On Thu, 2013-08-22 at 10:41 +0700, Thomas Frank wrote:
> Hello Gumstix Community,
[snip]
> Right now, I am struggling with a lot of newbie problems since my
> experience with embedded systems is rather limited. Also for now, I
> don't have a SD card, so I have only the stock Angstrom and probably
> need a cross compilation environment which would be my first problem. I
> am stuck with windows on my working PC but have Arch Linux (private
> laptop) and Ubuntu (VM) at my disposal. I have seen tutorials setting up
> an Open Embedded environment and the Gumstix introduction to
> cross-compilation (
http://gumstix.org/basic-cross-compilation.html) is
> just compiling a kernel with gcc-arm-linux-gnueabi.
>
> The next problem is McBSP pinout. There are now dedicated pins for this
> on the Alcatraz, but searching through your mailing list I read that
> certain pins can configured as McBSP signals. Searching through the
> documentation I have, I didn't find a way that explains this feature.
>
> In Summary:
> 1. Do I need a Open Embedded ? If yes, how to set it up correctly and on
> what system? (up-to-date tutorial?)
You're likely going to need a customized U-Boot and/or kernel to get the
pin-mux set up properly and to make use of the McBSP for something other
than sound/audio.
I'd recommend a Yocto build. The learning curve can be high, but in the
end, keeping up to date with the latest features is easier.
http://gumstix.org/software-development/yocto-project.htmlhttps://github.com/gumstix/Gumstix-YoctoProject-RepoSkipping ahead some steps...
To build the image files:
$ bitbake gumstix-console-image
(Takes about 2.5 hours for me on my 4-core laptop. A VM will take much
longer.)
To build a cross compilation toolchain, that only uses headers and
libraries that are installed in the target image:
$ bitbake gumstix-console-image -c populate_sdk
> 2. How to get McBSP signals on pins of the Alcatraz board ?
You will need to consult the TI OMAP Technical Reference Manual (freely
available from TI), the Gumstix Overo Reference document, and the
Alcatraz schematic (freely available from Gumstix) to understand the
pin-mux and what pins you can use.
If your electrical design needs pins configured ASAP, you will probably
need to modify u-boot source files:
board/overo/overo.c
board/overo/overo.h
If not, you can defer configuration of the pin mux to the linux kernel:
arch/arm/mach-omap2/board-overo.c
or in a custom kernel module, or maybe from user space using debugfs.
When setting the pin mux, to avoid frying hardware you must *avoid*:
floating CMOS inputs
bus fights on outputs
driving the OMAP I/O pins before the SYSEN signal is asserted
Regards,
Andy
> I don't mind RTFMs at all if you can point my to the right manuals or
> tutorials.
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