Blinky

The classic first program: blink an LEDLight-Emitting Diode on and off. Uses the gpio and sleep APIs.

Hardware

• Any ESP32 board with a built-in LEDLight-Emitting Diode, or an external LEDLight-Emitting Diode connected to a GPIOGeneral-Purpose Input/Output pin
• USBUniversal Serial Bus cable

Code

import {DigitalOut} from 'mikro/gpio'
import {sleep} from 'mikro/sleep'
import {memoryUsage} from 'mikro/sys'

const mem = memoryUsage()
console.log('free heap: %dKB', (mem.heapTotal - mem.heapUsed) / 1000)

// GPIO 15 is the built-in LED on XIAO ESP32C6. Replace with your board's LED pin.
const led = DigitalOut(15).orPanic('Failed to configure LED pin')

let level: 0 | 1 = 0
while (true) {
  level = level ? 0 : 1
  console.log(level ? 'HIGH' : 'LOW')

  const mem = memoryUsage()
  console.log('free memory: %dKB', (mem.heapTotal - mem.heapUsed) / 1000)

  led.write(level)

  await sleep(1000)
}

Connect the LEDLight-Emitting Diode's longer leg (anode) to GPIOGeneral-Purpose Input/Output 15 through a 220-ohm resistor. Connect the shorter leg (cathode) to GNDGround (0V reference). If your board has a built-in LEDLight-Emitting Diode, check the board documentation for its GPIOGeneral-Purpose Input/Output number.

Walkthrough

1. Memory check. memoryUsage() reports heap usage at startup. Useful for spotting leaks over time.

2. Pin setup. DigitalOut(15) claims GPIOGeneral-Purpose Input/Output 15 (the LEDLight-Emitting Diode on XIAO ESP32C6) and configures it as an output. .orPanic() crashes with a clear message if this fails (for example on an invalid GPIOGeneral-Purpose Input/Output number, or a GPIOGeneral-Purpose Input/Output pin that is already in use).

3. Main loop. Switches the pin between 0 and 1 every second.

4. Async delay. await sleep(1000) pauses for 1 second.

Create project

pnpm

pnpm create mikro --template blinky

npm

npm create mikro -- --template blinky

yarn

yarn create mikro --template blinky

bun

bun create mikro --template blinky

Run it

pnpm

pnpm install
pnpm mikro flash  # only needed once per board
pnpm mikro dev

npm

npm install
npx mikro flash  # only needed once per board
npx mikro dev

yarn

yarn install
yarn mikro flash  # only needed once per board
yarn mikro dev

bun

bun install
bunx mikro flash  # only needed once per board
bunx mikro dev

The LEDLight-Emitting Diode blinks, and the console prints memory usage every second.

View source on GitHub