UART RX interrupt loop

andyteufel — Mon, 01 Nov 2021 13:29:12 GMT

Hello,

I am trying to get UART running with EDMA on an MIMXRT1010. The problem I have is that once a "Receive Data Register Full" interrupt is triggered, the interrupt "gets stuck" and the interrupt handler is executed in a loop, even though nothing is being received anymore. Clearing the interrupt and status flags does not help.

This is what my interrupt handler looks like:

void LPUART1_IRQHandler(void) { log_info("IRQ: Status flags 0x%08X, FIFO flags 0x%08X", LPUART1->STAT, LPUART1->FIFO); if (LPUART_GetStatusFlags(LPUART1) & kLPUART_RxDataRegFullFlag) { uint8_t data = LPUART_ReadByte(LPUART1); log_info("UART RX: %02X", data); } NVIC_ClearPendingIRQ(LPUART1_IRQn); // This does not help SDK_ISR_EXIT_BARRIER; }

With that I get the following in the logs:

IRQ: Status flags 0x01E2C000, FIFO flags 0x00800099 UART RX: 00 IRQ: Status flags 0x01C2C000, FIFO flags 0x00C00099 IRQ: Status flags 0x01C2C000, FIFO flags 0x00C00099 ... (continues)

This is basically starving my application since the only thing that's running anymore is this interrupt handler. What am I doing wrong?

This is the UART initialization code:

#define BLUETOOTH_UART_RX_IOMUX IOMUXC_GPIO_09_LPUART1_RXD #define BLUETOOTH_UART_TX_IOMUX IOMUXC_GPIO_10_LPUART1_TXD #define BLUETOOTH_UART_PORT LPUART1 #define BLUETOOTH_UART_IRQn LPUART1_IRQn #define BLUETOOTH_UART_BAUDRATE 115200u #define LPUART_TX_DMA_CHANNEL 0u #define LPUART_TX_DMA_REQUEST kDmaRequestMuxLPUART1Tx #define BT_LPUART_DMAMUX_BASEADDR DMAMUX #define BT_LPUART_DMA_BASEADDR DMA0 void board_hal_uart_init(const board_hal_uart_config_t *p_config) { APP_ASSERT(p_config != NULL, "Invalid UART configuration"); APP_ASSERT(p_config->rx_isr_handler != NULL, "Invalid UART RX ISR handler"); APP_ASSERT(p_config->tx_done_callback != NULL, "Invalid UART TX done callback"); m_bluetooth_uart.p_config = p_config; IOMUXC_SetPinMux(BLUETOOTH_UART_RX_IOMUX, 0u); IOMUXC_SetPinMux(BLUETOOTH_UART_TX_IOMUX, 0u); IOMUXC_SetPinConfig(BLUETOOTH_UART_RX_IOMUX, GPIO_SLEW_RATE_CONFIG(GPIO_SLEW_RATE_SLOW) | GPIO_DRIVE_STRENGTH_CONFIG(GPIO_DRIVE_STRENGTH_R04) | GPIO_SPEED_CONFIG(GPIO_SPEED_FAST_150MHz) | GPIO_OPEN_DRAIN_CONFIG(GPIO_OPEN_DRAIN_ENABLED) | GPIO_PULLKEEP_CONFIG(GPIO_PULLKEEP_DISABLED) | GPIO_PULLKEEP_SELECT_CONFIG(GPIO_PULLKEEP_SELECT_KEEPER) | GPIO_PULL_CONFIG(GPIO_PULL_PU_22KOhm) | GPIO_HYSTERESIS_CONFIG(GPIO_HYSTERESIS_DISABLED)); IOMUXC_SetPinConfig(BLUETOOTH_UART_TX_IOMUX, GPIO_SLEW_RATE_CONFIG(GPIO_SLEW_RATE_SLOW) | GPIO_DRIVE_STRENGTH_CONFIG(GPIO_DRIVE_STRENGTH_R04) | GPIO_SPEED_CONFIG(GPIO_SPEED_FAST_150MHz) | GPIO_OPEN_DRAIN_CONFIG(GPIO_OPEN_DRAIN_ENABLED) | GPIO_PULLKEEP_CONFIG(GPIO_PULLKEEP_DISABLED) | GPIO_PULLKEEP_SELECT_CONFIG(GPIO_PULLKEEP_SELECT_KEEPER) | GPIO_PULL_CONFIG(GPIO_PULL_PU_22KOhm) | GPIO_HYSTERESIS_CONFIG(GPIO_HYSTERESIS_DISABLED)); lpuart_config_t uart_config; LPUART_GetDefaultConfig(&uart_config); uart_config.baudRate_Bps = BLUETOOTH_UART_BAUDRATE; uart_config.enableRx = true; uart_config.enableTx = true; status_t status = LPUART_Init(BLUETOOTH_UART_PORT, &uart_config, board_hal_uart_get_frequency()); APP_ASSERT(status == kStatus_Success, "Failed to initialize UART"); LPUART_EnableInterrupts(BLUETOOTH_UART_PORT, kLPUART_RxDataRegFullInterruptEnable); NVIC_SetPriority(LPUART1_IRQn, BLUETOOTH_UART_INTERRUPT_PRIORITY); EnableIRQ(BLUETOOTH_UART_IRQn); #if defined(FSL_FEATURE_SOC_DMAMUX_COUNT) && FSL_FEATURE_SOC_DMAMUX_COUNT DMAMUX_Init(BT_LPUART_DMAMUX_BASEADDR); DMAMUX_SetSource(BT_LPUART_DMAMUX_BASEADDR, LPUART_TX_DMA_CHANNEL, LPUART_TX_DMA_REQUEST); DMAMUX_EnableChannel(BT_LPUART_DMAMUX_BASEADDR, LPUART_TX_DMA_CHANNEL); #endif // Initialize the EDMA module edma_config_t dma_config; EDMA_GetDefaultConfig(&dma_config); EDMA_Init(BT_LPUART_DMA_BASEADDR, &dma_config); EDMA_CreateHandle(&m_bluetooth_uart.edma_handle, BT_LPUART_DMA_BASEADDR, LPUART_TX_DMA_CHANNEL); #if defined(FSL_FEATURE_EDMA_HAS_CHANNEL_MUX) && FSL_FEATURE_EDMA_HAS_CHANNEL_MUX EDMA_SetChannelMux(EXAMPLE_LPUART_DMA_BASEADDR, LPUART_TX_DMA_CHANNEL, DEMO_LPUART_TX_EDMA_CHANNEL); #endif // Create LPUART DMA handle LPUART_TransferCreateHandleEDMA(BLUETOOTH_UART_PORT, &m_bluetooth_uart.lpuart_edma_handle, lpuart_edma_transfer_callback, NULL, &m_bluetooth_uart.edma_handle, NULL); log_info("UART initialized"); }

Any help with this issue will be appreciated. Thank you.

Re: UART RX interrupt loop

andyteufel — Mon, 01 Nov 2021 16:07:43 GMT

I figured it out. See https://github.com/NXPmicro/mcux-sdk/pull/45

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