Minicom cannot print the bootloader information of the TX2 development board

hello,
I want to know the physical address range of the TX2 development board (please refer to here): First, I need to print the bootloader log information of the development board, and then obtain the physical address range based on the log information.

  1. In the TX2 development board, I used J21 (PIN8, PIN9, PIN10);
  2. The usb to ttl wire is FT232RL, RXD (white wire) is connected to pin 8, GND (black wire) is connected to pin 9, TXD (green wire) is connected to pin 19, and the red wire is not connected;
  3. The configuration information of minicom is as follows:
  •  serial device: /dev/ttyUSB0
    
  •  Bps/Par/Bits: 115200 8N1
    
  •  Hardware Flow Control: No
    
  •  Software Flow Control: Yes
    

However, minicom did not print any information, as if J21 did not transmit the information to the ubuntu PC.
may I know what is the reason?
Does TX2 enable J21 by default?
Before connecting J21 UART, do I need to do other operations to print bootloader information in minicom?
Thank you

The red wire is not used, and must not be connected. This is a +5V power output, but the Jetson has its own power.

The settings look correct. However, see:
http://www.jetsonhacks.com/2015/12/01/serial-console-nvidia-jetson-tx1/

The serial UART you use must be a 3.3V TTL logic level. If not, then failure is expected. J21 is enabled for serial console by default.

Minicom comes from the very old days when telephone modems needed “AT” commands to tell them how to operate. This is just a complication since serial consoles would misbehave if you start sending random init strings and such, but likely you would have still seen some output.

I prefer “gtkterm” ("sudo apt-get install gtkterm"). If you are a member of group “dialout”, then you don’t need sudo, but using minicom, and assuming the host PC side is “/dev/ttyUSB0” (it might be different, e.g., if it is a different brand it might be “/dev/ttyACM0”), then:
gtkterm -b 8 -t 1 -s 115200 -p /dev/ttyUSB0
(on the host PC side you can probably monitor “dmesg --follow”, and then plug in your USB serial UART…it will mention which “/dev/tty...” it is)

Do note that booting is actually a separate program compared to Linux. It is possible to enable in one but not in the other. Default is that it is enabled in both bootloader and Linux. If you do accidentally send a keystroke (or “AT” command) during bootloader stages, then expect this to be a possible reason for boot to halt and not continue (it might have dropped you into a U-Boot prompt, but this would be obvious if monitoring from your serial console program).

thank you for your reply.
I used gtkterm, but it still has no output. (I started to wonder if there is a problem with the usb to ttl line)
please help me.

There might be a need for a driver, but if the USB side’s “/dev/ttyUSB#” (it might be something other than “USB#”, depending on brand) exists, then it tends to mean USB is valid. However, it is something you can easily check. On the computer which is having the USB side plugged in, monitor “dmesg --follow”. Then, as you plug in the USB serial UART, you should see some log being printed. That log should be able to verify the device special file name, e.g., it should verify this is “/dev/ttyUSB0” (keep in mind that if you unplug and replug the device the “#” could increment until reboot).

The other half of that is that perhaps the “ttyS#” (or whatever the designation) might not be correct for the Jetson side. The docs here would be correct for a TX2, but if for example it was instead an industrial TX2i, then it might not be correct (I don’t have any of those variants):
http://www.jetsonhacks.com/2017/03/24/serial-console-nvidia-jetson-tx2/

Can you verify this UART is 3.3V logic level? Is there a URL with its model and/or specifications?

When USB side was plugged in PC, the monitor printed some log"…Detected FT232RL…attached to ttyUSB0…". when the device was unplugged, the monitor displayed “device disconnected”.
So, ubuntu PC can identity the USB device.
As for the voltage parameters of the UART, I am looking for information and I will update it later.
Thanks again.

FYI, that also guarantees the driver is in place and running correctly. IMHO, the FTDI driver which powers this is the least complicated and most reliable of serial UARTs, so I’m confident that whatever the issue is, it isn’t setup of drivers.

The problem has been solved.

The fundamental reason why minicom cannot print bootloader information is: the input voltage of the usb to ttl line is inconsistent with the output voltage of the UART of the TX2 development board.Therefore, I changed the line, and now the log information can be printed out in minicom!

Here, a special thanks to all the developers mentioned above who are concerned about this issue, they have given me a lot of help!

Thank you very much! ! !