M5Stack Core

The board as it appears on the Velxio canvas, with its full pin map read live from the simulator (regenerated by scripts/gen-boards.mjs, so it always matches what you can wire).

Family: Pro boards · Languages: Arduino C++, MicroPython, ESP-IDF

What is emulated

The M5Stack Core Basic is an all-in-one ESP32 device, so its projects need no wiring at all — place the board, press Run. It runs on the in-browser esp32js engine.

Peripheral	In the emulator
2” ILI9342C LCD, 320x240	Rendered live on the board art; drive it with M5.Lcd (M5GFX)
Front buttons A / B / C	GPIO 39 / 38 / 37, active-low — click them on the board art
Speaker (GPIO 25)	Plays through your computer at the sketch’s real pitch, from tone() and from M5.Speaker alike
microSD	On CS 4, sharing the LCD’s VSPI bus. A real FAT image that Velxio fills with your workspace files automatically; the SD Card panel loads your own
Battery and power	The IP5306 power manager answers, so M5.Power’s battery APIs work; the canvas-header battery slider sets what they read
M-Bus header	All four edges are wireable — see the pin card below

The board runs on the free plan, in all three ESP32 languages (Arduino C++, MicroPython, ESP-IDF).

Use M5Unified, not the classic M5Stack library

Every example here is written against M5Unified, M5Stack’s own replacement. The classic M5Stack library needs arduino-esp32 2.x and no longer compiles on the 3.x core — in the Arduino IDE too, not just here.

Reading the pin card

The pin table at the bottom of this page has 51 rows for a board with far fewer signals, and that is the real device’s doing: M5 prints the M-Bus card on all four edges of the case, naming the same bus twice.

• The left and top strips name signals by GPIO number — 3, 16, 21, 22.
• The right and bottom strips name the same signals by function — R0 is RXD0 (GPIO 3), R2 is GPIO 16, SDA is GPIO 21, SCL is GPIO 22, MO / MI / SCK are the SPI bus on GPIO 23 / 19 / 18, DA25 and DA26 are the two DACs, AD35 and AD36 the ADC-only inputs.

Both sides are wireable because they are the same M-Bus net, reachable from either side of the stack connector. A .1-style suffix on a name (GND.1, 5V.2) just distinguishes repeated power rails.

The tail of the bottom strip — 12, 13, 15, 0, 34 — carries M-Bus signals the printed card leaves out (the I2S lines and HPWR), kept wireable so nothing on the bus is unreachable.

Run your first example

The gallery ships nine ready-to-run M5Stack Core projects. Start with Hello LCD + Buttons: it does the two things every Core project builds on — draw on the LCD, read the three front buttons.

1. Open it

Go straight to velxio.dev/example/m5stack-core-hello, or open the examples gallery and pick M5Stack Core in the boards dropdown:

2. Look around the editor

The sketch is on the left, the board on the canvas, and there is nothing to wire — the board is the whole circuit. The Workspace tree shows sketch.ino next to a libraries.json holding the two the sketch needs (M5Unified and M5GFX), so the first build already has them.

3. Press Run

Velxio compiles the sketch with the real ESP32 Arduino toolchain in the cloud — the Output console streams the compiler — and then boots the firmware. The first build of a session takes the longest; after that, builds come from cache. When it boots, the LCD draws the title and Count: 0:

4. Press the buttons

Click A, B and C on the board art. A adds one, B adds ten, C resets — the counter below reads 13 after three A presses and one B:

That is the whole loop. From here, edit the sketch and press Run again — the first project tutorial covers the editor workflow in more depth.

How the sketch works

// M5Stack Core Basic — built-in LCD + 3 buttons (M5Unified)
#include <M5Unified.h>

void draw(int count) {
  M5.Lcd.fillRect(10, 165, 300, 50, TFT_BLACK);
  M5.Lcd.setTextColor(TFT_GREEN, TFT_BLACK);
  M5.Lcd.setTextSize(3);
  M5.Lcd.setCursor(10, 175);
  M5.Lcd.printf("Count: %d", count);
}

int count = 0;

void setup() {
  auto cfg = M5.config();
  // Force the Core Basic profile — QEMU can't run M5Unified's HW autodetect.
  cfg.fallback_board = m5::board_t::board_M5Stack;
  M5.begin(cfg);

  M5.Lcd.setRotation(1);           // landscape 320x240
  M5.Lcd.fillScreen(TFT_BLACK);
  M5.Lcd.setTextColor(TFT_WHITE, TFT_BLACK);
  M5.Lcd.setTextSize(3);
  M5.Lcd.setCursor(10, 25);
  M5.Lcd.print("Velxio x M5Stack");
  M5.Lcd.setTextSize(2);
  M5.Lcd.setCursor(10, 90);
  M5.Lcd.print("Core Basic (ESP32)");
  M5.Lcd.setCursor(10, 120);
  M5.Lcd.print("Press BtnA / B / C");
  draw(0);
}

void loop() {
  M5.update();
  if (M5.BtnA.wasPressed()) draw(++count);
  if (M5.BtnB.wasPressed()) draw(count += 10);
  if (M5.BtnC.wasPressed()) draw(count = 0);
  delay(10);
}

Piece by piece:

• cfg.fallback_board = m5::board_t::board_M5Stack is the one line worth copying into every sketch of your own. M5Unified normally sniffs which M5Stack device it is running on; naming the board outright skips that and lands on the Core Basic profile every time.
• M5.begin(cfg) brings up the display, buttons, speaker and power manager in one call.
• M5.Lcd is a full M5GFX surface. setRotation(1) puts the panel landscape at 320x240; the second colour argument to setTextColor is the background, which lets text overwrite itself without flicker.
• M5.update() at the top of loop() polls the buttons — without it, BtnA and friends never change.
• wasPressed() fires once per press, which is what makes the counter step instead of racing while you hold a button. isPressed() is the held-down variant.
• fillRect then printf is the simplest redraw: blank the strip the number lives in, then print the new one.

All Core examples in the gallery

Five of the nine are M5Stack’s official examples, ported to M5Unified and otherwise unchanged, so they double as a conformance check for the emulation:

Example	What it shows
Hello LCD + Buttons	The starter above — LCD plus the three buttons
HelloWorld (official)	The canonical first sketch on the 320x240 panel
Button (official)	A, B and C printing to the screen; hold B to clear
Display (official)	The vendor’s own tour of the LCD — sweeps, text, shapes
Speaker (official)	Real pitch through your computer: a 661 Hz beep, a held 112 Hz tone
Button piano	The three buttons as an instrument, with the note drawn on screen
LCD with Adafruit_ILI9341	The same panel driven by the generic Adafruit stack instead of M5GFX
TFCard (official)	Mount the card on CS 4, read and write hello.txt
microSD + LCD	Lists the card’s files on the screen — no card component to wire

Start your own project

Two ways to begin a Core project of your own:

• New workspace in the toolbar, then pick the M5Stack Core starter — it loads the official HelloWorld sketch as your starting point.
• Or Add Component, search for M5Stack, and place the board on any canvas yourself, then add M5Unified and M5GFX from the library manager.

Save with the toolbar’s Save button and the project — code, board and the microSD contents — lands in your projects.

Pins (51)

• 3
• 1
• 16
• 17
• 2
• 5
• 25
• 26
• 35
• 36
• RST
• BAT
• 3V3
• 5V
• GND
• R0
• T0
• R2
• T2
• G2
• G5
• DA25
• DA26
• AD35
• AD36
• RST.1
• BAT.1
• 3V3.2
• 5V.2
• GND.2
• 5V.1
• 3V3.1
• GND.1
• 21
• 22
• 23
• 19
• 18
• 5V.3
• 3V3.3
• GND.3
• SDA
• SCL
• MO
• MI
• SCK
• 12
• 13
• 15
• 0
• 34

Every pin above is clickable on the canvas — click one to start a wire. Board-level behavior, quirks and example links live on the family page.