Pin A2 and A4 spoilt ??

Joshua Lai · Joined: 19 Jul 2004 Posts: 42 Location: Malaysia, PJ

PIC 16F876, Compiler 2.734

I spent whole night, eeprom not working. Then found SDA always low.

I tested port A pin by pin using LED, and found that A2 and A4 always low, cannot output high or float.

Anyone has this problem before? Some pins spoilt and some ok? Crying or Very sad

ckielstra · Joined: 18 Mar 2004 Posts: 3680 Location: The Netherlands

Have you studied the description of port-A pins in the datasheet? If you did you would have discovered these pins are mixed with comparator and ADC functions. Did you disable both the comparator and analog function blocks?

Pin-A4 on most chips has an open collector output, you'll have to adjust your electronics for this.

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

http://www.microchipc.com/sourcecode/images/i2c.gif

Joshua Lai · Joined: 19 Jul 2004 Posts: 42 Location: Malaysia, PJ

I bought a new PIC, running the same program, everything is ok. Why?

That prove my old PIC really spoilt? But other port still working fine.

I bought PIC from fanell, what difference for 1 timer and 3 timers?

Joshua Lai · Joined: 19 Jul 2004 Posts: 42 Location: Malaysia, PJ

I saw the pin diagram, I used 1k pull-up resistors.

Software i2c can use any pin right?

Mark · Joined: 07 Sep 2003 Posts: 2838 Location: Atlanta, GA

Joshua Lai · Joined: 19 Jul 2004 Posts: 42 Location: Malaysia, PJ