Colour GLCD for calculator project

[Maximilian Hohmann]

Hello!

(05-16-2019 08:56 AM)grsbanks Wrote:  Just curious... What is a GLCD and why is it different from an LCD?

I would interpret the "G" as the initial letter of "Graphic".

Regarding the original question: The higher resolution graphics capable LCDs that I have played with so far all came with an Arduino "shield" for the connections. Two monochrome ones are installed in my 3D printers and I got another 2 or three colour ones for future experimenting. The ones I have tried so far all come with 8 bit parallel buses and require 11 or 12 lines in total.

However recently I acquired two "smart" LCD displays (with the intention of eventually using them for an Apollo guidance computer DSKY replica) from Nextion (https://nextion.itead.cc/). These are pretty amazing devices which come with their own microcontollers and on-board "intelligence" and require only minimal amounts of data transfer from their host computer. I guess it should be even possible to program them as a standalone four-function calculator with touch interface. On the internet I have seen stuff like standalone Tic-tac-toe.
These displays require a PC application for configulation and programming. The program can then be transferred either by a serial connection or (very easy!) via SD card. Once it is programmed, 2 way serial communication from the Arduino requires only two lines. The main disadvatage may be their price: the smallest 2.4in Nextion display costs around 15 $/Euros including shipping compared to a similar sized "dumb" TFT shield that comes for less than 3 $/Euros). The other disadvantge is the display itself which is not as good as those we know from our modern smartphones. Especially the viewing angle is somewhat limited.

I took some photos for comparison of some displays I pulled out of one of my tinkering boxes. The first one is for size comparison shows an overview of 3 Arduino boards (Nano, Mega and Uno) and 3 grahic displays:
A 2.8in dumb TFT Shield, a 3.5in Nextion and a 5in Nextion.



This is the backside of the dumb display shield . It shows how many lines are connected to the Arduino. It uses more connections than necessary for the display itself because it gives touch feedback as well and there is also an SD card interface and a temperature sensor. There are plenty of libraries online for these boards and lots of examples.



The next two pictures show the backsides of the 3.5 and 5 inch Nextion displays. The amount of components shows why they are more expensive. But the relative ease of programming and the minimal number of connections required compensates for the difference in price.

Regards
Max