树莓派系列教程9:按键
上两章我们讲解了在树莓派上如何点亮一个LED灯,这一章我们讲解一下按键以及事件中断。
一、bcm2835
01 #include
02 #include
03
04 #define KEY 20
05 int main(int argc, char **argv)
06 {
07 if (!bcm2835_init())return 1;
08 bcm2835_gpio_fsel(KEY, BCM2835_GPIO_FSEL_INPT);
09 bcm2835_gpio_set_pud(KEY, BCM2835_GPIO_PUD_UP);
10 printf("Key Test Program!!!!\n");
11 while (1)
12 {
13 if(bcm2835_gpio_lev(KEY) == 0)
14 {
15 printf ("KEY PRESS\n") ;
16 while(bcm2835_gpio_lev(KEY) == 0)
17 bcm2835_delay(100);
18 }
19 bcm2835_delay(100);
20 }
21 bcm2835_close();
22 return 0;
23 }
编译并执行,按下按键会看到窗口显示”KEY PRESS”,按Ctrl+C结束程序。
1 gcc –Wall key.c –o key –lbcm2835
2
3 sudo ./key
注:(1)bcm2835_gpio_fsel(KEY, BCM2835_GPIO_FSEL_INPT);设置管脚为输入模式(2)bcm2835_gpio_set_pud(KEY, BCM2835_GPIO_PUD_UP);设置为上拉模式
(3)bcm2835_gpio_lev(KEY);读取管脚状态
二、wiringPi
01 #include
02 #include
04 char KEY = 29;
05
06 int main()
07 {
08 if (wiringPiSetup() < 0)return 1 ;
09 pinMode (KEY,INPUT);
10 pullUpDnControl(KEY, PUD_UP);
11 printf("Key Test Program!!!\n");
12 while(1)
13 {
14 if (digitalRead(KEY) == 0)
15 {
16 printf ("KEY PRESS\n") ;
17 while(digitalRead(KEY) == 0)
18 delay(100);
19 }
20 delay(100);
21 }
22 }
编译并执行,按下按键会看到窗口显示”KEY PRESS”,按Ctrl+C结束程序。
1 gcc –Wall key.c –o key –wiringPi
2
3 sudo ./key
注:(1)pinMode (KEY,INPUT);设置管脚为输入模式
(2)pullUpDnControl(KEY, PUD_UP);设置为上拉模式
(3)digitalRead(KEY);读取管脚状态
通过中断的方式编程
01 #include
02 #include
03
04 #define button 29
05 char flag = 0;
06 void myInterrupt()
07 {
08 flag ++;
10
11 int main()
12 {
13 if(wiringPiSetup() < 0)return 1;
14 if(wiringPiISR(button,INT_EDGE_FALLING,&myInterrupt) < 0)
15 {
16 printf("Unable to setup ISR \n");
17 }
18 printf("Interrupt test program\n");
19 while(1)
20 {
21 if(flag)
22 {
23 while(digitalRead(button) ==0);
24 printf("button press\n");
25 flag = 0;
26 }
27 }
28 }
29
编译并执行
1 gcc –Wall Interrupt.c –o Interrupt -lwirngPi
2
3 sudo ./Interrupt
注:(1)wiringPiISR(button,INT_EDGE_FALLING,&myInterrupt);设置中断下降沿触发,myInterrupt 为中断处理函数。
三、python
01 #!/usr/bin/python
02 # -*- coding:utf-8 -*-
03 import RPi.GPIO as GPIO
04 import time
05
06 KEY = 26
07
08 GPIO.setmode(GPIO.BCM)
09 GPIO.setup(KEY,GPIO.IN,GPIO.PUD_UP)
10 while True:
11 time.sleep(0.05)
12 if GPIO.input(KEY) == 0:
13 print("KEY PRESS")
14 while GPIO.input(KEY) == 0:
15 time.sleep(0.01)
执行程序,按下按键会看到窗口显示”KEY PRESS”,按Ctrl+C 结束程序。
1 sudo python key.py 注:(1)GPIO.setup(KEY,GPIO.IN,GPIO.PUD_UP) 设置管脚为上拉输入模式
(2)GPIO.input(KEY ) 读取管脚值
通过中断模式编程
01 #!/usr/bin/python
02 # -*- coding:utf-8 -*-
03 import RPi.GPIO as GPIO
04 import time
05
06 KEY = 26
07
08 def MyInterrupt(KEY):
09 print("KEY PRESS")
10
11 GPIO.setmode(GPIO.BCM)
12 GPIO.setup(KEY,GPIO.IN,GPIO.PUD_UP)
13 GPIO.add_event_detect(KEY,GPIO.FALLING,MyInterrupt,200) 14
15 while True:
16 time.sleep(1) 注:(1)def MyInterrupt(KEY): 定义中断处理函数
(2) GPIO.add_event_detect(KEY,GPIO.FALLING,MyInterrupt,200) 增加事件检测,下降沿触发,忽略由于开关抖动引起的小于200ms 的边缘操作。
关于树莓派事件中断编程请参考:https://www.360docs.net/doc/8c18267880.html,/post/480073/focus/1797650173/