The init() badge
Everyone at init() takes home an M5Stack StopWatch: a tiny ESP32 computer with a round screen, two buttons, and a battery. Here’s what’s inside, what to build on it, and how to sign it in with AuthKit.
KEY A
Yellow button, upper left
KEY B
Blue button, upper right
Display
1.75″ round AMOLED touchscreen
PORT.A
Grove port for plug-in sensors and modules
USB-C
Charging, and flashing new code
Lanyard slots
Wear it with the lanyard at the bottom
PWR
Press to wake or reset, double-press for off
Magnets
Four in the back plate
Title
init() badge
ESP32-S3
Dual-core at 240 MHz
16 MB flash
Plus 8 MB of PSRAM
1.75″ AMOLED
466 × 466, round, with touch
Two buttons
Plus touch and a vibration motor
Wi-Fi and Bluetooth
And ESP-NOW, badge to badge
Motion
A 6-axis IMU and a real-time clock
Mic and speaker
Record and play back sound
450 mAh
Charges over USB-C
01Blueprints
Step-by-step guides written for this exact board. Each one ends with a prompt you can hand to your coding agent.
Featured · Identity
No keyboard, no problem. The badge shows a QR code, you approve on your phone, and it’s signed in as you. It’s the same flow AuthKit uses to sign in command-line tools.
How sign-in works
Badge to WorkOS
01Ask for a sign-in code
WorkOS to Badge
02A code, and a link for the QRgood for 5 min
Badge to Phone
03Scan the QRRRGQ-BJVS
Phone to WorkOS
04Approve in AuthKit
WorkOS to Badge
05Signed inthe badge checks every 5 s
Tilt the badge and a bubble floats around the round face.
A nine-week running plan that buzzes when it’s time to run or walk.
A live sound meter from the microphone, with a peak hold.
Hold KEY A to talk to nearby badges. No router, no internet.
One badge hosts, everyone else answers True or False, and the fastest right answer wins.
A little pet that shows what your coding agent is up to, and when it needs you.
02Toolchain
Arduino and M5Stack’s libraries get you from nothing to your first sketch in three steps.
In Arduino IDE, add M5Stack’s package index under Additional Boards Manager URLs, install M5Stack 3.3.7 or newer, and select M5StopWatch. Keep its default partition scheme so the init() firmware can go back on later.
https://static-cdn.m5stack.com/resource/arduino/package_m5stack_index.jsonInstall M5Unified 0.2.15+ and M5GFX 0.2.21+ with their dependencies. They own the display, buttons, power, and sensors.
Connect a USB-C data cable, hold PWR for about two seconds until the green LED lights, then release and pick the port.
#include <M5Unified.h>void show(const char* text) { auto& d = M5.Display; d.fillScreen(TFT_BLACK); d.drawString(text, d.width() / 2, d.height() / 2);}void setup() { auto cfg = M5.config(); M5.begin(cfg); M5.Display.setTextDatum(middle_center); M5.Display.setTextFont(&fonts::FreeMonoBold12pt7b); show("init()");}void loop() { M5.update(); // Poll buttons every pass; don't block here. if (M5.BtnA.wasPressed()) { show("KEY A"); M5.Power.setVibration(160); delay(40); M5.Power.setVibration(0); } if (M5.BtnB.wasPressed()) { show("KEY B"); }}Conference firmware
Install from desktop Chrome or Edge over USB. It works on badges that kept the conference storage layout, and checks before it writes anything.
Install firmwareFactory firmware
Flash the original StopWatch demo back with M5Burner. It won’t restore the conference build.
Recovery guide03Pinout
PORT.A takes Grove modules as-is. The header on the back has ten more pins for everything else.
On v1.0 badges, pin 14 is 5 V in, even where the sticker says BAT, so never connect a battery there. It’s the battery pin only on v1.0.1, marked *BAT. Revision notes
M5.Ex_I2CM5.Power.setExtOutput(true)Every other pin, including the internal I²C bus, is in M5Stack’s pin map.
04Agents
SKILL.md packs the board, verified library versions, and the gotchas into one file your coding agent reads before it writes a line.
---
name: m5stack-stopwatch
description: Build and troubleshoot firmware for the M5Stack StopWatch C152 ESP32-S3 dev kit distributed at WorkOS init().
---
# M5Stack StopWatch field guide
Read the StopWatch skill at https://workos.com/init/badge/SKILL.md. I’m building for the M5Stack StopWatch (C152) from WorkOS init(). Help me make a simple timer using its round screen and two buttons.
05References
The docs and code behind everything on this page.