STM32 USB转串口CDC官方示例程序修正

官方程序中有几个BUG导致只能单字节发送，用7位串口方式也有问题。查看源程序，发现有几个地方需要修改：

1.USB->UART 没有等串口发送完，现象是只能发一个字符

void USB_To_USART_Send_Data(u8* data_buffer, u8 Nb_bytes)

{

u32 i;

for (i = 0; i < Nb_bytes; i++)

{

USART_SendData(USART1, *(data_buffer + i));

//added by dreamdive

while(USART_GetFlagStatus(USART1, USART_FLAG_TXE) == RESET);

}

}

2.bool USART_Config(void)函数中，数据长度设置错误导致乱码

/*set the data type : only 8bits and 9bits is supported */

switch (linecoding.datatype)

{

case 0x07://数据长度7位

USART_InitStructure.USART_WordLength = USART_WordLength_8b;

break;

case 0x08://数据长度8位

//USART_InitStructure.USART_WordLength = USART_WordLength_9b;

//无较验位时用8位方式，否则用9位方式

if(linecoding.paritytype==USART_Parity_No)

USART_InitStructure.USART_WordLength = USART_WordLength_8b;

else

USART_InitStructure.USART_WordLength = USART_WordLength_9b;

break;

default :

{

USART_Config_Default();

return (FALSE);

}

}

3.void USART_To_USB_Send_Data(void)函数中，判断错误导致用7位串口方式时UART->USB乱码

if (USART_InitStructure.USART_WordLength == USART_WordLength_8b)

{

buffer_in[count_in] = USART_ReceiveData(USART1) & 0x7F;

}

else if (USART_InitStructure.USART_WordLength == USART_WordLength_9b)

{

buffer_in[count_in] = USART_ReceiveData(USART1);

}

改为：

if (linecoding.datatype == 0x07)

{

buffer_in[count_in] = USART_ReceiveData(USART1) & 0x7F;

}

else

{

buffer_in[count_in] = USART_ReceiveData(USART1);

}

经测试，8位无校验/带校验和7位无校验/带校验工作全部正常。

刚刚看了ST最新官方um0424.zip,修正和我想的一样，呵呵:-).