Power over Ethernet (PoE) network design

The challenge

Our client required an embedded platform running Linux to be used as a secure interface for network attached equipment. Its two Ethernet ports included one special PoE (power over Ethernet) to supply power for the unit. Further isolated and non isolated serial interfaces were needed to connect to legacy equipment.

The product needed to be reliable, cost effective, stand-alone and needed to have a 'quality build' finish to the enclosure.

The customer wanted the board to boot into Linux and to provide and manage their own application code.

The BitBox approach – embedded ARM® plus Linux

At BitBox we provided the electronic design of all the embedded hardware, plus firmware and software to support our client's team to build their own application.

Much of the technology was already in the BitBox libraries. The iMX28 core was known to be good and stable. We had used high speed signal integrity checking on the DDR2 SDRAM interface to ensure good eye diagrams for the data and address lines. Additionally, the core design had been stress tested at +80ºC and -40ºC for many weeks.

We used our tried and tested iMX28 core as the processing heart of the product which provided the customer with a known good engine as the product basis. By re-using an existing core this reduced the design cost for the customer and increased the chance of a 'right-first-time' design.

The new circuitry on the board was very carefully designed and was found to work first time with no modifications.

An SD card added code storage and data logging. An additional riser connector was required for possible future expansion.


We provided the customer with a well specified and reliable product within the quoted timescales and on budget. Our customer has now completed his code development and placed an order for the first 100 production units.

In addition we have two new projects being designed that will benefit from the iMX28 core design. They will not only benefit from the reliable core - but cheaper components since we are buying more of the same parts.

We are also looking at iMX6 dual and quad core designs – building our skills in more new technologies.

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