ADAU1452 acknowledges I2C Read Sequence, but no data is send


To read for example the SPDIF Receiver Lock Bit Detection Register I write:  start,0x70, 0xF6, 0x00, start, 0x71. I checked with the scope and all are acknowledged and it looks normal. But then SDA goes low and stays low. I have no problems with the I2C writes.

Anyone an idea what the problem could be?



  • Hello Paul,

    What is going on with the SCL line? After you send the repeated Start and the 0x71 to read the data you have to send clocks to clock out the data. So send 0x00 and 0x00 which will send out clocks and the DSP will drive the SDA line with the data. The 0x00 bytes are just dummy data and the I2C state machine will know it is not actually sending data but reading it. 

    This should take care of it. 

    Dave T