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一、硬件连接确认

串口选择开发板默认调试串口为 LPUART0，通过板载调试器连接USB虚拟串口。

查看原理图确认目标串口引脚。

PC端接入开发板J21，设备管理器会弹出端口。

二、核心代码实现

串口初始化代码

void BOARD_InitPins(void)
{
    /* PORT0: Peripheral clock is enabled */
    CLOCK_EnableClock(kCLOCK_GatePORT0);
    /* LPUART0 peripheral is released from reset */
    RESET_ReleasePeripheralReset(kLPUART0_RST_SHIFT_RSTn);
    /* PORT0 peripheral is released from reset */
    RESET_ReleasePeripheralReset(kPORT0_RST_SHIFT_RSTn);

    const port_pin_config_t port0_2_pin78_config = {/* Internal pull-up resistor is enabled */
                                                    kPORT_PullUp,
                                                    /* Low internal pull resistor value is selected. */
                                                    kPORT_LowPullResistor,
                                                    /* Fast slew rate is configured */
                                                    kPORT_FastSlewRate,
                                                    /* Passive input filter is disabled */
                                                    kPORT_PassiveFilterDisable,
                                                    /* Open drain output is disabled */
                                                    kPORT_OpenDrainDisable,
                                                    /* Low drive strength is configured */
                                                    kPORT_LowDriveStrength,
                                                    /* Normal drive strength is configured */
                                                    kPORT_NormalDriveStrength,
                                                    /* Pin is configured as LPUART0_RXD */
                                                    kPORT_MuxAlt2,
                                                    /* Digital input enabled */
                                                    kPORT_InputBufferEnable,
                                                    /* Digital input is not inverted */
                                                    kPORT_InputNormal,
                                                    /* Pin Control Register fields [15:0] are not locked */
                                                    kPORT_UnlockRegister};
    /* PORT0_2 (pin 78) is configured as LPUART0_RXD */
    PORT_SetPinConfig(PORT0, 2U, &port0_2_pin78_config);

    const port_pin_config_t port0_3_pin79_config = {/* Internal pull-up resistor is enabled */
                                                    kPORT_PullUp,
                                                    /* Low internal pull resistor value is selected. */
                                                    kPORT_LowPullResistor,
                                                    /* Fast slew rate is configured */
                                                    kPORT_FastSlewRate,
                                                    /* Passive input filter is disabled */
                                                    kPORT_PassiveFilterDisable,
                                                    /* Open drain output is disabled */
                                                    kPORT_OpenDrainDisable,
                                                    /* Low drive strength is configured */
                                                    kPORT_LowDriveStrength,
                                                    /* Normal drive strength is configured */
                                                    kPORT_NormalDriveStrength,
                                                    /* Pin is configured as LPUART0_TXD */
                                                    kPORT_MuxAlt2,
                                                    /* Digital input enabled */
                                                    kPORT_InputBufferEnable,
                                                    /* Digital input is not inverted */
                                                    kPORT_InputNormal,
                                                    /* Pin Control Register fields [15:0] are not locked */
                                                    kPORT_UnlockRegister};
    /* PORT0_3 (pin 79) is configured as LPUART0_TXD */
    PORT_SetPinConfig(PORT0, 3U, &port0_3_pin79_config);
}
status_t DbgConsole_Init(uint8_t instance, uint32_t baudRate, serial_port_type_t device, uint32_t clkSrcFreq)
{
    hal_uart_config_t usrtConfig;

    if (kSerialPort_Uart != device)
    {
        return kStatus_Fail;
    }

    /* Set debug console to initialized to avoid duplicated initialized operation. */
    s_debugConsole.serial_port_type = device;

    usrtConfig.srcClock_Hz  = clkSrcFreq;
    usrtConfig.baudRate_Bps = baudRate;
    usrtConfig.parityMode   = kHAL_UartParityDisabled;
    usrtConfig.stopBitCount = kHAL_UartOneStopBit;
    usrtConfig.enableRx     = 1U;
    usrtConfig.enableTx     = 1U;
    usrtConfig.enableRxRTS  = 0U;
    usrtConfig.enableTxCTS  = 0U;
    usrtConfig.instance     = instance;
#if (defined(HAL_UART_ADAPTER_FIFO) && (HAL_UART_ADAPTER_FIFO > 0u))
    usrtConfig.txFifoWatermark = 0U;
    usrtConfig.rxFifoWatermark = 0U;
#endif
    /* Enable clock and initial UART module follow user configure structure. */
    (void)HAL_UartInit((hal_uart_handle_t)&s_debugConsole.uartHandleBuffer[0], &usrtConfig);
    /* Set the function pointer for send and receive for this kind of device. */
    s_debugConsole.putChar = HAL_UartSendBlocking;
    s_debugConsole.getChar = HAL_UartReceiveBlocking;

    return kStatus_Success;
}
int main(void)
{
    char ch;

    /* Init board hardware. */
    BOARD_InitPins();
    BOARD_InitBootClocks();
    BOARD_InitDebugConsole();

    PRINTF("hello eeworld.\r\n");

    while (1)
    {
        ch = GETCHAR();
        PUTCHAR(ch);
    }
}
Building target: frdmmcxa156_hello_world.axf
Invoking: MCU Linker
arm-none-eabi-gcc -nostdlib -Xlinker -no-warn-rwx-segments -Xlinker -Map="frdmmcxa156_hello_world.map" -Xlinker --gc-sections -Xlinker -print-memory-usage -Xlinker --sort-section=alignment -Xlinker --cref -mcpu=cortex-m33 -mfpu=fpv5-sp-d16 -mfloat-abi=hard -mthumb -T frdmmcxa156_hello_world_Debug.ld -o "frdmmcxa156_hello_world.axf" ./utilities/fsl_assert.o ./utilities/fsl_debug_console.o ./utilities/fsl_memcpy.o ./utilities/fsl_str.o  ./startup/startup_mcxa156.o  ./source/hello_world.o ./source/semihost_hardfault.o  ./drivers/fsl_clock.o ./drivers/fsl_common.o ./drivers/fsl_common_arm.o ./drivers/fsl_gpio.o ./drivers/fsl_lpuart.o ./drivers/fsl_reset.o ./drivers/fsl_spc.o  ./device/system_MCXA156.o  ./component/uart/fsl_adapter_lpuart.o  ./component/lists/fsl_component_generic_list.o  ./board/board.o ./board/clock_config.o ./board/pin_mux.o   
Memory region         Used Size  Region Size  %age Used
   PROGRAM_FLASH:       11820 B         1 MB      1.13%
            SRAM:        8444 B       120 KB      6.87%
           SRAMX:          0 GB        12 KB      0.00%
Finished building target: frdmmcxa156_hello_world.axf
 
Performing post-build steps
arm-none-eabi-size 'frdmmcxa156_hello_world.axf'; arm-none-eabi-objcopy -v -O binary 'frdmmcxa156_hello_world.axf' 'frdmmcxa156_hello_world.bin'
   text	   data	    bss	    dec	    hex	filename
  11812	      8	   8436	  20256	   4f20	frdmmcxa156_hello_world.axf
copy from `frdmmcxa156_hello_world.axf' [elf32-littlearm] to `frdmmcxa156_hello_world.bin' [binary]
 

22:04:59 Build Finished. 0 errors, 0 warnings. (took 10s.918ms)

三.配置

引脚功能

四.接收效果