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Using the ADS1258EVM-PDK (MMB0) for a low-latency application

Diogenis Devletoglou
Prodigy 20 points
Other Parts Discussed in Thread: ADS1258, ADS1258EVM-PDK, ADS131E04

Hello,

We are contemplating using ADS1258 for a multi-channel data acquisition application. We intend to start prototyping with the ADS1258EVM, the MMB0 motherboard and supplied Windows drivers. Does anybody have any experience with this kit in developing a native Windows app? We are mostly concerned with the kind of latency one should expect, also with the sustained throughput over the USB link, using the supplied MMB0 Windows driver. The aggregate data rate of ADS1258 is above the USB max data rate, so what behavior should one expect when attempting to multiplex too many ADC channels over the USB link? How many ADC channels are feasible, for sustained throughput?

Thank you!

  • 0
    TI__Mastermind 44680 points

    Hi Diogenis,

    Welcome to the TI E2E forums!

    Unfortunately, I don't have experience developing Windows apps. However, I know that USB ought to be able to handle the data throughput from the ADS1258...USB 2.0 has a high speed mode that provides signaling rates up to 480 Mbit/s. The maximum throughput of the ADS1258 is 125kSPS * 24 bits/sample = 3Mbits/s; however, in a multi-channel system the ADC output will only be 23.7kSPS * 24 bits/sample = 0.57 Mbits/s because of the digital filter's settling time.

    The effective data rate per channel depends on the number of channels you're using. If you have 4 channels, each channel's effective data rate may be as high as 23.7kSPS / 4 Channels = 5.925 kSPS, but you'll still have 24-bit data coming out at 23.7kSPS.

    How many channels do you need to acquire and do you plan on using multiple ADS1258's?
    If you need to go to more than one ADS1258, than you'll likely need to double the required throughput to 1.14 Mbits/s.

    Best Regards,
    Chris

     

  • 0 in reply to Christopher Hall
    Prodigy 20 points
    Chris,

    This is very helpful, thank you! We are initially planning to use up to 4 channels, so your clarification on effective data rate and per channel rates was valuable. We had also misread the USB data rates vs. ADS1258 throughput - even the standard USB rate of 12 Mbps seems more than enough to handle the 0.5 Mbps incoming from ADS1258EVM-PDK. I am *assuming* the Windows OS and supplied driver will do a decent job of sustaining a throughput at these levels.

    Do you happen to have any other suggestions for 4-channel 24b ADCs, with a higher sampling rate per channel?

    Thanks a lot!
  • 0 in reply to Diogenis Devletoglou
    TI__Guru* 97465 points
    Diogenis,


    One other possible device would be the ADS131E04. It has four independent ADCs (instead of a large multiplexer) and a high data rate.

    www.ti.com/.../ADS131E04


    Joseph Wu