RA.4 Open collector,...

[tazntex]

I have it working with this code:
DEFINE OSC 4
CMCON=%00000111
VRCON = 0
PAUSEus 10
TRISA = %00000110
TRISB = %11110001
PORTA = %00000000
PORTB = %00000000
OPTION_REG.7 = 0
OPTION_REG.6 = 0
rf var porta.4

main:
low rf
pause 500
high rf
pause 500
goto main

Does it have something to do with me using the comparator on ra.1,ra.2? I have been reading the datasheet and it mentions ra.3,ra.4 in section5.1 PORTA and TRISA Registers, I am already using ra.3 with no problems as an output.

[gadelhas]

Hi;

Try this;

1 - Connect the RA4 Pin with the resistor to VCC;
2 - Connect the anode of the led beetwen the resistor and the RA4 Pin;
3 - Connect the Cathode of the led to GND

And post the result

[rsocor01]

The reason that you need a resistor between RA4 and Vcc, like Gadelhas mentioned above, is because RA4 in that chip is an Open Drain (OD) type.



Robert

[tazntex]

Sorry about the delay getting back to ya'll. Ok, your instructions said:
1 - Connect the RA4 Pin with the resistor to VCC;
2 - Connect the anode of the led beetwen the resistor and the RA4 Pin;
3 - Connect the Cathode of the led to GND

with or without step 2 the led is illuminated.

Thanks for the fast response.

[Bruce]

RA4 is C2OUT with the 1st configuration you had so you couldn't use it for a digital output. With comparators disabled you can.

This should work fine to drive your LED on RA4 ---|<|---/\/\/--VCC.

[tazntex]

Bruce, thats how I have it, However, I have brown out reset enable on my winpic programmer software, tried it with PICkit3, PICkit2 and it won't work, BUT if I turn off the brown out reset manually in WINPIC programmer, It WORKS
But I am going from 9v input to my breadboard, then LP2950ACZ-3.3 (3.3V) regulator to my processor, sure would be nice to use the low voltage (brown out).

Any ideas?

Thanks

[Bruce]

If turning an LED on is tripping reset you might want a larger cap on the reg output or larger series resistor for the LED. BOR definitely shouldn't trip unless you're dropping a lot of power.

Edit: Check the datasheet for Vbor. You may already be running marginal.