I have been fighting with a SainSmart 3.2" TFT screen. Actually, I have several, and have been using them with several Megas.
The display works flawlessly. No issues.
The SDCard works flawlessly. No issues.
The touchscreen is inconsistent. Sometimes, it works. Sometimes, not. This is the issue.
I'm using the latest libraries from RinkyDinkElectronics (formerly Henning Karlsen). I'm using the standard quickdraw, quickpaint, and button demos. I've inserted Serial.print statements to see what the actual TP_X and TP_Y values are.
The thing just won't work consistently. Some of the time it will work beautifully (and print appropriate TP_X and TP_Y values. Some of the time it will print "bad" TP_X and TP_Y values in the range 0..79 or so (as if it were mapping the screen into the smaller values).
Sometimes, leaving everything alone and just reloading the program will work. Sometimes, leaving the same program on and just enabling/disabling the serial monitor will reboot the device (as part of the enabling) and it will start working. Sometimes, not.
Anyone else have similar experiences?
As a side note, I picked up an AdaFruit 2.8" TFT and it works flawlessly...
Not personally, but I have been heavily involved trying to diagnose issues you describe. There is no concrete solution, but options that have (limited) degrees of success (in some cases), are :
Additional external power.
No additional external power.
Serial monitor open.
No serial monitor open.
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