18F4431 - RC6 not reading the input - Electronic Circuits Projects Diagrams Free

atferrari · 25th May 2009, 02:07 AM

18F4431 - DIP chip

I have made:

TRISC = '11111111' (all pins IN) and applied 10K pullup resistors to RC<7:0>.

The sole modules involving RC6 (AFAIK), SSPCON and RCSTA, = '00000000'.

My problem:

Reading PORTC is correct for all pins but RC6 which always reads '0'.

I measured the voltage at the pin, getting 0.28 V.

Also checked Silicon revision 3 to no avail.

Tested with two different chips.

What I am overlooking here?

Pommie · 25th May 2009, 03:06 AM

Sounds like you have a short on your board. With a 10k pullup and the pin set to input you should have 5V. Can you remove the chip and measure the voltage to see if it is a short?

Mike.

atferrari · 25th May 2009, 10:10 AM

Checked already, Mike. No short.

All peripherals except Power PWM control are disabled so I do not know what else to do. Wherever that pin is alluded to in the datasheet, it is shown involved with the EUSART only.

Any further idea will be welcome.

Gracias.

Pommie · 25th May 2009, 10:17 AM

Can you chop your code down to a bare minimum that still shows the same behavior and post it here?

Mike.

atferrari · 25th May 2009, 12:41 PM

Hola Mike again,

It was not a short but an open circuit!. The pin was floating, not seeing the 5V. I started to suspect that when found that for the first two seconds it was reading a 1 and then a 0.

Measured the voltage directly on the pin, with the micro in RESET and found that.

I just regret the so many hours checking software.

Gracias for replying.

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25th May 2009, 02:07 AM	#1
atferrari	18F4431 - RC6 not reading the input 18F4431 - DIP chip I have made: TRISC = '11111111' (all pins IN) and applied 10K pullup resistors to RC<7:0>. The sole modules involving RC6 (AFAIK), SSPCON and RCSTA, = '00000000'. My problem: Reading PORTC is correct for all pins but RC6 which always reads '0'. I measured the voltage at the pin, getting 0.28 V. Also checked Silicon revision 3 to no avail. Tested with two different chips. What I am overlooking here? __________________ Agustín Tomás In theory, there is no difference between theory and practice. In practice, however, there is.

25th May 2009, 03:06 AM	#2
Pommie	Sounds like you have a short on your board. With a 10k pullup and the pin set to input you should have 5V. Can you remove the chip and measure the voltage to see if it is a short? Mike.

25th May 2009, 10:10 AM	#3
atferrari	Checked already, Mike. No short. All peripherals except Power PWM control are disabled so I do not know what else to do. Wherever that pin is alluded to in the datasheet, it is shown involved with the EUSART only. Any further idea will be welcome. Gracias. __________________ Agustín Tomás In theory, there is no difference between theory and practice. In practice, however, there is. Last edited by atferrari; 25th May 2009 at 10:10 AM.

25th May 2009, 10:17 AM	#4
Pommie	Can you chop your code down to a bare minimum that still shows the same behavior and post it here? Mike.

25th May 2009, 12:41 PM	#5
atferrari	Problem solved Hola Mike again, It was not a short but an open circuit!. The pin was floating, not seeing the 5V. I started to suspect that when found that for the first two seconds it was reading a 1 and then a 0. Measured the voltage directly on the pin, with the micro in RESET and found that. I just regret the so many hours checking software. Gracias for replying. __________________ Agustín Tomás In theory, there is no difference between theory and practice. In practice, however, there is.