中电港萤火工场推出的GD32VW553-IOT开发板基于兆易创新（GigaDevice）GD32VW553系列MCU。这款MCU的CPU主频最高160MHZ，IP是基于芯来Nuclei N307处理器的riscv32位通用cpu IP，指令集支持I（整数指令）、M（整数乘除法指令）、A（原子指令）、F（单精度浮点指令）、D（双精度浮点指令）、C（压缩指令）。MCU配备4MB Flash, 320KB SRAM。无线通信方面支持WiFi6和BLE5.2。这规格应该和友商的ESP32-C6有一拼，所以笔者挺有兴趣的。

Linux下开发环境搭建

开发环境主要解决编译工具链、源码工程组织和烧录/调试。笔者的编译工具链没使用Nuclei的，而是用的通用xpack-riscv-none-elf-gcc工具链，笔者不太喜欢一个MCU就要搞一套工具链。源码工程组织笔者用cmake结合手写CMakeLists.txt。烧录调试笔者原来准备用openocd，但拿到板子那刻改主意了--板子的jtag引脚都没有，只是测量点，还是用串口烧录工具吧。

下载xpack-riscv-none-elf-gcc工具链

去xpack官网下载此工具链，笔者因以前下载过，所以直接沿用。

下载GD32VW553 Firmware Libraray

如果不开发WiFI/BT相关的，可以只下载Firmware Libraray，从https://www.gd32mcu.com/cn/download/7?kw=GD32VW5这里找到Firmware Libraray下载即可

点灯测试代码编写

因为板子无软件可控LED，所以笔者用串口打印模拟LED开和关。要打印么所以需要初始化串口，这个可参考官方Firmware Libraray中的Examples/USART/Printf/目录下代码。要延时么所以需要初始化MTIME，这相当于arm cortex-m下的systick，代码可参考官方Firmware Libraray中的Examples/GPIO/Running_led/。笔者的最终代码如下：

static void com_usart_init(void)
{
    /* enable COM GPIO clock */
    rcu_periph_clock_enable(RCU_GPIOA);
    rcu_periph_clock_enable(RCU_GPIOB);
    /* enable USART clock */
    rcu_periph_clock_enable(RCU_USART0);

    /* connect port to USART TX */
    gpio_af_set(GPIOB, GPIO_AF_8, GPIO_PIN_15);
    /* connect port to USART RX */
    gpio_af_set(GPIOA, GPIO_AF_2, GPIO_PIN_8);

    /* configure USART Tx as alternate function push-pull */
    gpio_mode_set(GPIOB, GPIO_MODE_AF, GPIO_PUPD_PULLUP, GPIO_PIN_15);
    gpio_output_options_set(GPIOB, GPIO_OTYPE_PP, GPIO_OSPEED_25MHZ, GPIO_PIN_15);

    /* configure USART Rx as alternate function push-pull */
    gpio_mode_set(GPIOA, GPIO_MODE_AF, GPIO_PUPD_PULLUP, GPIO_PIN_8);
    gpio_output_options_set(GPIOA, GPIO_OTYPE_PP, GPIO_OSPEED_25MHZ, GPIO_PIN_8);

    /* USART configuration */
    usart_deinit(USART0);
    usart_word_length_set(USART0, USART_WL_8BIT);
    usart_stop_bit_set(USART0, USART_STB_1BIT);
    usart_parity_config(USART0, USART_PM_NONE);
    usart_baudrate_set(USART0, 115200U);
    usart_receive_config(USART0, USART_RECEIVE_ENABLE);
    usart_transmit_config(USART0, USART_TRANSMIT_ENABLE);
    
    usart_enable(USART0);
}

int main(void)
{
    com_usart_init();
    systick_config();

    printf("\r\nHello GD32VW553\r\n");

    while(1) {
        printf("Led on\r\n");
        delay_1ms(500);
        printf("Led off\r\n");
        delay_1ms(500);
    }
}

CMakeLists.txt编写

注意下gcc的一些CFLAGS参数。例如因cpu是rv32imafdc，所以传递"-march=rv32imafdc -mabi=ilp32d"等等，然后把Firmware Libraray源码和头文件都添加好即可。笔者最终的CMakeLists.txt如下所示：

set(CMAKE_SYSTEM_NAME Generic)
set(CMAKE_SYSTEM_VERSION 1)
set(CMAKE_TRY_COMPILE_TARGET_TYPE "STATIC_LIBRARY")
cmake_minimum_required(VERSION 3.20)

set(CMAKE_C_COMPILER riscv-none-elf-gcc)
set(CMAKE_CXX_COMPILER riscv-none-elf-g++)
set(CMAKE_ASM_COMPILER riscv-none-elf-gcc)
set(CMAKE_AR riscv-none-elf-ar)
set(CMAKE_OBJCOPY riscv-none-elf-objcopy)
set(CMAKE_OBJDUMP riscv-none-elf-objdump)
set(SIZE riscv-none-elf-size)

set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
set(CMAKE_FIND_ROOT_PATH_MODE_PACKAGE ONLY)

add_compile_options(-march=rv32imafdc -mabi=ilp32d -mcmodel=medany -msmall-data-limit=8)
add_compile_options(-Os -fmessage-length=0 -fsigned-char -ffunction-sections -fdata-sections -fno-common)

project(gd32vw553 C ASM)
set(CMAKE_CXX_STANDARD 11)
set(CMAKE_C_STANDARD 99)
include_directories(Firmware/GD32VW55x_standard_peripheral/Include
                    Firmware/GD32VW55x_standard_peripheral
                    Firmware/RISCV/drivers
                    Examples/demo
                    Utilities
                    )

add_definitions(-DAT32F437ZMT7 -DAT_START_F437_V1)

file(GLOB_RECURSE SOURCES
                "Firmware/GD32VW55x_standard_peripheral/Source/*.c"
                "Firmware/GD32VW55x_standard_peripheral/system_gd32vw55x.c"
                "Firmware/RISCV/env_Eclipse/*.c"
                "Firmware/RISCV/env_Eclipse/*.S"
                "Firmware/RISCV/stubs/*.c"
                "Examples/demo/*.c"
                )

set(LINKER_SCRIPT ${CMAKE_SOURCE_DIR}/Firmware/RISCV/env_Eclipse/GD32VW553xM.lds)
add_link_options(
                -march=rv32imafdc -mabi=ilp32d -nostartfiles
                -Wl,--gc-sections,--print-memory-usage,--no-warn-rwx-segments,-Map,${PROJECT_NAME}.map
                --specs=nano.specs
                --specs=nosys.specs)
add_link_options(-T ${LINKER_SCRIPT})

add_executable(${PROJECT_NAME}.elf ${SOURCES} ${LINKER_SCRIPT})

# target_link_libraries(${PROJECT_NAME}.elf printfloat)
set(HEX_FILE ${PROJECT_BINARY_DIR}/${PROJECT_NAME}.hex)
set(BIN_FILE ${PROJECT_BINARY_DIR}/${PROJECT_NAME}.bin)
set(LST_FILE ${PROJECT_BINARY_DIR}/${PROJECT_NAME}.lst)
add_custom_command(TARGET ${PROJECT_NAME}.elf POST_BUILD
        COMMAND ${CMAKE_OBJCOPY} -Oihex $<TARGET_FILE:${PROJECT_NAME}.elf> ${HEX_FILE}
        COMMAND ${CMAKE_OBJCOPY} -Obinary $<TARGET_FILE:${PROJECT_NAME}.elf> ${BIN_FILE}
        COMMAND ${CMAKE_OBJDUMP} --all-headers --demangle --disassemble $<TARGET_FILE:${PROJECT_NAME}.elf> > ${LST_FILE
}
        COMMAND ${SIZE} --format=berkeley $<TARGET_FILE:${PROJECT_NAME}.elf>
)

编译

bcmake -B /tmp/build
cmake --build /tmp/build -j8

编译完毕以后在/tmp/build目录下有一个名为gd32vw553.bin的文件，此文件烧录进板子即可

固件烧录

这是笔者唯一未在linux下成功做到的步骤，所以最后是在windows下用官方烧录工具烧录的，具体步骤其它网友文章都都有，在此略过不提。

运行截图

启动minicom连/dev/ttyUSB0， 波特率115200bps，8n1。运行截图如下所示:

编译测试视频如下

https://www.bilibili.com/video/BV1YoZ8YbE7U/