The Computer Corner Take II (#9) by Bill Kibler

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Alternatives to NGW100 as an embedded server

The project gets a new board to play with!

Last year I worked on several embedded projects, one of which used SiLabs 8051 boards and chips. I liked the use of the developer boards for the project, because they provided an inexpensive way to get a project on line quickly and cheaply. These "Target/Prototyping" boards come in many flavors and cost from $35 to over $100.

Recently I used the Atmel NGW100 as a low cost platform for doing numerous projects instead of the SiLabs target boards. The idea was, this under $90 board would provide the base system for doing several projects. However I ran into one major progblem witht he USB port, it was a device or gadget port and not a host port. This means yuou would use it to talk to the board, not as a means of connecting device tot he board. I need to connect devices and plenty of them.

As I work on the board, I found the idea of linux worked great, buildroot was an outstanding tool, and my overall idea sound. What was off, was the USB port can be either device or host, and I need host, while the AP7000 of the NGW100 is device only. The failure was mine in not checking closer what the CPU can do and thus forced me to re-think the spec that I layed out.

The first step on the project was defining the design limits and needs. However, I orginally understated the cirteria and need to be more specific as I now know. The new criteria I selected is this:

If you look a the previous article (#6), you would see that only the USB/PIO items are different. I want to be able to use this for remote video using USB cameras, or as I said before, use the Phidgit system which is a USB based voltage and current montioring system I have installed on my solar array. My previous spec was too vague about USB and thus the NGW100 failed the USB compaiblity test. The new board needs to be USB host ports, ideally more than one as well.

New options to select

I started my board search all over again and ended up on the olimex site. They build a large number of prototype boards for several of the chip companies as well as being the major source of devloper and protoype boards. Their site has the best docs on their products and thus anyone thinking of buying on of their boards should go to that site first. I looked at numerous boards and checked their Euro prices before selcting a few possible choices.

What helped me make the selection was the Micro Controller Pros Web site, and their ARM with Linux selection. This selection shows only small boards that come with linux pre-installed. Compare that list to olimex site and see what boards are available in the USA. The MicroPros site is a bit light on the docs, while olimex gives it all to you as they are the source for what your getting.

The choices came down to three boards under the $150 mark, as it became claer I wasn't going to get what I needed for under $100. I like the LPC2468 at $122 the most. The STR-E912 was pretty neat, but lacked linux. The AT91SAM7x256 at $119 was pretty cool with it's LCD and eforth, but again no linux. A great option was the CS-E9302 running a ARM9 with linux, but at $174 was just too prciey. The LPC2468 uses uClinux, which is not buildroot, but seems like most of the linux system is there. After pooring over all the olimex docs, I decided to try the LPC2468. It seems to have the right mix of devices as well as the olimex "UEXT". This connector provides Power, SPI, USART, and I2c on one connector. MicroPros has a few boards that use this olimex standard interface. Should help building daughter boards for our porjects.

Some links

olimex home page - the place to get board information.
Micro Pros's Linux ARM page.

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