STM320U LPUART2 not working after waking up from the STOP0/ Sleep Mode.
Hello Everyone,
I am currently using LPUART2 for communication between an MCU (STM32U031) and an MPU (Application Processor).
Configuration parameters:
- Baud rate: 9600
- Stop bits: 1
- Parity: None
- Data bits: 8
Description:
Data exchange between MCU and MPU works perfectly when both devices are operating in normal power mode (i.e., not in sleep or stop modes). However, I am facing an issue when both MCU and MPU wake up from sleep/stop mode.
After wake-up ,The MCU is unable to receive data from the MPU, even though the MPU continues transmitting data. No IRQ handler is triggered on the MCU side.
Additional Details:
- I deinitialize the LPUART before entering sleep/stop mode.
- I reinitialize it immediately after wake-up.
Scenarios Tested:
Only MPU enters sleep (MCU remains active): After MPU wake-up, communication works perfectly.
Both MPU and MCU enter sleep: After wake-up, communication fails (MCU doesn’t receive data).
Observation:
It seems that the issue is related to LPUART behavior during low power transitions, since everything works fine when only the MPU performs sleep/wake operations and the MCU remains awake.
Please help identify if there is missing configuration or specific setup required for LPUART in low power modes?
I am open to share the source code and any other information.