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ADV7480 i2c issue

Now i am bringup ADV7480 , I am experiencing a strange problem that when the adv7480 use i2c to read the chip revision register ,

The phenomenon is like this,  the driver can get the first register 0XDF, but can't get the 0XE0, and All subsequent  i2c communications wil fail ,

Measure waveform shown that there is no ack after send slave ID the second time 

normal flow:

Start -->  slave ID  ->  write bit  ->  ACK  -> register address --> restart -->  slave ID --> read bit --> ACK --> data --> ACK

now the problem is no ACK after  the send read bit  , no flow the words marked in red above 

Has this ever happened to anyone ?

Thank you!
Best regards.

Parents Reply
  • Hi,

    So adv7480 's waveform is repeated start ,  not  stop & start like the illustration shown above?

            When seeing the below ADV7480 waveform and its seems like the waveform is same like normal start & stop.

           

     Please refer below expert comment for repeat start ,

        "Reading back is a 2 step process. First you write the index register address you want to read back from and then send another Start bit, slave read address and then read back the data. The second Start is sometimes referred to as a repeat start".

    Thanks,

    Poornima

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