Hi, Got my SparkFun GDM12864HLCM GLCD up and running on an Arduino 328 and Seeeduino V328. I would like the backlight on/off to be set in software. I was thinking I could set a digital pin to output mode and have the backlight ground attached so that when the pin goes low the backlight turns on. Would this work? How much current is the pin able to draw? Another thought is to maybe use one of the PWM pins to do the same but alter the PWM to effectively allow 256 different brightness settings. Any thoughts, comments appreciated...

Thanks. :)

How much current, at what voltage, does your back light need?

Output pins do not draw current. They supply current, up to 40mA at 5V.

Applying current (from the +V side of the back light) to an output pin is good for producing smoke.

Hi, 5V backlight supply, about 50mA current. I was under the impression that Arduino pins configured as outputs acts as an open collectors. Is this incorrect? I've seen a similar setup where the the ground line of the backlight on the SparkFun GLCD ( GDM12864H ) is connected to a digital PWM pin ( 17 ) on a DIOS 40 microcontroller. The brightness is adjusted by setting the pulse width of the pin. I was hoping to emulate this... ;)