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Practical Python Programming for IoT

You're reading from   Practical Python Programming for IoT Build advanced IoT projects using a Raspberry Pi 4, MQTT, RESTful APIs, WebSockets, and Python 3

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Product type Paperback
Published in Nov 2020
Publisher Packt
ISBN-13 9781838982461
Length 516 pages
Edition 1st Edition
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Author (1):
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Gary Smart Gary Smart
Author Profile Icon Gary Smart
Gary Smart
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Table of Contents (20) Chapters Close

Preface 1. Section 1: Programming with Python and the Raspberry Pi
2. Setting Up your Development Environment FREE CHAPTER 3. Getting Started with Python and IoT 4. Networking with RESTful APIs and Web Sockets Using Flask 5. Networking with MQTT, Python, and the Mosquitto MQTT Broker 6. Section 2: Practical Electronics for Interacting with the Physical World
7. Connecting Your Raspberry Pi to the Physical World 8. Electronics 101 for the Software Engineer 9. Section 3: IoT Playground - Practical Examples to Interact with the Physical World
10. Turning Things On and Off 11. Lights, Indicators, and Displaying Information 12. Measuring Temperature, Humidity, and Light Levels 13. Movement with Servos, Motors, and Steppers 14. Measuring Distance and Detecting Movement 15. Advanced IoT Programming Concepts - Threads, AsyncIO, and Event Loops 16. IoT Visualization and Automation Platforms 17. Tying It All Together - An IoT Christmas Tree 18. Assessments 19. Other Books You May Enjoy

Creating a Hall-effect sensor circuit

We will be building the following circuit on our breadboards. Similar to our HC-SR04 example and circuit in Figure 11.5, we need to use a voltage divider since our Hall-effect sensor outputs 5-volt logic, which we need to shift down to 3.3 volts:

Figure 11.10 – Hall-effect sensor circuit

You will notice that the output of this circuit is dualistic and will depend on which sensor you are using:

  • For a non-latching switch or latching switch type Hall-effect sensor, you will connect the circuit directly to GPIO 21 since the sensor will output a digital HIGH/LOW signal.
  • For a ratiometric type Hall-effect sensor, you will need to connect the sensor to your Raspberry Pi via your ADS1115 analog-to-digital converter since the sensor outputs a varying analog voltage.
I have not included the ADS1115 wiring in Figure 11.9 or in the following stepped breadboard layouts. We have already seen how to connect an analog output...
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