ÿþ' Copyright Brad Campbell, 2007 - All rights reserved



' Nasty way of reading a Pot using junkbox parts on one port pin



'       1k  4.7kð

' pin %%½ð¾ð3%%½ð¾ð%»ð¼ð 10k

'      103­ð®ð    ð



' Pretty basic. All junkbox parts 

' Just continuously updates the ADC value. I get 255 as a minimum and 3109 as a maximum.

' It's not particularly linear, but it's close enough for my immediate needs.



' A bigger cap and more careful value selection would help.



' A bottle of Stones does not an electrical engineer make!



' Adjust reload to change the number of samples taken and change the "shr" to crop the

' innefective bits.



' Nothing new here.. shoulders of giants 'n all that. Got the idea years ago looking at some

' Scott Dattalo PIC code.



VAR

  long conversion

  long pin





PUB start(inval) : ok

  pin := inval

  OK := cognew(@ADC,@conversion)



  

PUB getval : val

  val := conversion



DAT

ADC           org

              mov       da, par

              add       da, #4

              rdlong    db, da

              mov       da, #1

              shl       da, db

              mov       inpin, da



loop          mov       icnt, #0

              mov       da, reload

              andn      dira, inpin   

cloop         test      inpin, ina  wz

        IF_NZ jmp       #high

        IF_Z  jmp       #low

here          djnz      da, #cloop

              and       da, inpin

              shr       icnt, #2

              wrlong    icnt, par

              jmp       #loop



        

high          nop

              andn outa, inpin

              or        dira, inpin

              nop

              nop

              andn      dira, inpin

              nop

              jmp       #here

        

low           or                      outa, inpin

              or        dira, inpin

              nop

              nop

              andn      dira, inpin

              add       icnt, #1

              jmp       #here







zero    long  0

allones long  $FFFFFFFF

reload  long  $4000                             ' Number of samples

icnt    res   1

delay   res   1

inpin   res   1

da      res   1

db      res   1