• From: Germany
  • Registered: 2009-12-30
  • Posts: 10

Topic: Minimum brightness and battery usage (C1)

In the control panel I can set the brightness for the day mode and the night mode. The values are stored in a range between 0 and 100. If I set a value below 10 then the display is completely dark. I expect this limit is identical for all C1 units.

In battery mode the brightness is automatically reduced by a factor of 2. This means if the value is set to 100 in power supply mode and I unplug the power cord, it is set to 50 afterwards. If the value is set to 15 then it is reduced to 7.5 and the display becomes dark. This is strange, I first thought there was a problem with my battery.

So I have 2 suggestions:
- Limit the values defined in the control panel, so the minimum is 10. (Settings below 10 don't make sense).
- Change the code for entering battery mode so that the brightness doesn't get values below 10.

  • From: germany
  • Registered: 2010-01-06
  • Posts: 24

Re: Minimum brightness and battery usage (C1)

values below ten would make sense, if they wouldn´t black out the screen but drive it still darker than the now not yet dark enough darkest setting ;-)

would like it to get even darker, for i don´t want to illuminate my bedroom.

chumby is already pretty dark, but it could be dimmed even more to comfort all the chumb´s sleep out there :-)

kaba

kabatronix's Website

  • From: Germany
  • Registered: 2009-12-30
  • Posts: 10

Re: Minimum brightness and battery usage (C1)

I think this is a hardware limitation. Maybe the back light LEDs need a minimum voltage to work properly.

  • From: germany
  • Registered: 2010-01-06
  • Posts: 24

Re: Minimum brightness and battery usage (C1)

missed your reply, sorry

hardware is not the limit. backlight led are always driven with nominal voltage, dimming is achieved by change of duty cycle.
so in fact the leds are switch on and off very fast. by changing the off-time from zero over only short, then longer pulses you achive a smooth dim. so this is probably a simple programming issue.

cu

kabatronix smile

kabatronix's Website

  • From: Idaho
  • Registered: 2009-12-03
  • Posts: 111

Re: Minimum brightness and battery usage (C1)

I have found it depends on your chumby.  My chumby's screen goes black below 15.  So I have to set it to 15 for nightmode.  I saw others say 15 was they limit as well.  But some go down to 10