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ADS8681: How to write Device address for different device in a daisy-chain

Yang Ding
Prodigy 10 points
Part Number: ADS8681

There is one line in the datasheet that 'To operate multiple devices in a daisy-chain topology, the host controller must program the configuration registers in each device with identical values'  So the question is, how to write different 'device addr' to each device in the daisy-chain? 

  • 0
    TI__Guru**** 180981 points

    Hi Yang,

    Welcome to our e2e forum!  For the ADS8681, there is not really any addressing scheme.  You have to provide 32xN SCLKs and SDI bits to propagate through the chain and then set CONVST/CS.  The process is described in section 7.4.1.3 of the datasheet.  Please also review Figure 7-27 which shows how to manage 3 devices.

  • 0 in reply to Tom Hendrick
    Prodigy 10 points

    But D[15:12] in Output Data word is device address, following conversion result D[31:16]. So when multi devices are used in daisy-chain,  D[15:12] in every device will be the same 0000 ?

  • 0 in reply to Yang Ding
    TI__Guru**** 180981 points

    Hi Yang,

    For the ADS8681, the conversion timing needs to be the same for each device in the chain.  The SPI mode needs to be the same as well.  You can have different voltage levels and set address independently though.  You can have up to 16 different address locations.