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Hands-On Internet of Things with MQTT

You're reading from   Hands-On Internet of Things with MQTT Build connected IoT devices with Arduino and MQ Telemetry Transport (MQTT)

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Product type Paperback
Published in Oct 2019
Publisher Packt
ISBN-13 9781789341782
Length 350 pages
Edition 1st Edition
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Author (1):
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Tim Pulver Tim Pulver
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Tim Pulver
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Table of Contents (16) Chapters Close

Title Page
Copyright and Credits About Packt Contributors Preface 1. The Internet of Things in a Nutshell FREE CHAPTER 2. Basic Architecture of an IoT Prototype 3. Getting Started with MQTT 4. Setting Up a Lab Environment 5. Building Your Own Automatic Pet Food Dispenser 6. Building a Smart E-Ink To-Do List 7. Building a Smart Productivity Cube, Part 1 8. Building a Smart Productivity Cube, Part 2 9. Presenting Your Own Prototype 1. Assessments 2. Other Books You May Enjoy

Optimizing the dispenser code

Now, let's get back to coding. You probably tried out how the dispenser works with real material in it, controlled by sending commands as 1 and 0 over the Serial Monitor. Sending two commands to manually open and close the opening is not super useful.

Let's modify our code so that the servo automatically goes back to the closed position after x milliseconds. If you use a very fine material (such as sugar), this might be something like 150 milliseconds. For grainier material (dry cat food, for example), something in the seconds might be good. Remember, we always need to specify the time in milliseconds, so 2 seconds would be 2,000 milliseconds.

Save the existing sketch as a copy with the name ch5_02_servo_serial_auto_close.

To automatically close the cap shortly after it is opened, we need to add a few new variables. Follow these steps...

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