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ADV7181C I2C access

We are at the early stages of debugging a video board using the ADV7181C video serialiser.

When I write (R/W = W) a command through the I2C interface to the chip using address 0x21 (or 0x42 as stated in the manual) I receive an ack per each byte sent. This is good

But when I try to receive data (R/W = R) from this same address the address byte is not acknowledged and of course no communication takes place.

The manual creates some confusion in my mind about the I2C address, should it be shifted, should it not! Although I've tried all possible addresses and the only that is acknowledged when writing is in fact 0x21.

Could anyone give me some ideas about this?

thanks

  Eduardo

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  • FormerMember
    0 FormerMember

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.

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  • FormerMember
    0 FormerMember

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.

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