CircuitPython Essentials - Adafruit Industries

CircuitPython Essentials

Created by Kattni Rembor



Last updated on 2022-02-14 12:29:38 PM EST

?Adafruit Industries

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Table of Contents

CircuitPython Essentials

5

CircuitPython Pins and Modules

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6

6

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9

10

10

CircuitPython Pins

import board

I2C, SPI, and UART

What Are All the Available Names?

Microcontroller Pin Names

CircuitPython Built-In Modules

CircuitPython Built-Ins

11

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Thing That Are Built In and Work

Flow Control

Math

Tuples, Lists, Arrays, and Dictionaries

Classes, Objects and Functions

Lambdas

Random Numbers

11

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12

12

12

12

CircuitPython Digital In & Out

12

? Find the pins!

? Read the Docs

14

17

CircuitPython Analog In

17

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18

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19

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23

Creating the analog input

get_voltage Helper

Main Loop

Changing It Up

Wire it up

Reading Analog Pin Values

CircuitPython Analog Out

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Creating an analog output

Setting the analog output

Main Loop

Find the pin

CircuitPython Audio Out

? Play a Tone

? Play a Wave File

? Wire It Up

24

24

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25

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31

33

CircuitPython MP3 Audio

38

CircuitPython PWM

39

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PWM with Fixed Frequency

Create a PWM Output

Main Loop

PWM Output with Variable Frequency

Wire it up

Where's My PWM?

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48

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CircuitPython Servo

? Servo Wiring

? Standard Servo Code

? Continuous Servo Code

CircuitPython Cap Touch

? Create the Touch Input

? Main Loop

? Find the Pin(s)

CircuitPython Internal RGB LED

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Create the LED

Brightness

Main Loop

Making Rainbows (Because Who Doesn't Love 'Em!)

Circuit Playground Express Rainbow

CircuitPython NeoPixel

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Wiring It Up

The Code

Create the LED

NeoPixel Helpers

Main Loop

NeoPixel RGBW

Read the Docs

CircuitPython DotStar

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Wire It Up

The Code

Create the LED

DotStar Helpers

Main Loop

Is it SPI?

Read the Docs

CircuitPython UART Serial

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The Code

Wire It Up

Where's my UART?

Trinket M0: Create UART before I2C

CircuitPython I2C

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Wire It Up

Find Your Sensor

I2C Sensor Data

Where's my I2C?

CircuitPython HID Keyboard and Mouse

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CircuitPython Keyboard Emulator

Create the Objects and Variables

The Main Loop

Non-US Keyboard Layouts

CircuitPython Mouse Emulator

Create the Objects and Variables

CircuitPython HID Mouse Helpers

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? Main Loop

CircuitPython Storage

? Logging the Temperature

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CircuitPython CPU Temp

100

CircuitPython Expectations

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101

102

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103

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Always Run the Latest Version of CircuitPython and Libraries

I have to continue using CircuitPython 3.x or 2.x, where can I find compatible libraries?

Switching Between CircuitPython and Arduino

The Difference Between Express And Non-Express Boards

Non-Express Boards: Gemma, Trinket, and QT Py

Differences Between CircuitPython and MicroPython

Differences Between CircuitPython and Python

CircuitPython Resetting

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Soft Reset

Hard Reset

Reset Into Specific Mode

More Info

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CircuitPython Libraries and Drivers

107

CircuitPython Libraries

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CircuitPython Essentials

You've gone through the Welcome to CircuitPython guide (). You've already gotten everything setup, and you've gotten CircuitPython

running. Great! Now what? CircuitPython Essentials!

There are a number of core modules built into CircuitPython and commonly used

libraries available. This guide will introduce you to these and show you an example of

how to use each one.

Each section will present you with a piece of code designed to work with different

boards, and explain how to use the code with each board. These examples work with

any board designed for CircuitPython, including Circuit Playground Express, Trinket

M0, Gemma M0, QT Py, ItsyBitsy M0 Express, ItsyBitsy M4 Express, Feather M0

Express, Feather M4 Express, Metro M4 Express, Metro M0 Express, Trellis M4

Express, and Grand Central M4 Express.

Some examples require external components, such as switches or sensors. You'll find

wiring diagrams where applicable to show you how to wire up the necessary

components to work with each example.

Let's get started learning the CircuitPython Essentials!

CircuitPython Pins and Modules

CircuitPython is designed to run on microcontrollers and allows you to interface with

all kinds of sensors, inputs and other hardware peripherals. There are tons of guides

showing how to wire up a circuit, and use CircuitPython to, for example, read data

from a sensor, or detect a button press. Most CircuitPython code includes hardware

setup which requires various modules, such as board or digitalio . You import

these modules and then use them in your code. How does CircuitPython know to look

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