16F684 AtoD problem

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- 11th February 2009, 04:23
hell_pk

16F684 AtoD problem

Hi!
I am trying ADC of 16F684 with this simple code.The problem is that the analog input channels are pulled high.I have tried with different registers but all in vain.

PORTC=0
CMCON0=$07
'CMCON0=$00
ANSEL=$00
TRISC=$00
WPUA=$00 'doesnt effect the output
'OSCCON=%1110111

'configure ADC
ADCON1=%01110000
TRISA.0=1
PORTA=$00
ANSEL.0=1

ADCON0=%00000001

Define ADC_BITS 8 ' Set number of bits in result
Define ADC_CLOCK 3 ' Set clock source (3=rc)
Define ADC_SAMPLEUS 50 ' Set sampling time in uS

adval var word ' Create adval to store result
Res Var word

Define LCD_DREG PORTC
Define LCD_DBIT 0
Define LCD_RSREG PORTC
Define LCD_RSBIT 4
Define LCD_EREG PORTC
Define LCD_EBIT 5
DEFINE LCD_BITS 4

Lcdout $fe,1
loop:
ADCIN 0, adval

Res = 2*adval

Lcdout $fe, $80
Lcdout "T:", DEC2 Res,"C" 'text for the line 1

Pause 300
goto loop
- 11th February 2009, 20:43
mackrackit

I think this is all you need to set for this PIC. I have not used one for awhile...

Code:

Define ADC_BITS 8 ' Set number of bits in result Define ADC_CLOCK 3 ' Set clock source (3=rc) Define ADC_SAMPLEUS 50 ' Set sampling time in uS TRISA.0=1 ANSEL.0=1
- 13th February 2009, 05:20
hell_pk

I have Set these bits in my program but still the port pins are pulled up.
- 13th February 2009, 05:44
mackrackit

What is your analog source?
Can you post a schematic and your current code?
- 16th February 2009, 04:25
hell_pk

I have already posted the code.Analog source is simply a pot for 1-5V range.
- 16th February 2009, 07:19
Archangel

Hello hell_pk,
Try adding OPTION_REG.7 = 0 to the upper area of you code.
- 17th February 2009, 09:49
hell_pk

Still not working

I have added the line but still no result.very strange.
i have configured all registers ANSEL,WUPA etc in program.
What am I missing!!!
- 17th February 2009, 14:43
Adrian

You have all the inputs as digital inputs ANSEL = $00 Shouldn't A0 be an analogue input?

Adrian
- 17th February 2009, 16:07
mister_e

Out of curiosity, which compiler version are you using?
- 17th February 2009, 22:41
mackrackit

Quote:

Originally Posted by hell_pk

I have already posted the code.Analog source is simply a pot for 1-5V range.

Post #1 shows a lot of things but it is difficult to tell where the code is or the things you hace tried. Post your current code in tags like Mr.E suggest.

You have ANSEL set two different ways in post #1. Is that the way you have it in your code?

Did you read and try post #2? Some of the registers PBP handles for you when using ADCIN.
- 18th February 2009, 09:17
hell_pk

Compiler ver 2.50

Code:

Define ADC_BITS 8 ' Set number of bits in result Define ADC_CLOCK 3 ' Set clock source (3=rc) Define ADC_SAMPLEUS 50 ' Set sampling time in uS OPTION_REG.7 = 0 PORTC=0 CMCON0=$07 'CMCON0=$00 ANSEL=$01 TRISA=$01 TRISC=$00 WPUA=$00 'OSCCON=%1110111 'configure ADC ADCON1=%01110000 PORTA=$00 ADCON0=%00000001 adval var word ' Create adval to store result Res Var word ' Define LCD registers and bits Define LCD_DREG PORTC Define LCD_DBIT 0 Define LCD_RSREG PORTC Define LCD_RSBIT 4 Define LCD_EREG PORTC Define LCD_EBIT 5 DEFINE LCD_BITS 4 Lcdout $fe,1 loop: ADCIN 0, adval Res = 2*adval Pause 300 Lcdout $fe, $80 Lcdout "T:", DEC2 Res,"C" 'text for the line 1 Lcdout $fe, $80+8 ,#Res Lcdout $fe, $C0 'set cursor at the beginning of line 2 Lcdout "V: ", #adval 'formatted text for line 2 Pause 300 goto loop
- 18th February 2009, 15:08
mackrackit

Try commenting out these lines

Code:

ADCON1=%01110000 PORTA=$00 ADCON0=%00000001

I think they may be causing a conflict.
- 20th February 2009, 04:34
hell_pk

No luck

Still no luck.The Analog channel pulls up before ADCIN command therefore something must be wrong with register configs.
very frustrating!
- 20th February 2009, 06:59
mackrackit

Sorry for all the confusion, here is some tested code.
I have it running right now.

Code:

<html> <head></head> <body><pre><code>'16F684 ADCIN TEST @ __config _INTRC_OSC_NOCLKOUT & _WDT_ON & _MCLRE_OFF & _CP_OFF DEFINE ADC_BITS 8 ' Set number of bits in result DEFINE ADC_CLOCK 3 ' Set clock source (3=rc) DEFINE ADC_SAMPLEUS 50 ' Set sampling time in uS TRISA=%00000001 ANSEL=%00000001 ADX VAR BYTE START: HIGH PORTC.4 PAUSE 250 LOW PORTC.4 ADCIN 0, ADX PAUSE 250 SEROUT2 PORTC.5, 17197, [DEC ADX, $d, $a] GOTO START </code></pre></body> </html>