I notice some alignment issues on the answers with respect to the original question:
The OR want's to see the first output of a booting beagleboard (pocketbeagle here), not the port that is channeled over USB when the OS is up. I have had an analogous issue a while ago when I was confronted with a boot issue on a device. I discovered that the serial parameters differ from how the power is applied to the board: when using a direct USB connection with a host PC the serial interface functioned as described. When using a USB power supply or the 5V power input the serial parameters are different, I saw data coming in, but could not read them. Robert explained this is due a TI issue deep in the MPU, it has no relation to the OS upgrade we were trialling, so I left it there. My advice: dive into the TI documentation on the serial port and see what parameters TI gives it when it is unconfigured from the host. On the serial adapter: I use any serial adapter I can put my hands on, mostly ST Nucleo boards (they have a nice serial port on the programmer) I recently discovered that windows has altered it's USB to Serial adapter support and doesn't install the supporting drivers anymore out of the box for the adapters I use in my classes. It baffled me, as last year I gave the devices to the students and I had no issues. This year it only worked out of the box on those that use Linux (which is limited for fresh students, they will move over in the coming months 😉 ). I had to download the driver and make them install it prior to being able to use the adapters. Regards, Gwen Op ma 21 dec. 2020 om 00:21 schreef Robert Berger < [email protected]>: > 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 > > > > -- > > For more options, visit http://beagleboard.org/discuss > > --- > > You received this message because you are subscribed to the Google > > Groups "BeagleBoard" group. > > To unsubscribe from this group and stop receiving emails from it, > > send an email to [email protected] > > <mailto:beagleboard%[email protected]>. > > To view this discussion on the web visit > > > https://groups.google.com/d/msgid/beagleboard/ec68fc45-ed93-3bbc-bb0f-c8135531283f%40gmail.com > . > > > > -- > > For more options, visit http://beagleboard.org/discuss > > --- > > You received this message because you are subscribed to a topic in the > > Google Groups "BeagleBoard" group. > > To unsubscribe from this topic, visit > > https://groups.google.com/d/topic/beagleboard/omDhIBOeRYo/unsubscribe. > > To unsubscribe from this group and all its topics, send an email to > > [email protected] > > <mailto:[email protected]>. > > To view this discussion on the web visit > > > https://groups.google.com/d/msgid/beagleboard/CAG99bko4GrCfWn78BySwK64XBBtaeqdLGs7LkHS4WG_Ky%2B0Ctw%40mail.gmail.com > > < > https://groups.google.com/d/msgid/beagleboard/CAG99bko4GrCfWn78BySwK64XBBtaeqdLGs7LkHS4WG_Ky%2B0Ctw%40mail.gmail.com?utm_medium=email&utm_source=footer > >. > > -- > For more options, visit http://beagleboard.org/discuss > --- > You received this message because you are subscribed to the Google Groups > "BeagleBoard" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/beagleboard/afb96119-edbf-3cf0-3b69-df8c55cc6e22%40gmail.com > . > -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/CAFfeaG-teF9_GGguLST4%2BMtT15reD25fL1ujtCzsmbO71AuCBA%40mail.gmail.com.
