DEVICE MANUAL / C152WORKOS INIT()

M5STACK / ESP32-S3

StopWatch

Development kit reference

Setup, hardware specifications, and projects for the StopWatch kits distributed at WorkOS init().

Install conference badge Setup procedure SKILL.md

Install from Chrome on a computer with a USB-C data cable. Report an issue

Head-on M5Stack StopWatch with a slim black bezel, a rectangular yellow button at 10, a rectangular blue button at 2, and a pale purple clock display — 52 × 52 × 15.5 mmNot to scale

ESP32-S3Dual-core · 240 MHz

466 × 4661.75″ AMOLED touch

16 MB + 8 MBFlash + PSRAM

450 mAhBuilt-in battery

01 / SETUP

Setup procedure

1.1

Connect the device

Connect a USB-C data cable. Check the device guide for buttons, power controls, and download mode.

Open the device guide

1.2

Set up Arduino

Select the M5StopWatch board and install M5Unified and M5GFX. See the checklist below for required versions.

Set up Arduino

1.3

Run an example

Compile and upload the display example, or follow a complete StopWatch project from the resource index.

Browse examples

NOTE

Conference badge: use the browser installer for the init() build, or follow the Arduino guide below to develop your own firmware. Installing firmware replaces the device’s application; keep any image you want to restore.

Arduino setup checklist

Install the M5Stack package through Arduino Board Manager. Use version 3.3.7 or newer and select M5StopWatch.
Install M5Unified 0.2.15+ and M5GFX 0.2.21+ with their dependencies.
Connect a USB-C data cable. Hold the power/reset button for about 2 seconds until the green LED turns on, then release.
Select the device’s port. Compile and upload the official display example.

Restore M5Stack’s factory firmware with M5Burner. This restores the manufacturer’s demo, not an init() custom image.

02 / HARDWARE

Hardware specifications

Full specifications

M5Stack StopWatch

SKU C152. Check your board revision before using the expansion pins.

M5Stack product page

Display & touch: Round AMOLED · CO5300 display driver · CST820B touch
Input & feedback: 2 programmable buttons, power button, vibration motor
Motion & time: BMI270 6-axis IMU · RX8130CE real-time clock
Audio: MEMS microphone · ES8311 codec · AW8737A amplifier
Connectivity: 2.4 GHz Wi-Fi · USB-C · HY2.0-4P expansion port
Power & size: M5PM1 power management · 52 × 52 × 15.5 mm · 39 g

Expansion pins — hardware revision notice

On some v1.0 units, the rear pin printed “BAT” is actually 5V IN. Do not connect a battery to that pin. On v1.0.1, the “*BAT” marking refers to the battery pin. Read M5Stack’s sticker correction and revision-specific pin map before wiring accessories.

Check the official pin map

03 / RESOURCES

Resource index

PROJECT / ESPTEMBER

Couch to 5K

A StopWatch running timer with 27 workouts and two-button controls. Includes a build walkthrough.

REFERENCE

Hardware manual

Pin maps, schematics, power behavior, and firmware downloads.

ARDUINO

M5Unified

The shared device library. Start here for board initialization and peripherals.

DISPLAY

M5GFX

Graphics primitives, text, and drawing for the round display.

MICROPYTHON

UiFlow2 quick-start

Set up the matching firmware for visual blocks and Python.

ESP-IDF

Factory demo source

Explore a complete application and its own toolchain requirements.

RECOVERY

Restore factory firmware

M5Burner instructions for restoring M5Stack’s StopWatch firmware.

INSPIRATION

ESPtember projects

Small-screen projects and practical build notes. Check the board named in each guide.

04 / FOR AGENTS

Agent reference

SKILL.md

Read or download the Markdown skill for board specifications, setup requirements, revision notes, and source links.

EXAMPLE PROMPT

Read the StopWatch skill at /stopwatch/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.

Review generated firmware against the current M5Stack documentation.