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Original question:

I2C trouble on TMS320F28027 piccolo

TMS320F28027: I2C trouble on TMS320F28027 piccolo

Nadeem Zaki
Prodigy 150 points

Part Number: TMS320F28027

I have a customer looking for confirmation on the I@C hardware issue below:

We had some issues with the I2C that seems to be resolved. Some timing issues, STOP bit not being set correctly and adding the correct pull up resistors on the I2C bus seems to fix the issue. We have not had any issues since we added these fixes. The code is based on the EEPROM example in Control suite. While debugging this issue I found a thread in the forum that states an issue with the I2C was resolved by using different pins on the micro. This concerns me because we are using the same pin 28 in our application. Can you verify that there are no I2C hardware issues with the piccolo parts using pin 28?

  • 0
    Guru 30330 points
    Nadeem,

    Please point to the thread the customer has referenced.
    Is the customer referring to GPIO28?
    What hardware is being used? is it a TI EVM?

    There are no issues related to GPIO28 and I2C on this device. You would typically find this information in the Errata document for the device: www.ti.com/.../sprz292

    Thanks,
    Mark
  • 0 in reply to Mark Labbato
    Mastermind 7160 points
    Nadeem,

    What is the I2C clock rate you're using?

    If you could capture a waveform of clk and data line's signal, that would be helpful for analyse this.

    The higher clock rate you're using, the sharper rising&falling edge is needed for data and clock signal. The pull up resistor's value will affect the slope rate of falling and rising edge.
  • 0 in reply to Mark Labbato
    TI__Prodigy 150 points
    Please see the original thread, I asked this question as related question to this post: e2e.ti.com/.../69739
  • 0 in reply to Nadeem Zaki
    Guru 30330 points
    Nadeem,

    Is the customer using custom hardware or a TI kit?

    The kit used in the original post utilized GPIO28 and GPIO29 as UART channels. It is probable that the other components connected to GPIO28 caused the I2C to operate poorly as they likely impacted the rise/fall times of the I2C signals. switching to a different IO not connected to anything else on the board except for the EEPROM likely resolved the issue.

    If the customer is having issues or concerns and switching to a different pin resolves the issues, check the schematic for similar things.

    -Mark
  • 0 in reply to Mark Labbato
    TI__Prodigy 150 points
    Mark,

    The customer is using custom HW and the pins are not shared with any other components. I'm taking this offline to share schematic snippets.

    Best,
    Nadeem