STM32F103ZET6 capacitive touch button experiment
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Preface
The learning of STM32 can be divided into 3 versions.
1. Register version
2. Library function version
3. HAL library version
Due to personal reasons, I choose the library function version to learn STM32.
Tip: Problems such as software installation will not be explained! ! !
1. Basic principles of capacitive touch buttons
1 Introduction
There is an inductive capacitor between any two conductive objects . A button, a pad and the ground can also form an inductive capacitor. When the surrounding environment remains unchanged, the inductive capacitor value is a small, fixed value. When a human finger approaches the touch button, the inductive capacitance formed by the inductive capacitor formed by the human finger and the ground in parallel and the inductive capacitance formed by the ground will increase the total inductive capacitance. After the capacitive touch button IC detects that the sensing capacitance value of a button has changed, it will output a confirmation signal that a button is pressed. Because capacitive touch buttons have no mechanical structure, all detections are small changes in power, so they are more sensitive to various interferences. Therefore, touch button design, touch panel design, and touch IC selection are critical.
2. Work process
2. Hardware connection
Three, operation steps
1. Functions used
2. Operation steps
Fourth, the program source code
1.tpad.h
code show as below:
#ifndef __TPAD_H
#define __TPAD_H
#include "sys.h"
extern vu16 tpad_default_val;
void TPAD_Reset(void);
u16 TPAD_Get_Val(void);
u16 TPAD_Get_MaxVal(u8 n);
u8 TPAD_Init(u8 psc);
u8 TPAD_Scan(u8 mode);
void TIM5_CH2_Cap_Init(u16 arr,u16 psc);
#endif
2.tpad.c
code show as below:
#include "tpad.h"
#include "delay.h"
#include "usart.h"
#define TPAD_ARR_MAX_VAL 0XFFFF //最大的ARR值
vu16 tpad_default_val=0;//空载的时候(没有手按下),计数器需要的时间
//初始化触摸按键
//获得空载的时候触摸按键的取值.
//返回值:0,初始化成功;1,初始化失败
u8 TPAD_Init(u8 psc)
{
u16 buf[10];
u16 temp;
u8 j,i;
TIM5_CH2_Cap_Init(TPAD_ARR_MAX_VAL,psc-1);//以1Mhz的频率计数
for(i=0;i<10;i++)//连续读取10次
{
buf[i]=TPAD_Get_Val();
delay_ms(10);
}
for(i=0;i<9;i++)//排序
{
for(j=i+1;j<10;j++)
{
if(buf[i]>buf[j])//升序排列
{
temp=buf[i];
buf[i]=buf[j];
buf[j]=temp;
}
}
}
temp=0;
for(i=2;i<8;i++)temp+=buf[i];//取中间的6个数据进行平均
tpad_default_val=temp/6;
printf("tpad_default_val:%d\r\n",tpad_default_val);
if(tpad_default_val>TPAD_ARR_MAX_VAL/2)return 1;//初始化遇到超过TPAD_ARR_MAX_VAL/2的数值,不正常!
return 0;
}
//复位一次
void TPAD_Reset(void)
{
GPIO_InitTypeDef GPIO_InitStructure;
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE); //使能PA端口时钟
//设置GPIOA.1为推挽输出
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_1; //PA1 端口配置
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP; //推挽输出
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_Init(GPIOA, &GPIO_InitStructure);
GPIO_ResetBits(GPIOA,GPIO_Pin_1); //PA.1输出0,放电
delay_ms(5);
TIM_SetCounter(TIM5,0); //归0
TIM_ClearITPendingBit(TIM5, TIM_IT_CC2|TIM_IT_Update); //清除中断标志
//设置GPIOA.1为浮空输入
GPIO_InitStructure.GPIO_Mode=GPIO_Mode_IN_FLOATING; //浮空输入
GPIO_Init(GPIOA, &GPIO_InitStructure);
}
//得到定时器捕获值
//如果超时,则直接返回定时器的计数值.
u16 TPAD_Get_Val(void)
{
TPAD_Reset();
while(TIM_GetFlagStatus(TIM5, TIM_IT_CC2) == RESET)//等待捕获上升沿
{
if(TIM_GetCounter(TIM5)>TPAD_ARR_MAX_VAL-500)return TIM_GetCounter(TIM5);//超时了,直接返回CNT的值
};
return TIM_GetCapture2(TIM5);
}
//读取n次,取最大值
//n：连续获取的次数
//返回值：n次读数里面读到的最大读数值
u16 TPAD_Get_MaxVal(u8 n)
{
u16 temp=0;
u16 res=0;
while(n--)
{
temp=TPAD_Get_Val();//得到一次值
if(temp>res)res=temp;
};
return res;
}
//扫描触摸按键
//mode:0,不支持连续触发(按下一次必须松开才能按下一次);1,支持连续触发(可以一直按下)
//返回值:0,没有按下;1,有按下;
#define TPAD_GATE_VAL 100 //触摸的门限值,也就是必须大于tpad_default_val+TPAD_GATE_VAL,才认为是有效触摸.
u8 TPAD_Scan(u8 mode)
{
static u8 keyen=0; //0,可以开始检测;>0,还不能开始检测
u8 res=0;
u8 sample=3; //默认采样次数为3次
u16 rval;
if(mode)
{
sample=6; //支持连按的时候，设置采样次数为6次
keyen=0; //支持连按
}
rval=TPAD_Get_MaxVal(sample);
if(rval>(tpad_default_val+TPAD_GATE_VAL))//大于tpad_default_val+TPAD_GATE_VAL,有效
{
if(keyen==0)res=1; //keyen==0,有效
printf("r:%d\r\n",rval);
keyen=3; //至少要再过3次之后才能按键有效
}
if(keyen)keyen--;
return res;
}
//定时器2通道2输入捕获配置
void TIM5_CH2_Cap_Init(u16 arr,u16 psc)
{
GPIO_InitTypeDef GPIO_InitStructure;
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
TIM_ICInitTypeDef TIM5_ICInitStructure;
RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM5, ENABLE); //使能TIM5时钟
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE); //使能PA端口时钟
//设置GPIOA.1为浮空输入
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_1; //PA1 端口配置
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz; //速度50MHz
GPIO_InitStructure.GPIO_Mode=GPIO_Mode_IN_FLOATING; //浮空输入
GPIO_Init(GPIOA, &GPIO_InitStructure); //设置为浮空输入
//初始化TIM5
TIM_TimeBaseStructure.TIM_Period = arr; //设定计数器自动重装值
TIM_TimeBaseStructure.TIM_Prescaler =psc; //预分频器
TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1; //设置时钟分割:TDTS = Tck_tim
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up; //TIM向上计数模式
TIM_TimeBaseInit(TIM5, &TIM_TimeBaseStructure); //根据TIM_TimeBaseInitStruct中指定的参数初始化TIMx的时间基数单位
//初始化通道2
TIM5_ICInitStructure.TIM_Channel = TIM_Channel_2; //CC1S=01 选择输入端 IC2映射到TI5上
TIM5_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Rising; //上升沿捕获
TIM5_ICInitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI;
TIM5_ICInitStructure.TIM_ICPrescaler = TIM_ICPSC_DIV1; //配置输入分频,不分频
TIM5_ICInitStructure.TIM_ICFilter = 0x03;//IC2F=0011 配置输入滤波器 8个定时器时钟周期滤波
TIM_ICInit(TIM5, &TIM5_ICInitStructure);//初始化I5 IC2
TIM_Cmd(TIM5,ENABLE ); //使能定时器5
}
3.main.c
code show as below:
#include "stm32f10x.h"
#include "led.h"
#include "delay.h"
#include "beep.h"
#include "key.h"
#include "timer.h"
#include "usart.h"
#include "tpad.h"
extern u8 TIM5CH1_CAPTURE_STA;//输入捕获状态
extern u16 TIM5CH1_CAPTURE_VAL;
int main(void)
{
u8 t=0;
NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2);
uart_init(115200);
delay_init();
LED_Init();
Beep_Init();
KEY_Init();
TPAD_Init(6);
while(1)
{
if(TPAD_Scan(0))
{
LED2=!LED2;
}
t++;
if(t==15)
{
t=0;
LED1=!LED1;
}
delay_ms(10);
}
}
5. Experimental results
Press the capacitive touch button to control the on and off of LED2.
to sum up
1. After watching the video, be sure to write the program yourself.
2. Before programming the program, analyze the program and reason about the experimental phenomenon.
3. If the experimental phenomenon is inconsistent with the reasoning, the program must be carefully analyzed.