M5Stack-ATOMS3
A compact ESP32-S3 development kit by M5Stack, suitable for rapid prototyping and IoT applications.
M5Stack-ATOMS3 Pinout
22 pins
| Pin | GPIO | Labels | Status | Capabilities | Notes |
|---|---|---|---|---|---|
| 1 | 0 | G0 | strapping | - | |
| 2 | 1 | TXD2G1PWM | safe | - | |
| 3 | 2 | RXD2G2PWM | safe | - | |
| 4 | 3 | G3PWM | strapping | - | |
| 5 | 4 | G4PWM | safe | - | |
| 6 | 5 | G5PWM | safe | - | |
| 7 | 6 | G6PWM | safe | - | |
| 8 | 7 | G7ADC1PWM | safe | - | |
| 9 | 8 | G8ADC2PWM | safe | - | |
| 10 | 15 | SSPWM | safe | spi | |
| 11 | 17 | SCKPWM | safe | spi | |
| 12 | 21 | MOSIPWM | safe | spi | |
| 13 | 36 | G36PWM | safe | - | |
| 14 | 37 | G37PWM | safe | - | |
| 15 | 38 | SDAG38PWM | safe | i2c | |
| 16 | 39 | SCLG39PWM | strapping | i2c | |
| 17 | 40 | G40PWM | strapping | - | |
| 18 | 42 | G42PWM | strapping | - | |
| 19 | 43 | TXPWM | uart | uart | |
| 20 | 44 | RXPWM | uart | uart | |
| 21 | 48 | LED_BUILTIN | strapping | - | |
| 22 | - | MISO | safe | spi |
Start with these
13 pins with no boot or system involvementFreely assignable - no strapping, flash, USB or JTAG duties. Ideal first picks for buttons, sensors and LEDs.
Fine - with a little care
8 pins · 8 things to knowG0GPIO0 Bootstrapping pin (Chip boot mode selection) Strapping
Must be pulled high (default) or low (to enter UART download mode) at reset. Using it for other functions can interfere with boot mode configuration.
G3GPIO3 Bootstrapping pin (controls JTAG signal source) Strapping
Sampled at reset to select JTAG interface (USB Serial/JTAG controller vs. external pins). Improper use can disable external JTAG or alter debug interface.
SCLGPIO39 JTAG test clock (MTCK); IO MUX alternates CLK_OUT3 and SUBSPICS1 (chip select on the alternative SUBSPI memory bus, unused on standard modules) JTAG
Default JTAG TCK - keep it free if you debug over JTAG. It is not a flash or PSRAM line on standard modules: those sit on GPIO26-37.
G40GPIO40 JTAG test data out pin (MTDO) JTAG
Default JTAG TDO output for debugging. Using it as GPIO will interfere with JTAG debugging functionality.
G42GPIO42 JTAG test mode select pin (MTMS) JTAG
Default JTAG TMS signal for debugging. Using this pin for other purposes will disable the JTAG interface (unless JTAG is rerouted to USB).
TXGPIO43 UART0 transmit pin (U0TXD), default serial console TX UART
Used for bootloader output and UART console logs. If repurposed, you will lose the default serial output (and programming via UART0).
RXGPIO44 UART0 receive pin (U0RXD), default serial console RX UART
Used for bootloader input (download mode via serial). If repurposed, you cannot use the default UART0 download mode for programming the chip.
LED_BUILTINGPIO48 Octal SPI differential clock negative leg (SPICLK_N_DIFF), used only by the 1.8 V octal flash/PSRAM variants Other
Only the 1.8 V octal parts (ESP32-S3R8V, ESP32-S3R16V) run the differential memory clock here, and on those the pin works at 1.8 V instead of 3.3 V. On the common 3.3 V modules it is a normal GPIO - several devkits drive their RGB LED from GPIO48.
The M5Stack-ATOMS3 pinout brings out 22 pins - 21 usable GPIO.
For peripherals, I²C is mapped to SDA on GPIO38 and SCL on GPIO39; the SPI bus (MOSI, MISO, SCK, SS) is broken out in full; TX/RX on GPIO43 and GPIO44 cover serial logging and flashing.
If you want zero surprises, TXD2, RXD2, G4, G5 and 9 more are free of any such role - the safest first picks. 8 of the exposed pins carry boot-time or system duties on the ESP32-S3 (G0, G3, SCL and 5 more).
Getting started
flash your first firmware in ~2 minutesBoard: ESP32S3 Dev Module USB CDC On Boot: Enabled Flash Size: 8MB (64Mb) Flash Mode: DIO PSRAM: QSPI PSRAM Partition Scheme: 8M with spiffs (3MB APP/1.5MB SPIFFS) Upload Speed: 921600
// toggle GPIO1 - wire an LED and resistor to it
void setup() {
pinMode(1, OUTPUT);
}
void loop() {
digitalWrite(1, HIGH); delay(500);
digitalWrite(1, LOW); delay(500);
}[env:m5stack-atoms3]
platform = espressif32
board = esp32-s3-devkitc-1
framework = arduino
monitor_speed = 115200
upload_speed = 921600
board_build.arduino.memory_type = qio_qspi
build_flags = -DBOARD_HAS_PSRAMesp32-s3-devkitc-1 - or type it after board =.esp32:
board: esp32-s3-devkitc-1
variant: esp32s3
framework:
type: esp-idf
psram:
mode: quad
speed: 80MHz
# blink - GPIO1
output:
- platform: gpio
pin: 1
id: led_out
light:
- platform: binary
name: "LED"
output: led_outesp32-s3-devkitc-1 (same ids as PlatformIO).esptool.py --chip esp32s3 --port /dev/ttyACM0 \
--baud 921600 write_flash 0x0 firmware.bin--port = your /dev/tty* (macOS/Linux) or COMx (Windows).Specifications
ESP32-S3 · 24 × 24 mm · vs other ESP32 chips →Dimensions
About this board
At its core is the ESP32-S3 - a dual-core Xtensa with vector extensions suited to AI workloads.
Expect to pay about $15.50 - less than the ~$29 most ESP32-S3 boards go for.
Onboard you'll find an IPS LCD 0.85" 128x128 display, a Grove connector, an MPU6886 IMU, an IR transceiver and Screen buttons.
It flashes over native USB - no serial-converter driver needed, which isn't a given among ESP32-S3 boards.
Where to buy
prices are typical street pricesResources
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