Grape-Express Mini

find your future of development with the Grape-Express Mini


With the size of 5 to 10 cm, the board is very compact. Plugs around the board make it very comfortable to create a structure. The board has a pitch of 2.54mm so it is possible to put it anywhere on a compatible grid. Not only the hardware, but also the noble design with the black look makes the board modern.


The Microchip’s ATmega2560 microcontroller gives you every opportunity to develop something special. The microcontroller is clocked at 16MHz. It also has a crystal that can be used for precise applications. So that some more power can be obtained from the microcontroller, two more microcontrollers are available. Powerful microcontrollers also exist on the WIFI and the Bluetooth module, which, with the help of the main controller, can fully exploit the performance of the board.


On the board is a Bluetooth module RN4871 BLE (4.2). The module communicates with the microcontroller via UART. With the help of a PC, the module can be configured with the help of ASCII code. On the plug next to the module there is another I2C interface available. The module is very well suited for app and smart home applications.


The RN171 is a very powerful WIFI module. The module communicates with the microcontroller via UART. To make programming much easier, the module can be configured using a PC and ASCII code. The module has an external antenna connector, which allows the power of the WIFI module to be set to the maximum.


The Grape-Express Mini has a rechargeable battery. This is controlled by an intelligent circuit. When plugging in a USB cable, the battery is charged automatically and the switch between external power supply and battery takes place without interruption. The battery lasts up to 6 hours and is recharged within 20 minutes. This is the safest lithium-ion circuit that exists. The circuit protects the board from short circuits and overheating.

DCS (Dual Connector System)

The specially designed DCS connector system offers many advantages, such as plugging in components on both sides, as well as simply measuring a signal. The multiple use of a pin is possible. All connectors are aligned in 2.54mm pitch.


The Grape-Express Mini offers many possibilities to program it. Microchip offers an Atmel-ICE debugger that lets you easily program the board with the Atmelstudio. The programming interfaces JTAG and SPI are available for this. You can load a bootloader into the microcontroller via SPI, which also allows you to program the board via the USB directly with the PC, for example with the Arduino IDE.

Hardware Overview

GPIO Overview


  • Powerful Grape-Express Mini (16MHz)
  • Dimensions L = 100mm, B = 49mm, H = 22mm 
  • 256KB Flash, 4KB EEPROM, 8KB RAM
  • WiFi (also withe ASCII) with external antenna
  • Bluetooth 4.2 BLE (Bluetooth Low Energy)
  • Bluetooth and WiFi can be externally programmed and updates received
  • Multiple programming connectors (USB, ISP, JTAG)
  • 1,3″ OLED Display 
  • Internal 32,567kHz crystal
  • Safety in transfer data between microcontroller and WiFi, Bluetooth and external programmer.
  • WiFi and Bluetooth GPIO protection
  • Power switch on/off
  • Maximum 1,9A power from all pins of 5V
  • DCS (Dual Connector System) to use both sides
  • Internal RS232 controller for transfer date between PC and Grape-Express Mini
  • Power regulation chip 
  • No interruption in the program if the USB cable will disconnected
  • User LEDs to show the status of the battery and the wifi module
  • Second I2C bus on the Bluetooth module (254 devices possible)
  • Two different 3,3V safe supply for internal power
  • Battery life for about 6h (average usage of 85mAh), short circuit protection
  • Battery is fully charged in 20 minutes 
  • Also work with Arduino
  • Short circuit protection and overheating protection of the whole system 

Small projekt example

This is a project that was created in 5 minutes. By simply connecting additional electronics, a small software can be created within minutes, which makes the module an element of the Grape-Express Mini. In this example I want to show how easy the Grape-Express Mini Board is and how quickly you can come to a result.


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