Help with PIC18 analog comparator

[cbarberis]

Hi

Although I have been using Pics for a while, I am doing my first application using the built in comparators and I am somewhat confused as to how to use the CCS directives, specifically how the comparator interrupt isr works.

I need to use comparator one to sense a particular voltage level into RA0 the reference for this comparator is common to the second one using the internal reference which I selected to be 2.5V. I want comparator one to trigger whenever RA0 exceeds the reference and generate a interrupt. For comparator two I need to sense a voltage at RA1 and whenever this voltage drops below the reference, I want this comparator to generate an interrupt. I noticed that CCS has a ISR routine for the comparator module, but it seems that it only applies to comparator one. Reading the PIC18F2420 data sheet it indicates that either one of the comparators changing will generate an interrupt.
So my question is: 1. To know which of the comparators has triggered one has to test the status of bits C1OUT and C2OUT within the ISR routine and then upon leaving the ISR the CCS handler will take care of resetting things??

2. I can not seem to find the CCS configuration to set up the comparators so one detects above the ref and the other below the ref.

3. Does any one know if there is any interaction between the comparator module and the HLVD (High-Low voltage detect module) Can both be used at the same time? I see no reference to that in the data sheet.


This is how I have setup the analog channels might be using the adc on AN3:
setup_adc_ports(AN0_TO_AN3|VSS_VDD);
setup_adc(ADC_CLOCK_INTERNAL|ADC_TAD_MUL_0);

And this is how I have setup the analog comparators and vref:
setup_comparator(A0_VR_A1_VR);
setup_vref(VREF_HIGH|12);

Any help on the above is greatly appreciated.......... Thank you

[PCM programmer]

In the 18F2420 data sheet, in Figure 20-1, shows all the comparator
configurations. It looks like setup "100" is the one you want.