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ADS1282-SP: SDATAC command after RDATA command

Périg
Prodigy 10 points
Part Number: ADS1282-SP
Other Parts Discussed in Thread: ADS1282

Tool/software:

Hello,

In order to properly interrupt an acquisition sequence in the FPGA controlling the ADC, we are interested in knowing the behaviour of the ADS1282-SP when receiving an SDATAC command right after having received an RDATA command ?

Will the ADC ignore the SDATAC command and output a falling edge on DRDY once new data is ready ? Or will the SDATAC command have for effect to suppress the DRDY output even if the ADC was in RDATA mode and not RDATAC ?

Thank you.

Regards,

Périg (Electronics engineer)

  • 0
    TI__Guru 52146 points

    Hi Périg,

    Can you help me understand what you are trying to do here?

    The SDATAC command is there to exit RDATAC mode, and nothing else. If you are already reading data by using the RDATA command then you must already be in SDATAC mode. So why do you want to send this command again? Do you want to use the STANDBY and WAKEUP commands instead to control conversions? Please help explain 

    -Bryan

  • 0 in reply to Bryan Lizon86
    Prodigy 10 points

    Hi Bryan,

    Thank you for your answer.

    The ADC will be controlled by an FPGA executing an acquisition sequence (several RDATA commands with some time in between).

    Some external event can then interrupt this acquisition sequence. When the interruption happens after the RDATA command, while the FPGA waits for the DRDY falling edge, we want to know what is the best way to get out of the sequence (waiting for the DRDY falling edge before exiting the sequence is not an option for us).

    If the SDATAC does not have any effect here, maybe we will just get out of the sequence without sending any command to the ADC, and the DRDY falling edge will then be ignored by the FPGA, until a new sequence begins.

    Regards,

    Périg

  • 0 in reply to Périg
    TI__Guru 52146 points

    Hi Périg,

    You should be able to issue a STANDBY command to gate the DRDY signal. This assumes you are able to detect the interruption and send the STANDBY command before the next DRDY pulse

    Of course as you mentioned you can always just ignore the DRDY pulses after the interruption

    -Bryan

  • 0 in reply to Bryan Lizon86
    Prodigy 10 points

    Hi Bryan,

    Very well, thank you for your answer.

    I have one last question : even if the SDATAC command is not useful here, will the ADC be disturbed in any way if it receives an SDATAC command while not in RDATAC mode ?

    It could happen for example if we use the same "interruption routine" as the one we already use when interrupting a sequence where this time the ADC is used in the RDATAC mode.

    Regards,

    Périg

  • 0 in reply to Périg
    TI__Mastermind 46400 points

    Hi Périg,

    I ran some tests in the lab and was able to confirm that multiple SDATAC commands are simply treated as No-Operation commands.  You can repeat this command as many times as desired when not in RDATAC mode, and it will not have any adverse effects on the operation of the ADS1282.

    Regards,
    Keith Nicholas
    Precision ADC Applications

  • 0 in reply to Keith Nicholas
    Prodigy 10 points

    Hi Keith,

    Okay perfect, thank you for your tests.

    Regards,
    Périg