If the PIC has a 3.3 Volts input, and the output of the comparator is open collector, use a pull-up resistor from the output of the comparator to the power supply of the PIC.

Hi sir,

I am using propeller Quick start board which work on 3.3V

 

The comparator shouldn't need a buffer after it, but you could give it a shot.

If the voltmeter is swinging from 0V to 3.3V when off/on a line, it's working. It could be a code problem, what does the output measure when the uC is in circuit, reading the output of the comparator (still 0 or 3.3v? code problem)?

Yes the comparator is working and code are also working when i checked it with DIP switch taking place sensors.......
I am watching output in LED.

 

So you've tested the uC with switches and the uC works.

You've tested the Comparators with LEDs and the comparators work.

When you test the comparator with the uC, what are the voltages?

 

Have you added the pull up resistors as Bertus suggested?
If not it will not work.

 

Have you added the pull up resistors as Bertus suggested?

Where at output of comparator??
if yes should i use Schmitt Trigger 7414 Chip??

 

Yes, most of the examples in the datasheet use a 3K resistor to V+ which in your case is 3.3V.
Have you also connected all unused pins of the comparator to ground as recommended in the datasheet?
There should be no reason to use a 7414 chip, if you want you can add some hysteresis to the comparator (details in the datasheet).

 

I received your PM alright.

I don't have anything to add, though. I haven't worked with an IR system controlled by a uC before, so my input is negligible.

 

Yes, most of the examples in the datasheet use a 3K resistor to V+ which in your case is 3.3V.

OK, i will connect pull up resistance....

and

Have you also connected all unused pins of the comparator to ground as recommended in the datasheet?

Yes, i have 3 unused op-amp so, i have to connect all the input and output pin to ground ??

There should be no reason to use a 7414 chip, if you want you can add some hysteresis to the comparator (details in the datasheet).

Yeah, I have added 7414 to the output of comparator the reason is that it give digital output from L339 no other discrete value in between.