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TMS320F28P659DK-Q1: Wake up from LPM

KenF
Expert 7150 points

Part Number: TMS320F28P659DK-Q1

Tool/software:

Hello Experts,

My customer plans to build their own board with F28P65. Can you please answer the questions below?

Our understanding is, to wake up F28P65 from low power mode, F28P65 GPIO needs to be set to LOW from external. Their CAN transceiver (TCAN1044AEVDRQ1) has RXD but not output (GPIO) pin. Is there any way to wake up F28P65 from low power mode?

Best regards,
Ken

  • +1
    TI__Mastermind 37093 points

    Hi Ken,

    This depends on the specific type of Low-Power Mode the device is in: IDLE, STANDBY, or HALT. If exiting from STANDBY or HALT low power mode, externally driving the configured wakeup GPIO is required.

    The TCAN1044AEVQ1 part mentioned supports a Host Remote Wake Request as described in section 8.4.3.1 of the device datasheet.

    The following scenario should be possible for the application:

    • Before entering low power mode, configure the CAN RX pin to operate in GPIO mode with the wakeup function enabled.
    • MCU drives STB high, putting CAN transceiver in standby mode.
    • Qualified bus activity occurs, and a valid Wake-Up Pattern (WUP) is received.
    • The transceiver will toggle the RXD pin per device configuration.
    • The MCU GPIO pin, which is still connected to RXD, can recognize this as a valid wakeup pulse and execute WAKEINT.
    • Application immediately reconfigures the pin back to the original CAN RX mode and releases STB, taking the CAN transceiver out of standby mode.
    • Application continues as usual till the next low power mode.

    One caveat here is that any activity on the CAN bus will wake the device. 

    The watchdog interrupt can also be used to exit standby mode at some programmed interval, but this is not controllable by an outside entity, like activity on the CAN bus.

    Could the customer provide more details on their system power/wakeup requirements? This may allow us to help you find more solutions.

    Best Regards,

    Zackary Fleenor

  • 0 in reply to Fleenor
    TI__Expert 7150 points

    Thank you, Zackary Fleenor.

    We will try this. You can close this thread.

    Best regards,
    Ken