LPC55S28 some USART works and some no!

[MarcoGiammarini]

Dear,

I am working with a custom board with LPC55S28. In this board I am using 4 flexcomm  as USART and some works and some no and I don't understand why! The configuration is the same for all. The code is the following:

#define UART_LTE_PERIPHERAL                      ((USART_Type *)FLEXCOMM0)
//#define UART_LTE_CLOCK                           kPLL0_DIV_to_FLEXCOMM0
#define UART_LTE_CLOCK                           kFRO_HF_DIV_to_FLEXCOMM0
#define UART_LTE_PERIPHERAL_RESET                kFC0_RST_SHIFT_RSTn
#define UART_LTE_CLOCK_FREQUENCY                 CLOCK_GetFlexCommClkFreq(0U)
#define UART_LTE_BAUDRATE                        (115200ul)

#define UART_LTE_IRQ                             FLEXCOMM0_IRQn
#define UART_LTE_IRQ_HANDLER                     FLEXCOMM0_IRQHandler

#define UART_LTE_TX_GPIO                         GPIO
#define UART_LTE_TX_PORT                         0U
#define UART_LTE_TX_PIN                          30U
#define UART_LTE_TX_ALT_FUNC                     0x01u

#define UART_LTE_RX_GPIO                         GPIO
#define UART_LTE_RX_PORT                         0U
#define UART_LTE_RX_PIN                          29U
#define UART_LTE_RX_ALT_FUNC                     0x01u

#define UART_BLUETOOTH_PERIPHERAL                ((USART_Type *)FLEXCOMM7)
#define UART_BLUETOOTH_CLOCK                     kFRO_HF_DIV_to_FLEXCOMM7
#define UART_BLUETOOTH_PERIPHERAL_RESET          kFC7_RST_SHIFT_RSTn
#define UART_BLUETOOTH_CLOCK_FREQUENCY           CLOCK_GetFlexCommClkFreq(7U)
#define UART_BLUETOOTH_BAUDRATE                  (115200ul)

#define UART_BLUETOOTH_IRQ                       FLEXCOMM7_IRQn
#define UART_BLUETOOTH_IRQ_HANDLER               FLEXCOMM7_IRQHandler

#define UART_BLUETOOTH_TX_GPIO                   GPIO
#define UART_BLUETOOTH_TX_PORT                   0U
#define UART_BLUETOOTH_TX_PIN                    19U
#define UART_BLUETOOTH_TX_ALT_FUNC               0x07u

#define UART_BLUETOOTH_RX_GPIO                   GPIO
#define UART_BLUETOOTH_RX_PORT                   1U
#define UART_BLUETOOTH_RX_PIN                    29U
#define UART_BLUETOOTH_RX_ALT_FUNC               0x01u

// Modbus #1
#define RS485_1_PERIPHERAL                       ((USART_Type *)FLEXCOMM1)
#define RS485_1_CLOCK                            kFRO_HF_DIV_to_FLEXCOMM1
#define RS485_1_PERIPHERAL_RESET                 kFC1_RST_SHIFT_RSTn
#define RS485_1_CLOCK_FREQUENCY                  CLOCK_GetFlexCommClkFreq(1U)
#define RS485_1_BAUDRATE                         (115200ul)

#define RS485_1_IRQ                              FLEXCOMM1_IRQn
#define RS485_1_IRQ_HANDLER                      FLEXCOMM1_IRQHandler

#define RS485_1_TX_GPIO                          GPIO
#define RS485_1_TX_PORT                          0U
#define RS485_1_TX_PIN                           14U
#define RS485_1_TX_ALT_FUNC                      0x06u

#define RS485_1_RX_GPIO                          GPIO
#define RS485_1_RX_PORT                          0U
#define RS485_1_RX_PIN                           13U
#define RS485_1_RX_ALT_FUNC                      0x05u

// Modbus #2
#define RS485_2_PERIPHERAL                       ((USART_Type *)FLEXCOMM4)
#define RS485_2_CLOCK                            kFRO_HF_DIV_to_FLEXCOMM4
#define RS485_2_PERIPHERAL_RESET                 kFC4_RST_SHIFT_RSTn
#define RS485_2_CLOCK_FREQUENCY                  CLOCK_GetFlexCommClkFreq(4U)
#define RS485_2_BAUDRATE                         (115200ul)

#define RS485_2_IRQ                              FLEXCOMM4_IRQn
#define RS485_2_IRQ_HANDLER                      FLEXCOMM4_IRQHandler

#define RS485_2_TX_GPIO                          GPIO
#define RS485_2_TX_PORT                          0U
#define RS485_2_TX_PIN                           20U
#define RS485_2_TX_ALT_FUNC                      0x0Bu

#define RS485_2_RX_GPIO                          GPIO
#define RS485_2_RX_PORT                          0U
#define RS485_2_RX_PIN                           5U
#define RS485_2_RX_ALT_FUNC                      0x02u

static void initUART (bool exitLowPower)
{
    (void)exitLowPower;

    // 4G/LTE UART Management
    CLOCK_AttachClk(UART_LTE_CLOCK);
    RESET_ClearPeripheralReset(UART_LTE_PERIPHERAL_RESET);

    uint32_t pinConfig = (
                UART_LTE_TX_ALT_FUNC  |
                /* Selects pull-up function */
                IOCON_PIO_MODE(0)     |
                /* Standard mode, output slew rate control is enabled */
                IOCON_PIO_SLEW(0)     |
                /* Input function is not inverted */
                IOCON_PIO_INVERT(0)   |
                /* Enables digital function */
                IOCON_PIO_DIGIMODE(1));
    IOCON_PinMuxSet(IOCON,UART_LTE_TX_PORT,UART_LTE_TX_PIN,pinConfig);

    pinConfig = (
                UART_LTE_RX_ALT_FUNC |
                /* Selects pull-up function */
                IOCON_PIO_MODE(0)     |
                /* Standard mode, output slew rate control is enabled */
                IOCON_PIO_SLEW(0)     |
                /* Input function is not inverted */
                IOCON_PIO_INVERT(0)   |
                /* Enables digital function */
                IOCON_PIO_DIGIMODE(1));
    IOCON_PinMuxSet(IOCON,UART_LTE_RX_PORT,UART_LTE_RX_PIN,pinConfig);

    usart_config_t uartLTEConfig =
    {
        .baudRate_Bps = UART_LTE_BAUDRATE,
        .syncMode = kUSART_SyncModeDisabled,
        .parityMode = kUSART_ParityDisabled,
        .stopBitCount = kUSART_OneStopBit,
        .bitCountPerChar = kUSART_8BitsPerChar,
        .loopback = false,
        .txWatermark = kUSART_TxFifo0,
        .rxWatermark = kUSART_RxFifo1,
        .enableRx = true,
        .enableTx = true,
        .enableHardwareFlowControl = false,
        .enableMode32k = false,
        .clockPolarity = kUSART_RxSampleOnFallingEdge,
        .enableContinuousSCLK = false
    };
    USART_Init(UART_LTE_PERIPHERAL,&uartLTEConfig,UART_LTE_CLOCK_FREQUENCY);
    USART_EnableInterrupts(UART_LTE_PERIPHERAL, kUSART_RxLevelInterruptEnable | kUSART_RxErrorInterruptEnable);
    EnableIRQ(UART_LTE_IRQ);

    // BLE/DEBUG UART Management
    CLOCK_AttachClk(UART_BLUETOOTH_CLOCK);
    RESET_ClearPeripheralReset(UART_BLUETOOTH_PERIPHERAL_RESET);

    pinConfig = (
                UART_BLUETOOTH_TX_ALT_FUNC  |
                /* Selects pull-up function */
                IOCON_PIO_MODE(0)     |
                /* Standard mode, output slew rate control is enabled */
                IOCON_PIO_SLEW(0)     |
                /* Input function is not inverted */
                IOCON_PIO_INVERT(0)   |
                /* Enables digital function */
                IOCON_PIO_DIGIMODE(1));
    IOCON_PinMuxSet(IOCON,UART_BLUETOOTH_TX_PORT,UART_BLUETOOTH_TX_PIN,pinConfig);

    pinConfig = (
                UART_BLUETOOTH_RX_ALT_FUNC |
                /* Selects pull-up function */
                IOCON_PIO_MODE(0)     |
                /* Standard mode, output slew rate control is enabled */
                IOCON_PIO_SLEW(0)     |
                /* Input function is not inverted */
                IOCON_PIO_INVERT(0)   |
                /* Enables digital function */
                IOCON_PIO_DIGIMODE(1));
    IOCON_PinMuxSet(IOCON,UART_BLUETOOTH_RX_PORT,UART_BLUETOOTH_RX_PIN,pinConfig);

    usart_config_t uartBluetoothConfig =
    {
        .baudRate_Bps = UART_BLUETOOTH_BAUDRATE,
        .syncMode = kUSART_SyncModeDisabled,
        .parityMode = kUSART_ParityDisabled,
        .stopBitCount = kUSART_OneStopBit,
        .bitCountPerChar = kUSART_8BitsPerChar,
        .loopback = false,
        .txWatermark = kUSART_TxFifo0,
        .rxWatermark = kUSART_RxFifo1,
        .enableRx = true,
        .enableTx = true,
        .enableHardwareFlowControl = false,
        .enableMode32k = false,
        .clockPolarity = kUSART_RxSampleOnFallingEdge,
        .enableContinuousSCLK = false
    };

    USART_Init(UART_BLUETOOTH_PERIPHERAL,&uartBluetoothConfig,UART_BLUETOOTH_CLOCK_FREQUENCY);
    //FIXME: USART_EnableInterrupts(UART_BLUETOOTH_PERIPHERAL, kUSART_RxLevelInterruptEnable | kUSART_RxErrorInterruptEnable);
    //FIXME: EnableIRQ(UART_BLUETOOTH_IRQ);

    // Modbus #1 UART Management
    CLOCK_AttachClk(RS485_1_CLOCK);
    RESET_ClearPeripheralReset(RS485_1_PERIPHERAL_RESET);

    pinConfig = (
                RS485_1_TX_ALT_FUNC  |
                /* Selects pull-up function */
                IOCON_PIO_MODE(0)     |
                /* Standard mode, output slew rate control is enabled */
                IOCON_PIO_SLEW(0)     |
                /* Input function is not inverted */
                IOCON_PIO_INVERT(0)   |
                /* Enables digital function */
                IOCON_PIO_DIGIMODE(1));
    IOCON_PinMuxSet(IOCON,RS485_1_TX_PORT,RS485_1_TX_PIN,pinConfig);

    pinConfig = (
                RS485_1_RX_ALT_FUNC |
                /* Selects pull-up function */
                IOCON_PIO_MODE(0)     |
                /* Standard mode, output slew rate control is enabled */
                IOCON_PIO_SLEW(0)     |
                /* Input function is not inverted */
                IOCON_PIO_INVERT(0)   |
                /* Enables digital function */
                IOCON_PIO_DIGIMODE(1));
    IOCON_PinMuxSet(IOCON,RS485_1_RX_PORT,RS485_1_RX_PIN,pinConfig);

    USART_Init(RS485_1_PERIPHERAL,&uartModbus1Config,RS485_1_CLOCK_FREQUENCY);
//    USART_EnableInterrupts(RS485_1_PERIPHERAL, kUSART_RxLevelInterruptEnable | kUSART_RxErrorInterruptEnable);
//    EnableIRQ(RS485_1_IRQ);

    // Modbus #2 UART Management
    CLOCK_AttachClk(RS485_2_CLOCK);
    RESET_ClearPeripheralReset(RS485_2_PERIPHERAL_RESET);

    pinConfig = (
                RS485_2_TX_ALT_FUNC  |
                /* Selects pull-up function */
                IOCON_PIO_MODE(0)     |
                /* Standard mode, output slew rate control is enabled */
                IOCON_PIO_SLEW(0)     |
                /* Input function is not inverted */
                IOCON_PIO_INVERT(0)   |
                /* Enables digital function */
                IOCON_PIO_DIGIMODE(1));
    IOCON_PinMuxSet(IOCON,RS485_2_TX_PORT,RS485_2_TX_PIN,pinConfig);

    pinConfig = (
                RS485_2_RX_ALT_FUNC |
                /* Selects pull-up function */
                IOCON_PIO_MODE(0)     |
                /* Standard mode, output slew rate control is enabled */
                IOCON_PIO_SLEW(0)     |
                /* Input function is not inverted */
                IOCON_PIO_INVERT(0)   |
                /* Enables digital function */
                IOCON_PIO_DIGIMODE(1));
    IOCON_PinMuxSet(IOCON,RS485_2_RX_PORT,RS485_2_RX_PIN,pinConfig);

    USART_Init(RS485_2_PERIPHERAL,&uartModbus2Config,RS485_2_CLOCK_FREQUENCY);
//    USART_EnableInterrupts(RS485_2_PERIPHERAL, kUSART_RxLevelInterruptEnable | kUSART_RxErrorInterruptEnable);
//    EnableIRQ(RS485_2_IRQ);
}

The RS485_2 (flexcomm4) and LTE (flexcomm0) works and I can transmit data.  The other two doens't works and the tx line is always low. I check the pin and the configuration several times... can you help me to find the bug?

Best

Marco

[xiangjun_rong]

Hi,

First of all, you have to enable the IOCON module clock before you initialize the IOCON register, pls add the line at the first of the code.

I have checked the other code, it appears it is okay.

Hope it can help you

BR

Xiangjun Rong

CLOCK_EnableClock(kCLOCK_Iocon);

[MarcoGiammarini]

Hi @xiangjun_rong ,

thanks for your reply. In the code I put in the previous message I forgot the line to enable the IOCON, but before calling the initUarts() I enable the IOCON clock.

Any other tips?

BR

Marco

[xiangjun_rong]

Hi,

The SDK has the example of uart in interrupt mode, pls try to run it and check if there is issue.

I suggest you have the uart to transfer char repeatedly, then check if you can receive the char or check the waveform of the uart TX pin.

Hope it can help you

BR

XiangJun Rong