SainSmart 3.2" touchscreen - Inconsistent behavior

I have been fighting with a SainSmart 3.2" TFT screen. Actually, I have several, and have been using them with several Megas.

  1. The display works flawlessly. No issues.
  2. The SDCard works flawlessly. No issues.
  3. 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.
IDE V1.0.6
IDE V1.5.7

Coldtears is what Sainsmart are copying, buy ANYTHING except Saincrap hardware. Coldtears generally works straight out the tin, and prices are not now far off parity as Sainsmart are no longer the cheap brand they used to be, only in quality that is!! Available from MWC electronics store | eBay Stores

Good luck!



Thanks Graham.

I will try an external power supply. Also, I'm ordering some ColdTears parts now, always worth adding a supplier to my list.


Before you go spending cash on my say so, try IDE V1.0.6 first....



How did it come in the mail? Pins stuck in pink or black antistatic foam, inserted into a silver static shielding bag?

Antistatic foam:

Silver static shielding bag:

Or was it just stuck in staticky white foam, in a ziplock bag, stuffed into a standard bubble envelope?

I bought a bunch of displays and 2.4GHz modules from them, none protected from static discharge. All damaged.

Dave Jones of EEVBlog tests antistatic bags.

After receiving those items, I contacted Saindumb. They seem to be ignorant of proper ESD protection.

Note: Pink and blue antistatic foam and bags merely don't tend to generate a static charge, but provide no protection from outside discharge. That requires the silver or black bags.