[Gumstix-users] ADC/ McBSP advice and questions about writing a driver.

[Alex S. <kin...@gm...>]

Hello gumstix list!
Hopefully some kind sole can  help me.
My goal is to connect a serial ADC to McBSP3. It must be a McBSP (and not
McSPI) so we can use the sample rate generator to run the sample clock. I've
got an overo water and a chestnut board. My question is what is the best way
to go about writing the code. I see I can either write a driver that
interfaces to the McBSP library in the kernel, or add the ADC into the ALSA
framework. Initially I thought adding to the ALSA framework would be the
easier task, but as a hardware engineer I quickly got lost in the layers of
abstraction and could not figure it out. So I tried writing a simple char
driver wrapper for the McBSP library. Am I correct in thinking the steps to
get this all working are to request the bsp, stop the bsp, configure it,
then issue a mcbsp start, at which point I can call things like
omap_mcbsp_xmit_word? Thats what my code currently does but it hangs at the
"wait_for_completion" line in the xmid_word code.

I realize seeing my driver code would help, but I wanted to get to the root
question first. Is writing a simple char driver to DMA my raw adc data into
a userspace buffer easier than simply not reinventing the wheel and adding
support for my adc into the ALSA stuff...?

Thanks for the help and advice!

-Alex