Re: [Gumstix-users] Robostix IMU Serial

[Dave H. <dhy...@gm...>]

Hi Dylan,

Sorry to take so long to respond. Your email got marked as read - and
then I forgot about it.

On Tue, Apr 6, 2010 at 7:50 AM, DylanB <dbr...@un...> wrote:
>
> Hello,
>
>>> What does the build enviro. kernel do and why is it not the same from the
>>> start?
>>
>>The kernel verison of the build environment itself isn't all that
>>important. However, the version of the kernel which is targeted for
>>the gumstix is quite significant.
>
> Argh sorry confusing question. What I meant was why is the targeted kernel
> not the same?
>
> OK so if I want to get the kernel/libraries etc targeted by the build system
> to be the same as those on the Verdex where do I start? Is some variety of
> svn download required? I'm not sure where to look.

What I do is to setup whatever build environment I'm going to use (OE
or buildroot), build the kernel and rootfs and use the ones I built.
Then I'm 100% sure that everything matches.

> Also I have a couple of questions relating to the sertest program.
>
> "Some hardware requires a carriage return (0x0d) to function properly."
>
> Does this include level shifters? The reason I ask is that when I run
> sertest with the shifter (Rx and Tx crossed) connected  to the STUART on the
> robostix I get no feedback. The shifter has leds to show Rx and Tx working,
> only Tx seems to be doing something.

Level shifters don't care about the content.

In order for the level shifter to work, it requires the correct
voltages to be present at the right places.

The Tx and Rx from the STUART port are from the gumstix perspective
(so Tx is an output and Rx is an input).

Generally speaking, when using level shifters I ignore the Tx/Rx stuff
and just look at inputs and outputs.

So you need to make sure that you're connecting inputs to outputs.
This means that the Tx from the STUART needs to connect to the input
on the level shifter. And the Rx from the STUART needs to connect to
the output from the level shifter. And it needs to connect to the
logic-level side of the level shifter, and not the RS-232 level side.

> http://www.sparkfun.com/commerce/product_info.php?products_id=8780
> Could this be caused by the line carriage issue or might I have other
> problems? I'm assuming the code is compiled OK because when I do the same
> with no shifter then it works just fine.

You probably have the level shifter mis-wired.

RS-IN is the RS-232-level signal which is an input. It connects
through to Tx which is the corresponding logic-level output, which
should be connected to the STUART Rx (input) signal.

RS-OUT is the RS-232 level signal which is an output. Rx is the logic
level input, which needs to be connected to the STUART Tx (output)
signal.

> I've tried to use the suggested correction in the code but I am having
> difficulty compiling sertest.c. I get the following error:
> " ERROR: function do_compile failed
> ERROR: log data follows
> (/home/dylan/gumstix/gumstix-oe/tmp/work/armv5te-angstrom-linux-gnueabi/sertestdylan-1.0.0-r0/temp/log.do_compile.10283)
> | /tmp/ccy9OmAM.o: In function `main':
> | sertestdylan.c:(.text+0x500): undefined reference to `pthread_create'
> | collect2: ld returned 1 exit status "
>
> I though that pthreads.h would be a part of libc6-dev. I have that already
> so what else may I be missing?

You're actually getting a linker error, not a compiler error. Which
means that you need to add the pthreads library (i.e. -lpthreads) to
the link stage command line.

> Finally, if I have pre compiled recipes from say gumstix.com collection how
> do I know that they were compiled for my target system? How can I have
> bitbaked the basic image if my targeted kernel is different to the one that
> is on there?

I'm not sure.

-- 
Dave Hylands
Shuswap, BC, Canada
http://www.DaveHylands.com/