View Single Post
Old 03-19-2011, 11:32 AM   #5 (permalink)
bobski
EcoModding Apprentice
 
Join Date: Jan 2010
Location: Newark, DE
Posts: 143

'91 CRX - '91 Honda CRX DX
90 day: 34.91 mpg (US)
Thanks: 0
Thanked 14 Times in 14 Posts
Quote:
Originally Posted by dcb View Post
The mpguino uses pwm for contrast control bobski, to keep the component count down
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.
  Reply With Quote