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ADS131E08: Switching between direct configuration and daisy chain data reading

Martin Seeger
Expert 5411 points

Part Number: ADS131E08

Dear Team,

our customer intends to use 7 ADS131E08.

Since the configuration is different channel by channel, they plan to configure each ADS131 individually (by /CS).

However they like the read out via daisy chain.

Now the question:
> Is it possible to first configure the device in the standard configuration and by external logic switch the architecture to Daisy Chain?

Thanks and best regards
Martin

  • 0
    TI__Guru 69076 points
    Hello Martin,

    Thanks for posting their question.

    I believe what the customer is describing should be possible. Essentially, you would configure all devices in a daisy-chain on the board, with the exception that each /CS pin would use a separate GPIO on the MCU. When writing to the device registers, you would only select one device at a time and leave the interface of the other devices disabled. When reading data, all /CS pins would have to be set low at the same time.

    Does that sound like what the customer wants to do?

    Best Regards,
  • 0 in reply to Ryan Andrews
    TI__Expert 5411 points
    Hello Ryan,

    thanks a lot for your answer.

    Okay, so did I understand it correctly, that the PCB Schematics would be a combination of both implementations? So the data flow would be in daisy chain but with individual /CS?

    Regarding the programming: The customer would have to send one long SPI package with the configuration at the right place for the selected ADS? And the rest of the data would be ignored by the other ADS131s because /CS would not be active?

    Best Regards
    Martin
  • 0 in reply to Martin Seeger
    TI__Guru 69076 points

    Hi Martin,

    That's how I imagine it working on the ADS131E08. Individual /CS pins can be used to set unique register settings for each device. All /CS could be enabled at once to allow for one long daisy-chain SPI transaction during data collection. The data rates would have to be integer multiples of one another and the devices would need to be synchronized to the same CLK edge. Devices with slower data rates would output repeated data that the customer could ignore.

    To write to the individual devices, I imagine the customer would enable /CS1, write registers, disable /CS1 and enable /CS2, write registers, etc.

    Best Regards,

  • 0 in reply to Ryan Andrews
    TI__Expert 5411 points
    Hi Ryan,
    great, thanks a lot for the answer.
    We will try that.
    Keeping you posted if there are follow up questions.

    Best Regards
    Martin