BS8116A-3
IRQ 外部中断请求 NMOS输出内部上拉
SCL
SDA IIC通信接口
VDD 供电电压2.2-5.5V

Ct电容: 0~25 pF
电容越大灵敏度越低

1、 软件使用流程

初始化
将IIC的两个引脚初始化为复用开漏模式
按键引脚设置上拉输入 下降沿触发外部中断

void KEY_Init(void)
{
	//uint8_t status;
	GPIO_InitTypeDef  GPIO_InitStructure;
	EXTI_InitTypeDef	EXTI_InitStructure;
	NVIC_InitTypeDef	NVIC_InitStructure;
		
	RCC_APB2PeriphClockCmd(RCC_APB2Periph_AFIO|RCC_APB2Periph_GPIOB|RCC_APB2Periph_GPIOG,ENABLE);	//使能复用功能时钟
	
  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6|GPIO_Pin_7;	 // 端口配置
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
	GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_OD;
  GPIO_Init(GPIOB, &GPIO_InitStructure);					 //根据设定参数初始化GPIO 
	
  GPIO_SetBits(GPIOB,GPIO_Pin_6|GPIO_Pin_7);
	
	GPIO_InitStructure.GPIO_Pin = GPIO_Pin_5;
	GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPU;
	GPIO_Init(GPIOB,&GPIO_InitStructure);
	
	GPIO_EXTILineConfig(GPIO_PortSourceGPIOB,GPIO_PinSource5);

	EXTI_InitStructure.EXTI_Line=EXTI_Line5;	//KEY2
	EXTI_InitStructure.EXTI_Mode = EXTI_Mode_Interrupt;	
	EXTI_InitStructure.EXTI_Trigger = EXTI_Trigger_Falling;
	EXTI_InitStructure.EXTI_LineCmd = ENABLE;
	EXTI_Init(&EXTI_InitStructure);	 	//根据EXTI_InitStruct中指定的参数初始化外设EXTI寄存器
	
	NVIC_InitStructure.NVIC_IRQChannel = EXTI9_5_IRQn;			//使能按键WK_UP所在的外部中断通道
	NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0x02;	//抢占优先级2， 
	NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0x03;					//子优先级3
	NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;								//使能外部中断通道
	NVIC_Init(&NVIC_InitStructure); 

}

当产生外部中断开始读取键值

void EXTI9_5_IRQHandler(void)
{
    OS_CPU_SR cpu_sr;
    OS_ENTER_CRITICAL();              // Tell uC/OS-II that we are starting an ISR    //
	  OSIntEnter();
    OS_EXIT_CRITICAL();
	  
    if(EXTI_GetITStatus(EXTI_Line5) != RESET)
    {
        EXTI_ClearITPendingBit(EXTI_Line5);
			 Touch_key = Touch_Key_Analysis();//读取Key 并返回
			 if( Touch_key != 0xFF && EnsureKeyFlag != 1 )  
       OSSemPost(KEYBOARDFLAG);
    }
    OSIntExit(); /* Tell uC/OS-II that we are leaving the ISR       */
}

uint16_t Touch_Key_Analysis(void)
{

	uint16_t Key_Val;
	uint16_t Key_Val_H;
	uint16_t Key_Val_L;
	Key_Val_H = GetKey(0x09);
	Key_Val_L = GetKey(0x08);
	Key_Val = (Key_Val_H<<8)|Key_Val_L;
	switch(Key_Val)
	{
		case	Key1_Pres : 
					return 1;//#0x23
		case	Key2_Pres:
					return 4;
		case 	Key3_Pres:
					return 7;
		case	Key4_Pres:
					return '*';
		case	Key5_Pres:
					return 2;//*0x2A
		case	Key6_Pres:
					return 5;
		case 	Key7_Pres:
					return 8;
		case	Key8_Pres:
					return 0;
		case	Key9_Pres:
					return 3;
		case	Key10_Pres:
					return 6;
		case	Key11_Pres:
					return 9;  // 10
		case	Key12_Pres:
					return '#';  // 11
		case	Key13_Pres:
					return 12; // 12
		default: return 0xFF; 
	}
}