What TFT LCD are compatible?

Alexander Soto

Greetings everyone,

I am looking to start a long term project with the Onion Omega. I have the Arduino dock and extension.

I am wondering what TFT LCD screens would work? I am looking for something in the range of 2.8 in or 3.2 in with touchscreen functionality.

Could something like this work?
https://www.adafruit.com/products/1651

Also, is it possible to connect more than one screen with an onion omega?

Kit Bishop

Hi, the device you reference uses the SPI interface. Not sure whether or not the Omega has any SPI capabilities (anyone?). Though if it doesn't, there are libraries around that can do SPI over GPIO pins - while slower than hardware SPI these could probably be adapted for the Omega.

However, you say that you have the Arduino extension - this is basically an Arduino to which the Omega can communicate via I2C
The Arduino does have hardware SPI so you could connect to that then get the Omega to talk to the Arduino to control the display.

Finally, regarding multiple displays - so long as you have SPI access multiple SPI devices can be connected to the same SPI interface, all that is needed is that each SPI device use a separate GPIO pin as an enable line to control which SPI device is being accessed at any one time.

Alexander Soto

Kit,

Thank you very much! I appreciate your time and all of the information you have shared. With the information you have provided I will purchase this TFT screen and work on it during the weekend (unless you or anyone knows of one that is similar).

Thank you once again.

Kit Bishop

@Alexander-Soto Don't know in detail what your requirements are.
A quick Google search came up with several displays similar to the Adafruit one you referenced.
However most of these are SPI.

I did find a couple that had I2C interface but they may not satisfy your requirements (they are also significantly larger):

While in general, I prefer I2C rather than SPI (it is easier to use and uses fewer pins), I2C is in general slower than SPI - so it really depends on your needs.
Good luck

Pedro Baco

I believe that SPI can't be used in ómega since it's been used for the memory chip already. Please correct me if i'm wrong.

Alexander Soto

@Kit-Bishop

As of right now I'm modeling with paper. I'm looking to create a teaching tool, I hope to use 4-5 screens in the shape of a cube and have students in middle school and highschool use it.

Imagine a cube similar to this in shape,
http://www.amazon.com/Clear-Spinning-Photo-Silver-Photos/dp/B0079Q75HO/ref=pd_bxgy_201_2?ie=UTF8&refRID=0DRXGS0P49WJJ2YCXMBQ

but 4-5 of the faces of the cube consist of a touchscreen TGT LCD screen powered by the onion omega.

Kit Bishop

@Alexander-Soto Sounds cool I would imagine that if your budget stretches to it, larger higher resolution screens might be preferable.

I have been having a look around and there are kernel mode drivers for OpenWrt that can do bitbang SPI access over standard GPIO pins. Don't know what the performance would be like, but should be capable of being built for the Omega

Alexander Soto

@Kit-Bishop

Sounds great!

I'm still debating between the size / resolution. Ideally, the screen and the cube itself should be created for someone who is from 13 to 18+ years old and held by their hands a la Rubix Cube.

This should be a fun project! I'll keep you posted!