RePhone is one of the most unique and interesting development board platform that created by Seeed Studio, with RePhone you can not only DIY a special phone for yourself, but also enchant things around you with cellular connectivity. The first edition of RePhone core is Xadow – GSM+BLE, this time we provided another 2 edition of RePhone core which with higher performance and lower power consumption, one of them is the RePhone core 2G Atmel32u4 v1.0.

The RePhone core 2G Atmel32u4 v1.0 is a new Arduino compatible RePhone core 2G board, which is based on Atmel32u4 and SIM800H, Most features of RePhone Core 2G Atmel32u4 v1.0 is the same as Xadow – GSM+BLE, such as offering rich range of communication protocols – GSM, GPRS, and Bluetooth, supporting quad-band 850/900/1800/1900Mz, and supporting 2G Nano SD card. But the solution of Atmel32u4 plus SIM800H has dropped power consumption a lot comparing to Xadow – GSM+BLE. If you are looking for a high-performance and low power consumption Rephone core to enchant the world, then this new RePhone core 2G module is the best choice.

We also provide an even more powerful version of new RePhone core 2G because its solution is AtmelSAMD21+SIM800. Click here to find it.


  1. This product DOESN'T include a lopo-battery, and there's no lipo-battery sold at our Bazaar as well, any 3.7V lipo-battery will work
  2. This product DOESN'T include a Mic, Speaker and 3.5mm handset input, you need to buy a Xadow Audio for those function.



  • Atmega32u4 work at 16MHz
  • Works with Arduino IDE (based on Arduino Leonardo bootloader)
  • Embedded with lithium battery management chip
  • User button


  • Quad band850/900/1800/1900MHz
  • GPRS multi-slot class 12/10
  • GPRS mobile station class B
  • Meet the GSM 2/2 + standard
    • Class 4 (2 W @850/900MHz
    • Class 1 (1 W @1800/1900MHz)
  • bluetooth:compatible3.0+EDR
  • FM:band limits 76~109MHz,Tuning step by step 50KHz
  • Via ATcommand control 3GPP TS 27.007, 27.005 and SIMCOM enhance ATcommand set
  • Low power
  • Operating temperature range : -40 ~+85 °C


Item Value
Microcontroller Atmega32U4
Operating Voltage 3.3V
DC Current per I/O Pin 50
Flash Memory 32 KB of which 4KB used by bootloader
Clock Speed 16 MHz
Lenght 68 mm
Width 30 mm
Weight 12 gr.

Hardware Overview

  • **1- **11pin Xadow Connector
  • **2- **User Button(D3)
  • **3- **Micro USB connector for programming and power
  • **4- **35pin Xadow Connector
  • **5- **Jst1.0 Battery Connector
  • **6- **Nano Sim Card (same to iPhone ⅚/7)
  • **7- **Atmega32U4 IC
  • **8- **Charge status monitor LED
    • blink - no battery insert
    • on - charging
    • off - charge done
  • **9- **IC - ETA6003(datasheet)
  • **A- **ICSP pads
  • **B- **Antenna Connector
  • **C- **I/O PIN pad
  • **D- **SIM800H

Pin map


Click to view larger image.


  • INT1 connect to D7
  • INT2 connect to D12

Arduino IDE

After you download and install the latest Arduino IDE, then click here to add the board to your Arduino IDE.

Install the Driver (For Windows)

When the first time to insert the board, you should get a USB COM device name RePhone 2G SAMD21 that need to install a driver. Click on the below button to download driver for the board.

To make sure the driver was installed successful, open your Device Manager to see if RePhone 2G 32U4 exists.

Hello World

Now we can upload our first demo - Hello World to the board.

Open your Arduino IDE copy the blow code:

void setup()

void loop()
    Serial.println("Hello world!");

And Then,

  • Click on Tools > Board > RePhone core 2G-Atmel32u4

If you can not find the RePhone core 2G-Atmel32u4, please check How to Add Seeed boards to Arduino IDE

  • Click on Tools > Port to select a right port number. (Don't choose COM1)

Then click on the Upload button on the left-top of Arduino IDE, seconds later the sketch was uploaded successful.

If the uploading is success, you should the some info in red.

Open Serial Monitor of your Arduino IDE and you will get "Hello World" printed per seconds.

AT Command Mode

RePhone core 2G board support AT command mode. TX/RX of SIM800H is connected to Serial1(D0/D1) of AtemlSAMD21.

Copy the below code and upload to your board.

#include "atmel32u4_gprs.h"

void setup()

    Serial.println("SIM800 Serial Debug Test ...");

    while(0 != gsm.sendATTest())
        Serial.println("sim800 init error!");

    Serial.println("sim800 init O.K!");

void loop()

Open your Serial monitor and wait for GSM init ok. printed on the monitor, then you can input a command. Try to input an "AT" to get an "OK".


All command must be end with a new line(\r\n).

Click on below button to get detailed AT command documentation.


We had made many examples to show you how this module work. At the every beginning, please

  1. Insert a nano SIM card
  2. Insert the antenna
  3. If you got a lipo-battery, insert it to the board as well

Click on File > Examples then you can open those examples.


  • Bluetooth_AT_Command_And_Music_Play: Play music via bluetooth
  • GSM_GPRS_HTTP_GET: Http get hello.txt from mbed.org
  • GSM_Receive_SMS: Receive SMS
  • GSM_Voice_Call: Receive voice call
  • SIM800_Serial_Debug: AT command mode



  • button_test: On-board button test


  • lcm_display_test: LCD display exampledkdsafdfds


  • rephone_menu_test

RePhone Family

There are several chainable add-on modules to extend the features and functionalities – Xadow Audio, Xadow LED 5x7, Xadow Basic Sensors, Xadow Duino, Xadow GPS v2 and Xadow NFC v2.

GPS v2 Basic Sensors NFC v2
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Get More Details Get More Details Get More Details
LED 5 x 7 Audio Xadow GSM Breakout
Get More Details Get More Details Get More Details

Schematic Online Viewer


Tech Support

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