ESP32 + Joy-IT touch screen

 Intro

As I have said a number of times before Elektor is a great place to find introductory projects.  The January/February 2020 edition contains an article on attaching a Joy-IT touch screen to an ESP32.  The example provides a very neat interface to the Elektor Weather Station project and shows what it is capable of.  The system makes use of littlevGL an application by Gabor Kiss-Valose which does all the graphics and touch screen heavy lifting.  It works on linux and other platforms as well as ESP32 and appears to be coming a popular/standard product.  To make life simple I purchased the Joy-IT touch screen from Elektor and also, after a false start, purchased an ESP32 devkitC from eBay.

Installation

The Arduino IDE is used for this project.  After connecting and testing board connectivity with a blink program (set LED to GPIO 2) I needed to set up the ESP32_eSPI software and littlevgl and configure them.  There are 10 wires used in the interface, including power and SPI, so it isn't too complicated.  The Elektor article comes with the required libraries and configuration files as a download.  This made it easy to setup, I copied libraries and configuration files across as appropriate.  In addition to TFT and LVGL libraries, other libraries are included for MQTT, json and CRC32.

Testing

There is a basic TFT test in the TFT_eSPI examples so I compiled/uploaded and it displayed pretty colours and text.

I then took the Elektor Weather Station Example, set the "demo" flag and compiled it.  Very impressively out comes the Weather Station screen, complete with touch screen capability and demo data .

Conclusion

This is great as it provides examples of tabs, gauges, meters, labels and touch screen input.  It should be easy to modify for my own purposes.  As an extra it gives me a way in to using MQTT and JSON data on Arduino/ESP32.  It is an excellent introduction to a wonderful product which can be quite challenging.  The littlevgl software and Joy-IT screen can also be used on an RPI.  At first sight the ESP32 usage, utilising wifi to obtain data updates seems best.  Then the ESP32/screen only need to be switched on when in use and don't need to be near an RPI.