SX Networking

Rsadeika

As my project starts to grow in size, I am thinking the direction that I may have to turn to is, possibly four sx28 interconnected. Now,·I have seen some schemes -·SPI, I2C, Dallas '1-wire', and maybe a plain RS-232 setup. I guess what I need to know is if anybody has done any setups like this. Basically, for now I am thinking one master and four slaves, with the possibility of adding a slave or two at the most. Anybody have any suggestions or things to look out for. Also, while heading in this direction, the master may need some management capabilities. For example I tell the master to do such and such at a specified time, and the task can and·will·different at diferrent request times. Any ideas or do I need a reality check.

Guenther Daubach

Rsadeika,

one of my very first SX-related projects was a system with one SX-controlled master, and many SX-controlled slaves , where the slaves either handled up to 64 pushbuttons and LEDs, or 16 potentiometers, incremental data wheels, and other stuff.

Usually, I don't advertize my SX book here (actually, it's the first time I do it). In the Application Samples section of the book, you will find the description of such a system, handling the necessary communication via the I²C bus. So if you have a chance to grab that book, please have a look at it. BTW, all the source code published in the book is available at the Parallax site for free download. But - although most of the code is heavily commented - the additional explanations in the book might be handy to really understand what goes on.

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Greetings from Germany,

Günther

Jim Palmer

As a non-affiliate, I would also recommend the book. Though I was not planning to impement the I²C, I still happened to read it and found it very specific in detail. So far, the only issue that I have had with the book (and I am a very picky person) is that it's index in the back suffers from the same thing as some of my programs - "off by one" error [noparse]:D[/noparse]

I like the SX-Key/Blitz Development System Manual that came with the SX-Key as it makes a good quick reference for the assembler, but I almost always refer to Günther's book when I want to understand the hows or whys of something.

Jim

Guenther Daubach

Jim,

thank you for the "off by one" information - you are the first reader reporting it. I'll take special care of that matter when preparing the next edition.

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Greetings from Germany,

G

Rsadeika

I purchased the SX tech kit that included your book, so I am well aware of your examples. The problem is, I am not an experienced assembly programmer, not the SX type anyway. As I gain knowledge in that area I will probably find out how valuable your book really is.

For the time being I prefer to use SX Basic as the tool of choice for my prototypes. With the inline assembly capabilities of SX Basic I think that I can impove on some code efficency. But, for quick and dirty, I am using SX Basic.

I was looking forward to seeing some discussion on the merits of I2C vs SPI vs Dallas vs RS-232. I have looked at the examples that you can find on the Parallax download area, the Scenix examples in particular, and again the problem, assembly code.

To narrow down what I am looking for, it is linking the processors (sx28) together. In the Scenix examples they have code for both the I2C and SPI protocol, which probably leads to another thread, how do you implement a VP within SX Basic code.

Another thought, if I have an SX28 dedicated to accessing extra memory, via eeproms, for example, how much maximum memory can the SX28 access in terms of kilobytes?