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ADS7250: SPI interface Question

Part Number: ADS7250
Other Parts Discussed in Thread: ADS7253

Hi 

I want to connect ADS7250 and F28377s via SPI

and i checked datasheet of ADS7250.. and I found 2-SDO line...

How two connect 2-SDO line with DSP ??  One SPI module has only one SPISOMIx.. 

Or connecting one-sdo line works correctly?? then.. how to get two conversion data from this connection??

Best Regards..

Moonsun

  • Hello Moonsun,

    For this device, when CS is pulled low and the clock is toggled, data will come out on both SDO lines. SDO-A will have the data for ADC_A and SDO-B will have the data for ADC_B.
    There are multiple SPI interfaces on the processor. You could set up the processor so that when one CS goes low, it will enable two MISO pins. These pins could then be connected to the SDO-A and SDO-B pins. You would need to submit a question to the forum that supports the F28377S to find out how to set that up.
    Another possibility is is to use 2 SPI interfaces on the processor. The CS signals would get ORed together and that output would be connected to the CS pin of the ADS7250. Then when each SPI interface brings the CS low, the ADS7250 would write out the data on both SDO outputs, but the processor would only read it on the SPI interface that has brought CS low. You would then read each SDO output right after each other.

    Mike
  • Hello Moonsun

    Apart from what mike has suggested

    Please take a look at ADS7253. This device has SDI pin over which you can program the output data mode.

    You can get both channels data on single SDO line by selecting (32 clock single SDO mode or 16 clock single SDO mode). Please refer to page 41 and page 44 of datasheet for more information.

    Let us know if this solves your problem

    Thanks & Regards

    Abhijeet