Re: [Embedlets-dev] RE: (I2C?) SPI is *much* faster (and much less flexible)

[Ted K. <tk...@ya...>]

Bruce wrote:

> I2C is about 100 kbits (if memory serves), SPI can be a few MBits. If you 
> have to pick a standard for speed SPI wins.

I would say to choose flexibility over speed in every case except those that
absolutely need maximum speed.  As an example, C is the current language speed
standard and yet slow, flexible Java is replacing it for most applications
where maximum speed is not the main design constraint.

Beyond this, the original I2C bus was limited to 100kbits but since then they
have come out with a 400kbit spec:

http://www.esacademy.com/faq/i2c/general/i2cfastm.htm


and a 3.4Mbit spec:


http://www.esacademy.com/faq/i2c/general/i2chighspeedm.htm



> I2C can be multi-master or peer-peer though I've never seen an 
> implementation. That's one advantage for it.

If I2C can be made to work like a mini-ethernet then it is exactly what I am
looking for because this is the way to maximize Java's potential.  What I am
after is a baby ethernet-like network for the JSIMM backplane, not a peripheral
expansion bus which is what SPI and I2C have traditionally been used for.

I think that one reason one does not see many peer-to-peer I2C implementations
is that the software needed to develop a distributed application based on a
peer-to-peer infrastructure is extremely tough to write from scratch.  Java
solves this problem.



> SPI is *much* faster on TINI, JStik, JStamp, etc.

I like the motto 'Flexibility over speed'.  This principle explains why a lot
more minivans are sold anually than dragsters, and it is my opinion that I2C
based peer-to-peer has the potential to outsell SPI on the JSIMM backplane if
implemented correctly.


Ted

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