Use android tablet as 2nd display

Story

I am at partial vacation now, meaning that I plan to work 2 out of 3 days here @Chania / Crete. I've took my notebook and Android tablet with me, but since I've used to work on big displays I am not really satisfied with this 1366x768 display my old Dell laptop has.

Solution

It appears that using your android tablet as display is pretty simple thing. I've been able to solve it after reading this post but since it took almost an hour, here is short version which worked pretty well for me.

Pre-requisites

  • Install Termux on Android side (optional)
  • Install bVNC Free on Android side (or any other VNC client of your choice)

Connect your devices

May be simple WiFi connection will be enough, but it will travel to/from external WiFi and it might be pretty slow, especially if signal strenght is not good (my case). Instead, I've used this method:

  • Enable USB tethering @Android side:
    • Wireless & networks
      • Tethering & portable hotspot
        • USB tethering ON Screenshot_20190426-105457.jpg
  • Forward VNC connection. There could be 2 possible methods.
    • Before connecting, find out your IP address:
      ip a l
      ...
      inet 192.168.42.95/24 brd 192.168.42.255 scope global noprefixroute enp0s20u2
      
    • You probably can connect directly to 192.168.42.95 in your VNC client
    • But I do SSH forwarding and connect to localhost always (this way I avoid any reconfiguration on Android):
      ssh -L 5900:localhost:5901 user@192.168.42.95
      

      (I do it from Android Termux session)

Configure additional screen on Xorg

  1. Use this command to configure custom mode for your display. My Android display is 1920x1200:
    gtf 1920 1200 60
    
    # 1920x1200 @ 60.00 Hz (GTF) hsync: 74.52 kHz; pclk: 193.16 MHz
    Modeline "1920x1200_60.00"  193.16  1920 2048 2256 2592  1200 1201 1204 1242  -HSync +Vsync
    

    Do it once, no need to repeat this command for new xorg session

  2. Configure mode (every time for new xorg session)
    xrandr --newmode "1920x1200_60.00"  193.16  1920 2048 2256 2592  1200 1201 1204 1242  -HSync +Vsync
    
    xrandr --addmode VIRTUAL1 "1920x1200_60.00"
    
  3. Turn external display ON
    xrandr --output VIRTUAL1 --mode "1920x1200_60.00" --rotate left --right-of LVDS1
    

    Note: I've added screen rotation because I feel it more comforable to use external display in Portrait mode. You can skip that, removing this option

Configure VNC connection on Android

As I am using SSH forwarding, my connection uses localhost and port 5900. Also, I've enabled "Always active" for screen to prevent screen from turning off.

Screenshot_20190426-111107.jpg

Result

image-39d295f5-3d2d-448f-a6f1-8857ec82667b.jpg

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