On 04/29/2016 09:43 AM, Florian Feldbauer wrote:
On 04/28/2016 03:47 PM, Robert Nelson wrote:
On Thu, Apr 28, 2016 at 1:56 AM, florian.feldbauer85 via BeagleBoard
<[email protected]> wrote:
Hey,
I had a look at the kernel source at github. From the code
I would say the 8250 driver supports RS485. Only the
"rs485-rts-active-high" flag from the device tree overlay
seems not to be supported. But the same setting can be done via
the struct serial_rs485 from user space.
Also RS485 seems to be working to a limited point.
Again: The only problem is receiving messages, which seems for
what ever reason to be limited to 49 bytes.
If my kernel is not supporting RS485 I would expect that either
sending or receiving is not working at all.
But from all the Pictures I linked in my previous mails, you can
see, that the 8250 driver is switching the
RTS signal with the correct polarity.
Can someone point to to the kernel source for the kernel I am
using (4.4.6-ti-r15)?
Grab https://github.com/RobertCNelson/yakbuild follow the readme..
For 4.4.6-ti-r15, select:
toolchain="gcc_linaro_gnueabihf_5"
kernel_tag="4.4.6-ti-r15"
source:
https://github.com/RobertCNelson/linux-stable-rcn-ee/tree/4.4.6-ti-r15
Regards,
--
Robert Nelson
https://rcn-ee.com/
Hey,
I rebuild the kernel changing the configuration as mentiond by Taceant,
copied the new kernel onto my SD card and put it back into my BBB.
The board boots, everything seems fine, so I install
the device tree overlays (bb.org-overlay repo) and reboot the board,
as suggested by the install script.
After that, the BeagleBone Black no longer boots.
Here is what I changed in the kernel config:
~ > diff yakbuild/KERNEL/.config yakbuild/KERNEL/.config.old
2551c2551,2552
< # CONFIG_SERIAL_8250_OMAP is not set
---
> CONFIG_SERIAL_8250_OMAP=y
> CONFIG_SERIAL_8250_OMAP_TTYO_FIXUP=y
2565,2566c2566
< CONFIG_SERIAL_OMAP=y
< # CONFIG_SERIAL_OMAP_CONSOLE is not set
---
> # CONFIG_SERIAL_OMAP is not set
Did I miss anything? I tried this with Kernel version 4.4.6-ti-r15 as well
as 4.4.8
I mounted the SD card and deleted the initrd.img-`uname -r` file. After
that, the BeagleBone was booting again.
But: Loading the BB-UART4-RS485 device tree overlay manually, I can now
receive data over the RS485 bus,
but I can no longer send data.
So it seems the OMAP driver is not working either. Actually now it is
even worse than before using the 8250 driver.
Florian
--
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