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Ethernut 5

The second 32 bit board of our Open Source Hardware family is based on an ARM9 CPU. Beside Nut/OS it is capable of running Linux.

Software Support

Firmware Update
There are several ways to recover or update the firmware.

Yocto Project Support for Ethernut 5
How to build a customized Linux distribution based on the Yocto Project.

Ångström Linux
An earlier board support package (BSP) that contains the Ångström distribution.

As an alternative to Linux, this tiny OS with TCP/IP stack has a ready-to-use configuration for Ethernut 5.

A first stage boot loader loads U-Boot from serial flash.

U-Boot Environment
Learn how to customize the Ethernut 5 boot loader.

ARM Cross Development with Eclipse
Ethernut 5 Source Code Debugging
Both documents explain how to setup Eclipse and OpenOCD to allow source code debugging of Nut/OS applications. While the first, newer document describes the Eclipse configuration in a more general way, the second one contains a step by step guide of a slightly different setup.

OpenOCD Configuration for Ethernut 5
explains in detail, how to configure OpenOCD for Ethernut 5. While most developers will typically use the ready-to-run configuration files included in the Turtelizer package, it may be sometimes required to go deeper.

Provides a PLL configuration table.



The AT91SAM9XE was the first ARM9 CPU offered by Atmel, which has embedded Flash memory. Compared to the AT91R40008 CPU used on Ethernut 3, the AT91SAM9 provides a large number of peripherals.


In addition to 512 kByte Flash and 32 kByte SRAM that are embedded in the CPU, the board contains 128 MBytes SDRAM, 1 GBytes NAND Flash and 4 MBytes serial DataFlash.

Additionally, a MultiMediaCard/SD-Card socket and an USB host connector is available to connect external memory cards or sticks.


SMSC's LAN8710I with Auto-MDIX support is used on Ethernut 5.0 for 10/100 Mbit Ethernet connectivity.


Like all Ethernuts, this board offers a 64-pin expansion port for attaching external custom hardware.

Although featuring a completely different CPU, all care has been taken to maintain compatibility with previous Ethernut boards for external hardware. Special functions like the memory bus, a secondary USART or the I2C and SPI busses are still located at the same expansion port pins. Note however, that technology was switched from 5V to 3.3V and that the pins are not 5V tolerant.

Power Supply

Flexible power supply had been a feature of all Ethernut boards, but Ethernut offers more than any of them. You can alternatively use:

An ATmega168 on the back side of the board is used as a power management controller.

Hardware Revisions

The board revision is printed in copper on the back side of the board.

Ethernut 5.0 Rev-F
The initial revision was published in Mai 2011.