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CCS/PGA970: Multiple Devices setup

Anuj Sharma40
Intellectual 360 points
Part Number: PGA970

Tool/software: Code Composer Studio

Could you pl let me know the most efficient way of connecting multiple devices on SPI bus(or any other) without too many lines. We may need to connect as much as 128 devices.

  • 0
    TI__Guru 63905 points

    Hello Anuj,

    The way we've seen most customers accomplish this is by MUX'ing the SPI signals around to the different devices to minimize the number of processor lines.  While all 128 devices may be in the calibration system you'll likely only be calibrating one or two sensors at a given time at a time and therefore you can use one Master and then MUX the signals around to the different PGA970 devices.

    The primary customer support engineer for this device is out of the office through Jan 4 but we may reach back out to learn a little more about what you're trying to accomplish once he returns.

  • 0 in reply to Collin Wells
    Intellectual 360 points
    Thanks for your reply. The issue is chip select is required to be asserted for communication with each PGA970 device. We have a master and slave design with upto 128 PGA970 to be connected as slaves. Kindly advise a solution as we cannot have 128 chip select lines.
  • 0 in reply to Anuj Sharma40
    TI__Mastermind 31655 points

    Hi Anuj,

    For 128 devices you can use a MUX to reduce the number of required chip select lines to only 7. Another thing to keep in mind is the strength of your master's SPI data line driver. Having 128 devices on a single bus could very well exceed the capacitance limit for the master device.

    Regards,