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Original question:

ADS1278: ads1278

ADS1278: How to connect DOUT1-8 when using discrete mode with SPI protocol

Manu Chang
Intellectual 1990 points
Part Number: ADS1278

Hi,

My customers would like to use ADS1278 pairing with F280039 DSP to read the data transferred from ADC. They prefer to use SPI protocol along with the discrete data output mode for DOUT.

Their question is that since the SPI protocol only have one MISO pin, how to connect the DOUT1-8 pin with the DSP pin? Should they connect the DOUT1-7 to the GPIO pins of DSP and DSP will read the data on these once the DRDY pin is low?

Pls help to give an explanation on how the data is transferred when using SPI protocol with discrete data output mode, thanks!

BR,

Manu

  • 0
    TI__Mastermind 46490 points

    Hello Manu,

    Typically, if using discrete output mode, you would interface to an FPGA where you can implement an 8-input SPI interface.  In addition, if interfacing to a microcontroller, TDM mode is typically used, where all channel data is output on DOUT1.  Since the ADS1278 digital interface can support the highest speed mode using TDM on the single DOUT1 pin, this is usually the preferred approach.

    You need to reach out to the C2000 team for specifics on how to use SPI with 8 parallel inputs to see if this is possible.  However, I would recommend using SPI TDM mode, which will support a maximum data rate of 105ksps with 8 channels enabled over a single DOUT1 pin.  In this case, you can use the standard SPI module on the C2000 or any MCU.

    Regards,
    Keith Nicholas
    Precision ADC Applications.