1.使能时钟
使能时钟函数原代码如下:
/**
* @brief Enables or disables the High Speed APB (APB2) peripheral clock.
* @param RCC_APB2Periph: specifies the APB2 peripheral to gates its clock.
* This parameter can be any combination of the following values:
* @arg RCC_APB2Periph_AFIO, RCC_APB2Periph_GPIOA, RCC_APB2Periph_GPIOB,
* RCC_APB2Periph_GPIOC, RCC_APB2Periph_GPIOD, RCC_APB2Periph_GPIOE,
* RCC_APB2Periph_GPIOF, RCC_APB2Periph_GPIOG, RCC_APB2Periph_ADC1,
* RCC_APB2Periph_ADC2, RCC_APB2Periph_TIM1, RCC_APB2Periph_SPI1,
* RCC_APB2Periph_TIM8, RCC_APB2Periph_USART1, RCC_APB2Periph_ADC3,
* RCC_APB2Periph_TIM15, RCC_APB2Periph_TIM16, RCC_APB2Periph_TIM17,
* RCC_APB2Periph_TIM9, RCC_APB2Periph_TIM10, RCC_APB2Periph_TIM11
* @param NewState: new state of the specified peripheral clock.
* This parameter can be: ENABLE or DISABLE.
* @retval None
*/
void RCC_APB2PeriphClockCmd(uint32_t RCC_APB2Periph, FunctionalState NewState)
{
/* Check the parameters */
assert_param(IS_RCC_APB2_PERIPH(RCC_APB2Periph));
assert_param(IS_FUNCTIONAL_STATE(NewState));
if (NewState != DISABLE)
{
RCC->APB2ENR |= RCC_APB2Periph;
}
else
{
RCC->APB2ENR &= ~RCC_APB2Periph;
}
}
根据源代码可知,需要两个参数,第一个参数为使能的寄存器,第二个参数为使能状态
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOC,ENABLE);
2.设置/初始化端口模式
初始化代码如下,有两个参数,第一个参数选择初始化的端口,第二个参数设置模式
/**
* @brief Initializes the GPIOx peripheral according to the specified
* parameters in the GPIO_InitStruct.
* @param GPIOx: where x can be (A..G) to select the GPIO peripheral.
* @param GPIO_InitStruct: pointer to a GPIO_InitTypeDef structure that
* contains the configuration information for the specified GPIO peripheral.
* @retval None
*/
void GPIO_Init(GPIO_TypeDef* GPIOx, GPIO_InitTypeDef* GPIO_InitStruct)
{
uint32_t currentmode = 0x00, currentpin = 0x00, pinpos = 0x00, pos = 0x00;
uint32_t tmpreg = 0x00, pinmask = 0x00;
/* Check the parameters */
assert_param(IS_GPIO_ALL_PERIPH(GPIOx));
assert_param(IS_GPIO_MODE(GPIO_InitStruct->GPIO_Mode));
assert_param(IS_GPIO_PIN(GPIO_InitStruct->GPIO_Pin));
/*---------------------------- GPIO Mode Configuration -----------------------*/
currentmode = ((uint32_t)GPIO_InitStruct->GPIO_Mode) & ((uint32_t)0x0F);
if ((((uint32_t)GPIO_InitStruct->GPIO_Mode) & ((uint32_t)0x10)) != 0x00)
{
/* Check the parameters */
assert_param(IS_GPIO_SPEED(GPIO_InitStruct->GPIO_Speed));
/* Output mode */
currentmode |= (uint32_t)GPIO_InitStruct->GPIO_Speed;
}
/*---------------------------- GPIO CRL Configuration ------------------------*/
/* Configure the eight low port pins */
if (((uint32_t)GPIO_InitStruct->GPIO_Pin & ((uint32_t)0x00FF)) != 0x00)
{
tmpreg = GPIOx->CRL;
for (pinpos = 0x00; pinpos < 0x08; pinpos++)
{
pos = ((uint32_t)0x01) << pinpos;
/* Get the port pins position */
currentpin = (GPIO_InitStruct->GPIO_Pin) & pos;
if (currentpin == pos)
{
pos = pinpos << 2;
/* Clear the corresponding low control register bits */
pinmask = ((uint32_t)0x0F) << pos;
tmpreg &= ~pinmask;
/* Write the mode configuration in the corresponding bits */
tmpreg |= (currentmode << pos);
/* Reset the corresponding ODR bit */
if (GPIO_InitStruct->GPIO_Mode == GPIO_Mode_IPD)
{
GPIOx->BRR = (((uint32_t)0x01) << pinpos);
}
else
{
/* Set the corresponding ODR bit */
if (GPIO_InitStruct->GPIO_Mode == GPIO_Mode_IPU)
{
GPIOx->BSRR = (((uint32_t)0x01) << pinpos);
}
}
}
}
GPIOx->CRL = tmpreg;
}
/*---------------------------- GPIO CRH Configuration ------------------------*/
/* Configure the eight high port pins */
if (GPIO_InitStruct->GPIO_Pin > 0x00FF)
{
tmpreg = GPIOx->CRH;
for (pinpos = 0x00; pinpos < 0x08; pinpos++)
{
pos = (((uint32_t)0x01) << (pinpos + 0x08));
/* Get the port pins position */
currentpin = ((GPIO_InitStruct->GPIO_Pin) & pos);
if (currentpin == pos)
{
pos = pinpos << 2;
/* Clear the corresponding high control register bits */
pinmask = ((uint32_t)0x0F) << pos;
tmpreg &= ~pinmask;
/* Write the mode configuration in the corresponding bits */
tmpreg |= (currentmode << pos);
/* Reset the corresponding ODR bit */
if (GPIO_InitStruct->GPIO_Mode == GPIO_Mode_IPD)
{
GPIOx->BRR = (((uint32_t)0x01) << (pinpos + 0x08));
}
/* Set the corresponding ODR bit */
if (GPIO_InitStruct->GPIO_Mode == GPIO_Mode_IPU)
{
GPIOx->BSRR = (((uint32_t)0x01) << (pinpos + 0x08));
}
}
}
GPIOx->CRH = tmpreg;
}
}
模式的源代码如下,包含引脚,速度,模式,三项内容。
typedef struct
{
uint16_t GPIO_Pin; /*!< Specifies the GPIO pins to be configured.
This parameter can be any value of @ref GPIO_pins_define */
GPIOSpeed_TypeDef GPIO_Speed; /*!< Specifies the speed for the selected pins.
This parameter can be a value of @ref GPIOSpeed_TypeDef */
GPIOMode_TypeDef GPIO_Mode; /*!< Specifies the operating mode for the selected pins.
This parameter can be a value of @ref GPIOMode_TypeDef */
}GPIO_InitTypeDef;
3.输出
输出高电平的源代码为
/**
* @brief Sets the selected data port bits.
* @param GPIOx: where x can be (A..G) to select the GPIO peripheral.
* @param GPIO_Pin: specifies the port bits to be written.
* This parameter can be any combination of GPIO_Pin_x where x can be (0..15).
* @retval None
*/
void GPIO_SetBits(GPIO_TypeDef* GPIOx, uint16_t GPIO_Pin)
{
/* Check the parameters */
assert_param(IS_GPIO_ALL_PERIPH(GPIOx));
assert_param(IS_GPIO_PIN(GPIO_Pin));
GPIOx->BSRR = GPIO_Pin;
}
输出低电平的源代码为
/**
* @brief Clears the selected data port bits.
* @param GPIOx: where x can be (A..G) to select the GPIO peripheral.
* @param GPIO_Pin: specifies the port bits to be written.
* This parameter can be any combination of GPIO_Pin_x where x can be (0..15).
* @retval None
*/
void GPIO_ResetBits(GPIO_TypeDef* GPIOx, uint16_t GPIO_Pin)
{
/* Check the parameters */
assert_param(IS_GPIO_ALL_PERIPH(GPIOx));
assert_param(IS_GPIO_PIN(GPIO_Pin));
GPIOx->BRR = GPIO_Pin;
}
需要两个参数,第一个参数指明哪个寄存器组,第二个参数指明哪个端口
最终点亮的代码为
GPIO_ResetBits(GPIOC,GPIO_Pin_13);