ADC setup on 12F1822 ??

[swr999]

Hello!

Has anyone been successful on getting data from the ADC on a 12F1822? While I can get 8-bit conversions, I cannot get 10-bit results. I have puzzled through the related registers from reading the data sheet. Briefly, I find that setting ADCON1.7 stops the ADC from working. Clearing ADCON1.7 lets it work in 8-bit mode.

Reading the errata sheet they show problems with the ADC, and a possible workaround, but I'm not convinced that is my problem since the problem also occurs on a 12F1840.

I can post example code, but initially I just wanted to know if someone on the forum is able to get 10-bit data from a 12F1822, or a 12F1840.

Thanks!

[richard]

works for me

#CONFIG
cfg1 = _FOSC_INTOSC
cfg1&= _WDTE_ON
cfg1&= _PWRTE_OFF
cfg1&= _MCLRE_OFF
cfg1&= _CP_OFF
cfg1&= _CPD_OFF
cfg1&= _BOREN_ON
cfg1&= _CLKOUTEN_OFF
cfg1&= _IESO_ON
cfg1&= _FCMEN_ON
  __CONFIG _CONFIG1, cfg1
cfg2 = _WRT_OFF
cfg2&= _PLLEN_OFF
cfg2&= _STVREN_ON
cfg2&= _BORV_19
cfg2&= _LVP_OFF
  __CONFIG _CONFIG2, cfg2
#ENDCONFIG
DEFINE ADC_BITS 10 ' Set number of bits in result
DEFINE ADC_SAMPLEUS 50 ' Set sampling time in uS
ADCON1=$f0      'rc clk vdd ref   right justify
      osccon=$6A    '4 mhz
      anselA=1       'dig i/o
        ' CMCON0=7        ' compare off 
      trisA=001
      
  adval var word    
  main:
  pause 5  
   ADCIN 0, adval
 lata=0
 
 if adval > 500 then lata.2= 1 'led1
 if adval> 200  then  lata.1=1' led2
  
  goto main

[swr999]

Thanks ^^^
I am doing the same register setups as you show, except that I'm using AN2 (ANSELA=%0100, TRISA=%01100). In addition I have ADCON0.0=1 (enable ADC). I'll try removing this. I'll work on this and post my results.
Thanks again!

[richard]

ADCON0.0=1 serves no purpose the ADCIN code will do that for you

[HenrikOlsson]

This may be obvious but since you didn't post your code I'll say it anyway.
The variable you're putting the result in is declared as a WORD, right?

/Henrik.

[richard]

looks like "Occam's Razor" may have struck again

[swr999]

... The variable you're putting the result in is declared as a WORD, right? /Henrik.

Yes, it's a WORD. But thanks!

[tekart]

Not sure if you figured this out, but 10bit AD need to be read out as RIGHT justified, and 8 bit reads should be LEFT justified. Here's a config that works for 8-bit:
ADCON0.0 = 1 ' AD ON
ANSELA = %00000001 ' select analog vs digital (1=analog)
ADCON1.7 = 1 ' bit7 = 1 = LEFT justified
define adc_bits 8 ' set ADC as 8 bit

[swr999]

Thank you^^^. Yes, I got it sorted out. I think my initial confusion resulted from some interaction between PBP3 DEFINEs for the ADC module and some direct settings I was also doing on some ADC-related registers. Everythings good now. Thanks again!