I have a common (16 pin, direct connect) 5V LCD that I usually have run with a standard 5V Arduino Leonardo. However, I also have a 3.3V/8Mhz Arduino Pro Mini that I wish to run the LCD from. Can I simply run the Pro Mini directly off of 3.3V and the LCD directly off of 5V, and just connect the data lines between them directly, or should there be some types of logic level translator or anything? I presumed that data would only be flowing TO the LCD, not back FROM it, so damaging the Pro Mini didn't seem to be a problem. However, I want to find out before I potientially mess something up.....
The LCD signal is probably 5 volts so 3.3 volts would probably not work (I'm not entirely sure about this)
I would use a transistor from the Arduino and have it bring the logic signal up to 5 volts just to play it safe
No, the 3.3V for the logic signals works fine. I have connected a 3.3V PIC to a 5V LCD and the signals work fine. For a 1, the 5V LCD needs a 2.5V logic signal, which 3.3V is above. My concern is the 5V LCD damaging the 3.3V Arduino. Does anybody else have any experience/knowledge with this?
Put a diode from the arduino to the LCD that way the electricity will only go from arduino to LCD and the diode will drop the voltage a bit to about 3.2 or 3.1 volts