Android Things: Connect to Serial Debug Console

I've been trying to connect to the serial console of a Raspberry Pi 3 with Android Things using USB to TTL cable from my Linux (Ubuntu) machine. Despite I connected the cable as per the documentation, all I get when executing the minicom command is the following

with no chance to type in any character. So I neither can see any kernel messages nor shell into the device.

What am I missing?

Solution

Linux (Ubuntu)

What's in?

GNU Screen
Minicom
- minicom one-line-command (short answer)
- minicom UI (long answer, detailed)

GNU Screen

Run in terminal

sudo screen port_name 115200

See below (step 2) to find out port_name, e.g /dev/ttyUSB0. Hit Ctrl-A, then K, then Y to exit screen. Execute sudo apt-get install screen if not installed.

Minicom

Short answer

Run in terminal

sudo minicom -b 115200 -o -D port_name

See below (step 2) to find out port_name, e.g /dev/ttyUSB0. Hit Ctrl-A, then X to exit minicom.

Long answer (UI)

minicom should be properly configured in order to open the connection. The general steps are as follows:

Install minicom with
```
sudo apt-get install minicom
```
Connect Rpi3 with your host machine using USB-to-TTL cable and open the terminal. Find the tty connections with
```
dmesg | grep -e tty
```

In my case I get

where ttyUSB0 is the board.

Run minicom and select the serial port setup with
```
sudo minicom -s
```

You should see

Check (or set) the settings for the tty connection. Make sure that /dev/ttyX corresponds to your connection, the one you get in the step 2 instead of X, and Bps/Par/Bits set as per the documentation.

Similar to

Now hit Exit and, if everything had been properly set up, the connection should be running. If you type the ls command you should see Android Thing's root directory

For exiting minicom hit Ctrl-A, then hit Q, then Yes: