ESP32 Controller

Write an ESP32 program in Go, and let esp32-transpiler turn it into an Arduino sketch. It is for anyone who would rather have a program type-checked and tested on a computer than debug it down a serial cable.

Each package mirrors the Arduino calls a sketch makes, so the Go source and the sketch it becomes read the same way.

Install

go get github.com/andygeiss/esp32-controller

Blink an LED

Implement Controller. Setup becomes the sketch's setup(), and Loop becomes loop(), which the board calls over and over.

package main

import (
	"github.com/andygeiss/esp32-controller"
	"github.com/andygeiss/esp32-controller/digital"
	"github.com/andygeiss/esp32-controller/serial"
	"github.com/andygeiss/esp32-controller/timer"
)

const led = 2

type blinker struct{}

func (b *blinker) Setup() error {
	serial.Begin(serial.BaudRate115200)
	digital.PinMode(led, digital.ModeOutput)
	return nil
}

func (b *blinker) Loop() error {
	digital.Write(led, digital.High)
	timer.Delay(500)
	digital.Write(led, digital.Low)
	timer.Delay(500)
	return nil
}

func main() {
	var c esp32_controller.Controller = &blinker{}
	if err := c.Setup(); err != nil {
		return
	}
	for {
		if err := c.Loop(); err != nil {
			return
		}
	}
}

What each package covers

Package	Go call	Arduino call
digital	PinMode	pinMode
digital	Write	digitalWrite
random	Num, NumBetween	random
random	Seed	randomSeed
serial	Available	Serial.available
serial	Begin	Serial.begin
serial	Print, Println	Serial.print
timer	Delay	delay
wifi	Begin, BeginEncrypted	WiFi.begin
wifi	BSSID, RSSI, SSID	WiFi.BSSID and friends
wifi	Disconnect	WiFi.disconnect
wifi	EncryptionType	WiFi.encryptionType
wifi	LocalIP, SetDNS	WiFi.localIP
wifi	ScanNetworks	WiFi.scanNetworks
wifi	Status	WiFi.status
wifi	Client	WiFiClient

Build and test

make is the only command surface. make check runs every gate against the working tree; make ci runs the same gates against the commit, and is what has to be green before a push.

Baseline deviations

This module follows the engineering baseline. Four of its library rules collide with the job in SPEC.md, because the exported names have to mirror Arduino's C API for the transpiler to match them. All four are waived on the record:

• No package-level mutable state (project-types/library.md) — waived 2026-09-06 by Andy. An Arduino sketch keeps pin and network state in globals, and the transpiler maps these onto them. Scoped to the exported variables in digital (GPIOModes, GPIOValues), serial (AvailableN, Baud) and wifi (Current*); no other package holds state, and none of it is safe to touch from more than one goroutine, which the package docs say.

• context.Context first on anything that blocks (stack/go.md) — waived 2026-09-06 by Andy. Arduino's delay() takes no context and a sketch has nothing to cancel it from. Scoped to timer.Delay, the only call in the module that blocks.

• A library returns, it does not print (project-types/library.md) — waived 2026-09-06 by Andy. Printing is what these calls are: they become Serial.print in the sketch. Scoped to serial.Print, serial.Println, wifi.Client.Println and wifi.Client.Write, which write to standard output and nowhere else. Nothing in the module logs.

• The consumer declares the interface (patterns/go-ports-adapters.md) — waived 2026-09-06 by Andy. Controller is declared here rather than by the caller, because the transpiler has to recognise one agreed shape to emit setup() and loop() from. Scoped to that one two-method interface; adding a third method would be a breaking change, so it stays at two.