Do you have a question on Embedded electronics and controls? Ask our Expert, Paul Clarke

Hey Paul,

I am starting out with Embedded "stuff" and I had a question. What's the deal with the various manfuactuers in terms of the chips? I want to design something that uses an ARM7 or above and I see that you can get the processor chip from Atmel, Philips, Samsung, etc.

What motiviates a circuit designer to use one brand over another?

Also, we would like to work in the .net MF environment. If you know of any procs that have a ported .mf framework, any insight would be appreciated. I looked at the other IDEs and don't really want to use assembly or an Embedded brand derivative of C for development. After like 8 languages, it gets crazy to go after more if you know what I mean.

Many Thanks!

Ed

You don't really give enough detail about the kind of work you plan to make any but the most general advice possible. Embedded covers everything from very simple (like a relay timer with 2 logic level inputs and 2 outputs) to very complex (like a network router or a Satnav).

If you come back with a bit more detail I'll try to help.

Regardless of the size of the job I would think very carefully about the .Net Micro Framework. I think it would be fair to say that this has not been the succes that MS hoped it would be (and they have "open sourced" it). There are very few ports and it looks far too resource hungry for simple applications. For applications which are more like an embedded PC I think you would probably be better off with WinCe (or Windows Embedded Compact 7 as we are meant to call it ) which would allow you to stick with Visual Studio type development tools and keep you in the mainstream of the MS eco system.

The good news (if you go that way) is that modern (Cortex) ARM micros are programmed in standard C and the use of assembler is not required.

Michael Kellett

You don't really give enough detail about the kind of work you plan to make any but the most general advice possible. Embedded covers everything from very simple (like a relay timer with 2 logic level inputs and 2 outputs) to very complex (like a network router or a Satnav).

If you come back with a bit more detail I'll try to help.

Regardless of the size of the job I would think very carefully about the .Net Micro Framework. I think it would be fair to say that this has not been the succes that MS hoped it would be (and they have "open sourced" it). There are very few ports and it looks far too resource hungry for simple applications. For applications which are more like an embedded PC I think you would probably be better off with WinCe (or Windows Embedded Compact 7 as we are meant to call it ) which would allow you to stick with Visual Studio type development tools and keep you in the mainstream of the MS eco system.

The good news (if you go that way) is that modern (Cortex) ARM micros are programmed in standard C and the use of assembler is not required.

Michael Kellett

In my case, we buy a product manufactured by others and programmed by others per our spec. The device uses an ARM5 processor. We wanted to refresh and change a bunch of different things to "do it ourselves". So, on the surface, anything greater than an ARM5 in terms of feature-set, speed, etc. is better.

Other than using ther standard IO (Analogs & Digitals; I need 12 analog inputs and 8 digital inputs with 8 digital outputs), we need to have ethernet (10/100) and at least one serial port. There is no external display requirement so we won't have to worry about that.

Ultimately, think of the application as one where we are using a serial port to read/control the analogs and digitals of the proc and an ethernet port that allows the same along with a CLI and a small web server. There is more in terms of whats connecting to the analogs and digitals but until I can get this going, that part of the concept is moot. I can verify the values with a meter on the output and short the digitals to test the inputs.

I get what you are saying about the .net CF. I see that it tends to take up a lot of overhead. My concern with going with a standard C implementation is everything has to be created from scratch. For instance, if I want a simple web server, I would have to decode the HTML and then respond back per HTML standards. With a .net implementation, it can handle the actual back and forth syntax for me.

Are there C libraries available that handle that type of stuff that you know of?

Also, if we went that route, what IDE would be used for Standard C?

If we went with a WinCe implementation, does that require Microsoft licensing?

Sorry for all the questions but I am trying to rapidly wrap my head around this.

Thanks so much!

Ed

Hello Ed,

There are several ARM Cortex micro controllers which support the kind of IO and Ethernet you describe. You need to look carefully to see that the peripherals are good enough. ST, NXP and TI (Luminary) all offer potentially suitable devices. Some of the TI Cortex M3 parts have on chip ethernet MAC and PHY which can be good, NXP and ST parts need an off chip PHY.

My experience is with the Keil(ARM) tool set which is quite pricey but works. You code in C but they offer libraries for a basic real time scheduler and very basic web support. You have spotted the gap in this approach compared with .net (or similar)  - once you get into serious web serving you are going to have  a lot to do yourself. It all comes down to volumes - if you are going to make tens of thousands it may well be worth the software effort to use a cheap micro - if the volumes are low then Wince (or similar) on a bigger processor makes more sense.

I don't know enough about your application to call it one way or annother but I feel that if that web server thing might grow you could save yourselves a lot of grief with a big OS, on the other hand the micro controllers coded in C are much easier to deal with for simple IO.

It's never easy ! (and if it was no one would pay you to do it)

Michael Kellett