Zero/dev/serial-console
Radxa Zero > Development Guide > Serial Console
Radxa Zero exports a dedicated serial console, which can access the low level debug message.
Contents
Requirement
- Radxa Zero
- USB Type-C power adapter and USB Type-C charging data cable
- Host PC with Windows or Linux
- USB to TTL serial cable
- The definition of each pin of USB to TTL cable is showing like this:
Note
- The default baudrate of Radxa Zero is 115200 , please check if your USB to TTL cable support 115200 bps 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 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.
| Radxa Zero | <---> | 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 Radxa Zero u-boot and kernel console is:
baudrate: 115200 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.zero, add the following content:
pu port /dev/ttyUSB0 pu baudrate 115200 pu bits 8 pu parity N pu stopbits 1 pu rtscts No
Now run minicom zero to use the config above and connects to the Radxa Zero 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 115200, connection type as Serial.
Write zero in the Saved Sessions column and press Save.
For category Connection---Serial, do the setting:
Once finish the setting, press Open button to start.
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