Friday, 19 April 2013

Cheap TFT Displays

The photo shows a (very) cheap 2.4" TFT LCD/SD/Touchscreen combo purchased (as always) from China, via eBay and PayPal. (Love those blemishes!) Here is what the manufacturer thinks it can do:

This device is a parallel TFT display, unlike the SPI one discussed previously. Its bus can be either 8 or 16 bits wide. Even in 8-bit mode it uses up a whopping 12 I/O pins.

It is well supported (on Arduino anyway) by Henning Karlsen's excellent UTFT library. In the picture it is running the UTFT_Demo_320x240 (configured as S6D1121_8, should you care). However you should follow his advice and edit memorysaver.h in order to comment out all of the other devices supported by this excellent library. Even so, the sketch comes in at over 25kB (and you have to partially disconnect it before upload if you have a USB-Serial Arduino-alike because two of those I/Os belong to the hardware serial port).

So this device pretty much maxes out an ATMega328. About the only application I can imagine for this combination is some sort of digital picture frame with touch-swiping. Even then it would be a tight squeeze to get the sketch and the further SD and UTouch libraries in under 32kB --- and that's without reckoning on the I/Os needed to drive the two extra devices.