STM32最簡單的外設莫過於IO口的高低電平控制了, Proteus仿真STM32F103R6的跑馬燈程序。
一、原理圖
二、跑馬燈C程序
// 粗略延時函數
static void delay(unsigned int n)
{
for(unsigned int i=0; i<n; i++)
{
for(unsigned int j=0; j<1024; j++)
{
for(unsigned int k=0; k<1024; k++)
{
__asm("nop");
}
}
}
}
int main(void)
{
// 使能GPIOB端口時鐘
// RCC起始地址:0X40021000
// RCC_APB2ENR偏移地址:0X18
*(unsigned int *)(0X40021000 + 0X18) |= (1 << 3);
// 配置IO口爲輸出模式
// CNFy[1:0]: 00 - 通用推輓輸出模式
// MODEy[1:0]:01 - 輸出模式,最大速度10MHz
for(unsigned int i=0; i<8; i++)
{
// GPIOB起始地址:0X40010C00
// GPIOx_CRL偏移地址:0X00
*(unsigned int *)(0X40010C00 + 0X00) |= (1 << (4*i+0));
*(unsigned int *)(0X40010C00 + 0X00) &= ~(1 << (4*i+1));
*(unsigned int *)(0X40010C00 + 0X00) &= ~(1 << (4*i+2));
*(unsigned int *)(0X40010C00 + 0X00) &= ~(1 << (4*i+3));
}
// 設置IO口爲高電平,關閉LED燈
// GPIOB起始地址:0X40010C00
// GPIOx_ODR地址偏移:0X0C
*(unsigned int *)(0X40010C00 + 0X0C) |= 0xFF;
while(1)
{
for(unsigned int i=0; i<8; i++)
{
// 設置IO口爲低電平,打開LED燈
// GPIOB起始地址:0X40010C00
// GPIOx_ODR地址偏移:0X0C
*(unsigned int *)(0X40010C00 + 0X0C) &= ~(1 << i);
delay(1);
// 設置IO口爲高電平,關閉LED燈
// GPIOB起始地址:0X40010C00
// GPIOx_ODR地址偏移:0X0C
*(unsigned int *)(0X40010C00 + 0X0C) |= (1 << i);
delay(1);
}
}
}