如何理解STM32的程序GPIO_Init(GPIOB, &GPIO_InitStructure);
GPIO_Init(GPIOB, &GPIO_InitStructure); //调用函数GPIO_Init();
//被调用函数
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;
}
}
程序中使用的固件库是V3.5固件库,传入的参数GPIOB是指向结构体类型的指针变量还是结构体的首地址?
&GPIO_InitStructure 这个很明确传入的是结构体的首地址,关于传入的参数GPIOB不知道怎么理解,请高人指点! STM32的V3-5固件库 指向结构体的指针变量 结构体类型的数据
[解决办法]
GPIO_Init(GPIOB, &GPIO_InitStructure);
用结构体GPIO_InitStructure内已经赋过值的参数或者默认的参数,来初始化GBIO端口B的控制、方式寄存器,决定端口B的工作方式。
你只要看看STM32的例程,很容易明白,不需要高人。
[解决办法]
你查看下GPIOB的类型GPIO_TypeDef是怎么定义的,应该是一个结构体,里面的成员是和GPIO的控制寄存器一一对应的,然后GPIOB或者GPIOA是这个类型但是其地址固定的
说简单点
其实就是一个常数地址,指向GPIOB的相关寄存器
[解决办法]