LPUART1 interrupt stuck in HAL_UART_IRQHandler on STM32MP2 (RS485 + ReceiveToIdle)

[rutiklunagariya6]

 

Hi everyone,

I am working on an STM32MP2 platform and facing a persistent issue with LPUART1 in interrupt mode.

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Setup

• MCU: STM32MP2
• UART used: LPUART1 (RS485 communication via MAX485)
• Debug UART: UART5 (polling mode, printf works fine)
• Using:
  • HAL_UARTEx_ReceiveToIdle_IT() for RX
  • HAL_UART_Transmit() for TX
• Baudrate: 115200

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Problem

When using interrupt mode, the system gets stuck in:

 

HAL_UART_IRQHandler()

The interrupt keeps triggering continuously and the system appears stuck (infinite IRQ loop).

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Observations

• Polling mode (HAL_UART_Receive) works perfectly
• Sensor communication works fine in polling
• Issue only happens in interrupt mode

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What I already checked

 NVIC enabled correctly:

HAL_NVIC_SetPriority(LPUART1_IRQn, 5, 0);
HAL_NVIC_EnableIRQ(LPUART1_IRQn);

 IRQ handler is correct:

void LPUART1_IRQHandler(void)
{
HAL_UART_IRQHandler(&hlpuart1);
}

No wrong handle (huart1) is used anywhere

FIFO configuration added:

HAL_UARTEx_SetTxFifoThreshold(&hlpuart1, UART_TXFIFO_THRESHOLD_1_8);
HAL_UARTEx_SetRxFifoThreshold(&hlpuart1, UART_RXFIFO_THRESHOLD_1_8);
HAL_UARTEx_DisableFifoMode(&hlpuart1);