内容介绍

项目和设计思路介绍

非常开心能够参与并顺利完成Funpack 5-1的活动，本次项目的方向是任务1：串口通信

基础题目：使用MCXA346开发板的UART串口输出“Hello, DigiKey Funpack 5-1”。

项目的整体开发方向是

先熟悉恩智浦MCU的开发环境
熟悉MCXA346的UART模块
初始化UART，并输出“Hello, DigiKey Funpack 5-1”到上位机串口助手。

硬件系统框图

软件流程图

硬件介绍（控制器及使用外设）

主控制器MCXA346介绍

FRDM-MCXA346 是一款紧凑且可扩展的开发板，可让你快速基于FRDM-MCXA346微控制器单元(MCU)开展原型设计。它们提供行业标准的接口，可轻松访问MCU的I/O，配备集成的开放标准串行接口、外部闪存和板载MCU-Link调试器。通过 MCUXpresso Developer Experience提供其他工具，如面向附加板的扩展板中心和面向软件示例的应用代码中心。

板卡特性：

微控制器
- MCX A346 Arm® Cortex®-M33内核，运行频率高达180MHz
- 高达1MB的闪存，高达256KB的RAM，带8KB的纠错码(ECC)，支持乘法累加单元(MAU)和SmartDMA、控制器局域网灵活数据速率(CAN-FD)、低功耗通用异步收发器(LPUART)、低功耗串行外设接口(LPSPI)、低功耗内部集成电路(LPI2C)、DMA和低压差稳压器(LDO)
连接
- 高速通用串行总线(HS USB) Type-C连接器(板载MCU-Link调试器)
- 控制器局域网(CAN)/I3C/串行外设接口(SPI)/I²C/UART连接器(Arduino，外设模块(PMOD)/微控制器总线(mikroBUS)，未安装(DNP))
- Wi-Fi连接器(Arduino，外设模块(PMOD)/微控制器总线(mikroBUS)，未安装(DNP))
- 摄像头连接器(SmartDMA)
调试器
- 板载MCU-Link调试器，带有CMSIS-DAP
- JTAG/SWD/SWD连接器
扩展选项
- Arduino®接头
- FRDM接头
- Pmod™ *DNP
- mikroBUS™
- SmartDMA/摄像头接头
- 通用输入/输出1 (GPIO1)接头
- 通用输入/输出2 (GPIO2)接头

UART外设

本次项目使用的LPUART模块是LPUART2。它与MCU-LINK连接，可以把字符串打印到上位机。

开发环境搭建

系统的开发使用的是恩智浦的MCUXPRESSO IDE，其内置了SDK下载，编译，调试等多个功能。一站式完成项目开发。

官方SDK可以选择从恩智浦SDK Builder网站自行制作：

也可以打开MCUXPRESSO后，在Installed SDKs一栏中，点击“Download and Install SDKs”：

然后输入开发板型号：

之后会自动从官网服务器下载并安装SDK：

硬件实现功能展示

按下开发板RST复位，然后观察串口助手：

关键代码

LPUART2相关宏定义：

#define BOARD_DEBUG_UART_TYPE     kSerialPort_Uart

#define BOARD_DEBUG_UART_CLK_FREQ 12000000U



#ifndef BOARD_DEBUG_UART_BAUDRATE

#define BOARD_DEBUG_UART_BAUDRATE 115200U

#endif



#define BOARD_DEBUG_UART_BASEADDR   (uint32_t) LPUART2

#define BOARD_DEBUG_UART_INSTANCE   2U

#define BOARD_DEBUG_UART_CLK_ATTACH kFRO_LF_DIV_to_LPUART2

#define BOARD_DEBUG_UART_RST        kLPUART2_RST_SHIFT_RSTn

#define BOARD_DEBUG_UART_CLKSRC     kCLOCK_LPUART2

#define BOARD_UART_IRQ_HANDLER      LPUART2_IRQHandler

#define BOARD_UART_IRQ              LPUART2_IRQn

初始化LPUART2引脚：

void BOARD_InitDEBUG_UARTPins(void)

{

    /* PORT2: Peripheral clock is enabled */

    CLOCK_EnableClock(kCLOCK_GatePORT2);

    /* LPUART2 peripheral is released from reset */

    RESET_ReleasePeripheralReset(kLPUART2_RST_SHIFT_RSTn);

    /* PORT2 peripheral is released from reset */

    RESET_ReleasePeripheralReset(kPORT2_RST_SHIFT_RSTn);



    const port_pin_config_t port2_2_pin35_config = {/* Internal pull-up resistor is enabled */

                                                    .pullSelect = kPORT_PullUp,

                                                    /* Low internal pull resistor value is selected. */

                                                    .pullValueSelect = kPORT_LowPullResistor,

                                                    /* Fast slew rate is configured */

                                                    .slewRate = kPORT_FastSlewRate,

                                                    /* Passive input filter is disabled */

                                                    .passiveFilterEnable = kPORT_PassiveFilterDisable,

                                                    /* Open drain output is disabled */

                                                    .openDrainEnable = kPORT_OpenDrainDisable,

                                                    /* Low drive strength is configured */

                                                    .driveStrength = kPORT_LowDriveStrength,

                                                    /* Normal drive strength is configured */

                                                    .driveStrength1 = kPORT_NormalDriveStrength,

                                                    /* Pin is configured as LPUART2_TXD */

                                                    .mux = kPORT_MuxAlt3,

                                                    /* Digital input enabled */

                                                    .inputBuffer = kPORT_InputBufferEnable,

                                                    /* Digital input is not inverted */

                                                    .invertInput = kPORT_InputNormal,

                                                    /* Pin Control Register fields [15:0] are not locked */

                                                    .lockRegister = kPORT_UnlockRegister};

    /* PORT2_2 (pin 35) is configured as LPUART2_TXD */

    PORT_SetPinConfig(PORT2, 2U, &port2_2_pin35_config);



    const port_pin_config_t port2_3_pin36_config = {/* Internal pull-up resistor is enabled */

                                                    .pullSelect = kPORT_PullUp,

                                                    /* Low internal pull resistor value is selected. */

                                                    .pullValueSelect = kPORT_LowPullResistor,

                                                    /* Fast slew rate is configured */

                                                    .slewRate = kPORT_FastSlewRate,

                                                    /* Passive input filter is disabled */

                                                    .passiveFilterEnable = kPORT_PassiveFilterDisable,

                                                    /* Open drain output is disabled */

                                                    .openDrainEnable = kPORT_OpenDrainDisable,

                                                    /* Low drive strength is configured */

                                                    .driveStrength = kPORT_LowDriveStrength,

                                                    /* Normal drive strength is configured */

                                                    .driveStrength1 = kPORT_NormalDriveStrength,

                                                    /* Pin is configured as LPUART2_RXD */

                                                    .mux = kPORT_MuxAlt3,

                                                    /* Digital input enabled */

                                                    .inputBuffer = kPORT_InputBufferEnable,

                                                    /* Digital input is not inverted */

                                                    .invertInput = kPORT_InputNormal,

                                                    /* Pin Control Register fields [15:0] are not locked */

                                                    .lockRegister = kPORT_UnlockRegister};

    /* PORT2_3 (pin 36) is configured as LPUART2_RXD */

    PORT_SetPinConfig(PORT2, 3U, &port2_3_pin36_config);

}

初始化时钟 180MHz:

void BOARD_BootClockFROHF180M(void)

{

    uint32_t coreFreq;

    spc_active_mode_core_ldo_option_t ldoOption;

    spc_sram_voltage_config_t sramOption;



    /* Get the CPU Core frequency */

    coreFreq = CLOCK_GetCoreSysClkFreq();



    /* The flow of increasing voltage and frequency */

    if (coreFreq <= BOARD_BOOTCLOCKFROHF180M_CORE_CLOCK) {

        /* Set the LDO_CORE VDD regulator level */

        ldoOption.CoreLDOVoltage = kSPC_CoreLDO_OverDriveVoltage;

        ldoOption.CoreLDODriveStrength = kSPC_CoreLDO_NormalDriveStrength;

        (void)SPC_SetActiveModeCoreLDORegulatorConfig(SPC0, &ldoOption);

        /* Configure Flash to support different voltage level and frequency */

        FMU0->FCTRL = (FMU0->FCTRL & ~((uint32_t)FMU_FCTRL_RWSC_MASK)) | (FMU_FCTRL_RWSC(0x4U));

        /* Specifies the operating voltage for the SRAM's read/write timing margin */

        sramOption.operateVoltage = kSPC_sramOperateAt1P2V;

        sramOption.requestVoltageUpdate =  true;

        (void)SPC_SetSRAMOperateVoltage(SPC0, &sramOption);

    }





    /*!< Set up system dividers */

    CLOCK_SetClockDiv(kCLOCK_DivAHBCLK, 1U);               /* !< Set SYSCON.AHBCLKDIV divider to value 1 */

    CLOCK_SetClockDiv(kCLOCK_DivFRO_HF, 1U);               /* !< Set SYSCON.FROHFDIV divider to value 1 */

    CLOCK_SetupFROHFClocking(180000000U);              /*!< Enable FRO HF(180MHz) output */

    CLOCK_SetupFRO12MClocking();                /*!< Setup FRO12M clock */



    CLOCK_AttachClk(kFRO_HF_to_MAIN_CLK);       /* !< Switch MAIN_CLK to kFRO_HF */



    /* The flow of decreasing voltage and frequency */

    if (coreFreq > BOARD_BOOTCLOCKFROHF180M_CORE_CLOCK) {

        /* Configure Flash to support different voltage level and frequency */

        FMU0->FCTRL = (FMU0->FCTRL & ~((uint32_t)FMU_FCTRL_RWSC_MASK)) | (FMU_FCTRL_RWSC(0x4U));

        /* Specifies the operating voltage for the SRAM's read/write timing margin */

        sramOption.operateVoltage = kSPC_sramOperateAt1P2V;

        sramOption.requestVoltageUpdate =  true;

        (void)SPC_SetSRAMOperateVoltage(SPC0, &sramOption);

        /* Set the LDO_CORE VDD regulator level */

        ldoOption.CoreLDOVoltage = kSPC_CoreLDO_OverDriveVoltage;

        ldoOption.CoreLDODriveStrength = kSPC_CoreLDO_NormalDriveStrength;

        (void)SPC_SetActiveModeCoreLDORegulatorConfig(SPC0, &ldoOption);

    }



    /*!< Set up clock selectors - Attach clocks to the peripheries */

    CLOCK_AttachClk(kCPU_CLK_to_TRACE);                    /* !< Switch TRACE to CPU_CLK */



    /*!< Set up dividers */

    CLOCK_SetClockDiv(kCLOCK_DivFRO_LF, 1U);               /* !< Set SYSCON.FROLFDIV divider to value 1 */

    CLOCK_SetClockDiv(kCLOCK_DivWWDT0, 1U);                /* !< Set MRCC.WWDT0_CLKDIV divider to value 1 */

    CLOCK_SetClockDiv(kCLOCK_DivTRACE, 2U);                /* !< Set MRCC.TRACE_CLKDIV divider to value 2 */



    /* Set SystemCoreClock variable */

    SystemCoreClock = BOARD_BOOTCLOCKFROHF180M_CORE_CLOCK;

}

初始化LPUART2模块：

void BOARD_InitDebugConsole(void)

{

    /* attach 12 MHz clock to FLEXCOMM0 (debug console) */

    CLOCK_SetClockDiv(kCLOCK_DivLPUART2, 1u);

    CLOCK_AttachClk(BOARD_DEBUG_UART_CLK_ATTACH);



    RESET_PeripheralReset(BOARD_DEBUG_UART_RST);



    DbgConsole_Init(BOARD_DEBUG_UART_INSTANCE, BOARD_DEBUG_UART_BAUDRATE, BOARD_DEBUG_UART_TYPE,

                    BOARD_DEBUG_UART_CLK_FREQ);

}

包含头文件：

#include "fsl_debug_console.h"

打印指定字符串到串口助手：

PRINTF("Hello, DigiKey Funpack 5-1\r\n");

总结

通过本次Funpack活动，首次接触NXP单片机，并实现了使用串口UART打印指定字符串到串口的功能。

本期活动获益良多，感谢硬禾与Digikey提供的平台，感谢诸位网友提供的协助！