EasyLoader (beta)

Current Product Don't Have Test Firmware

Note: pls, use PC chrome/edge browser, if can't connect, refresh the webpage.

1. Click connect button

2. After connected successfully, pick a firmware

3. Click the burn button

4. After burning successfully, Unplug the device and restart.



SKU:C122-B, K122




The newly M5Stamp C3U featuring ESPRESSIF ESP32-C3 RISC-V MCU, with Wi-Fi 5 (LE) connectivity, applicable for home appliances and Industrial Automation. By combining RSA-3072-based secure boot and the AES-128-XTS-based flash encryption. The compact size and powerful functions, make it applicable for multiple IoT scenarios.

The M5Stamp C3U is based on 32-bit RISC-V micro controller, and operates at a maximum clock frequency of 160 MHz. With 400 KB of internal RAM and 4 MB Flash, it can facilitate many different use cases, involving connected devices. The M5Stamp C3U provides, Furthermore, the exceptional heat resistance plastic enclosure is sustained at a higher operating temperature.

Note: If you need to use SPIFFS filesystem in Arduino IDE. Please install a patch package first.

Product Features


    • Three types soldering options are available (SMT, DIP, fly wire);
    • High-temperature resistant plastic enclosure, Peak temperature = 230℃;

    • M5Stamp C3 contains 5V->3.3V DC/DC design, GPIOx14;
    • USB Type C port;
    • Programmable RGB LED x1, Reset button x1, button x1;
    • 3D antenna, providing stable and reliable wireless communication.

    • Arduino, ESP32-IDF (UIFlow support coming soon)


  • DIY, Prototyping
  • Industrial Automation
  • Smart Home
  • Wearable Devices
  • Medical Devices
  • Consumer Electronics

Note: The newly updated C3U shares the same features as C3, but the difference is that M5Stamp C3U without the USB download chip and the program download method is different((The C3U uses the ESP32-C3's built-in USB Serial for program download)). If you are looking for a more affordable project, you can add this to your shopping list!

Program Download/Notes

Enter the program download mode operation:
1. Long press the center button (G9) of STAMP C3U under power failure condition.
2. Connect to the computer, after the port is successfully identified, program burning.
USB CDC enabled:
By default, USB CDC is not enabled, the serial port output started by C3U will be output through UART0, if you need to output through USB, please use IDE to make it USB CDC before downloading the program option enabled. (Arduino users can enable it through Tools->USB CDC on Boot-Enabled, IDF users please refer to ESP IDF official documentation.)

product comparison

Model Master IO quantity Button IO USB chip USB interface function
STAMP-C3 ESP32-C3 13 G3 CH9102 Download / Serial
STAMP-C3U ESP32-C3 14 G9 / Download / JTAG / CDC Serial


Specifications Parameters
ESP32-C3 32bit RISC-V single-core processor, clocked at 160 MHz
Wi-Fi 2.4 GHz band supports 20 MHz and 40 MHz bandwidth, IEEE 802.11 b/g/n protocol, data rate up to 150 Mbps
Input voltage 5V @ 500mA
HMI Programmable physical button x 1, reset debugging button x 1, programmable RGB LED (SK6812) x 1
USB interface TypeC x1
Antenna Type 2.4G 3D Antenna
Module peripheral interface resources ADC, GPIO, SPI, UART, I2C, I2S, PWM, RMT, DMA, USB serial port, TWAI
IO interface x14 G0, G1, G3, G4, G5, G6, G7, G8, G9, G10, G18, G19, G21, G22
IO interface spacing 2.54mm
Fixing screw specifications M2*4 countersunk head hexagon socket mechanical teeth
Net weight 3.8g
Product size 34 * 20 * 4.6mm
Packing size 85*55mm sealing bag (translucent)


  • Purchase link
  • M5Stamp C3U (5pcs):
    • 5 x M5Stamp C3U
    • 5 x Heat Resistant Sticker

  • Purchase link
  • M5Stamp C3U Mate:
    • 1 x M5Stamp C3U
    • 1 x Heat Resistant Sticker
    • 2 x 2.54-12P female headers
    • 2 x 2.54-10P pin headers
    • 2 x 90° HY2.0-4P terminals
    • 1 x 1.5mm hex key


SK6812 (RGB LED) and Button

SK6812 DI /
Button / SW


Module size

  • C3&C3U

The shell supports Reflow Profile





Q1: How do I remove the speaker floor noise when the M5Core is on or running?

Execute the following statement in Setup() of the Arduino program

Q2: How does M5Core2 stack modules?

When M5Core2 is stacked with other M5 modules, you need to remove the battery base of Core2, which does not support module stacking.

Q3: A timeout error is displayed when uploading the program to the device

Reason and solution: The power supply current of the port is insufficient, which can cause the device to not enter the download mode normally. You can try to connect a capacitor (>0.1uF) between the RST pin and the GND pin, or when uploading the program, set the G0 Short-circuit to GND, so that G0 can be set to a low level state normally

Q4: How to solve the phenomenon of automatic signal triggering of M5Core button A

Add the header file #include <driver/adc.h> and the function adc_power_acquire(); in the Arduino program

Q5: M5 device battery life

The battery life of the controller is affected by various factors such as battery capacity, operating status, and load, so there is no fixed value. Reducing the load and adopting a sleep strategy can effectively increase the battery life.

Q6: Can multiple modules with batteries be stacked at the same time?

Support multiple stacks, the total capacity of the batteries in parallel increases, and the voltage remains unchanged. However, since the discharge of each battery is not balanced during use, there is a voltage difference between the batteries, which may cause the battery to charge backwards. .(will lose part of the battery capacity)

Q7: M5 master supports WiFi connection to 5G frequency band

ESP32 module currently does not support WiFi in 5G band, only 2.4G.

Q8: The RS485 device cannot communicate normally/data is garbled. Packet loss, etc.

Confirm whether the TX/RX pin on the TTL side of the pin is correct, try to add two 120Ω terminal resistors at the beginning and end of the device line to reduce signal reflection interference

Q9: The difference between different masters and camera products

Click the link below to view the product comparison table

Q10: M5 camera image blur, how to adjust the focal length

Rotate the lens to adjust the focal length within a certain range

Q11: The control RGB LED pin of FACE II BOTTOM conflicts with the I2S DOUT pin of CORE2


Q1: How to read the programmed firmware?

Use esptool to read the flash content of esp32 and export the bin file. Refer to the detailed operation

Q2: Several solutions for esp32 board download failure in Arduino IDE board management

Restart the Arduino IDE, the computer uses the mobile AP mobile network to download.

Method 3: Download the resource package provided by M5Stack for direct installation, and extract the contents to the board management path of Arduino, such as (C:\Users\Sean\AppData\Local\Arduino15\packages), https://m5stack.oss-cn-shenzhen.aliyuncs.com/resource/arduino/packages/m5stack_v2.0.0.zip
Q3: Arduino SPIFFS file upload operation

Refer to the Github link below, use arduino-esp32fs-plugin for file upload

Q4: When M5Burner burns firmware, an error pop-up window or exception occurs

Check if the COM of the corresponding device is selected and if the M5Burner is the latest version

Q5: Does the M5 master device support multi-language display (Chinese, English, Japanese, Russian, etc.)?

UIFlow users can switch the Label font to Unicode, Arduino users can use the Chinese font library provided in the M5GFX driver library

Q6: The program cannot load the SD card normally

Confirm whether the SD card format is FAT32, and no partitions exist.

Q7: How to use Bluetooth, HTTP, SD, WebServer, FreeRTOS and other features in Arduino IDE

You can refer to the following link for other ESP32 users to share the case program

Q8: How to download programs for STAMP C3U

STAMP C3U enters program download mode operation: 1. Long press the center button (G9) of STAMP C3U when the power is off. 2. Connect to the computer, after the port is successfully identified, program burning.

Q9: How STAMP C3U defines UART0 output mode

By default, USB CDC is not enabled, the serial port output started by C3U will be output through the default pins (G20, G21) of UART0. If you want to output through USB, please use the IDE to output Its USB CDC option is enabled. (Arduino users can enable it through Tools->USB CDC on Boot-Enabled. For IDF users, please refer to the ESP IDF official documentation.)

Q10: Unable to connect to UIFlow Desktop IDE

Refer to the UIFlow documentation of the corresponding device to check whether the device has entered the USB programming mode.

Q11: NBIoT devices cannot connect to the network normally

Make sure that the NBIoT used is not locked. Frequent device replacement or after activating the IoT card, using traffic in different places may cause the card to be locked. If the above situation occurs, please contact the IoT card supplier. If you are using the IoT card matching M5, please contact M5 after-sales through e-commerce or email. (provide the ICCID of the IoT card)


Q1: Consultation for after-sales problems of products

Describe the problems encountered in detail. Screenshots of the programs involved or files can be added as attachments and sent to M5Stack's official after-sales email

Q2: Code Resources, Cases, User Communication