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ADS114S08: Fastest channel transition case

Ryuuichi machida
Guru 12695 points
Part Number: ADS114S08

Tool/software:

Hi,

I would like to discuss how I can realize fastest channel transition by using ADS114S08.
Now, we will use three differential channel for sensor.
I would like to change next channel as soon as device can.

I know some device have automatic channel sequencer (or channel scan).
However, from viewpoint of cost and noise performance, I would like to use this device.

Here is my understanding about channel transition flow.

1. Enable CH0 by setting "INPMUX" register
2. Send "start" command
3. After confirming "DRDY", read "Data" from "DOUT".

4. Change next channel (Enable CH1 by setting "INPMUX" register) and perform same procedure above "1" to "3".

Then I have following question.

Q1. I'm not sure when I can enable next channel at the earliest.
Is there any infromation about this ?
Q2. Is above procedure is fastest case ? If you have any idea to realize fastest channel transition, could you please let me know ?

Best Regards,

  • 0
    TI__Guru 52496 points

    Hi Ryuuichi machida,

    The ADS114S08 automatically restarts the conversion process whenever the INPMUX register is changed. Therefore you can just pull the ADC START pin high so the ADC continuously converts, then whenever you change the INPMUX register the conversion will automatically restart. Then you don't need to send the START command each time.

    Assuming you pull the START pin high, then you just need to

    1. send WREG command to change the INPMUX register
    2. wait for DRDY to transition from high to low
    3. read data from DOUT

    Then repeat #1-3. This is the fastest way to cycle through the ADS114S08 channels

    -Bryan

  • 0 in reply to Bryan Lizon86
    Guru 12695 points

    Hello Bryan-san,

    Thank you for your reply.

    >The ADS114S08 automatically restarts the conversion process whenever the INPMUX register is changed. 
    Is there any fixed delay time specification between time after changing INPMUX register and starting sampling ?

    Best Regards,

  • +1 in reply to Ryuuichi machida
    TI__Guru 52496 points

    Hi Ryuuichi machida,

    See the relevant datasheet sections below for the programmable delay time in the ADS114S08. Selecting this time delays the start of conversion. Otherwise the next conversion starts immediately

    -Bryan