Blinking LED with Micropython and ESP32

This proyect makes a simple and a RGB LED blink or fade using Micropython on a ESP32.

If you want to setup a Python 3 virtual environment or your ESP32 doesn't have Micropython flashed yet, take a look at https://github.com/danielwohlgemuth/setup-micropython-esp32.

Install

Install the dependencies listed inside the requirements.txt file.

pip install -r requirements.txt

ampy --help
rshell --help

Pinout

The pinout of my ESP32 looks like this.

Image from http://forum.fritzing.org/t/esp32s-hiletgo-dev-boad-with-pinout-template/5357

You can find the pinout for other ESP32's by searching for pinout on http://esp32.net/ and follow those links.

Single LED

Setup circuit

Connect the ground pin to the shorter leg. Connect pin 23 to the other leg, with a 470Ω resistor in between to prevent de LED from burning out. If you don't have a resistor with that exact value, just use something close enough.

Since I didn't have 470Ω resistors, I used two 1kΩ resistors in parallel, to get 500Ω. The formula for that is 1/Rt = 1/R1 + 1/R2 + .... In this case 1/Rt = 1/1000 + 1/1000 --> 1/Rt = 2/1000 --> Rt = 1000/2 --> Rt = 500.

You could also use two 220Ω resistors in series/sequentially to add up to 440Ω.

Connect to interactive shell

rshell --port /dev/ttyUSB0 repl

You can exit the shell by pressing CTRL + X.

If you can't reconnect afterwards, you might need to restart your ESP32 by pressing the EN button.

Try manually

Once you are connected to the interactive shell, try these commands to turn the LED on and off.

import machine

led = machine.Pin(23, machine.Pin.OUT)

led.value(1)
led.value(0)

If the LED doesn't turn on, it might just be connected the wrong way around. Connect the ground pin to the longer leg and pin 23 to the other leg and try again.

Try examples

After verifying that the circuit works correctly, upload the examples and execute them after a restart. The uploaded file has to be called main.py and gets executed when the ESP32 starts up.

blink.py blinks the LED once long and twice short.

cp blink.py main.py
ampy --port /dev/ttyUSB0 put main.py
# Restart the ESP32 to execute it by pressing the EN button

fade.py fades the LED on and off according to a sine wave using pulse width modulation (PWM).

cp fade.py main.py
ampy --port /dev/ttyUSB0 put main.py

RGB LED

Setup circuit

Connect the ground pin to the longer leg. Connect pin 23, 22, and 21 with the other legs, with a 470Ω resistors between each pin and the LED.

fade-rgb.py fades the RGB LED using three sine waves, with the start of each sine wave shifted from the others to make the three color light up at different times.

cp fade-rgb.py main.py
ampy --port /dev/ttyUSB0 put main.py

fade-hsv.py fade the RGB LED by converting from the HSV (Hue, Saturation, Value) color space to RGB to have three times in a cycle where only one color is lit up.

cp fade-hsv.py main.py
ampy --port /dev/ttyUSB0 put main.py