PIC16F876A - PortC 3, 4, 5 are not outputing

[Raslan]

Good Morning
MCU: PIC16F876A
HW : EasyPic4

Problem: PortC pin 3 ,4 and 5 can not output anything

Test Code:

Code: Select all

main:
     TrisB = 0x00   ' Set port B to digital input
     TrisC = 0xFF   ' Set Port C to digital output
     While True
                   PortB = PortC  ' Copy the status of portC to portB
     Wend

What is the problem?
I have tested the code over three MCUs... are my MCUs having problem?
in the datasheet never found any relevant information regarding this issue

Thank you for your kind help
Best Regards
Razi

[paulfjujo]

hello



do you want to display the reading of port C ?
what about comparator ?

[Raslan]

hello

do you want to display the reading of port C ?
what about comparator ?

I would like to make it simple like this
if I write this code

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PortC = 0xFF

then it is expected that all port C have digital High (+5V). However, the actual result is:
PortC.0 is High
PortC.1 is High
PortC.2 is High
PortC.3 is no change (LOW)
PortC.4 is no change (LOW)
PortC.5 is no change (LOW)
PortC.6 is High
PortC.7 is High

[Sparky1039]

Problem: PortC pin 3 ,4 and 5 can not output anything

This is because you configured all pins of PortC as inputs.

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TrisC = 0xFF   ' Set Port C to digital output

[Raslan]

Problem: PortC pin 3 ,4 and 5 can not output anything

This is because you configured all pins of PortC as inputs.

Code: Select all

TrisC = 0xFF   ' Set Port C to digital output

I wish it was easy as the above... but actually I did a mistake when I was writing my question... but in reality I did

Code: Select all

TrisC = 0x00

so the problem is not solved yet...

[Sparky1039]

Forum members can't provide you good advice if you don't supply correct or complete information. Proof read your post before submitting next time.

Last thing to check is, make sure the MSSP module (I2C/SPI) is disabled if you are not planning to use it.
SSPCON1.SSPEN = 0; // <bit 5> disable MSSP module

Outside of the TRISC register configured as outputs and the MSSP module disabled, there is nothing else to prevent the ports from working correctly as an output (except a damaged part). Have you tried something simple like blinking an LED on these ports and see if that works?