Hi,
My comments are in-line.
On 21/12/2020 01:05, jonnymo wrote:
Looking at the post from Google GMail, it does not specify what board
the post is from. It just says Beagle Board.
Yes it's not obvious:
https://groups.google.com/forum/embed/?place=forum/beagleboard#!category-topic/beagleboard/pocketbeagle/omDhIBOeRYo
^^^^^^^^^^^^
Are you trying to connect directly to the PB via serial or are you
using something like a FTDI interface to communicate to via serial?
I tried with this[1] and this[2]
[1]
https://www.amazon.co.uk/dp/B07BBPX8B8/ref=sspa_dk_detail_1?psc=1&pd_rd_i=B07BBPX8B8&pd_rd_w=bMrBp&pf_rd_p=1055d8b2-c10c-4d7d-b50d-96300553e15d&pd_rd_wg=x9xga&pf_rd_r=4CE6P3A41TY2T1YEWT9D&pd_rd_r=8d2c3d2f-1616-48b7-909a230a9812d43d&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEzSko1VE9HOTZUUklQJmVuY3J5cHRlZElkPUEwODg0NTU5MTdWWENKTDRESDE1MiZlbmNyeXB0ZWRBZElkPUEwNTYxNzYwMkRDUlBZRUk4TzJKMCZ3aWRnZXROYW1lPXNwX2RldGFpbCZhY3Rpb249Y2xpY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU=
[2] https://www.artekit.eu/products/accessories/comm/ak-rs232/
Assuming you are using some sort of Linux host, if you type 'dmesg' it
should tell you what tty device enumerated for the interface.
Yes of course.
Also, have you set the 'udev' entries on your host for the BeagleBoard
device?
No. Why would I do that?
The USB to serial device is /dev/ttyUSB4.
The virtual USB device shows up.
Ex See the "mkudevrule.sh" script from the following link:
https://beagleboard.org/getting-started
Jon
Regards,
Robert
On Sun, Dec 20, 2020 at 2:15 PM Robert Berger
<[email protected] <mailto:[email protected]>> wrote:
Hi,
My comments are in-line.
On 20/12/2020 22:54, Dennis Lee Bieber wrote:
> On Sat, 19 Dec 2020 02:16:56 -0800 (PST), in
> gmane.comp.hardware.beagleboard.user "robert.berger"
> <[email protected]
<mailto:[email protected]>>
wrote:
>
> There is a distinct lack of information in this post.
>
>> Hi,
>>
>> I tried in a couple of ways to get something out of the serial
console
>> while booting (U-Boot, kernel, console,..)
>>
> Which Beagle are you using?
Pocketbeagle
I posted it under "pocketbeagle" and thought that would be more
obvious,
but it does not seem to be.
>
>> This seems extremely unstable and random.
>
> What results have you obtained that cause you to make that
statement.
screen /dev/ttyUSB4 115200
From "nothing" to some gibberisch (non ASCII characters, sometimes
some
ASCII characters)
after the board is booted screen /dev/ttyACM0 115200 works fine, but
that's NOT what I want.
> Presuming you are wired properly to the board,
That could be one problem, I guess, hence I am searching for a device
which might work, as already indicated in another reply and the
docs[3][4]
[3] https://shop.mikroe.com/ftdi-click
[4]
https://www.ftdichip.com/Support/Documents/DataSheets/Cables/DS_TTL-232R_RPi.pdf
I wired
Board Adapter
Txd Rxd
Rxd Txd
GND GND
For the RS232 solution I also added 3.3V.
I don't dare to switch from 3.3 to 5V, since this could cause damage.
> and configured the USB side
> for the serial bit rate*, anything the board sends on the UART
should be
> available via the virtual serial port on the USB side.
Not really everything the board sends. Out of the box only stuff from
the time the "virtual" serial port starts.
I see the "virtual" serial port, but I would like to see the "console"
output starting from the first line of MLO.
debian@beaglebone:~$ cat /proc/cmdline
console=ttyO0,115200n8 root=/dev/mmcblk0p1 ro rootfstype=ext4 rootwait
coherent_pool=1M net.ifnames=0 lpj=1990656 rng_core.default_quality=100
quiet
I am also a bit confused about the ttyO0, although there is also a
ttyS0;)
So I am not sure which one is supposed to be the "real" serial.
>
>>
>> One device I tried is this[1] with 3.3V.
>>
>> Another device is this[2].
>>
>> Can you please advise which serial adapter to use?
>>
>
> Given how most computers have been dropping RS-232
connections, #2
> seems to be an exercise in futility -- You have a 3.3V TTL UART being
> converted to full 9-pin RS-232, only to then need an RS-232 to
USB adapter
> to connect to modern computers.
Not really.
1) Quite a few boards have TTL or real RS-232 outputs. So why go to USB
and not directly to good old RS-232?
2) I have a board farm and console servers with RS-232 connectors (RJ45
connectors with RS232 signals), which would be my preferred solution.
Unfortunately some newer boards only have USB connectors. Those I
connect via USB cables to USB hubs. But in any case I would like to see
the complete boot log (from MLO) and not just when the kernel is
available.
>
>
>
> * The USB protocol itself does not care about bit-rate -- it
works in USB
> speed packets. However, the chip-set on the adapter needs to be
told what
> bit-rate the far end is sending...
>
>
Regards,
Robert
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