communication transports

Postby Richard-TX » 21.06.2013, 09:14

Maja wrote:I do not understand this discussion anymore :roll:

Price is ruling - always!

In the Embedded Systems tier ("Near Field Communication" = short distances < 1 m) I2C is without any "price / performance" competition - mainly as of the price factor and and availability of component families - it is "Public Domain" technology!
(I am using always I2C technology connecting "PLC" boards for my train hobby - ONE € level !)
Cheers!


You are correct and I agree. Price is really linked to performance and that also brings things around to what level of performance is good enough. What is acceptable? What isn't? How well does a given solution scale on a practical basis?

The discussion is about various bus technologies and what is appropriate for model railroads.

Price is a definite factor and when it comes to price I2C is the clear winner. Adding a 16 servo controller to an existing I2C controller with frog switching, software feedback, and hardware feedback is about $55 with $40 of that going toward relays. A similar ESU solution would be $250.

I think that for a moderate layout I2C is acceptable. For larger layouts, multiple TCP based I2C controllers would work nicely. I could be wrong.

I am starting to think that having multiple I2C buses controlled by multiple Raspberry Pi computers might not be a bad idea.

The wonderful thing is that Rocrail can communicate with almost any current technology and has the ability to grow to any future technology. For that I am eternally grateful to Rob and the Rocrail team!

Everyone that uses Rocrail should donate to the project and donate often. In all the years I have been doing computers as a career (1988) Rocrail is the only piece of software that I have ever given any money to. The level of support, speed of break fixes, upgrades, and more is better than anyone else big or small. Some of the companies I have dealt with to get bugs fixed are AT&T, Microsoft, Sun Micro, Redhat, Oracle, Sybase, CA, IBM, and many more. Rocrail's support has them all beat.

For those that have never had to ask for help, all the more reason to support the project.

Rocrail is like owning a fine German car like an Audi. The only way you go back to owning something else is with much kicking and screaming.
Richard-TX
 

Postby Richard-TX » 25.06.2013, 00:23

I was wrong about SPI. SPI does have a CS/CE but with only 1 CS/CE and using MCP23S17 port expanders, a total of eight 16 port chips for a total of 128 i/o ports.

The Raspberry has 2 CS/CE lines so the total number of chips it can address on the SPI bus is 256.

http://www.erik-bartmann.de//download/P ... P23S17.pdf
Richard-TX
 

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