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TM4C1230E6PM: TM4C1230E6PM I2C problem!

Siyavash Asadi
Intellectual 665 points
Part Number: TM4C1230E6PM
Other Parts Discussed in Thread: INA219,

Hello,

In my design I used TM4C1230E6PM as controller and INA219 as current shunt amplifier. we faced a weird problem in I2C interface. Also I used 4.7K Ohms pull up resistor for SDA and SCL lines but the problem is we have a drop in SDA line instead of having 0-3.3V pulse it is around between 0-1.8V even I used 1K Ohms resistor but it changed to 0.3V-2.9V. This problem sometimes solved without making any change in design. Also it seems it is occurred randomly but the problem doesn't solve even by changing INA219 or TM4C1230E6PM. If we will not find the problem source we have to change parts for mass production.

Any help would be greatly appreciated.

Sincerely yours,

Siyavash

  • 0
    TI__Guru*** 131470 points

    Hello Siyavash,

    Have you read through this app note to understand how to calculate the pull-up values on your I2C bus? http://www.ti.com/lit/an/slva689/slva689.pdf

    It sounds like with 1kOhm that you are seeing a worst case of 2.9V? Or has the voltage been lower with 1kOhm? 2.9V should be plenty enough to be read as a logic high by the I2C peripheral, so if that is consistently the case then I think you need to assess the pull-up resistor values closely.