Yes, any sort of bit banging is resource intense, and you would probably
want to run it in its own process. This is allow you to use Linux's
interrupts. You could make it more efficient by writing your own
interrupt handler and running the bit banging as a thread, but there are
a lot of caveats here and I don't want to go that far.
You probably want to try to use the built-in NSSP. Keep in mind that
SPI devices can usually be configured for multi-drop, which means that
you can run more than one SPI device off of a single SPI master (e.g.
the gumstix). If you can find a way to use the NSSP, you won't have to
re-invent an SPI driver, which is nice. The driver should act just like
a FIFO/pipe, meaning that you wouldn't have to do anything extra in
I hope that addresses your questions. If you are up to it, I recommend
getting a book about Linux Drivers. There's an O'Reilly book online
that's downloadable as a free PDF.
[mailto:gumstix-users-admin@...] On Behalf Of Peter
Sent: Monday, February 20, 2006 15:57
Subject: [Gumstix-users] GPIO as SPI
This would mean bypassing the serial interface and using four GPIO lines
to build up the data words, yes ? Wouldn't this chew up a lot of
resources ? I assume something like this would run in its own thread...
Concerning the robostix - does using the SPI implys an extra layer of
complexity (e.g. programming), or can the SPI be accessed directly from
the gumstix ?
Sorry for all of the noob questions...
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