hi:friend i have a led project ,need linear dimming, use ARM K60N512VMD100 ADC to control PWM dimming. the ADC is 0.5V-5V, pwm ratio 2% to 100%. step need greater than 200. if me use read table , the curve is not linear . have you one tell me ,how can i to do , is the ARM powerful for the job,
the curve is not linear what curve LED intensity vs pulse width is pretty linear, I have worked 10+ years with LED (dimming) and never had to 'correct'
is the ARM powerful for the job, the above can be done with any processor (8051 to pentium) that has an ADC and PWM
friend->thanks
"what curve LED intensity vs pulse width is pretty linear"
But the human eye's perception is not?
No - most of our senses requires exponentially stronger stimuli.
So to dim display in the dark needs to be very, very, very much weaker than a strong display in daylight.
I have 10000 intensity steps in the displays I have programmed. And that is still not really dark when viewed in a dark room.
But the human eye's perception is not? correct; however the 'percieved' intensity vs ambient is.
"correct; however the 'percieved' intensity vs ambient is."
Not really sure I understand what you mean with that.
if you reduce ambient, the eye 'likes' you to reduce your sign or whatever by the same percentage
Yes, when the quotient between ambient and LED output is the same, the eyes will be happy as long as we are within the supported adjustment range of the eyes. Cameras would have a hard time capturing data if it wasn't enough to adjust aperture/time/ISO to adjust the light level of all parts of the photo with the same number of stops and have the viewer accept the capture.
i have a led project ,need linear dimming more than a million LEDs have are dimmed relative to ambient by my code