Rock3/dev/serial-console

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    ROCK 3 >  Development Guide >  Serial Console

ROCK 3 exports a dedicated serial console, which can access the low level debug message.

The default baudrate of ROCK 3 is 1500000(1.5Mbps), please check if your USB to TTL cable support 1.5Mbps baudrate. Some model of CP210X and PL2303x have baudrate limitation, please check the specified model. We also tested that some cheap PL2303x based cable does not work well. Make sure choose a high quality one. The instructions below use a FT232RL based cable.

It seems that the serial tool on macOS platform can not support custom baudrate such as 1.5Mbps due to driver restriction. If you know how to set custom baudrate on macOS, please add an item here to show your findings.

Connection

Connect the USB to TTL serial cable as below. Don't connect the red wire.

ROCK 3	<--->	USB to TTL cable
RX(pin 10)	<--->	Green wire
TX(pin 8)	<--->	White wire
GND(pin 6)	<--->	Black wire

Serial setting on host PC

The default serial setting for ROCK 3 u-boot and kernel console is:

   baudrate: 1500000
   data bit: 8
   stop bit: 1
   parity  : none
   flow control: none

Linux

Minicom is the serial tool that supports wide range baud rate.

Install minicom:

   sudo apt-get update
   sudo apt-get install minicom

Plug in the USB to TTL cable, kernel `dmesg | tail` should show the following device:

   [1036835.654076] usb 1-6.4.3: new full-speed USB device number 103 using xhci_hcd
   [1036835.755730] usb 1-6.4.3: New USB device found, idVendor=0403, idProduct=6001
   [1036835.755732] usb 1-6.4.3: New USB device strings: Mfr=1, Product=2, SerialNumber=0
   [1036835.755733] usb 1-6.4.3: Product: USB <-> Serial
   [1036835.755734] usb 1-6.4.3: Manufacturer: FTDI
   [1036835.756728] ftdi_sio 1-6.4.3:1.0: FTDI USB Serial Device converter detected
   [1036835.756750] usb 1-6.4.3: Detected FT232BM
   [1036835.757195] usb 1-6.4.3: FTDI USB Serial Device converter now attached to ttyUSB0

/dev/ttyUSB0 is our device here.

Setup minicom

First add current user to plugdev group to use minicom without sudo or root.

   sudo usermod -a -G plugdev $USER

Edit your ~/.bashrc and add the following line with some default parameter

   alias minicom='minicom -w -t xterm -l -R UTF-8'

Login to a new terminal to take effect.

Create and edit file ~/.minirc.rock3, add the following content:

   pu port             /dev/ttyUSB0
   pu baudrate         1500000
   pu bits             8
   pu parity           N
   pu stopbits         1
   pu rtscts           No

Now run minicom rock3 to use the config above and connects to the ROCK 3 serial console.

Windows

Putty is also great serial tool that supports wide range baud rate.

Plug in the USB to TTL cable to you windows PC. Viewing the device manager you can find the COM number. Here it is COM3.

Launch the application Putty on your windows PC. And do the setting as follows:

For category Session, set serial line as COM3, speed ad 1500000, connection type as Serial.

Write rock3 in the Saved Sessions column and press Save.

For category Connection---Serial, do the setting:

Once finish the setting, press Open button to start.

macOS

Download and install the PL2303 Mac OS X Driver(Universal Binary Driver)
Install CoolTerm(Universal Binary)
Click the Option menu and set the following:
- Port: select usbserial-xxx
- Baud rate: choose custom and input 1500000
- No flow control nor DTR/RTS

Click save icon to save the configuration as rock3 and click connect icon
Boot your ROCK 3 and you will see the serial console ouput

FAQs

1.While using debug console, there is system startup information on the screen, but the keyboard cannot be used to input text?

One of the reason would be the wrong setting of the serial tool, such as the Hardware Flow Control, etc. Here we should disable the Hardware Flow Control.

Troubleshooting

Post your issue at the forum: https://forum.radxa.com/c/dev