STM32L151中USB虚拟串口的问题，各位大侠江湖救急！！

wujie_shao · 发表于 2015-12-24 19:20:34

最近在做USB虚拟串口，USB的库用了STM32_UsbVirtualCom示例工程中的库，但是目前的板子芯片是STM32L151CBT的，所以修改了部分时钟和GPIO配置，外围电路使用原子君的旗舰版中的DP上拉1.5K至3.3V；目前插入PC没有任何反应，测量上拉电阻电压只有0.1V。

代码如下：
void USB_Config(void)
{
Set_System();

Set_USBClock();

USB_Interrupts_Config();

USB_Init();
}

void Set_System(void)
{
GPIO_InitTypeDef GPIO_InitStructure;

QUEUE_PacketCreate(&m_QueueUsbComRx, m_UsbComRxBuf, sizeof(m_UsbComRxBuf));
QUEUE_PacketCreate(&m_QueueUsbComTx, m_UsbComTxBuf, sizeof(m_UsbComTxBuf));

RCC_APB2PeriphClockCmd(RCC_APB2Periph_SYSCFG,ENABLE);
/* Enable USB_DISCONNECT GPIO clock */
RCC_AHBPeriphClockCmd(RCC_APB2Periph_GPIO_DISCONNECT, ENABLE);
}

void Set_USBClock(void)
{
/* Select USBCLK source */
//RCC_USBCLKConfig(RCC_USBCLKSource_PLLCLK_1Div5); （这里L151系列的没有这个寄存器）

/* Enable the USB clock */
RCC_APB1PeriphClockCmd(RCC_APB1Periph_USB, ENABLE);
}

void USB_Interrupts_Config(void)
{
NVIC_InitTypeDef NVIC_InitStructure;

NVIC_PriorityGroupConfig(NVIC_PriorityGroup_1);

NVIC_InitStructure.NVIC_IRQChannel = USB_LP_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 1;
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);

}

void USB_Init(void)
{
pInformation = &Device_Info;
pInformation->ControlState = 2;
pProperty = &Device_Property;
pUser_Standard_Requests = &User_Standard_Requests;
/* Initialize devices one by one */
pProperty->Init();
}

端口配置如下：
//GPA11 -->USBDM GPA12 --->USBDP
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_11 | GPIO_Pin_12;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_40MHz;
GPIO_Init(GPIOA, &GPIO_InitStructure);
GPIO_PinAFConfig(GPIOA, GPIO_PinSource11, GPIO_AF_USB);
GPIO_PinAFConfig(GPIOA, GPIO_PinSource12, GPIO_AF_USB);

时钟配置为外部8MHz, PLLMUL 12, PLL DIV 3为系统时钟。代码如下：
static void SetSysClock(void)
{
__IO uint32_t StartUpCounter = 0, HSEStatus = 0;

/* SYSCLK, HCLK, PCLK2 and PCLK1 configuration ---------------------------*/
/* Enable HSE */
RCC->CR |= ((uint32_t)RCC_CR_HSEON);

/* Wait till HSE is ready and if Time out is reached exit */
do
{
HSEStatus = RCC->CR & RCC_CR_HSERDY;
StartUpCounter++;
} while((HSEStatus == 0) && (StartUpCounter != HSE_STARTUP_TIMEOUT));

if ((RCC->CR & RCC_CR_HSERDY) != RESET)
{
HSEStatus = (uint32_t)0x01;
}
else
{
HSEStatus = (uint32_t)0x00;
}

if (HSEStatus == (uint32_t)0x01)
{
/* Enable 64-bit access */
FLASH->ACR |= FLASH_ACR_ACC64;

/* Enable Prefetch Buffer */
FLASH->ACR |= FLASH_ACR_PRFTEN;

/* Flash 1 wait state */
FLASH->ACR |= FLASH_ACR_LATENCY;

/* Power enable */
RCC->APB1ENR |= RCC_APB1ENR_PWREN;

/* Select the Voltage Range 1 (1.8 V) */
PWR->CR = PWR_CR_VOS_0;

/* Wait Until the Voltage Regulator is ready */
while((PWR->CSR & PWR_CSR_VOSF) != RESET)
{
}

/* HCLK = SYSCLK /1*/
RCC->CFGR |= (uint32_t)RCC_CFGR_HPRE_DIV1;

/* PCLK2 = HCLK /1*/
RCC->CFGR |= (uint32_t)RCC_CFGR_PPRE2_DIV1;

/* PCLK1 = HCLK /1*/
RCC->CFGR |= (uint32_t)RCC_CFGR_PPRE1_DIV1;

/*

LL configuration */
RCC->CFGR &= (uint32_t)((uint32_t)~(RCC_CFGR_PLLSRC | RCC_CFGR_PLLMUL |
RCC_CFGR_PLLDIV));
RCC->CFGR |= (uint32_t)(RCC_CFGR_PLLSRC_HSE | RCC_CFGR_PLLMUL12 | RCC_CFGR_PLLDIV3);

/* Enable PLL */
RCC->CR |= RCC_CR_PLLON;

/* Wait till PLL is ready */
while((RCC->CR & RCC_CR_PLLRDY) == 0)
{
}

/* Select PLL as system clock source */
RCC->CFGR &= (uint32_t)((uint32_t)~(RCC_CFGR_SW));
RCC->CFGR |= (uint32_t)RCC_CFGR_SW_PLL;

/* Wait till PLL is used as system clock source */
while ((RCC->CFGR & (uint32_t)RCC_CFGR_SWS) != (uint32_t)RCC_CFGR_SWS_PLL)
{
}
}
else
{
/* If HSE fails to start-up, the application will have wrong clock
configuration. User can add here some code to deal with this error */
}
}

请各位大侠们江湖救急一下，帮我分析分析，可能哪里配置错了，谢谢！