I2C8 not communicating

Adam Mixter

Other Parts Discussed in Thread: EK-TM4C1294XL

Hello All,

I'm working with I2C7 and I2C8 with the same group of addressed chips. I2C7 is configured the same way as I2C8. I2C7 is receiving and sending data as expected. When I try a the same code with I2C8_BASE replacing I2C7_BASE, there are no addressed recieved from the I2C8 address. Is there something special about I2C8?

over 9 years ago

0 Amit Ashara over 9 years ago

TI__Guru**** 244400 points

Hello Adam

Which device is it? Also have you configured the IO corresponding to I2C8 for I2C mode?

Regards
Amit

0 Adam Mixter over 9 years ago in reply to Amit Ashara

Intellectual 320 points

Hi Amit,

I'm using the TM4C129XL EK. I believe I have configured I2C8 to operate on pins PA2 and PA3.

0 Amit Ashara over 9 years ago in reply to Adam Mixter

TI__Guru**** 244400 points

Hello Adam

PA2 and PA3 are connected on booster pack 2 header to PQ3 and PQ2 via a 0 ohm resistor. I hope these two pins PQ2 and PA3 are not being used and converted to input only. Also is there a Pull up resistor on PA2 and PA3?

Regards
Amit

0 Adam Mixter over 9 years ago in reply to Amit Ashara

Intellectual 320 points

Hey Amit,

Thanks for the reply. I don't believe there is a pull up resistor. What would happen if PQ2 and PA3 are being used not as input only?

Thanks!
Adam

0 Amit Ashara over 9 years ago in reply to Adam Mixter

TI__Guru**** 244400 points

Hello Adam

Without a Pull Up: www.ti.com/.../spma073.pdf

If PQ2 and PQ3 are being used as output then there would be a bus contention. If you have to use PQ2 and PQ3 then remove the 0Ohm resistor.

Regards
Amit

0 Adam Mixter over 9 years ago in reply to Amit Ashara

Intellectual 320 points

Hi Amit,

It looks like returning PQ2 and PQ3 to input only solved the problem. Do you happen to know which 0 Ohm resistor connects PQ2 to PA3 and PQ3 to PA2? It would make my life a bit easier removing the resistor. Would I see any further complications from it's removal?

Regards,
Adam

0 Amit Ashara over 9 years ago in reply to Adam Mixter

TI__Guru**** 244400 points

Hello Adam

You can check that in the schematics for EK-TM4C1294XL as part of the User Guide for the resistors.

The schematics also mention why this 0Ohm has been put.

Regards
Amit

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I2C8 not communicating