Please help with reading Modulated IR OUTPUT

[Picman99]

Hi I'm using a 16F84A (when I'm not using a 16F628A) but thats beside the point. I am building a Hexapod and am trying to control direction using modulated (38khz) ir signal. Transmitter -->works FINE. Receiver should be high output shifting to low in IR presence. I was going to read its output with a PIC (PortB.4) and if high go to one routing if low goto another. The problem is that the low signal is around 1.8V so the pic is not registering a low and therefore not switching. Do I have to use the PORTA as comparator function??????????? Please help. By the way I am programming in high level basic and am not too up on assembly code!!!!!!!!!!!!!!!!!! Find Attached the IR Test Code.

 

[Nigel Goodwin]

Hi I'm using a 16F84A (when I'm not using a 16F628A) but thats beside the point. I am building a Hexapod and am trying to control direction using modulated (38khz) ir signal. Transmitter -->works FINE. Receiver should be high output shifting to low in IR presence. I was going to read its output with a PIC (PortB.4) and if high go to one routing if low goto another. The problem is that the low signal is around 1.8V so the pic is not registering a low and therefore not switching. Do I have to use the PORTA as comparator function??????????? Please help. By the way I am programming in high level basic and am not too up on assembly code!!!!!!!!!!!!!!!!!! Find Attached the IR Test Code.

Try checking the IR circuit in the hardware section of my PIC tutorials, it's ABSOLUTELY VITAL! that you include the decoupling components shown, this could be your problem - I also like to use a pull-up resistor on the output, again this is shown on my circuit.

I presume you're running the transmitter LED at very low power?, and shielding it from the receiver?.

 

[Picman99]

Ir Receiver

Thanks Nigel. Sorry I took so long to get back. I had decoupled but only with 1000 pics. Replaced with 47 micros and all seems well. I'm building up hard wired boards now. Fingers Crossed. Thanks again

 

[Nigel Goodwin]

Re: Ir Receiver

Thanks Nigel. Sorry I took so long to get back. I had decoupled but only with 1000 pics. Replaced with 47 micros and all seems well. I'm building up hard wired boards now. Fingers Crossed. Thanks again

Don't forget the 47 ohm series resistors as well!.