newbie here looking for example code

Don't know your exact situation so I don't know if this would be helpful, but I have some 68HC12 assembly code for driving multiplexed

7-segment displays to display a min:sec value on a Dragon12 board. It's yours if you'd like it.

Mike

Hayley schrieb:

Hi,

think you mean Microchip PICs

-> click input/output and then Display-LED -> ANxxx

HTH Michael

thank you for your help,

I don't know why you would want to program that horrible device, but if you insist, here are some of my first micro (PIC16F84) learning experiments. BTW, I quickly moved to the AVR. Never looked back.

------------------------------------------------------------------------ ; exp5.asm

; This program will take 4-bit binary data in port A and decode it ; to 7-segment display, with hex digits 'A' 'b' 'C' 'd' 'E' 'F' ; in addition to the numeric digits. A lookup table is addressed ; by the data to be decoded. The table contains the 7-segment pattern ; to display the corresponding digit.

; This program uses the relative addresing concept, or "computed jump" ; A later experiment will set up the table and address it using ; program memory paging, which will allow for large tables (almost 256 ; bytes). But, the table for this experiment is small. list p=16f84 radix hex

; cpu equates (memory map)

w equ 0 f equ 1 porta equ 0x05 portb equ 0x06 pc equ 0x02 ; program counter register

org 0x000

start clrw tris portb ; make all port B lines an output

decode movf porta,w ; get port A data call segments ; decode into 7 segment xorlw 0xFF ; complement all bits because the ; LED is common anode movwf portb ; send it out port B goto decode ; do it ad infinitum

segments addwf pc,f ; index pc into following instructions retlw 0x3F ; '0' retlw 0x06 ; '1' retlw 0x5B ; '2' retlw 0x4F ; '3' retlw 0x66 ; '4' retlw 0x6D ; '5' retlw 0x7D ; '6' retlw 0x07 ; '7' retlw 0x7F ; '8' retlw 0x6F ; '9' retlw 0x77 ; 'A' retlw 0x7C ; 'b' retlw 0x39 ; 'C' retlw 0x5E ; 'd' retlw 0x79 ; 'E' retlw 0x71 ; 'F'

end

------------------------------------------------------------------------ ; exp6.asm ; ; This program takes a count input at T0CKI and displays the full ; 8-bit counter datum in hex on a 2 digit 7 segment display. ; This is the first exercise in display multiplexing. ; ; Hardware Context: ; ; Port B bits 0-7 connect through 220 ohms to cathodes a-g ; respsectively. Port A bits 0-1 enable digits 1-2 respectively. ; A logic 0 on a Port A "digit select output" line enables the digit ; by connecting its common anode to Vdd (+5V) via a p-MOSFET.

list p=16f84 radix hex

; cpu equates (memory map)

w equ 0 f equ 1 porta equ 0x05 portb equ 0x06 counter equ 0x01 pc equ 0x02 ; program counter register count_copy equ 0x0C ; first G.P. register to store ; working copy of counter delay equ 0x0D ; next G.P. register for delay ; iterator org 0x000

start clrw tris portb ; make all port B lines output movlw b'00010000' ; All port A bits except RA4/T0CKI tris porta ; make them outputs

clrf counter

; movlw 0xAA ; movf counter,w ; load a fixed value to test

multiplex movf counter,w ; grab the count datum movwf count_copy ; store a copy of it andlw 0x0F ; mask out the high nibble call segments ; decode into 7 segment format xorlw 0xFF ; invert the bits bsf porta,1 ; turn off digit 2 movwf portb ; send 7 segments to port B bcf porta,0 ; turn on digit 1 call wait_500u ; wait 500 us

swapf count_copy,w ; swap nibbles of the count datum ; and get into W andlw 0x0F ; mask off the high nibble of W, ; which is the low nibble of the count! call segments ; decode into 7 segment format xorlw 0xFF ; invert the bits bsf porta,0 ; turn off digit 1 movwf portb ; send 7 segments to port B bcf porta,1 ; turn on digit 2 call wait_500u ; wait 500 us

goto multiplex ; ad infinitum stop goto stop

wait_500u movlw d'166' ; this will give about 500us delay movwf delay d_loop decfsz delay,f goto d_loop return

segments addwf pc,f ; index pc into following instructions retlw 0x3F ; '0' retlw 0x06 ; '1' retlw 0x5B ; '2' retlw 0x4F ; '3' retlw 0x66 ; '4' retlw 0x6D ; '5' retlw 0x7D ; '6' retlw 0x07 ; '7' retlw 0x7F ; '8' retlw 0x6F ; '9' retlw 0x77 ; 'A' retlw 0x7C ; 'b' retlw 0x39 ; 'C' retlw 0x5E ; 'd' retlw 0x79 ; 'E' retlw 0x71 ; 'F'

end

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Good day!

--
_____________________
Christopher R. Carlen
crobc@bogus-remove-me.sbcglobal.net
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