Quote:
Originally Posted by dcb
The mpguino uses pwm for contrast control bobski, to keep the component count down
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Yes, I am fully aware of that. I
can and
have read the diagram.
Slow pulsing of the contrast suggests that either the duty cycle the MPGuino code is outputting is varying (you're on your own there) or the PWM signal isn't compatible with the model of LCD being used. Since the signal isn't a true analog voltage (as a potentiometer would produce) but a square wave, perhaps the frequency of the wave conflicts with some internal timing of the display hardware. Unfortunately, that doesn't explain why the display works fine on the contrast adjustment screen but not elsewhere. That detail alone suggests a software bug.
Try the potentiometer setup to make sure it isn't a problem with the display module. Once you're sure the display is working as designed, work on the MPGuino.