STM32F2系列之USART學(xué)習(xí)

F2系列USART初始化注意點：

需要用到的外設(shè)文件有：

stm32f2xx_usart.c; //串口相應(yīng)函數(shù)

stm32f2xx_gpio.c; //GPIO初始化

stm32f2xx_rcc.c; //時鐘初始化

misc.c; //中斷初始化

初始化主要包括8個部分。

1、使能GPIO時鐘：

RCC_AHB1PeriphClockCmd(GPIOX, ENABLE);

2、使能UART時鐘：

RCC_APB1PeriphClockCmd(RCC_APB1Periph_USARTX, ENABLE);

3、將GPIO引腳連接到USARTX：

原始函數(shù)：GPIO_PinAFConfig(GPIO_TypeDef* GPIOx, uint16_t GPIO_PinSource, uint8_t GPIO_AF);

GPIO_AF可選如下：

GPIO_AF_RTC_50Hz；GPIO_AF_MCO；GPIO_AF_TAMPER；GPIO_AF_SWJ；GPIO_AF_TRACE；GPIO_AF_TIM1；GPIO_AF_TIM2；GPIO_AF_TIM3；GPIO_AF_TIM4；GPIO_AF_TIM5；GPIO_AF_TIM8；GPIO_AF_TIM9；GPIO_AF_TIM10；GPIO_AF_TIM11；GPIO_AF_I2C1；GPIO_AF_I2C2；GPIO_AF_I2C3；GPIO_AF_SPI1；GPIO_AF_SPI2；GPIO_AF_SPI3；GPIO_AF_USART1；GPIO_AF_USART2；GPIO_AF_USART3；GPIO_AF_UART4；GPIO_AF_UART5；GPIO_AF_USART6；GPIO_AF_CAN1；GPIO_AF_CAN2；GPIO_AF_TIM12；GPIO_AF_TIM13；GPIO_AF_TIM14；GPIO_AF_OTG1_FS；GPIO_AF_OTG2_HS；GPIO_AF_ETH；GPIO_AF_FSMC；GPIO_AF_OTG2_FS；GPIO_AF_SDIO；GPIO_AF_DCMI；GPIO_AF_EVENTOUT；

連接TX：

GPIO_PinAFConfig(GPIOX, GPIO_PinSourceY, GPIO_AF);

連接RX：

GPIO_PinAFConfig(GPIOX, GPIO_PinSourceY, GPIO_AF);

4、配置GPIO的TX和RX：

TX配置：

GPIO_OType = GPIO_OType_PP；

GPIO_PuPd = GPIO_PuPd_UP；

GPIO_Mode = GPIO_Mode_AF；

GPIO_Pin = GPIO_Pin_XX;

GPIO_Speed = GPIO_Speed_50MHz;

RX配置：

GPIO_Mode = GPIO_Mode_AF;

GPIO_Pin = GPIO_Pin_XX;

5、串口初始化：

USART_InitStructure.USART_BaudRate = 115200;

USART_InitStructure.USART_WordLength = USART_WordLength_8b;

USART_InitStructure.USART_StopBits = USART_StopBits_1;

USART_InitStructure.USART_Parity = USART_Parity_No;

USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;

USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;

USART_Init(USARTx, &USART_InitStructure)；

6、如需要用到中斷，則還需進行中斷優(yōu)先級配置：

以下為配置UART5中斷為0優(yōu)先級組，搶占優(yōu)先級和子優(yōu)先級分別為0。

void NVIC_Configuration(void)

{

NVIC_InitTypeDef NVIC_InitStructure;

/* Configure the NVIC Preemption Priority Bits */

/* Configure one bit for preemption priority */

/*優(yōu)先級組說明了搶占優(yōu)先級所用的位數(shù)，和子優(yōu)先級所用的位數(shù)在這里是1，7 */

NVIC_PriorityGroupConfig(NVIC_PriorityGroup_0);

/* Enable the USART1 Interrupt */

NVIC_InitStructure.NVIC_IRQChannel = UART5_IRQn; //設(shè)置串口5中斷

NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0; //搶占優(yōu)先級0

NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0; //子優(yōu)先級為0

NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; //使能

NVIC_Init(&NVIC_InitStructure);

}

7、選擇并使能相應(yīng)中斷：

USART_ITConfig(USART1, USART_IT_RXNE, ENABLE); //使能接收中斷

USART_ITConfig(USART1, USART_IT_TXE, ENABLE); //使能發(fā)送緩沖空中斷

USART_ITConfig(USART1, USART_IT_TC, ENABLE); //使能發(fā)送完成中斷

等等；

8、使能USART：

USART_Cmd(USARTx, ENABLE);

以下程序是官網(wǎng)給的初始化。

void STM_EVAL_COMInit(COM_TypeDef COM, USART_InitTypeDef* USART_InitStruct)

{

GPIO_InitTypeDef GPIO_InitStructure;

/* Enable GPIO clock */

RCC_AHB1PeriphClockCmd(COM_TX_PORT_CLK[COM] | COM_RX_PORT_CLK[COM], ENABLE);

if (COM == COM1)

{

/* Enable UART clock */

RCC_APB1PeriphClockCmd(COM_USART_CLK[COM], ENABLE);

}

/* Connect PXx to USARTx_Tx*/

GPIO_PinAFConfig(COM_TX_PORT[COM], COM_TX_PIN_SOURCE[COM], COM_TX_AF[COM]);

/* Connect PXx to USARTx_Rx*/

GPIO_PinAFConfig(COM_RX_PORT[COM], COM_RX_PIN_SOURCE[COM], COM_RX_AF[COM]);

/* Configure USART Tx as alternate function */

GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;

GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;

GPIO_InitStructure.GPIO_Pin = COM_TX_PIN[COM];

GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;

GPIO_Init(COM_TX_PORT[COM], &GPIO_InitStructure);

/* Configure USART Rx as alternate function */

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;

GPIO_InitStructure.GPIO_Pin = COM_RX_PIN[COM];

GPIO_Init(COM_RX_PORT[COM], &GPIO_InitStructure);

/* USART configuration */

USART_Init(COM_USART[COM], USART_InitStruct);

/* Enable USART */

USART_Cmd(COM_USART[COM], ENABLE);

}