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ADS1118: Single mode option delay time

Dudi Varshavski
Prodigy 110 points
Part Number: ADS1118

I would like to know what is the delay time after single shot conversion completed, considering the power down state, before new configuration can be set.

I am configuring the device for single mode and triggering the SS bit, then waiting for DOUT signal to toggle low and starting communicating after ~300ns. In the new communication i trigger the SS again and expecting to see DOUT at '1' for the new conversion time but instead DOUT stay '0'. Therefor my system assume a new data available and start reading it write after completing the previous communication.

Please see in the attached scope image 2 cycles of communication: first after correct conversion and second right after the previous one. i always set SS bit to '1'.

Yellow is DOUT

Turquoise is nCS

Purple is CLK

Thanks,

Dudi

  • 0
    TI__Guru* 98045 points
    Dudi,


    In single-shot mode, it takes about 20us to start up the device again from a power-down condition. Then the conversion starts. However, I'm not sure if the DOUT/DRDY comes back up during that 20us. The DOUT/DRDY may return high after it the device is commanded to start a new conversion. You can try extending out the time between the read of the device and the start of the new conversion just to check.

    For an alternate method, I would use the 32-bit data transmission cycle with Config Register readback. This is shown in Figure 40 (or you could use Figure 41 instead). By reading back the full configuration register, this should force DOUT/DRDY high again after reading the first data. After that, you can start another single-shot conversion.


    Joseph Wu
  • 0 in reply to Joseph Wu
    Prodigy 110 points
    Thank you Joseph,
    Your replay is answering my question and now i understand i have two options to work with signle mode. Waiting 20us before starting new communication or communicating twice with the device, once only to read the registers and second to start new conversion.

    Many thanks,
    Dudi