GD32F103内部Flash做虚拟U盘

Posted 2021-09-08 qlexcel

直接使用官方例程，有如下注意点：
1、USB的时钟是48MHz，需要根据自己的系统主频来分频。否则时钟频率不对，USB会枚举失败，电脑提示设备描述符获取失败。
在如下文件和位置设置宏定义来选择系统主频。

然后根据自己的主频来设置分频：

/*!
    \\brief      configure the different system clocks
    \\param[in]  none
    \\param[out] none
    \\retval     none
*/
void rcu_config(void)
{
    /* enable USB pull-up pin clock */ 
    rcu_periph_clock_enable(RCU_GPIOA);
	
    /* enable the power clock */
    rcu_periph_clock_enable(RCU_PMU);

    /* configure USB model clock from PLL clock */
    rcu_usb_clock_config(RCU_CKUSB_CKPLL_DIV2);  //主频96M，二分频就是48M

    /* enable USB APB1 clock */
    rcu_periph_clock_enable(RCU_USBD);
}

如上，主频是96M，二分频就是48M。
如果主频是72M，就是1.5分频。

/* use HXTAL (XD series CK_HXTAL = 8M, CL series CK_HXTAL = 25M) */
//#define __SYSTEM_CLOCK_HXTAL                    (uint32_t)(__HXTAL)
//#define __SYSTEM_CLOCK_24M_PLL_HXTAL            (uint32_t)(24000000)
//#define __SYSTEM_CLOCK_36M_PLL_HXTAL            (uint32_t)(36000000)
//#define __SYSTEM_CLOCK_48M_PLL_HXTAL            (uint32_t)(48000000)
//#define __SYSTEM_CLOCK_56M_PLL_HXTAL            (uint32_t)(56000000)
#define __SYSTEM_CLOCK_72M_PLL_HXTAL            (uint32_t)(72000000)
//#define __SYSTEM_CLOCK_96M_PLL_HXTAL            (uint32_t)(96000000)
//#define __SYSTEM_CLOCK_108M_PLL_HXTAL           (uint32_t)(108000000)

    /* enable USB pull-up pin clock */ 
    rcu_periph_clock_enable(RCC_AHBPeriph_GPIO_PULLUP);
 
    /* enable the power clock */
    rcu_periph_clock_enable(RCU_PMU);
 
    /* configure USB model clock from PLL clock */
    rcu_usb_clock_config(RCU_CKUSB_CKPLL_DIV1_5);
 
    /* enable USB APB1 clock */
    rcu_periph_clock_enable(RCU_USBD);

2、需要根据自己的芯片型号更改Flash页面大小，比如GD32F103C8T6的页面大小为1K，GD32F103VCT6的页面大小为2K

#define PAGE_SIZE                     ((uint32_t)(1024))
#define NAND_FLASH_BASE_ADDRESS       ((uint32_t)(0x08000000 + 0x04000))
#define NAND_FLASH_END_ADDRESS        ((uint32_t)(0x08000000 + 0x10000))

修改了页面大小，同时还需要修改写扇区函数

比如页面大小为1K，那么写函数修改为：

/*!
    \\brief      write data to multiple blocks of flash
    \\param[in]  pBuf: pointer to user buffer
    \\param[in]  write_addr: address to be write
    \\param[in]  block_size: block size
    \\param[in]  block_num: number of block
    \\param[out] none
    \\retval     status
*/
uint32_t flash_write_multi_blocks (uint8_t *pBuf,
                           uint32_t write_addr,
                           uint16_t block_size,
                           uint32_t block_num)
{
    uint32_t i, page;
    uint32_t start_page = (write_addr / PAGE_SIZE) * PAGE_SIZE + NAND_FLASH_BASE_ADDRESS;
    uint32_t *ptrs = (uint32_t *)pBuf;

    page = block_num;

    for(; page > 0; page--){
        fmc_page_erase(start_page);

        i = 0;

        do{
            fmc_word_program(start_page, *ptrs++);
            start_page += 4;
        }while(++i < 256);
    }

    return 0;
}

实验结果：

和普通的U盘效果一样，可以读写、格式化。