TM4C1290NCPDT: Errata about GPIO#09, that's PB0 and PB1

Jordan Zhou

Genius 10470 points

Part Number: TM4C1290NCPDT

Hi,

Customer wants to use PB0 and PB1 as I2C (400k, 4.7k to 3.3V).

Is it possible? If yes, how to make sure there's no current draw?

Thanks a lot.

Br, Jordan

over 5 years ago

0 Bob Crosby over 5 years ago

TI__Guru 72500 points

Yes, they can be used. In order to limit damage from ESD events, a 100Ω resistor should be placed in series between the I2C bus and the pins (PB0/PB1) on the microcontroller. This will affect the low level generated on the I2C bus, but with a 4.7KΩ pullup resistor the low level seen on the bus will be only 70mV above ground. Just do the calculation for your I2C bus and check the Vil level requirements for the slave devices on your bus.

0 Jordan Zhou over 5 years ago in reply to Bob Crosby

TI__Genius 10470 points

Bob,

Is this OK?

How do get 70mV with 4.7K?

0 Bob Crosby over 5 years ago in reply to Jordan Zhou

TI__Guru 72500 points

Yes, that is the correct circuit. The voltage for a low will be 3.3v x (100 Ohms / (100 Ohms + 4,700 Ohms)) = 0.069V

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TM4C1290NCPDT: Errata about GPIO#09, that's PB0 and PB1