Colour GLCD for calculator project

[Dan]

(05-16-2019 10:35 AM)Maximilian Hohmann Wrote:  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.

Thanks for the detailed response Max, much appreciated. The Nextion displays look nice but I don't know if they will work with my 3.3V logic microcontroller. So I am leaning towards something like the 2.8 inch display above, but larger, around 3.5 inches. I like the parallel interface and the SD card interface. And the ready availability of interface software is a must for me - these things can be a real pain to get working otherwise.

However I'm not sure if this particular 2.8 inch display will work with my 3.3V logic microcontroller. A lot of these displays are designed for the Arduino/RPi and feature additional circuitry to convert 5V to 3.3V, perhaps the shield is expecting 5V from the pins?

Also, how do you find the performance of the higher resolution displays in general? Does it take a noticeable amount of time to refresh the screen? You certainly don't want the user waiting for the value entered on the command line to appear on the stack!

Once I find a display, Dirk Heisswolf, creator of the AriCalculator hardware, has kindly agreed to start designing PCB's to turn my TI LaunchPad prototype into a handheld unit, which is pretty exciting. The idea is to plug one PCB with the keys and display attached to it into the male header pins on top of the LaunchPad, and the other PCB for the power supply into the female pins underneath the LaunchPad.

So if anyone knows of a quality 3.3V GLCD around 3.5 inches with parallel interface and SD card connection, please let me know!

EDIT: Even without TFT, parallel + SD card uses a lot of pins, judging from the underside of the 2.8 inch. The TI LaunchPad has 40 pins but 14 are used for the 8 row, 6 column matrix keypad. Perhaps SPI is better - it really depends on how long it will take to redraw the higher resolution display. I am about to upgrade to the TM4C1294XL, which is 120MHz, so hopefully that will give acceptable results.