PIC analog input and digital output on the same PORT

[shsn]

I am having difficulties having both analog input and digital output on the same port on PIC16F716.
On PIC16F716, PORTA (5 pins) can be used for both analog inputs or digital inputs. I would like to have;
RA0/AN0 as analog input and RA2/AN2 as digital output which will be connected to an LED.

void main() {
     TRISA = 0x02;                    // Initialise PORTA RA2 as INPUT, rest as OUTPUT
     TRISB = 0;                         // Initialise PORTB as OUTPUT
     PORTB = 0;                        // Set PORTB as OUTPUT
     do {
        adc_val = ADC_read(1);
        volts_m = (long)adc_val*5000/256;
        driveLED (volts_m);
     }
     while(1);
}

Although RA1/AN1 is correctly set as analog input (because it works according to driveLED function) but the LED connected to the RA2/AN2 is not doing anything.
Can anyone point me to the right direction?

Thank you.

 

[hemnath]

I'm not sure how can you send the long 'volts_m' value to driveLED function. Just try simple program to glow the led on pin RA2.
Please specify what compiler are you using?

if using ccs c compiler, use this

use the line

output_high(PIN_A2);

instead of

driveLED (volts_m);

 

[jjeevan007]

can u post the full code

 

[Tahmid]

You haven't shown the driveLED function. So, we don't know what's happening there.

As for RA2/AN2, you need to make it digital by setting ADCON1 appropriately.

Add this line to your code:

ADCON1 = 4;

This will make AN2 digital and AN0, AN1 and AN3 analog.

Here's how it should be:

void main() {
     TRISA = 0x02;                    // Initialise PORTA RA2 as INPUT, rest as OUTPUT
     [B]ADCON1 = 0x04;[/B]                 // AN2 Digital
     TRISB = 0;                         // Initialise PORTB as OUTPUT
     PORTB = 0;                        // Set PORTB as OUTPUT
     do {
        adc_val = ADC_read(1);
        volts_m = (long)adc_val*5000/256;
        driveLED (volts_m);
     }
     while(1);
}

ADCON1 register (from the datasheet):

Hope this helps.
Tahmid.