CBarn24050
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 Posted:
Fri Dec 10, 2004 6:42 pm Post subject:
Re: LED Display Driver for use with PIC? |
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| Quote: | Subject: Re: LED Display Driver for use with PIC?
From: Noel Henson noel@noels-lab.com
As mentioned before, "the order of magnitude is correct." Nice work. But if
we were starting anew, how small could it be made?
Noel
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I cant remeber the original spec now but lets say 4 digits with 4 buttons,
buttons driven via a diode from the multiplex output feeding back to a single
port pin. Digits and multiplex pattern alternated in the top 8 registers of a
PIC 16c870. Button information returned in the msb of the multiplex register
(only need the lower 4 bits for multiplexing). FSR reg dedicated to this thread
(could be shared with care by other threads). Code in ISR something like
movlw B'11111000'
iorwf fsr,f
movf 0,w
movwf segment_port
incf fsr,f
movf 0,w
movwf multiplex_port
bcf 0,7
btfsc multiplex_port,7 ;(button input line)
bsf 0,7
incf fsr,f
Now I,ve written it I'll leave you to test and debug it.
mo |
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