A/D converter from 16F876

[Francesc]

Hi all, we would use the A/D converter on pin RA5 and use an external voltage reference on pin RA3 from 16F876.
I write thats lines, but that not work with our 2,5V external reference connected on pin RA3.

What configuration we need ??

Also, when include the line SETUP_ADC_PORTS(A_ANALOG_RA3_REF), the LCD not show nothing.

#include <16f876.h>
#device ADC=10
#USE DELAY(CLOCK=4000000,RESTART_WDT)
#include <LCD2.C>
#USE FAST_IO(A)
#USE FAST_IO(B)

LONG TEMP=0;

VOID MAIN()
{
SETUP_ADC(ADC_CLOCK_DIV_8);
SETUP_ADC_PORTS(A_ANALOG_RA3_REF);//If include that line, LCD not show nothing.
LCD_INIT();

lcd_gotoxy(1,1);
LCD_PUTC("TEST:");

while(1)
{
RESTART_WDT();
set_tris_a(0x28); ////RA3 / RA5 inputs

SET_ADC_CHANNEL(4);
TEMP=READ_ADC();
delay_ms(200);
display(); //Show results

}
}

Please, Help

Merry Christmas for all

[PCM programmer]

My suggestions are:

1. First, make it work with the internal Vref. (ie., VDD).
Don't attempt to use the external Vref until later.
So use this line for the A/D setup:
SETUP_ADC_PORTS(ALL_ANALOG);

2. Get rid of the WatchDog Timer, during initial testing.
Use NOWDT in your #fuses statement.

Once you have it working, then you can put these other
features back in, one at a time.

Questions:

1. You said that if you put in this line, the LCD shows "nothing".
SETUP_ADC_PORTS(A_ANALOG_RA3_REF);

What do you mean by "nothing" ? Do you mean that it shows
a value of 0000 ? Or, do you mean the LCD is blank ?

2. What pins on the PIC are used by the LCD ? Does it use
any pins on Port A ?

[Francesc]

Hi all,
When we include that line SETUP_ADC_PORTS(A_ANALOG_RA3_REF) on my program the LCD display is blank, not show nothing.
Also, not work with external reference,but it work with internal reference.
The pins used for LCD are all PORT B and bits 1,2,3 of PORT A.
That are the code

Please Help me!!!

#include <16f876.h>
#device ADC=10
#USE DELAY(CLOCK=4000000)
#include <LCD2.C>
#USE FAST_IO(A)
#USE FAST_IO(B)
LONG TEMP=0;
VOID MAIN()
{
SETUP_ADC(ADC_CLOCK_DIV_8);
SETUP_ADC_PORTS(A_ANALOG_RA3_REF);//If include that line, LCD not show nothing.
LCD_INIT();
lcd_gotoxy(1,1);
LCD_PUTC("TEST:");
while(1)
{
RESTART_WDT();
set_tris_a(0x28); ////RA3 / RA5 inputs
SET_ADC_CHANNEL(4);
TEMP=READ_ADC();
delay_ms(200);
display(); //Show results
}
}

Merry Christmas

[PCM programmer]