I have been making projects based around a 2.2" TFT display which uses the ILI9341 driver chip, this display can be connected to and controlled by an Arduino UNO. As a bit of background reading you may find my instructable here useful.
During debugging of one of my battery powered Arduino projects I needed to have a portable terminal to look at the debug output being printed to the serial pins. To achieve this I built the small portable display terminal described herein.
The unique part of this project is that the sketch uses the built in hardware scrolling feature of the ILI9341 chip, this takes the processing burden off the Arduino AVR microcontroller and means that the display can keep up with serial text messages at 9600 baud.
The ILI9341 and GFX libraries featured in this instructable has been optimised for speed, some of the speed enhancing features use direct PORT access to the ATmega328 registers so it is important to use an Arduino board based on that processor chip. These speed improvements means that characters in the proportional font 2 can be printed to the screen at more than 1000 characters per second... which is a bit faster than I can read them!
Though the development has been done with a UNO, the final battery powered terminal will be based around the smaller Pro Micro, with a battery pack and 3 AA batteries this will be nice and portable.
The connections between the display and UNO are not the same as my other instructable, for this project connect as follows:
It is important to include the 1K8 resistors to GND with this 2.2" display as otherwise it will not work. The 1K2 and 1K8 resistors are a "potential divider", acting as a logic level shifter so that the logic level at the display is reduced from 5V to around 3V. Pin 9 of the display does not need to be connected up.
Once programmed the Terminal can be connected to another Arduino to monitor the serial output:
Output text messages sent using Serial.print from the other Arduino to the Terminal will be displayed. At 9600 baud the Terminal manages to keep up with the data flow.