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FDC2214: I have a question about FDC2214 sleep mode

Jim Yao
Prodigy 60 points
Part Number: FDC2214

Hi, 

When I use FDC2214 continuously, the data normally fluctuates around 2000
But when I say that FDC2214 enters sleep mode and then exits, the data will change to a difference of 50000 from the original value. Is this normal?

  • 0
    TI__Expert 3435 points

    Hi,

    No, it is not normal. Can you compare all the registers before entering sleep mode and after exiting the sleep mode?

    Regards

    Sharath.

  • 0 in reply to Sharath Vallamkonda
    Prodigy 60 points

    Hi,Sharath.

    I compared the registers, they are consistent, except for DRIVE_CURRENT_CH0

    I set DRIVE_CURRENT_CH0 to 0xF800, but the data obtained by reading DRIVE_CURRENT_CH0 is 0XFAC0 or other data, anyway, 0:10 is not all 0 or not all 1.

    Regards

    Jim.

  • 0 in reply to Jim Yao
    TI__Expert 3435 points

    Hi,

    Can you monitor the input pins on the scope before and after sleep mode? I am curious whether the gain or other settings have changed because of sleep mode.

    What are you reading when you restart the device?

    Regards

    Sharath

  • 0 in reply to Sharath Vallamkonda
    Prodigy 60 points

    Hi,Sharath

    Thanks for your reply

    P1 is monitor the input pins on the scope before sleep mode

    P1 before sleep mode

    p2 after sleep mode

    Sorry, I can't see the difference between the two...

    BTW,I don’t understand what "What are you reading when you restart the device?" means.

    Regards

    Jim.

  • 0 in reply to Jim Yao
    TI__Expert 3435 points

    Hi Jim,

    Do you see this issue when you power cycle it? Or, does it show only after coming back from sleep mode? 

    I did not notice that on the EVM when the sleep mode was toggled. Please compare your setup with EVM to find the root cause.

    Let us know if you still have issues after that.

    Regards

    Sharath.

  • 0 in reply to Sharath Vallamkonda
    Prodigy 60 points

    Hi,Sharath

    There will be no problem after restarting.

    In fact, this abnormality occurs when FDC2214 keeps entering and exiting sleep mode.

    My current workflow is 1) exit sleep mode, 2) read data, 3) enter sleep mode, 4) exit sleep mode, 5) read data, 6) enter sleep mode...always loop.

    Regards

    Jim.

  • 0 in reply to Jim Yao
    TI__Expert 7599 points

    Hi Jim,

    As Sharath pointed out can you please run this test on the EVM and also help to compare the setups between the EVM and your setup ? If you can let us know the difference in the EVM and your setup, schematics or layout we can look into this. 

    Also, I noticed that in your scope measurements the oscillation signals are below ground it appears that you may not be probing the signals correctly or have a ground connection missing. Can you address this as well ? 

    Let us know when you would have these measurements for us and the next steps.