STM32基本的按键IO设置

只看该作者 · 2014-5-26 22:53

最近开始学习STM32 ，按键IO口设置这儿始终不太明白
为甚么在在IO口设置成输入模式后，还要将PA0和PC13的ODR 寄存器设为输出啊
下面程序中PA0,PC13用于按键  ； PB0，PC3,PC4用于LED

RCC->APB2ENR |= 1<<3;       //Enable clock of GPIOB
RCC->APB2ENR |= 1<<4;       //Enable clock of GPIOC
RCC->APB2ENR |= 1<<2;       //Enable clock of GPIOC

//ÉèÖÃLED¶Ë¿ÚÄ£Ê½
GPIOB->CRL |= 0x00000001; //Set PB0 mode push output 10MHZ
GPIOB->ODR |= 1 << 0;       //Set PB0 output 1 (GPIOÉèÖÃÎªÊä³öºóÄ¬ÈÏÎª0£¬ËùÒÔÐèÒª½«¶Ë¿Ú¸³Öµ1£¬·ÀÖ¹Æô¶¯ºóLEDÁÁ)

GPIOC->CRL |= (0x00000001 << (4 * 3)); //Set PC3 mode push output 10MHZ
GPIOC->ODR |= 1 << 0;       //Set PC3 output 1

GPIOC->CRL |= (0x00000001 << (4 * 4)); //Set PC4 mode push output 10MHZ
GPIOC->ODR |= 1 << 0;       //Set PC4 output 1

//ÉèÖÃ°´¼ü¶Ë¿ÚÄ£Ê½
GPIOA->CRL &= 0xfffffff0; //Set PA0 INPUT
GPIOA->CRL |= 0x00000008;

GPIOC->CRH &= 0xfff0ffff; //Set PC13 INPUT
GPIOC->CRH |= 0x00080000;

GPIOA->ODR |= 1 << 0;
GPIOC->ODR |= 1 << 13;[/code]