Expansion bus issue

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1

Where can I find some good instructions on how to use the BB expansion
bus and i2c, GPIO...??

ps: has anybody tried qt?? working ok with angstrom??

thanks,

Saul

2

qt3 and qt4 are working well.

regards,

Koen

3

Saul,

Where can I find some good instructions on how to use the
BB expansion
bus and i2c, GPIO...??

need to be a little more specific as to what kind of information you need. do you need information on the software side, kernel or userspace, or do you need hardware information such as voltage levels and interface specifics?

Dave

4

I took a look at the bb data sheet and turns out not all the pins are
available, correct? I needed some voltage information, To connect
beagle to a MSP430..I wanted to use the mcSPI interface...I believe
the kernel is already configured to support it....also, if I wanted to
access the OMAP pins, could I do it through a regular C program, I
guess, I know assembly will do but I' m a little confused by the modes
and how they change the pins...I means, in mode 0 a pin is something,
in mode 1...for another, I can only pick one mode, right?? sorry for
the manby questions...I' m jmust really new to all this.

Saul

5

Hi Saul,

You can select the pin-mode for each pin on its own. Meaning - You can
select i.e. mode 0 for one pin and mode 2 for another in case you would
like...

@Gerald: Maybe you could change the pinmux table in the next revision of the
SRM to indicate that the muxing of the pins can be done on an individual
basis and not only as a single mode for all pins. It might be it's already
stated in the SRM (I can't remember), but apparent people (not being used to
OMAP :slight_smile: are still confused about how this works. Maybe a link/pointer to
the TRM pinmux table would do?

Best regards
  Søren

6

There are about 16 GPIO pins that look usable on the Beagle Board's
expansion connector.
They are all 1.8 V logic signals, so you will need a level translator
chip for anything with
other logic levels. I wrote a message in the thread "slow GPIO
access" on Oct 1, 2009
that included a very short C program that sets the mux for GPIO_168
(expansion
header pin 24) and then toggles it as fast as it can until you kill
the program.

Jon