I know this is an old subject but Ive seatche the inthernet and the forum without any luck . I'm working on a water control project and trying to use the 128x64 ST9720 driver LCD currently I'm using u8glib and it runs fine, but there is a big problem I have an interface with the LCD and some buttons (4 buttons with resistors on one analog input) while I don't really care about the refresh rate of the screen, the picture loop is taking a lot of time of the main loop and when I press a button it takes a long time for it to be recognized, i guess its because AnalogRead() executes only 3-4 times a second and there is not always a match in the value for it to be recognized.
A while ago when i was choosing the hardware for the project I thought of a DUE or a MEGA. I have both now, but chose the DUE for the project because it faster and its 3.3v that is better for interfacing a SD card and a bluetooth module, and thought it would me much faster with the LCD in the loop, but its not.
Ive tried using HW SPI on the due but no luck, It just won't work, although it says here https://code.google.com/p/u8glib/wiki/device that with Page size of 512 Bytes it supposed to work on the DUE, I dont really know what that means. It is working on the mega.
so I think my options are: 1. use another method/library for the LCD with HW SPI enabled for faster loop. (I really like u8glib) 2. use some clever programming in order to "draw" on the screen only when needed - so the main loop wont "draw" every time / all my tries to do so have failed 3. use an extra arduino mini/micro/nano to only drive the screen while every thing else will be done by the DUE. (have no real theory on how to do this) 4. use the MEGA instead with HW SPI, hope for a fast loop and use level shifters for the SD and Bluetooth. 5. you will suggest something hyper-simple and clever and i will be a happy man :)
any suggestions ? thank you in advance