Intro: Raspberry Pi: Android Cell Phone or Tablet As Screen
Have you ever wanted to buy the Raspberry Pi Official Touchscreen, but not had the $75+ to spare? Let your stinginess be a misfortune no more! Through some trial and error and much searching on the Raspberry Pi forum, I found a simple method for VNCing or SSHing into the Raspberry Pi on any wifi network: [insert divine singing here] Wifi Hotspot on an Android phone or tablet! In this instructable, and my very first, I will walk you through the ridiculously easy process of getting VNC working on any wifi network other than the any one previously logged into on the Pi itself.
Step 1: Materials
You will need:
-an android tablet or cell phone with wifi hotspot capability
-a standard USB-micro USB cable (for power)
A standard 5v~2.4A wall charger or a USB female to micro USB male adaptor (for power from your device on the go)
-A Raspberry Pi 3 with latest Raspbian Pixel OS installed
-a case for the Pi (optional)
Step 2: Software
First, you want to download VNC Viewer on Google Play. Next, you want to connect the Pi to a monitor and select "enable VNC" in raspi-config. If you can't do this because you don't have a screen, put the SD card into a computer and save a file called vnc in the raspi-config directory (it will enable and delete the file on boot). This works with SSH, so I assume it works with VNC.
Step 3: Enable Hotspot
Now, you want to enable wifi hotspot in the Android settings of your phone or tablet. Next, go onto your Pi via an HDMI screen and log into the now available wifi hotspot of your phone or tablet. Log out of the Pi. Next, go into the Terminal and type: hostname -I. That is an i, not an L. In VNC Viewer, click add user, and input in the IP address of your Pi that you got in the last step. You can name it whatever you want. Put the Pi in to power, and click connect. This should connect you to your pi via your phone or tablet's wifi or mobile data. Yay! You did it!
Step 4: Add-ons
You can also put Velcro on the screen device and the Pi case to make it all in one piece, and with the USB to micro USB adapter, you can power it on the go too for a (mobile data) portable Pi. See the photo above for portability setup.