On Thu, 11 Sep 2003 01:19:48 +0100, Mike Harrison wrote:
::You'll need more than 8 pins to read the switches - (OK it may be
::possible on a '675 using the ADC
::but will be a bit of a pain) - an 18 pin device will be a lot
::easier!

Couldn't he multiplex the BCD switches only 4 lines for the BCD and
two control pins to differentiate between Hz and FRACT_Hz.

Wire OR the BCD outputs to the PIC and either alternate between the
two CONTROL pins or if necessary use an extra pin for an ENTER button
and just press it after each wheel has been thumbed appropriately.

Example snippet

//Read 2 BCD switches multiplexed to same port
clrf CONTROL_PORT       ;Port that controls the C pin of switches
bsf COMTROL_PORT, SwitchX1 ;Set bitX connected to Cx switch X becomes
live
delay ;wait for debounce end
movf BCD_PORT,w ;Copy reading of BCD pins on BCD_PORT to w
movwf BCDx1             ;Save it in that wheels file
bcf CONTROL_PORT,SwitchX1       ; release that BCD wheel
delay ;wait short while maybe a NOP here
bsf CONTROL_PORT, SwitchX2      ;Do agian but for the second wheel.
movf BCD_PORT,w
movwf BCDx2
bcd CONTROL_PORT,SwitchX2

rest of program

Colin
--
cdb, bodgy1@optusnet.com.au on 11.09.2003

I have always been a few Dendrites short of an Axon and believe me it
shows.

Light travels faster than sound. That's why some people appear bright
until they speak!

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