Hi, About the RS485 support on the BBB, you have to modify the driver omap serial and control the gpio that you want. But if you want a quick solution, i already made a patch for that :)
You just need to :
git clone git://github.com/RobertCNelson/linux-dev.git
cd linux-dev/
git checkout origin/am33x-v3.8 -b tmp
in the linux-dev folder, you have the KERNEL folder. You just need to put
the file in the patches/omap folder and edit the patch.sh :
:
${git} "${DIR}/patches/omap/000X-omap-rs485-support.patch"
in the linux-dev folder :
cp system.sh.sample system.sh
edit the file system.sh:
be sure that you have :
##For TI: OMAP3/4/AM35xx
ZRELADDR=0x80008000 <== uncomment !
the correct path to your sdcard :
MMC=/dev/sdc
to build the kernel , you just need to use this command : ./build_kernel.sh
to install the new kernel to your sdcard : ./tools/install_kernel.sh
On Tue, Jan 21, 2014 at 10:52 PM, Alexander Hiam <hiamalexan...@gmail.com>wrote:
> Yeah I noticed that. I was hoping to go the ioctl route because I'm
> working on a cape that gives the option of RS232 or RS485 on UART4, so the
> runtime switching would be great.
>
> Hopefully I'm just doing something stupid, but I can't get it to work
> through ioctl. I've tried in both C and Python on an Angstrom image with
> 3.8, this testing image, and an old Angstrom with 3.2 on the original BB.
> The tests I'm trying are here:
> https://gist.github.com/alexanderhiam/8548894
>
> On all three bones the C ioctl() call raise errno 25. On the two with 3.8
> the Python ioctl() call raises 'IOError: [Errno 25] Inappropriate ioctl for
> device' and on the bone with 3.2 it raises 'IOError: [Errno 22] Invalid
> argument'.
>
> I was under the impression that you had to enable the RS485 ioctl settings
> when building the kernel, but I can't remember where I got that idea and I
> haven't actually tried it yet :p
>
> Perhaps I should start a new thread for this one...
>
> -Alex
>
>
> On Tuesday, January 21, 2014 3:49:38 PM UTC-5, RobertCNelson wrote:
>
>> On Tue, Jan 21, 2014 at 2:33 PM, Robert Nelson <robert...@gmail.com>
>> wrote:
>> > On Tue, Jan 21, 2014 at 2:14 PM, Alexander Hiam <hiamal...@gmail.com>
>> wrote:
>> >> Thanks Robert, I just booted it for the first time and so far so good.
>> I see
>> >> that there's still no ioctl for RS485 mode on the UARTs though. Is
>> there a
>> >> reason RS485 support isn't enabled on the BB kernel builds?
>> >
>> > There is no module for "rs485" you need to call the omap-serial driver
>> > with the proper ioctls
>> >
>> > https://git.kernel.org/cgit/linux/kernel/git/stable/linux-
>> stable.git/tree/Documentation/serial/serial-rs485.txt?id=
>> refs/tags/v3.8.13
>>
>> Looks like you can enable it on boot time too..
>> https://git.kernel.org/cgit/linux/kernel/git/stable/linux-
>> stable.git/tree/Documentation/devicetree/bindings/serial/
>> rs485.txt?id=refs/tags/v3.8.13#n28
>>
>> Regards,
>>
>> --
>> Robert Nelson
>> http://www.rcn-ee.com/
>>
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000X-omap-rs485-support.patch
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