gpio_test.py

import RPi.GPIO as GPIO
from PCF8574 import PCF8574_GPIO
from Adafruit_LCD1602 import Adafruit_CharLCD
from time import sleep, strftime, time
from datetime import datetime
from threading import Lock
import pigpio # run sudo pigpiod

# Simple pi program to run three buttons, an LCD, and a servo.
# Uses code from Freenove kit scripts.

#####################################################################
# Constants
#####################################################################

green_button_pin = 13
blue_button_pin = 5
red_button_pin = 6

servo_pin = 23

message_time_delay = 2 # Seconds

#####################################################################
# Global Variables 
#####################################################################

# Use physical pin numbering
GPIO.setmode(GPIO.BCM)

# Servo
GPIO.setup(servo_pin, GPIO.OUT)


class Servo:
    lock = Lock()
    pwm = None
    
    def __init__(self):
        with self.lock:
            self.pwm = pigpio.pi()
            self.pwm.set_mode(servo_pin, pigpio.OUTPUT)
            self.pwm.set_PWM_frequency(servo_pin, 50)

        
    def goto(self, position):
        with self.lock:
            self.pwm.set_servo_pulsewidth(servo_pin, position)
    


# LCD Message
class Message:    
    text = ""
    time_posted = 0
    lock = Lock()
    
    def set(self, new_message):
        with self.lock:
            self.text = new_message.center(16)
            self.time_posted = time()
    
message = Message()
servo = Servo()

# LCD Setup
PCF8574_address = 0x27  # I2C address of the PCF8574 chip.
PCF8574A_address = 0x3F  # I2C address of the PCF8574A chip.

mcp = None

# Create PCF8574 GPIO adapter.
try:
    mcp = PCF8574_GPIO(PCF8574_address)
except:
    try:
        mcp = PCF8574_GPIO(PCF8574A_address)
    except:
        print ('I2C Address Error !')
        exit(1)
        
lcd = Adafruit_CharLCD(pin_rs=0, pin_e=2, pins_db=[4,5,6,7], GPIO=mcp)

#####################################################################
# Functions
#####################################################################



def green_button_callback(channel, message, servo):
    print("Green button was pushed!")
    message.set("GREEN BUTTON")
    servo.goto(500)

def blue_button_callback(channel, message, servo):
    print("Blue button was pushed!")
    message.set("BLUE BUTTON")
    servo.goto(1500)

def red_button_callback(channel, message, servo):
    print("Red button was pushed!")
    message.set("RED BUTTON")
    servo.goto(2500)
    
def get_cpu_temp():     # get CPU temperature and store it into file "/sys/class/thermal/thermal_zone0/temp"
    tmp = open('/sys/class/thermal/thermal_zone0/temp')
    cpu = tmp.read()
    tmp.close()
    return '{:.2f}'.format( float(cpu)/1000 ) + ' C'
 
def get_time_now():     # get system time
    return datetime.now().strftime('    %H:%M:%S')
    
def loop():
    mcp.output(3,1)     # turn on LCD backlight
    lcd.begin(16,2)     # set number of LCD lines and columns
    while(True):         
        #lcd.clear()
        lcd.setCursor(0,0)  # set cursor position
        if(time() - message.time_posted < message_time_delay):
            lcd.message(message.text + '\n')
        else:
            lcd.message( ('CPU: ' + get_cpu_temp()).center(16) + '\n' )
        lcd.message( get_time_now() )   # display the time
        sleep(0.5)
        
def destroy():
    """Kill everything"""
    pwm.stop()
    lcd.clear()


#####################################################################
# Set up GPIO Pins
#####################################################################



# Buttons
# Set pins to be inputs and set initial value to be pulled low (off)
GPIO.setup(green_button_pin, GPIO.IN, pull_up_down=GPIO.PUD_DOWN) 
GPIO.setup(blue_button_pin, GPIO.IN, pull_up_down=GPIO.PUD_DOWN) 
GPIO.setup(red_button_pin, GPIO.IN, pull_up_down=GPIO.PUD_DOWN) 

# Setup event on pin 10 rising edge
GPIO.add_event_detect(green_button_pin, GPIO.RISING, callback=lambda x: green_button_callback(x, message, servo), bouncetime=500)
GPIO.add_event_detect(blue_button_pin, GPIO.RISING, callback=lambda x: blue_button_callback(x, message, servo), bouncetime=500)
GPIO.add_event_detect(red_button_pin, GPIO.RISING, callback=lambda x: red_button_callback(x, message, servo), bouncetime=500)

try:
    loop()
except KeyboardInterrupt:
    destroy()

GPIO.cleanup() # Clean up