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AD7293 RSx+Mon Background enable register readback

Category: Datasheet/Specs
Product Number: AD7293

Hi, I am writing a driver to communicate with the AD7293 over SPI, with an SCLK of 12MHz. I am using the official EVAL kit for this chip, it is powered by the internal regulator, but the communications are with an off-board ARM MCU.

I encountered a weird issue during write/readback of the RSx+mon Background Enable Register (0x23):

If I write to the MSB of the register, the value read back in a subsequent read appears to be shifted 3 bits to the left.

For example:

- Write 0x800 to register 0x23 (set bit 11);

- Read: 0x4000 from 0x24 (bit 14 is set)

Shouldn't I read the same value that was written? This seems to be the case for other registers (i.e: TsenseX filter enable bits).

Here is the logic analyzer output on the SPI bus:

Top Replies

  • Hi  ,

    thank you for your question.

    The register in question is the VPP,VDD & DACMON background enable register (address – 35 or x23) from the configurations page.

    I would like to point out…

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  • Hi  ,

    thank you for your question.

    The register in question is the VPP,VDD & DACMON background enable register (address – 35 or x23) from the configurations page.

    I would like to point out, that there is known bug in the logic. 

    Which means that while writing to this register the data format is as follows.

     

    Bit

    D15 – D12

    D11 – D8

    D7 – D4

    D3 – D0

    Function

    Reserved

    RS3+MON – RS0+MON

    BI-VOUT3mon – BI-VOUT0mon

    VDD3  – VDD0

     

    However when reading from this register, the data format is:

     

    Bit

    D15

    D14 – D11

    D10 – D8

    D7 – D4

    D3 – D0

    Function

    Reserved

    RS3+MON – RS0+MON

    000

    BI-VOUT3mon – BI-VOUT0mon

    VDD3  – VDD0

     

    This is different to all other registers in the part where the read and write data formats are the same. Data (i.e. the RSx+MON background enable status) in the upper byte is not lost (just shifted).

    Let me know, if you will have any further queries. 

    Regards,

    Arnost

  • Hi  , thank you for the prompt reply! Is there an errata sheet for known issues available?

  • Hi  ,

    unfortunately, we don't have errata sheet for the same, we are considering, where it will be documented for future references. 

    Regards,

    Arnost 

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