Basic comparator configuration

[apwallace]

Hello,
I am trying to get the most basic comparator program working. I do not require interrupts for this. From reading things, all I should have to do is:

setup_comparator(A0_A2_A1_A2);

And then, I should just be able to use C1OUT and C2OUT as variables in my program. They should toggle to 1 or 0 as appropriate.

However, I'm never getting either to toggle regardless of the different analog voltages I apply on the pins.

I've pasted the relevant section of my code below.

I definitely appreciate your help.
Thanks,
Andy Wallace


Processor 16F87
MPLAB ICD2




#include <16F87.h>
#fuses NOWDT, NOPUT, MCLR, NOBROWNOUT, NOLVP, NOCPD, NOWRT, CCPB3, NOPROTECT, INTRC, NODEBUG
#use delay(clock=4000000)
#device ICD=TRUE

void backlight(int1 blstatus)
{
//backlight status 1=ON, 0=OFF
//ON-->output 0 Volts
//OFF-->output 5 Volts
if (blstatus==1){
output_low (PIN_A6); //A3 and A6 tied together to drive Backlight
output_low (PIN_A3);
}
else {
output_high (PIN_A6);
output_high (PIN_A3);
}
}


void main() {

int lcdadd,cond, seg;
int percentfill, segout, segfill, condition, delay,cnt,pfill_out,delaycnt;
char c;

int1 blstatus; //backlight =1 for ON, 0 for OFF
blstatus=0; //initialization only

setup_oscillator(OSC_INTRC|OSC_4MHZ);
set_tris_a (0b00000111); //Configures all as output
set_tris_b (0b00000001);
port_b_pullups(TRUE);

setup_comparator(A0_A2_A1_A2);
//setup_comparator(NC_NC_A1_A2);

while(1)
{
backlight(1);
delay_ms(1000);
backlight(0);
delay_ms(1000);

while(C1OUT){}

backlight(1);
delay_ms(500);
backlight(0);
delay_ms(500);
backlight(1);
delay_ms(500);
backlight(0);
delay_ms(500);
backlight(1);
delay_ms(500);

}
}

[apwallace]

Upon looking at the LST file. It appears to be simply pointing at the wrong register.

I did the manual configuration below, without using the setup_comparator() function. It now works properly.

Andy


#include <16F87.h>
#device ICD=TRUE

#fuses NOWDT, NOPUT, MCLR, NOBROWNOUT, NOLVP, NOCPD, NOWRT, CCPB3, NOPROTECT, INTRC, NODEBUG
#use delay(clock=4000000)


#byte sfr_cmcon =0x9c
#byte sfr_pie2=0x8d //peripheral interupt enable register
#bit myCMIE =0x8d.6 //comparator enable enable

#bit myC1OUT = 0x9c.6
#bit myC2OUT = 0x9c.7

void backlight(int1 blstatus)
{
//backlight status 1=ON, 0=OFF
//ON-->output 0 Volts
//OFF-->output 5 Volts
if (blstatus==1){
output_low (PIN_A6); //A3 and A6 tied together to drive Backlight
output_low (PIN_A3);
}
else {
output_high (PIN_A6);
output_high (PIN_A3);
}
}


void main() {

int lcdadd,cond, seg;
int percentfill, segout, segfill, condition, delay,cnt,pfill_out,delaycnt;
char c;

int1 blstatus; //backlight =1 for ON, 0 for OFF

myCMIE=0;
sfr_cmcon=03;

blstatus=0; //initialization only
setup_oscillator(OSC_INTRC|OSC_4MHZ);
set_tris_a (0b00000111);
set_tris_b (0b00000001);
port_b_pullups(TRUE);

//setup_comparator(A0_A2_A1_A2);
//setup_comparator(NC_NC_A1_A2);


while(1)
{
backlight(1);
delay_ms(1000);
backlight(0);
delay_ms(1000);

while(myC1OUT){}

backlight(1);
delay_ms(500);
backlight(0);
delay_ms(500);
backlight(1);
delay_ms(500);
backlight(0);
delay_ms(500);
backlight(1);
delay_ms(500);

}
}