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Original question:

IWRL1432: Wakeup through UART RX

IWRL1432: Read serial port data in low power mode

MZB
Intellectual 440 points
Part Number: IWRL1432

Hi.

I enabled the low power mode in mmwave_demo and configured it to wake up through serial port. So far I've been able to wake up the radar using uartA, but I can't read data from the serial port. Because I need to send serial data to the radar at irregular intervals in low power mode. At present, I find that after waking up, the radar immediately goes into low power mode after processing a frame of data, so I need to know how to read the serial port data after waking up. Please guide me.

best wishes.

  • 0
    TI__Mastermind 19240 points

    Hello.  After processing the data it should be output over UART before entering low power mode.  This is enabled by starting the tlv_task as shown below.  You will also have to check to make sure that the processing time will not take up so much time as to make sure there is enough time to enter the low power mode within the set frame time.  

    In low power mode you won't see any output as all the peripherals are disabled, and only enabled upon wakeup.  In addition, the processing and tlv transmit tasks are deleted and recreated only upon exit from low power mode.  What information are you trying to send during the low power mode?

    Sincerely,

    Santosh

  • 0 in reply to Santosh Krishnan
    Intellectual 440 points

    HI.

    I want to receive serial data from the master MCU in low-power mode, so the master MCU controls the radar through serial protocol. When entering low power, the CLItask task is deleted. I created a new task to read UartA data and do not delete it when low power is used. But we still can't read the data.

  • 0 in reply to MZB
    TI__Mastermind 19240 points

    Hello.

    I am looking into this, and will have a response by the end of the day Monday.  Just for more clarification, is this a follow up on the previous thread where you were trying to use UARTA as a wakeup source?  Will this host MCU send a command to wakeup the device?

    Sincerely,

    Santosh

  • 0 in reply to Santosh Krishnan
    Intellectual 440 points

    Hi.

    The MCU can wake up the radar, but the MCU serial port data cannot be read.

    Best wishes

  • 0 in reply to MZB
    TI__Mastermind 19240 points

    Where are you creating this logging task, and if it is created inside of the powerManagementTask, are you making sure that the UARTA is still enabled at the time of the task's execution?  You could try explicitly enabling the UARTA pin in the task as well to guarantee that at the time of the task's execution, the UARTA is enabled and can be woken up.

    Sincerely,

    Santosh

  • 0 in reply to Santosh Krishnan
    Intellectual 440 points

    This logging task is actually created in mmwave_demo and is not deleted in the powerManagementTask. When a task is performed, uartA is open and can be awakened by uartA, but the data cannot be read. From the point of the process, a serial port immediately after awakening dpctask data processing tasks, and then execute after mmwDemo_TransmitProcessedOutputTask into low power mode, no time to read the uart data.

  • 0 in reply to MZB
    TI__Mastermind 19240 points

    Hello.

    Let me look into the functionality of the UART port if it is being used as a wakeup source.  

    MZB said:
    From the point of the process, a serial port immediately after awakening dpctask data processing tasks, and then execute after mmwDemo_TransmitProcessedOutputTask into low power mode, no time to read the uart data.

    Just to make sure I understand correctly, are you indicating that you are not having enough time to read data due to wakeup immediately starting the execution of the application, and if so, I would suggest 1)expanding your frame time and 2) polling for UART data and holding there until you receive the information you need/command to continue with the execution flow, similar to the way sensorStart is required to essentially exit the cli task and continue with the execution of the application.

    Sincerely,

    Santosh

  • 0 in reply to Santosh Krishnan
    Intellectual 440 points

    Hi.

    Sleep timer and serial port as the wake source, when the frame idle does not immediately enter the low-power mode, but reserve a little time to read and process the serial port data, and then enter the low-power mode. Is that how you understand it? However, if the frame time is shorter, then the time to go to sleep is shorter. It is necessary to increase the frame time, which has a greater impact on the speed measurement.

  • 0 in reply to MZB
    TI__Mastermind 19240 points
    MZB said:
    when the frame idle does not immediately enter the low-power mode, but reserve a little time to read and process the serial port data, and then enter the low-power mode

    Correct.  I believe we are on the same page about leaving enough time to be able to read the data before entering low power mode.  However, I wanted to also check if you were using the USB/XDS UART connection for UART A.  If this is the case, you will not be able to read data as UARTA via XDS is only TX.  You will need to populate the resistor R147 and route the RX signal through the boosterpack connections.  You can determine which specific pin is RX via the schematic.

    Sincerely,

    Santosh