So a friend called me because he had an idea for a product/prototype but lacks the skills to construct anything...
Anyway as I am familiar with AVRs I thought about buying a Mega328 xplained board because it has debugging and go from there. First off he wanted a timer and some buttons so I thought, yeah that's fine, slap in a HD44780 an some buttons. This morning he texted me saying he also wanted some kind of protection from tampering with the settings (enter a PIN/code to access settings) so I thought about adding a keypad. But summing up with buttons/keypad and character LCD I figured I might as well go directly for a touchscreen display?
However I've only ever worked with a graphical display once before with AVR and ARM, and it was a bit slow to update the screen (even slow-ish on the ARM) because you had to update the entire LCD every time you wanted to change something.
I don't plan on doing any extraordinary graphics on the screen, just a simple menu with some basic settings, some text like a timer counting down and of course a "keypad on screen" for the access PIN. I don't need a lot of resolution (enough to make the keypad on screen) nor a lot of colors, really I guess I could do with monochrome even.
Could you recommend me any cheap-ish, widely available touchscreen that I could use for my prototype? (Available on ebay?)
One that I can readily connect to an 8-bit AVR (maybe SPI)?
Maybe one that I can partially update the screen, so I don't have to write to the entire screen to change only a part of it? Or at least that I can update the screen fast-ish (less than 1 second)?
Maybe something where there exists example code somewhere on the internet to start out with?