I finally broke down and purchased the shield for my Sainsmart 3.2" LCD screen after trying to wire it entirely with individual wires, which produced very poor results including inverse colors, weird lines, sd card slot didn't work and it didn't properly clear the screen. Now with the shield it works perfectly (with my MEGA 2560) and even the SD card works. My project I'm using it for is automating an aquarium as much as possible, which requires the Arduino to be running constantly (for the lights) but I don't necessarily want the screen to be on constantly. So I've been researching various options and most people seemed to be referencing a trimmer pot on the shield, which I didn't have. I have the ElecFreaks Mega Shield V2.2, which has a serious lack of information, ElecFreaks only has info for V1.2 and V2.0. So I did more research on the shields and found the following information:
LCD shield V1.0, trimmer pot circled
LCD shield V2.0, chip circled
The chip circled in the V2.0 is the same one on my V2.2 and by using a microscope it says AMS1117 3.3H327PE. Research on this chip yields the following information:
"AMS1117 series of adjustable and fixed voltage regulators are designed to provide 1A output current and to operate down to 1V input-to-output differential. The dropout voltage of the device is guaranteed maximum 1.3V at maximum output current, decreasing at lower load currents. On-chip trimming adjusts the reference voltage to 1.5%."
Which leads me to believe that the LCD (I imagine only the backlight) can be adjusted via the arduino instead of previous attempts for the V1.0 (which I found online) of removing the trimmer pot and using a transistor.
Does anyone have any experience with this particular shield (or even V2.0)?
I do not have exactly the same shield, but the similar versions from iteadstudio. I have ordered a shield, similar to your white shield.
This is my expectation:
The var pot was there to adjust backlight brightness. This is now a fixed resistor in the new shields (should be ok from my perspective). The voltage regulator probably has nothing todo with the var pot.
The controller in principle (at least according to the datasheets) should be able to control the backlight. However, according the schematic of your shield, a fixed current is applied to the backlight. So, for your shield (and also the one which i had ordered) i do not expect that the backlight can be changed.
Even more difficult: Before using a display (from a different vendor) with this adapter shield, it should be checked if the resistor is ok for your display. According to the schematic, your shield has a 10 Ohm resistor. Depending on the forward voltage and the maximum current for the backlight, the resistor might be ok, to high or too low. If the resistor is too low, then it also might destroy the backlight. ... only my personal thoughts, but i will check this for my own displays first, before i connect display and adapter board together.
Ok cool, I really appreciate the response. Hopefully we can figure something out, I've read about other attempts online at bending the backlight pin 90 degrees outward so that it can be individually operated, but hopefully it doesn't come down to that. As for the safety of the backlight, I believe it operates at 3.3V, and the shield uses the 3.3V pin on the Arduino. The ElecFreaks wiki for the LCD screen states the following (in very broken english): "TFT01 is work at 3.3v DC, if you need to connect the module with the 5v voltage I/O , you need to add the 30k and 20k resistors to reduce voltage." So as long as the shield is utilizing the 3.3V then I think we're in the clear.
Speaking of utilizing the voltages, does anybody know how to tap into the Arduino's voltage/ground pins once the shield is in place?
I have the same shield. I use the library's from henning karlsen (Electronics - Henning Karlsen)
In the manual that comes with the download he has made a function to turn on and off the lcd.
I found this discussion becouse i want to adjust the brightness, wich I cant figgure out.
Maybe a stupid question, but is that chip that regulates the voltage not for the entire screen, not just the backlight?
All the librarys bij henning karlsen work perfect by the way.