[Day52] 2022-04-12(화) 라즈베리파이1 - GPIO1(PUSH버튼) - 김서연 강사님

[1] GPIO

  1. PUSH 버튼

    1) PUSH버튼 예제1

      - 풀다운 방식으로 연결

push_test1.py

import RPi.GPIO as GPIO
import time

push_btn = 26
GPIO.setmode(GPIO.BCM)
GPIO.setup(push_btn, GPIO.IN, pull_up_down=GPIO.PUD_DOWN)

try:
    while True:
        if GPIO.input(push_btn) == GPIO.HIGH:
            print("버튼이 눌려짐")
        else:
            print("버튼이 안 눌려짐")
        time.sleep(0.1)
except KeyboardInterrupt:
    print("end")
finally:
    GPIO.cleanup()

    2) PUSH버튼 예제2

      - 위의 예제에서 문제로 채터링 문제가 있음

      - 아두이노와 달리 디바운싱을 위한 복잡한 작업을 별도로 하지 않고, event 방식으로 해결할 수 있음

push_event_test.py

import RPi.GPIO as GPIO
import time


# button의 상태가 변하면 호출될 callback function을 정의
def mycallback(channel):
    print("버튼이 눌려짐")


push_btn = 26
GPIO.setmode(GPIO.BCM)
GPIO.setup(push_btn, GPIO.IN, pull_up_down=GPIO.PUD_DOWN)
# Event 방식으로 핀의 상태를 처리 - GPIO.RISING(LOW->HIGH), GPIO.FALLING(HIGH->LOW), GPIO.BOTH
GPIO.add_event_detect(push_btn, GPIO.FALLING, callback=mycallback)

try:
    while True:
        time.sleep(0.1)
except KeyboardInterrupt:
    print("end")
finally:
    GPIO.cleanup()

    3) PUSH버튼 예제3

      - 풀업 방식으로 연결

      - GPIO.wait_for_edge(channel, edge, timeout) 메소드
        - 입력핀으로부터 RISING(or FALLING)이 발생할 때까지 timeout에 지정한 시간(ms)만큼 기다렸다가 작업
        - ex) GPIO.wait_for_edge(push_btn, GPIO.RISING, timeout=1000)

push_event_test2.py

import RPi.GPIO as GPIO
import time


# button의 상태가 변하면 호출될 callback function을 정의
def mycallback(channel):
    print("버튼이 눌려짐")


push_btn = 26
GPIO.setmode(GPIO.BCM)
GPIO.setup(push_btn, GPIO.IN, pull_up_down=GPIO.PUD_UP)
# Event 방식으로 핀의 상태를 처리 - GPIO.RISING(LOW->HIGH), GPIO.FALLING(HIGH->LOW), GPIO.BOTH
GPIO.add_event_detect(push_btn, GPIO.RISING, callback=mycallback)

# GPIO.wait_for_edge() 메소드
# 입력핀으로부터 RISING(or FALLING)이 발생할 때까지 timeout에 지정한 시간(ms)만큼 기다렸다가 작업
# GPIO.wait_for_edge(push_btn, GPIO.RISING, timeout=1000)

try:
    while True:
        time.sleep(0.1)
except KeyboardInterrupt:
    print("end")
finally:
    GPIO.cleanup()

    4) LED 예제

led_exam3.py

# led_exam3.py
# led 2개가 번갈아 켜지고 꺼지도록 구현하기

import RPi.GPIO as GPIO
import time

led_pin1 = 23
led_pin2 = 24
led_state1 = GPIO.LOW
led_state2 = GPIO.HIGH
GPIO.setmode(GPIO.BCM)
GPIO.setup(led_pin1, GPIO.OUT)
GPIO.setup(led_pin2, GPIO.OUT)

try:
    while True:
        led_state1 = not led_state1
        led_state2 = not led_state2
        GPIO.output(led_pin1, led_state1)
        GPIO.output(led_pin2, led_state2)
        time.sleep(1)
except KeyboardInterrupt:
    print("end")
finally:
    GPIO.cleanup()

    5) PUSH 버튼+LED 예제1

      - 풀다운 방식 연결

push_led_exam.py

# push_led_exam.py
# push를 누르면 led가 켜지고 push누르면 led가 꺼지도록 작업하기

import RPi.GPIO as GPIO
import time

led_pin = 24
push_btn = 26
led_state = GPIO.LOW
GPIO.setmode(GPIO.BCM)
GPIO.setup(led_pin, GPIO.OUT)
GPIO.setup(push_btn, GPIO.IN, pull_up_down=GPIO.PUD_DOWN)


def push_btn_callback(channel):
    global led_state
    led_state = not led_state
    GPIO.output(led_pin, led_state)


GPIO.add_event_detect(push_btn, GPIO.RISING, callback=push_btn_callback, bouncetime=100)

try:
    while True:
        time.sleep(0.1)
except KeyboardInterrupt:
    print("end")
finally:
    GPIO.cleanup()

    6) PUSH 버튼+LED 예제2

push_led_exam2.py

# push_led_exam2.py
# push버튼 두 개를 이용해서 하나를 누르면 led가 켜지고 다른 push 버튼을 누르면 led가 꺼지도록 작업하기

import RPi.GPIO as GPIO
import time

led_pin = 24
push_btn1 = 19
push_btn2 = 26

GPIO.setmode(GPIO.BCM)
GPIO.setup(led_pin, GPIO.OUT)
GPIO.setup(push_btn1, GPIO.IN, pull_up_down=GPIO.PUD_DOWN)
GPIO.setup(push_btn2, GPIO.IN, pull_up_down=GPIO.PUD_DOWN)


def push_btn_callback1(channel):
    GPIO.output(led_pin, GPIO.HIGH)


def push_btn_callback2(channel):
    GPIO.output(led_pin, GPIO.LOW)


GPIO.add_event_detect(push_btn1, GPIO.RISING, callback=push_btn_callback1, bouncetime=100)
GPIO.add_event_detect(push_btn2, GPIO.RISING, callback=push_btn_callback2, bouncetime=100)
try:
    while True:
        time.sleep(0.1)
except KeyboardInterrupt:
    print("end")
finally:
    GPIO.cleanup()

    7) PUSH버튼+LED 예제3

push_led_exam3.py

# push_led_exam3.py
# push버튼 4개, led 4개
# 각각의 push버튼이 led를 제어할 수 있도록 - 1
# 함수로 정의해서 사용해보기 - 2
# 객체를 정의해서 사용해보기 - 3

import RPi.GPIO as GPIO
import time

GPIO.setmode(GPIO.BCM)


class PushLED:
    def __init__(self, led_pin, push_btn):
        self.led_pin = led_pin
        self.push_btn = push_btn
        self.led_state = GPIO.LOW
        GPIO.setup(self.led_pin, GPIO.OUT)
        GPIO.setup(self.push_btn, GPIO.IN, pull_up_down=GPIO.PUD_DOWN)
        GPIO.add_event_detect(self.push_btn, GPIO.RISING, callback=self.push_btn_callback, bouncetime=200)

    def push_btn_callback(self, channel):
        self.led_state = not self.led_state
        GPIO.output(self.led_pin, self.led_state)


if __name__ == "__main__":

    obj1 = PushLED(22, 19)
    obj2 = PushLED(23, 20)
    obj3 = PushLED(24, 21)
    obj4 = PushLED(25, 26)

    try:
        while True:
            time.sleep(0.1)
    except KeyboardInterrupt:
        print("end")
    finally:
        GPIO.cleanup()

 

- 끝 -