[beagleboard] userland SPI master on beaglebone A3?

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1

hi,

i just got a beaglebone A3. it's nice!

but, having never used a beagleboard before, and being generally new
to embedded linux, i'm slightly confused by the virtual device system
in /sys/class/

thanks to some online examples, i can map the /sys/class/gpio/
locations and poll / set GPIO pins.

but what i would really like is to use the beaglebone as an SPI
master, and the correct use of the /sys/class/spi/ locations remains
mysterious.

is it easy to explain? is there some existing example code for
userland SPI? or should i proceed directly to writing a device driver?

i've tried looking online a bit, and found only missing links and some
references to apparently nonexistent SPI drivers. so it seemed like a
good time to post the question.

many thanks for your help!

- ezra b

2

i'm also looking for a solution here-- can anyone offer some
direction?

thanks,

brian

3

Hey Guys,

Some resources I have seen others post on here that look to be useful:

http://beagleboardxm.org/blog/2011/03/22/progress-spi-is-working-on-the-beagleboard-xm/

http://www.kernel.org/doc/Documentation/spi/spidev

http://www.kernel.org/doc/Documentation/spi/spi-summary

http://elinux.org/EBC_Exercise_05_I2C

The main page where I started looking for this is here:
http://elinux.org/index.php?title=Category:ECE497

I'm new to the beaglebone myself (only had it for a couple weeks), but
the ECE497 has been a great resource. Its designed for previous beagle
boards, but the information applies with a bit of thinking. I wish I
could be of more help, but this is the extent of my current knowledge
(for now)

Have a good one,

~magyarm

4

many thanks!

so, this is the one that i think i needed to look at:

http://beagleboardxm.org/blog/2011/03/22/progress-spi-is-working-on-the-beagleboard-xm/

and the upshot of it seems to be that i have to patch the kernel with
HW-specific configuration as in:

http://elinux.org/BeagleBoard/SPI/Patch-2.6.37

in order to make the SPIDEV driver available. which is to say,
experimenting with SPI settings requires rolling a new kernel for
every change...

can anyone simply confirm that this is correct?

again, sorry for the naive questions; your time is greatly appreciated!

-eb

5

Eb:

did you able to solve this problem. We are also little bit confused
regarding how to make the SPI work in BeagleBone. Any help from
someone would be appreciated. Thanks.

-SH

6

Does this work the same as on the other Beagle Boards?

Rick