I2C Communication is failed after a month

I am using ZL38051 Audio processor with RA6M2 microcontroller.

Using SCI I2C to control Zl38051. It was working fine before a month but now  i2c failed  ( I don't know why) .When I write something and try to read no I2C interrupt triggered.


R_SCI_I2C_Write return FSP_SUCCESS

R_SCI_I2C_Read return FSP_SUCCESS 

with or without Free RTOS. (FSP v3.6)


  • Hello Progmem,

    1. Do you have only one board to test? If not, is it the same issue at all boards?

    2. Is it any possibility to make sure that the audio processor chip hasn't been broken? If for some reason it holds one of the lines low, the reading will not happen.

    3. If you have an oscilloscope or a logic analyzer, it would be very good to see what's going on at the I2C lines.

    4. Maybe you have made some changes in the code recently that lead to this wrong operation?

    Kind regards,


    If this response, or one provided by another user, answers your question, please verify the answer. Thank you!
    RenesasRulz Forum Moderator

  • Could we get a little more information:
    In simple IIC mode, the open-drain setting for the communication ports should be made on the port side.
    Do you have pull up resistors (on I2C output pins)as required by I2C standard suitable for rise and fall times against the set I2C frequency?
    Also, since you are using SCI for I2C; SCI is configurable as a Simple IIC only (master-only). And the max transfer rate is 384kbps and Only 7-bit slave address is supported.

    Have you monitored the I2C pin outputs:
    When you do a R_SCI_I2C_Write, do you see the I2C waveform starting with the START, slave address, ACK....etc and the STOP bits at the set I2C frequency (I assume 384kbps)?

    Thank you