Ra4 not working - Electronic Circuits Projects Diagrams Free

i2c2k · 4th June 2004, 11:06 PM

Hi!

I use the pin RA4 of a PIC16F876A to drive a LED, but the LED never flashes although I didn't forget anything (set TRIS register etc., I tried several chips).
By the way I use RA0/AN0 as an analog input.
Has anybody experienced the problem already and can tell me, how I can solve it?

cya
i2c2k[/code]

**Nigel Goodwin** · 5th June 2004, 12:00 AM

Quote:

Originally Posted by i2c2k

Hi!

I use the pin RA4 of a PIC16F876A to drive a LED, but the LED never flashes although I didn't forget anything (set TRIS register etc., I tried several chips).
By the way I use RA0/AN0 as an analog input.
Has anybody experienced the problem already and can tell me, how I can solve it?
[/code]

RA4 is usually an open-collector output (see the datasheets), so you can only sink current, not source it.

RonH · 7th June 2004, 04:01 AM

Put a pullup resistor on it and you'll be set.

Ron

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

4th June 2004, 11:06 PM	(permalink)
i2c2k	Ra4 not working Hi! I use the pin RA4 of a PIC16F876A to drive a LED, but the LED never flashes although I didn't forget anything (set TRIS register etc., I tried several chips). By the way I use RA0/AN0 as an analog input. Has anybody experienced the problem already and can tell me, how I can solve it? cya i2c2k[/code]

7th June 2004, 04:01 AM	(permalink)
RonH	Put a pullup resistor on it and you'll be set. Ron