I need to turn off the LCD screen of a simple Arduino system in order to save battery. For this reason, I was thinking of using a NPN transitor. I would connect the collector directly to the pin 16 (K) of my LCD, the emitter to ground, and the base to a digital output pin via a 10k resistor. The output of this pin would depend on the input of the pushbutton. Would there be any issue with this?
Also, I read that there is a noDisplay() function in the Liquid Crystal Library. Should I combine the noDisplay() method with the transistor method? noDisplay blanks the display, but has no influence on backlight, right? So would a positive effect on power consumption be due to less data being transferred through the datapins?
Yes the backight transistor will work ok, though you can also turn the transistor on /off from the Arduino as well as the switch or even both together if you use diodes in series from both devices.
There is a No Display example here, though how much power it will save , not sure, never used it.
If you have a good meter you can measure it and let us know.
You also want to look a putting the 328 into Sleep mode, that will save more power.
Thanks a lot!
When you say put the 328 into sleep mode you mean out the Arduino MEGA328 in sleep mode? The Arduino still needs to do stuff while the LCD is on so I don't think this would work in my case
Yes, meant putting it to sleep, again plenty of examples around and on how to wake it up, does you program need to run all the time, bet 90% of it does not.
The other point to consider to save power is the type of regulator you use and how much current it takes, again masses of info on choosing the right regulator and / or battery if you search the forum.