10F206 comparator with int voltage reference not working??

[spero]

Has anyone successfully used the 10F206 comparator using the internal voltage reference (0.6V) as the negative reference for the comparator? I cannot get the comparator to change the CMPOUT bit to 0.

I'm trying to implement a cheap and nasty battery low detect as follows;

When the battery falls to its cutoff level, a resistive potential divider will present 0.6V at the CIN+ pin (GP0). The negative reference of the comparator is setup to use the internal voltage reference.

My code to setup and read the comparator output bit is as follows;

-----------------------------------------
#bit CMPOUT = 0x07.7
#bit CMPON = 0x07.3

#asm // Setup and enable comparator - load CMCON0 reg
movlw 0xFB
movwf 0x07
#endasm

delay_us(1); // Let comparator stabilise before reading
if(CMPOUT == 0)
bat_low = TRUE; // If Vin+ < Vin- then set flag

output_high(PIN_B2);

CMPON = 0; // Disable comparator before going to sleep
set_tris_b(0x09); // Set TRIS again after comparator has fiddled with them...
sleep();
--------------------------------------------------

Cheers,
Spero.

[mcafzap]

[Guest]

Thanks...I found my problem; I had a == instead of a = and my flag was never being set, so the comaparator was working all the time!