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Original question:

ADS1299: ADS1299 reset issue

ADS1299: DRDY(Bar) stops after some conversions

Nikint Kshirsagar
Prodigy 50 points
Part Number: ADS1299

Hello,

We have raised few queries about ADS1299 reset and DRDY(Bar) signal stop in between the measurement recently. We have captured SPI timings and verified analog and digital power supplies as per suggestions and they looks clean.

We captured a video in which we have observed DRDY(Bar) signal stopped after some time. We confirmed that firmware doesn't stop measurement.

We have few queries about the ADS1299-

1. Does SPI peripheral of ADS1299 resets chip which stops DRDY(Bar) signal?

2.  What will be the cause of DRDY(Bar) signal stops?

Any leads can be helpful.

Note: - In the video, signals has some noise which was due to wires connected to SPI pins.

  • 0
    TI__Genius 11550 points

    Hi Nikint,

    Thanks for the post. 

    The START pin or the START/STOP command are the two options to start or stop a data conversion for the device. The device does not issue a DRDYB signal (conversions halted) when START is low, or the START command has not been sent.

    After the initial power-up sequence (Figure 76) and device reset, please verify that the DRDYB signal will toggle continuously at the default data rate without any SPI communication by setting the START pin high. Have the team resolved the RESET issue in the previous post to isolate if this is a hardware or software issue?

    I have attached this E2E post with a similar issue where you may find helpful.

    Thanks

    -TC

  • 0 in reply to TCT
    Prodigy 50 points

    Dear TCT,

    Thanks for the suggestions. We will look for DRDYB signals occurs as per data rate after power up sequence and keeping START pin HIGH.

    We had updated few interrupt priorities in STM32 micro-controller. We kept device for long run and multiple times "START" and "STOP" the operation, in which we didn't observed any issue.

    But still there is a catch, we  used HAL_SPI_Receive_IT() function to read the data from ADS1299 when DRDY interrupt logged. Function requires an array to store the data. We observed that after initializing array to zero (As we kept interrupt priorities changed) before calling the function, issue is not observed and if we remove array initialization to zero, issue observed (DRDYB signal stop). 

    Even we tried SPI communication disabled, we haven't observe the issue (DRDYB signals occurs as per data rate).

    Regarding the ADS1299 RESET  issue, It is similar to DRDYB stop issue. When we updated the interrupt priorities, issue looks to be resolved.

    Well all above scenarios we tested are related to SPI. So our question remains the same, whether SPI peripheral of ADS1299 causes any issue in ADS1299??

    Note: - We are using START, RESET, PWDN pins to control "START", "STOP", "RESET" and power ON/OFF operation.

  • 0 in reply to Nikint Kshirsagar
    TI__Genius 11550 points

    Hi Nikint,

    Thanks for the additional information. 

    I am not familiar with the SPI operation of the STM32 microcontroller, so I cannot comment on it. However, it seems like this is not the device issue but a software one from your description. I am not aware of any issue with the ADS1299 SPI interface causing the DRDYB and device RESET issue you are seeing. Please let us know if we can provide further assistance.

    Thanks

    -TC

  • 0 in reply to TCT
    Prodigy 50 points

    Dear TCT,

    As SPI peripheral of ADS1299 does not cause any issue in chip, we will debug further in STM32 firmware and it's library part. 

    We are very thankful to you for sharing us useful information.

    Thank you.

    - Nikint