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Internet of Things with Python

You're reading from   Internet of Things with Python Create exciting IoT solutions

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Product type Paperback
Published in May 2016
Publisher Packt
ISBN-13 9781785881381
Length 388 pages
Edition 1st Edition
Languages
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Author (1):
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Gaston C. Hillar Gaston C. Hillar
Author Profile Icon Gaston C. Hillar
Gaston C. Hillar
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Toc

Table of Contents (13) Chapters Close

Preface 1. Understanding and Setting up the Base IoT Hardware 2. Working with Python on Intel Galileo Gen 2 FREE CHAPTER 3. Interacting with Digital Outputs with Python 4. Working with a RESTful API and Pulse Width Modulation 5. Working with Digital Inputs, Polling and Interrupts 6. Working with Analog Inputs and Local Storage 7. Retrieving Data from the Real World with Sensors 8. Displaying Information and Performing Actions 9. Working with the Cloud 10. Analyzing Huge Amounts of Data with Cloud-based IoT Analytics A. Exercise Answers Index

Reading pushbutton statuses with digital inputs and the mraa library


We will create a new PushButton class to represent a pushbutton connected to our board that can use either a pull-up or a pull-down resistor. The following lines show the code for the new PushButton class that works with the mraa library. The code file for the sample is iot_python_chapter_05_01.py.

import mraa
import time
from datetime import date

class PushButton:
    def __init__(self, pin, pull_up=True):
        self.pin = pin
        self.pull_up = pull_up
        self.gpio = mraa.Gpio(pin)
        self.gpio.dir(mraa.DIR_IN)

    @property
    def is_pressed(self):
        push_button_status = self.gpio.read()
        if self.pull_up:
            # Pull-up resistor connected
            return push_button_status == 0
        else:
            # Pull-down resistor connected
            return push_button_status == 1

    @property
    def is_released(self):
        return not self.is_pressed

We have to specify the pin...

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