;-----------------------------------------------------------------------------------
;LOOKUP TABLES
;-----------------------------------------------------------------------------------
LookUpTable:
ADDWF PCL,f
RETLW b'01110111' ;0
RETLW b'01000100' ;1
RETLW b'00111110' ;2
RETLW b'01101110' ;3
RETLW b'01001101' ;4
RETLW b'01101011' ;5
RETLW b'01111011' ;6
RETLW b'01000110' ;7
RETLW b'01111111' ;8
RETLW b'01001111' ;9
RETLW b'01110111' ;0
DigitTable:
ADDWF PCL,f
GOTO digit1
GOTO digit2
GOTO digit3
GOTO digit4
ADigitTable:
ADDWF PCL,f
GOTO Adigit1
GOTO Adigit2
GOTO Adigit3
GOTO Adigit4
;-----------------------------------------------------------------------------------
;START
;-----------------------------------------------------------------------------------
Start:
;Bank 3
BSF STATUS,RP1
BSF STATUS,RP0
CLRF ANSELH
CLRF ANSEL
;Bank 1
BCF STATUS,RP1
BSF STATUS,RP0
BCF TRISB,0
BSF TRISA,0 ;hours
BSF TRISA,1 ;minutes tens
BSF TRISA,2 ;minutes ones
BSF TRISA,3 ;clock or alarm
BSF TRISA,4 ;alarm on/off
BCF TRISA,5 ;alarm
CLRF TRISC ;seven segments
BCF TRISB,1 ;transistors
BCF TRISB,2
BCF TRISB,3
BCF TRISB,4
BCF OPTION_REG,T0CS ;Use internal clock
BCF OPTION_REG,PSA ;Use prescaler with TMR0
BCF OPTION_REG,PS2 ;Set prescaler to 8
BSF OPTION_REG,PS1
BCF OPTION_REG,PS0
BSF OSCCON,IRCF2
BSF OSCCON,IRCF1
BSF OSCCON,IRCF0
BSF OSCCON,SCS
;Bank 0
BCF STATUS,RP1
BCF STATUS,RP0
MOVLW h'06'
MOVWF TMR0
MOVLW d'10'
MOVWF ten
MOVLW d'100'
MOVWF hundred
MOVLW d'60'
MOVWF Seconds
MOVLW d'10'
MOVWF MinuteOnes
MOVLW d'6'
MOVWF MinuteTens
MOVLW d'1'
MOVWF HourOnes
MOVLW d'1'
MOVWF HourTens
MOVLW d'10'
MOVWF AMinuteOnes
MOVLW d'6'
MOVWF AMinuteTens
MOVLW d'1'
MOVWF AHourOnes
MOVLW d'1'
MOVWF AHourTens
CLRF digitkeep
CLRF Adigitkeep
BCF PORTB,1
BCF PORTB,2
BCF PORTB,3
BCF PORTB,4
BSF INTCON,GIE
BSF INTCON,T0IE
GOTO MainLoop
;-----------------------------------------------------------------------------------
;MainLoop
;-----------------------------------------------------------------------------------
MainLoop:
BTFSC PORTA,4
CALL Check_Alarm
BTFSS PORTA,4
BCF PORTA,5
BTFSC PORTA,3
GOTO Change_Alarm
GOTO Display_Time
;-----------------------------------------------------------------------------------
;Check_Alarm
;-----------------------------------------------------------------------------------
Check_Alarm:
MOVF HourTens,w
SUBWF AHourTens,w
BTFSS STATUS,Z
RETURN
MOVF HourOnes,w
SUBWF AHourOnes,w
BTFSS STATUS,Z
RETURN
MOVF MinuteTens,w
SUBWF AMinuteTens,w
BTFSS STATUS,Z
RETURN
MOVF MinuteOnes,w
SUBWF AMinuteOnes,w
BTFSS STATUS,Z
RETURN
BSF PORTA,5
;-----------------------------------------------------------------------------------
;Display_Time
;-----------------------------------------------------------------------------------
Display_Time:
CALL DisplayTime
BTFSS PORTA,2
GOTO $+7
BTFSC PORTA,2
GOTO $-1
DECFSZ MinuteOnes
GOTO $+3
MOVLW d'10'
MOVWF MinuteOnes
CALL DisplayTime
BTFSS PORTA,1
GOTO $+7
BTFSC PORTA,1
GOTO $-1
DECFSZ MinuteTens
GOTO $+3
MOVLW d'6'
MOVWF MinuteTens
CALL DisplayTime
BTFSS PORTA,0
GOTO $+11
BTFSC PORTA,0
GOTO $-1
BTFSS HourTens,0
GOTO $+7
DECFSZ HourOnes
GOTO $+4
MOVLW d'9'
MOVWF HourOnes
CLRF HourTens
GOTO MainLoop
DECFSZ HourOnes
GOTO $+5
MOVLW d'3'
MOVWF HourOnes
MOVLW d'1'
MOVWF HourTens
CALL DisplayTime
GOTO MainLoop
;DisplayTime
;-----------------------------------------------------------------------------------
DisplayTime:
MOVF digitkeep,w
GOTO DigitTable
DisplayNow:
BTFSS PORTB,0
GOTO $-1
BCF PORTB,0
INCF digitkeep
MOVF digitkeep,w
BCF STATUS,C
ADDLW b'11111100'
BTFSC STATUS,C
CLRF digitkeep
RETURN
;Display Tables
;-----------------------------------------------------------------------------------
;Selects the digit using the DigitTable
;Goes to appropriate digit subroutine and executes the commands and access the
;lookup tables at the end of the program to send the proper hex configuration back to
;the display time subroutine
digit1:
BCF PORTB,2
BCF PORTB,3
BCF PORTB,4
MOVF MinuteOnes,w
SUBLW d'10'
CALL LookUpTable
MOVWF PORTC
BSF PORTB,1
GOTO DisplayNow
digit2:
BCF PORTB,1
BCF PORTB,3
BCF PORTB,4
MOVF MinuteTens,w
SUBLW d'6'
CALL LookUpTable
MOVWF PORTC
BSF PORTB,2
GOTO DisplayNow
digit3:
BCF PORTB,1
BCF PORTB,2
BCF PORTB,4
MOVF HourOnes,w
BTFSC HourTens,0 ; Skip if HourTens = 0
GOTO $+6 ; Go six lines down in code from here
SUBLW d'10'
CALL LookUpTable
MOVWF PORTC
BSF PORTB,3
GOTO DisplayNow
SUBLW d'3'
CALL LookUpTable
MOVWF PORTC
BSF PORTB,3
GOTO DisplayNow
digit4:
BCF PORTB,1
BCF PORTB,2
BCF PORTB,3
MOVF HourTens,w
BTFSS HourTens,0 ; Skip if HourTens is 1
GOTO $+4
CALL LookUpTable
MOVWF PORTC
BSF PORTB,4
GOTO DisplayNow
;-----------------------------------------------------------------------------------
;ISR
;-----------------------------------------------------------------------------------
ISR:
MOVWF w_temp
SWAPF STATUS,W
MOVWF STATUS_temp
BTFSC INTCON,T0IF
CALL Time
SWAPF STATUS_temp,W
MOVWF STATUS
SWAPF w_temp,F
SWAPF w_temp,W
RETFIE
;TIMER
;-----------------------------------------------------------------------------------
Time:
BCF INTCON,T0IF
MOVLW h'06'
MOVWF TMR0
;1 uS
BSF PORTB,0
DECFSZ ten
RETURN
;10 uS
BSF PORTE,0
MOVLW d'10'
MOVWF ten
DECFSZ hundred
RETURN
;1 S
MOVLW d'100'
MOVWF hundred
DECFSZ Seconds
RETURN
;60 S ~ 1 M
MOVLW d'60'
MOVWF Seconds
DECFSZ MinuteOnes
RETURN
;600 S ~ 10 M
MOVLW d'10'
MOVWF MinuteOnes
DECFSZ MinuteTens
RETURN
;3600 S ~ 60 M ~ 1 H
MOVLW d'6'
MOVWF MinuteTens
DECFSZ HourOnes
RETURN
BTFSS HourTens,0 ; Skip if HourTens = 0
GOTO $+5 ; Go six lines down in code from here
MOVLW d'9'
MOVWF HourOnes
CLRF HourTens
RETURN
MOVLW d'3'
MOVWF HourOnes
MOVLW d'1'
MOVWF HourTens
RETURN
;-----------------------------------------------------------------------------------
;Change_Alarm
;-----------------------------------------------------------------------------------
Change_Alarm:
CALL ADisplayTime
BTFSS PORTA,2
GOTO $+7
BTFSC PORTA,2
GOTO $-1
DECFSZ AMinuteOnes
GOTO $+3
MOVLW d'10'
MOVWF AMinuteOnes
CALL ADisplayTime
BTFSS PORTA,1
GOTO $+7
BTFSC PORTA,1
GOTO $-1
DECFSZ AMinuteTens
GOTO $+3
MOVLW d'6'
MOVWF AMinuteTens
CALL ADisplayTime
BTFSS PORTA,0
GOTO $+11
BTFSC PORTA,0
GOTO $-1
BTFSS AHourTens,0
GOTO $+7
DECFSZ AHourOnes
GOTO $+4
MOVLW d'9'
MOVWF AHourOnes
CLRF AHourTens
GOTO MainLoop
DECFSZ AHourOnes
GOTO $+5
MOVLW d'3'
MOVWF AHourOnes
MOVLW d'1'
MOVWF AHourTens
CALL ADisplayTime
GOTO MainLoop
;DisplayTime
;-----------------------------------------------------------------------------------
ADisplayTime:
MOVF Adigitkeep,w
GOTO ADigitTable
ADisplayNow:
BTFSS PORTB,0
GOTO $-1
BCF PORTB,0
INCF Adigitkeep
MOVF Adigitkeep,w
BCF STATUS,C
ADDLW b'11111100'
BTFSC STATUS,C
CLRF Adigitkeep
RETURN
;Display Tables
;-----------------------------------------------------------------------------------
;Selects the digit using the DigitTable
;Goes to appropriate digit subroutine and executes the commands and access the
;lookup tables at the end of the program to send the proper hex configuration back to
;the display time subroutine
Adigit1:
BCF PORTB,2
BCF PORTB,3
BCF PORTB,4
MOVF AMinuteOnes,w
SUBLW d'10'
CALL LookUpTable
MOVWF PORTC
BSF PORTB,1
GOTO ADisplayNow
Adigit2:
BCF PORTB,1
BCF PORTB,3
BCF PORTB,4
MOVF AMinuteTens,w
SUBLW d'6'
CALL LookUpTable
MOVWF PORTC
BSF PORTB,2
GOTO ADisplayNow
Adigit3:
BCF PORTB,1
BCF PORTB,2
BCF PORTB,4
MOVF AHourOnes,w
BTFSC AHourTens,0 ; Skip if HourTens = 0
GOTO $+6 ; Go six lines down in code from here
SUBLW d'10'
CALL LookUpTable
MOVWF PORTC
BSF PORTB,3
GOTO ADisplayNow
SUBLW d'3'
CALL LookUpTable
MOVWF PORTC
BSF PORTB,3
GOTO ADisplayNow
Adigit4:
BCF PORTB,1
BCF PORTB,2
BCF PORTB,3
MOVF AHourTens,w
BTFSS AHourTens,0 ; Skip if HourTens is 1
GOTO $+4
CALL LookUpTable
MOVWF PORTC
BSF PORTB,4
GOTO ADisplayNow
END
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Digital Alarm Clock
