I want to use a cheap android tablet as a GUI for my Arduino project.

So I have a semi complete arduino project and a cheap android tablet. I want use the tablet to receive and display variable values from the arduino. I also want to adjust the value of the variables with the tablet. I have looked into blynk, but it doesn't support USB OTG. I also looked into using android studio to build my own app but it seems like it'd take me a year to put out a finished project with the amount of spare time I can feasibly devote to the project. Ideally I will have some sort of UI worked out inside of a week. My project is on and I am flying blind at the moment. I already have code written for a menu with an lcd and buttons, but I think my two year old ruined my lcd and backpack because it no longer turns on.

Here is what I envision:

arduino regularly sends tablet values to tablet via USB OTG.
tablet displays these variables with buttons to increase and decrease the variable.
if I push the button to increase variable "baz," tablet sends "incBaz" to arduino.
then arduino does something like

"if (Serial.Read()=incBaz) {baz++;}"

can someone point me in the right direction. I could use a good serial communication tutorial or three and an easy to learn app, something like blynk, that supports USB OTG and some examples and tutorials using that app.

My interweb searches are making me feel like I am going to have to learn android development....

Possibly, but you might have a look at the various controllers available before you run off to re-invent the wheel. And, now that we are in the 21st century, you might also look beyond the constraints of the USB connection.

I want use the tablet to receive and display variable values from the arduino. I also want to adjust the value of the variables with the tablet.

Seems like something you can do with any terminal. The only reason why I got a cheap android was so that I could use Bluetooth Graphics Terminal.
I believe Blynk is an Internet of Things facility, and doesn’t have much to do USB connections.

If you can live with a text interface then running a ANSI terminal emulator on the tablet is an option, however you'll need to communicate via WIFI/Ethernet as dealing with hardware serial interfaces isn't something that Android is really designed for.

Your Arduino sends plain text ANSI escape sequences to control the cursor position and display text etc.
The advantage of this system is that the display will work equally well on all common operating systems. There is no platform specific code.

Text mode isn't as limiting as it sounds. For example,

Everything you see on this image, including the buttons and lines, are text characters.

You also have the option of doing a web interface which will allow you to use a web browser as the front end. Again, everything you send is plain text and platform independent.

Take a look at the MIT App Inventor. They might have ready to use USB OTG templates. I've used the program to make interfaces for Bluetooth and HTML.
Although, first thing to check is, is your tablet OTG capable? It's a specific protocol. Otherwise you're just talking serial communication.

You might find something intresting in Control5P library from Processing. If your okay with having your .ino in your tablet you can call functions through a gui interface formated in Processing...allin your tablet.

Bluetooth is not hard to implement and would do away with the cable.

MIT App Inventor will do all you need, as mentioned by another. Plenty of examples to follow.

Does your project require that things happen in real time like steering an RC car or is it something less time sensitive like getting weather station data whenever you want to view the temperature?

If it is not real time, I would make a web interface and make HTTP requests to update any data that needs to be updated. Android tablets should come with a web browser and can make the HTTP requests for you with a standard HTML GUI.

This thread has been dormant for over two years. The original poster hasn't been active on the forum for about 18 months.

I think you might be wasting your time trying to help.