OpenWRT device without USB interface

[JA5AEA]

Hi,

I have been running aprx along with soundmodem on the lap-top PC
almost a year and I am considering to use OpenWRT device instead of
the lap-top PC.

I have a few un-used OpenWRT devices without USB interface and I am
wondering aprx can use ttyS0 instead of ttyUSB0 to interface to TNC.
As you know, ttyS0 is required at bootoload as system console but SSH
can take over after OpenWRT is loaded. This means ttyS0 is free for
aprx usage by the proper description of aprx.conf.

Am I correct?

Regards,

de JA5AEA

[Edward Czajka]

I use the serial port. All of my work is on my blog.

Ki6psp.blogspot.com

Ed

Sent from my iPhone

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[OE1RFC / Clemens Hopfer]

Hi,

On Thursday 20 October 2011 06:52:14 JA5AEA wrote:
> As you know, ttyS0 is required at bootoload as system console but SSH
> can take over after OpenWRT is loaded. This means ttyS0 is free for
> aprx usage by the proper description of aprx.conf.

The openWRT kernel is sending its kernel logs to ttyS0 and there is a serial
console (afaik stty) running on it. You can turn that off, but I'm not sure
how.
Also I've seen some bootloaders halt when they receive something (no matter
what) over the serial line while booting (eg. a KISS frame from the TNC) which
might be a problem.

Some devices also have a ttyS1, which is completely unused.

73 de OE1RFC,
Clemens

[JA5AEA]

Ed and Clemens,

Thank you for your prompt responses.

Ed,

Thank you for your recommendation to read your blog. It is interesting
to read the other topics beside my concern but I conclude that I
should change the subject from "OpenWRT device without USB interface"
to "OpenWRT device with single serial interface". Yes, WRT-54GL is
nice to have two serial interfaces and one (ttyS0) can be used for
console and the other (ttyS1) to APRX.

Clemens,

Yes, you know my concern. I am playing with Fon2201 and WZR-300NH and
these syslogs tell me that OpenWRT kernel takes over the console
device definition from bootloader at the beginning phase of kernel
loading.

-------------------------------------------------------------------------------

Sep8 fon2201 kernel infor kernel::console [tty0] enabled, bootconsole
disabled.

-------------------------------------------------------------------------------

I am looking OpenWRT Buildroot make menuconfig to tweak this setting
but I have not yet found out.

It is interesting that you have already experienced the connection of
KISS TNC to the system console (ttyS0) and you share my concern and
know the specific issue about the interference from TNC at boot-time.

I welcome the suggestion (from others) to solve my concern.

Regards,

take

de JA5AEA

On Oct 20, 5:49 pm, "OE1RFC / Clemens Hopfer" <data...@wireloss.net>
wrote:

>  signature.asc
> < 1KViewDownload

[Svend Stave]

Hi JA5AEA,

You may also find some useful info at www.kissoz.dk

Regards

de OZ1EKD

Ed and Clemens,

Ed,

Clemens,

----------------------------------------------------------------------------
---

----------------------------------------------------------------------------
---

Regards,

take

de JA5AEA

--

[JA5AEA]

Steve,

Thank you for your comment.

I looked www.kissoz.dk but I could not find the page related to our
discussion.

I am glad if you specify the page.

I am digging up the Linux manuals related to "serial console" and
found the terminology of "netconsole", which "logs kernel printk
messages over UDP allowing debugging of problem where disk logging
fails and SERIAL CONSOLES ARE IMPRACTICAL". I confirmed the selection
can be done between "serial console" and "netconsole" by OpenWRT
kernel configuration command i.e. make kernel_menuconfig. Actual
selection is "Device Drivers -> character devices -> serial drivers ->
Console on 8250/16550 and capture serial support" or "Device Drivers -
> network device support -> Network Console logging support".

The further investigation tells me that the loader such as U-boot and
perhaps, Red-boot have the similar selection capability between
"serial console" and "netconsole" and this may solve the problem of

interference from TNC at boot-time.

I count it will take a few days or weeks until reporting the results
of "netconsole" implementation on my OpenWRT devices.

Again, thank you very much to share my concerns and I am glad to be
able to touch the essential embedded Linux system features through
practical APRX implementation discussion.

Regards,

take

de JA5AEA

[Svend Stave]

The Linksys and likes have 2 serial ports, ttyS0 (console) and ttyS1 (free
to use)
Else have a look at TP-link 1043 and some of the ASUS both having USB - I
useone with a 3G modem on one usb and the radio modem on the other...

Regards

[JA5AEA]

I am now successful to disable ttyS0 for both console and BusyBox
usage and freed ttyS0 for aprx. This means the simple and low cost
wireless LAN products such as Fon, which have neither USB port nor
multi-serial interfaces, can be used for aprx platform along with
conventional serial interfaced TNCs.

1. Disable BusyBox

Comment out the line of "ttyS::askfirst:/bin/ash--logiin statement "
in /etc/inittab file

You can still access BusyBox via LAN port through SSH/Telenet.

2. Disable system console after kernel boot

make kernel_menuconfig

a. [*] Networking support --->
Device Drivers --->
Character devices --->
Serial drivers --->
Uncheck the following statement [ ] Console on 8250/16550 and
compatible serial port

b. Kernel hacking --->
Uncheck the following statement [ ] Built-in kernel command line

3. Move the kernel command line to the boot script eliminating console
definition
In the case of fon2201, exec -c "rootfstype=squshfs,jff2"

I am still working on "netconsole" but this is not mandatory as long
as the boot process is healthy.

Regards,

de JA5AEA

[Svend Stave]

Hi m8,

Use ttyS1... Most routers have both ttyS0 and ttyS1.

73 de OZ1EKD