A desperate PIC user looking for quick help,
My project using PIC16C77 which does everything except driving PIN_A4.
I tried everything even wrote a plain-vanilla code which does nothing else
just driving PIN_A4 and PIN_A5. PIN_A5 works fine but PIN_A4 does not.
I removed the pin from the socket make sure nothing short or any strange
I carefully checked PIN_A4 and the PIN not initialized as T0CKI.
I simulated on MPLAB works well.
I tried both way with TRIS and without.
I am running the PIC at 4MHz, no watchdog timer, no brownout protection, no
Sorry about my stupidity of course PIN_A4 open drain type
and will not work without pull-up resistor.
Looks like to write a letter helps solving mysteries.
RA4 is open drain output you need pull up resister .
Remember this. almost every PIC has open drain on RA4
if you do not want to use pull up resister make RA4 input
then one of your input make output.
Peter Schultz wrote:
Dr. Imre Bartfai
note, that especially the RA4 (in contrary to all other pins) has an
open-collector driver in the PIC, i. e. it is not capable to SOURCE any
current, only sink can.
On Mon, 29 Jun 1998, Peter Schultz wrote:
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