Topics

#!/usr/bin/env python

import rospy
import RPi.GPIO as GPIO
from std_msgs.msg import Bool

# buttons GPIO pins 
#   button 1 - gpio 11
#   button 2 - gpio 12

class rpi_button():

    def __init__(self):
        # init variables
        self.BUTTON_GPIO = 11
        # set GPIO kot BCM
        GPIO.setmode(GPIO.BCM)
        # set button IO as input
        GPIO.setup(self.BUTTON_GPIO, GPIO.IN)
        # set loop frequency to 10 Hz
        self.rate = rospy.Rate(10)

        # define publisher
        # rospy.Publisher("topic_name", varType, queue_size)
        self.pub = rospy.Publisher('/button_state', Bool, queue_size=10)

        self.ctrl_c = False
        rospy.on_shutdown(self.shutdownhook)

    def read_button(self):
        while not self.ctrl_c:
            #  read GPIO pin
            gpio_state = GPIO.input(self.BUTTON_GPIO)
            # define msg as Bool variable
            self.msg = Bool()
            # msg has a data "data"
            self.msg.data = gpio_state
            # send msg
            self.publish_once()

    def publish_once(self):
        """
        This is because publishing in topics sometimes fails the first time you publish.
        In continuous publishing systems, this is no big deal, but in systems that publish only
        once, it IS very important.
        """
        while not self.ctrl_c:
            connections = self.pub.get_num_connections()
            if connections > 0:
                self.pub.publish(self.msg)
                #rospy.loginfo("Msg Published")
                break
            else:
                self.rate.sleep()

    def shutdownhook(self):
        # works better than the rospy.is_shutdown()
        # this code is run at ctrl + c

        # clear all GPIO settings
        GPIO.cleanup()
        self.ctrl_c = True

if __name__ == '__main__':
    # initialise node
    rospy.init_node('button_state_publisher', anonymous=True)

    # initialise class
    btn = rpi_button()
    try:
        btn.read_button()
    except rospy.ROSInterruptException:
        pass

#!/usr/bin/env python

import rospy
from std_msgs.msg import Bool
import RPi.GPIO as GPIO

# GPIO za LED:
#   Green 1 - GPIO 2
#   Green 2 - GPIO 3
#   Yellow 1 - GPIO 4
#   Yellow 2 - GPIO 5
#   Red 1 - GPIO 6
#   Red 2 - GPIO 7

class rpi_led():

    def __init__(self):
        # init variables
        self.LED_GPIO = 7
        # set GPIO kot BCM
        GPIO.setmode(GPIO.BCM)
        # set all leds
        for ii in range(2,8):
            # set IO as outputs
            GPIO.setup(ii,GPIO.OUT)

        # define subscriber
        # rospy.Subscriber('topic_name', varType, callback)
        self.sub = rospy.Subscriber('/button_state', Bool, self.button_state_callback)

        self.ctrl_c = False
        rospy.on_shutdown(self.shutdownhook)

    def button_state_callback(self, msg):
        # the code that is executed when data is received
        # turn on LED
        GPIO.output(self.LED_GPIO, msg.data)

    def resetLed(self):
        # reset all leds
        for ii in range(2,8):
            # turn off all leds
            GPIO.output(ii,False)

    def shutdownhook(self):
        # works better than the rospy.is_shutdown()
        # this code is run at ctrl + c

        # clear all settings
        GPIO.cleanup()
        self.ctrl_c = True

if __name__ == '__main__':
    # initialise node
    rospy.init_node('led_actuator')
    # initialise class
    led_act = rpi_led()
    # reset leds
    led_act.resetLed()
    try:
        # loop
        rospy.spin()
    except rospy.ROSInterruptException:
        pass