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Original question:

ADS8586S: Serial data interface combining DOUTA and DOUTB into single SPI

ADS8586S: Serial data interface combining DOUTA and DOUTB into single SPI

senthil raj
Prodigy 60 points

Part Number: ADS8586S

When i use only DOUTA in serial data read mode. what should be DOUTB terminated to (Low/High)

Can I leave the ChipSelect Pin always high (connect to Vdd) and just use CONVSTA & CONVSTB to sample the data & SCLK to read multiple samples after BUSY returns to low

Does FRSTDATA go high after every CONVSTA/CONVSTB to represent the first channel data for that sample cycle or does it go high only once after power up first data read operation or every time ChipSelect toggles after CONVSTA/CONVSTB

  • 0
    TI__Mastermind 25070 points

    Hello, 

    If you do not plan to use DOUTB, it can be grounded. 

    CS is intended to hold the output line in a tri state when they are not being read, this allows for the lines to be shared with other devices. To be able to read data, CS needs to be low. Data can be read during or after a conversion, but data should not be read across a BUSY  falling edge, this is shown in the timing requirements shown below. During a BUSY transition, CS is high. Also, there are minimum delay times given between state changes of CS and BUSY that are longer than 0. All which imply that CS should not be low although the datasheet does not directly state it.

    The last question, FRSTDATA goes high every time the output of the first analog channel is read. Thus this signal will change states consistently while the device running not just once when the device is powered up. This signal is meant to be a sort of notification for you to let you know when you are back at channel 1. This pin goes high on the falling edge of CS  when channel 1 is being read. 

    Regards

    Cynthia 

  • 0 in reply to Cynthia
    Prodigy 60 points

    Thanks for the detailed response.