ATmega256RFR2 Xplained Pro

Created by Scott Schmit, last modified on Jun 24, 2014



The ATmega256RFR2 Xplained Pro development kit allows for complete evaluation of the ATmega256RFR2 dual purpose IC. The ATmega256RFR2 integrates an 8-bit AVR microcontroller with a low power 2.4GHz RF transceiver. It provides industry leading RF performance for single chip solutions with decreased power consumption. Xplained Pro is the latest series of low-cost development boards for Atmel MCUs. The Xplained Pro series shares a common form factor along with various daughter cards that are capable of interfacing with the Xplained Pro development boards. The ATmegaRFR2 Xplained Pro board, specifically, is capable of interfacing with the I/O daughter card, the OLED daughter card, and the PROTO daughter card. The ATmega256RFR2 Xplained Pro eval board comes with an on-board embedded debugger (EDBG) which enables the user to debug the RFR2 without needing an external debugger. The EDBG also serves as a Data Gateway Interface (DGI) and Virtual COM Port (VCP).

ATmega256RFR2 Specs

Flash 256 KB
Max Freq 16MHz
Serial Comm SPI, TWI, UART
ADC Channels 8 x 10b
Max Data Rate 2Mb/s
TX Power 3.5dBm
TX Power Consumption 14.5mA
RX Sensitivity -100dBm
RX Power Consumption 12.5mA

Daughter Cards

I/O1 Daughter Card

OLED1 Daughter Card

PROTO1 Daughter Card

Hardware / Purchase Links


ATmega256RFR2 Xplained Pro Board

Xplained Pro Daughter Cards

Useful Downloads

  • Atmel Studio 6.1 - must use Studio 6.1 or later for this board. Previous revisions of Studio do not interface properly with the embedded debugger.
  • Atmel Lightweight Mesh (ALM) - Free, lowpower, proprietary mesh wireless network; software stack for AVR microcontrollers from Atmel.
  • BitCloud for megaRF - Free, ZigBee PRO wireless network software stack for megaRF devices.
  • Tera Term - Free open source terminal emulator; Useful for communicating with UART using keyboard characters.


These tutorials are put in order of difficulty with the first one being the easiest to understand. If the reader has limited experience with Atmel products, it is recommended to perform each of the following tutorials in order. If the reader already has fairly extensive experience with 8-bit AVR microcontrollers, feel free to jump to the Peer2Peer project to get started with wireless communication. Once the reader feels comfortable with these tutorials, feel free to open some of the ATmega256RFR2 Xplained Pro example projects in ASF, as the ASF provides some additional wireless communication examples.

Blinky LED

Using the 16MHz Crystal

ADC, UART, and I/O Daughter Card

Peer2Peer Wireless Communication using ALM

Multi-Node Wireless Communication using ALM

Additional Info / Known Issues

  • The Xplained Pro series of development kits all use a USB micro-B connector for power and programming interface. A USB cable comes with the ATmega256RFR2 Xplained Pro Starter Kit, but does not ship with the ATmega256RFR2 Xplained Pro Evaluation Kit. Here’s a link to a USB cable that will work for the eval kit.
  • Atmel Studio 6.1 or later must be used for this development kit. Prior versions of Atmel Studio do not support the EDBG interface. Also, the EDBG drivers will not install properly without Atmel Studio 6.1 installed. Here’s a link to a free download of Atmel Studio 6.1
  • In the ATmega256RFR2 device, the value within the Clock Prescaler register will have different effects depending on the System Clock Source.
    • By default, the CLKPR register will read 0x00, regardless of clock source. However, 0x00 will give a division factor of /2 when using the internal RC oscillator, while 0x00 will give a division facter of /1 for all other clock sources.
    • The RFR2 Xplained Pro board ships with the ATmega256RFR2 running off its internal 16MHz RC oscillator and the CKDIV8 fuse is programmed by default. Since the internal 16MHz RC oscillator is the source, the system clock will be: 16MHz / 2 / 8 = 1MHz;
    • The built-in 1:2 prescaler that comes with the 16Mz internal RC allows for backward compatibility with software meant for older mega devices running off an 8MHz internal RC.
    • If the user wants to change the clock source from the internal 16MHz RC oscillator to the board-mounted 16MHz crystal, leaving the CLKPR register at its default value will change the system clock from 1MHz to 2MHz because the CLKPR division factor will be /1 instead of /2. This isn’t a problem so much as an inconvenience. If the user switches from the internal 16MHz RC oscillator to the external 16MHz crystal, the CLKPS3:0 bits must be changed accordingly within the CLKPR register from application code to ensure proper timing.
    • See section 11.11.2 of the ATmega256RFR2 datasheet for full explaination and a table of division factors.
  • The OLED daughter card is intended to be connected to EXT3 on the Xplained Pro boards. The 3 LEDs on the OLED daughter card are not excessible to the MCU if connected to EXT3 of the RFR2 Xplained Pro board. The OLED that’s loaded on the OLED daughter card can be controlled using the ATmega256RFR2 board. However, the OLED datasheet and the OLED controller datasheet are not excessible to the public. The user must submit a request to the respective manufacturer for device datasheets.

Comments from the Author

The reader is strongly encouraged to read through all of the documents referenced on this page. I encourage you to sift through the various datasheets, as well as the ALM stack in Atmel Studio and try and implement available functionality that is not covered in any of these tutorials. This page is not meant to give you all of the answers for wireless network implementation. It is a starting point, meant to give you some basic examples that you can build on and apply in more complex applications. I hope you enjoy experimenting with Atmel’s RF products and the Xplained Pro eval boards!

  • Scott