This post is older than 2 years and might not be relevant anymore
More Info: Consider searching for newer posts

oscillation at the embed analog front end circuits of SAADC in nRF52832

Hello,

I found the strange phenomena on nRF52832.

By using the SAADC, I have some noise on ADC Data only at a certain temperature range.

Temperature range is depend on individual IC.

I might be the circuit oscillation at analog front end of SAADC, I think.

(internal reference voltage or op amp etc,)

I tried to switch DCDC on/off, but there's no difference on phenomena.

Anyone can resolve it?

I attach the files of real data and measurement condition.

Best regards,

Kiyoshi Iwai

3426.SAADC_noise_devzone.zip

Parents
  • Hi Kenneth,

    marking is following.

    CIAA chips are "N52832  CIAAE1 1803AA" all.

    QFAA chips are "N52832 QFAAB0 1740JK" and "N52832 QFAAB0 1701FH".

    And why don't you use our project?

    Our software engineer  took a long time (almost 3 days) to modify the project which can be submitted to other company. And Avnet also used this project  and confirmed to recreate this issue.

    You are going to waste all things ?

    I strongly recommend to compile our project, use our project and reproduce this issue at your Lab.

    This problem is almost on Hardware obviously, I think.

    Could you find the root cause of Hardware as soon as possible?

    (And please return this to public mode.)

     

    Best regards,

    Kiyoshi Iwai

     

  • Hi Kiyoshi,

    Thank you for providing the chip markings.

    The reason for not using your project is that the test lab must perform the tests in a controlled manner, to ensure we can identify if this is a hardware issue. If we test using your software, then we will not know if it's caused by software or hardware. This is currently the highest priority task to find out.

    The test lab are preparing test firmware, and hopefully the automated test can run during tonight, so we have results by tomorrow. That is the plan. I will let you know if there is any delay.

    Best regards,
    Kenneth

  • Kiyoshi Iwai said:

    And when i tried using the VDD/4 as reference voltage instead of internal 0.6V,

    I supplied power to the boards by normal power-supply (3.0V).

    But I still had this issue by using normal power-supply, not CR2032.

    If you have long wires for the power supply, I would expect you could see the same. So I want to ask nicely that you try:

    Use 2x AAA for supply (with short wires) and 2x AAA for analog input (or a single AAA is likely easier). Make sure power supply is connected directly to VDD without any diode in reverse direction.

    Another questions:

    - If you test the same board multiple times, does it always happen on the identical temperature?

    - Can you share boards you know is failing with us?

    Best regards,
    Kenneth

  • Hi,

    How long did you stay at one temperature step on automatic test?

    (How many  AD samples in one step?)

    And is this data  on the oversampling mode? (14bit output)

    Thanks

    Kiyoshi Iwai

  • Hi Kiyoshi,

    7168 samples are done at each temperature, all measurements are 14-bit (128x oversampled). The lab use single AA as analog input.

    Best regards,
    Kenneth 

  •  "If you test the same board multiple times, does it always happen on the identical temperature?"

    => Yes.

    "Can you share boards you know is failing with us?"

    => What do you mean?  You need our board? But Your DK has same issue too, so you can

       find the problem by using DK.

     

    And I will check with 2xAAA, but you already design your DK which you intend to operate with CR2032?

    Thanks

    Kiyoshi Iwai

  • You mean 5us x 128 x 7168 =4.5sec ?  It's too short, I think.

    Could you check again  with longer interval time( 30min-1 hour)at one temperature ,

    and go next temperature.  You may use wider temperature step. (5 or 10 degree C)

    Thanks,

    Kiyoshi Iwai

Reply Children
No Data
Related