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ADS1282-HT: ADS1282 Chip Select Solution

Marius Raducanu
Intellectual 680 points
Part Number: ADS1282-HT
Other Parts Discussed in Thread: ADS1282, ADS1281

Hello,

I want to have on the same SPI, the ADS1282 and a DAC (AD5600) - sharing the same SCLK and DIN.

The problem is that the ADS1282 doesn't have a Chip Select and if I send data to the other SPI device (AD5600), it takes commands/data on the DIN.

I have a few options but I don't know if they are doable or what is the best one:

1 - disable the ADS1282 CLK

2 - hold in reset the ADS1282

3 - neglect the effect of sending data on the same SPI to the DAC - hooping that it doesn't change anything in the ADC1282

4 - use a different SPI - not preferred

Question: How can I disable the ADS1282 when I send data to the DAC?

Thanks,

Marius Raducanu 

  • +1
    TI__Mastermind 18900 points

    Hello Marius,

    Not having a chip select is a typical problem for the ADS1282, the two ways we recommend to do it are:

    • Use separate SPI peripherals for each device on the bus, which is your option 4 and your least recommended
      OR
    • MUX or use a logic gate with the SCLK signal so that you only communicate with one device at a time. Which is what I assume your option 1 is.
      • I could also interpret it as holding the signal coming into the CLK pin but I'm pretty sure that will cause the device to reset (which is similar to 2). Not sure there's anything wrong doing it this way but losing the register settings every time its put into reset is more of a hassle than its worth
      • Either way, I've provided a schematic of for using multiple devices (ADS1282/ADS1281 in this case) which could help as a reference3107.ADS1281-2 Shared SPI Schematic (1).pdf

    I would actively argue against option 3 as this sounds like a debug nightmare if any issues were to occur.

    Best,

    -Cole

  • 0 in reply to Cole Macias
    Intellectual 680 points

    Hello Cole,

    Thanks for your response.

    A agree with your recommendation but the hardware is already built and I have to do option 2. I will reset the ADC1282 and re-write the registers after using the DAC. This is not a big problem because I use the DAC to set a reference for a Strain Gauge circuit (calibration) that is done only when the tool is powered - anyway, this system is a prototype and in the final product I will use 2 SPIs.

    Thanks,

    Marius Raducanu