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Built-in project · ESP32 DevKit V1

MicroPython PWM fade on an ESP32

MicroPython on an ESP32 DevKit: machine.PWM at 1 kHz on D4 sweeps the duty up and down with duty_u16(), so the LED breathes in and out. The whole build, an ESP32 DevKit and 2 more parts, runs here in your browser on the firmware below; open it in the editor to change the wiring or the code and run it again.

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The parts retail for about $9.15. On Mokxi they're free.

MicroPython PWM fade on an ESP32 · ESP32 DevKit V1live0.000 s 0.00x
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The circuit itself, running here on the simulator. Press what can be pressed; click anything else to open it in the editor.

The code

The MicroPython code exactly as the editor opens it. Change a line there and press Run: the board runs it on the official MicroPython firmware, with nothing to compile.

main.py · ESP32 DevKit V1
# MicroPython on an ESP32 DevKit: an LED that breathes.
# The LED on D4 is driven by PWM at 1 kHz; the duty goes up and down
# from 0 to 65535 in steps, so the LED fades in and out.
from machine import Pin, PWM
import time

led = PWM(Pin(4), freq=1000)

while True:
    for duty in range(0, 65536, 2048):
        led.duty_u16(duty)
        time.sleep_ms(20)
    for duty in range(65535, -1, -2048):
        led.duty_u16(duty)
        time.sleep_ms(20)
    print("breath")

Parts list

3 parts, plus the jumper wires. They retail for about $9.15; on Mokxi they're free.

How it is wired

3 connections, pin by pin, read from the circuit itself. Each line is one set of pins joined together, by a jumper wire or a breadboard strip.

  • ESP32 DevKit V1 pin D4; Resistor, 220 Ω pin 1
  • Resistor, 220 Ω pin 2; LED, green pin A
  • Ground: LED, green pin C

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