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ADS1299: Daisy chain with another ADC family

mohsen fatoorechi
Prodigy 60 points
Part Number: ADS1299
Other Parts Discussed in Thread: ADS1292, , ,

Hi,

I currently have a setup where I have daisy chained two ADS1299s to have 16 channels. This works fine and I get the correct data. However, I do not need all the extra 8 channels and would like to use a secondary cheaper ADC such as ADS1292. Is it possible to daisy chain these two different ADC families?

Regards

Mohsen

  • 0
    TI__Guru 59776 points

    Hello Mohsen,

    Thanks for your post and welcome to our forum!

    This approach has me a bit skeptical. In theory, the ADS1299 does not care where the incoming data is from on the DAISY_IN pin. However, the interface, register map, and SPI command definitions are very different between the two devices. You would need a separate /CS signal for each one, which defeats the purpose of daisy-chaining them together. It would be more practical if you shared their SPI buses and ensured that you only activated one device at a time for SPI communication.

    Another approach would be to use an ADS1299-4 and an ADS1299-6. This would give you the 10 channels that you need with identical interfaces, register maps, and SPI commands. You could daisy-chain the two of them without any concerns.

    Best Regards,

  • 0 in reply to Ryan Andrews
    Prodigy 60 points
    Thanks Ryan, I think the best approach is treating them as separate SPI devices as you mentioned, but perhaps feed the second device from the clock of the first (cascading devices).

    I could use ADS1299-4, but that is an expensive chip compared to ADS1292.