STM32F042G6移植USB CDC例程教學

ul4

STM32F042G6有32KB flash, 6KB ram, QFN-28(4x4mm)
可以用内部高精度48MHz RC(HSI48)直接驱动USB，从此不用外部晶振！
个人认为十分适合拿来做USB应用

但是因为low pin count的缘故
ST在20及28pin的STM32F042中将PA11/12与PA9/10这两组接脚做了复用

Pin pair PA11/12 can be remapped instead of pin pair PA9/10 using the SYSCFG_CFGR1 register

因为USB接脚对应至PA11/12，所以我们使用前必须先做切换
顺带一提启用CAN也要切换IO

由于ST目前还没有针对STM32F042提供例程
所以要从STM32F072的例程来修改：
基于ST例程STM32F0x2_USB-FS-Device_Lib V1.0.0的Virtual_COM_Port
添加了两行
app.c

1. int main(void)
   
2. {
   
3.   /*!< At this stage the microcontroller clock setting is already configured,
   
4.   this is done through SystemInit() function which is called from startup
   
5.   file (startup_stm32f072.s) before to branch to application main.
   
6.   To reconfigure the default setting of SystemInit() function, refer to
   
7.   system_stm32f0xx.c file
   
8.   */  
   
9. 
   
10.        
    
11.   /*The SYSCFG registers can be accessed only when the SYSCFG
    
12.   interface APB clock is enabled.
    
13.   To enable SYSCFG APB clock use:
    
14.   RCC_APB2PeriphClockCmd(RCC_APB2Periph_SYSCFG, ENABLE).*/
    
15.   RCC_APB2PeriphClockCmd(RCC_APB2Periph_SYSCFG, ENABLE);
    
16. 
    
17. 
    
18.   /*!< PA11 and PA12 remapping bit for small packages (28 and 20 pins).
    
19.   0: No remap (pin pair PA9/10 mapped on the pins)
    
20.   1: Remap (pin pair PA11/12 mapped instead of PA9/10) */
    
21.   SYSCFG->CFGR1 |= SYSCFG_CFGR1_PA11_PA12_RMP;
    
22. 
    
23.   /* The Application layer has only to call USBD_Init to
    
24.   initialize the USB low level driver, the USB device library, the USB clock
    
25.   ,pins and interrupt service routine (BSP) to start the Library*/
    
26.   USBD_Init(&USB_Device_dev,
    
27.             &USR_desc,
    
28.             &USBD_CDC_cb,
    
29.             &USR_cb);
    
30.   
    
31.   while (1)
    
32.   {
    
33.   }
    
34. }

复制代码

最后别忘了去stm32072b_eval.c及stm32072b_eval.h修改USART的接脚定义
STM32F042G6没有port D!

xiaoyigechaos

还有哪些型号有高精度内部RC振荡器？

ul4

目前好像有STM32F042, STM32F072, STM32F078, STM32L052, STM32L062, STM32L063系列

aammoo

STM32F042好买吗？价格多少？

jacky_shen

大神，STM32F042的例程请给我一份。

阿喀琉斯

                学习

wenzhi

移植f072例程到f042g6没成功，还在找原因

清浅笑忘

试了大神的配置，还是不能枚举，usb一点反应也没有