Quote Originally Posted by Mike, K8LH View Post
Has anyone tried "gamma" correction to smooth out LED brightness level changes? I just added a 64 level rom "gamma" array to the program in the previous post and it made an amazing difference in the smoothness of the fade.
yep... tryed it in 3 ways:
1. Simple ISR-based software PWM with floating (table-generated) pulse widths.
2. Strobing /OE of external latches (54 PWM channels/PIC16f877a) with HW PWM output (table-generated) + SW PWM (i had to slightly increase LED current to get more brightness, as the full duty cycle hadn't been achievable, almost like with 1.5x charlieplexing)
3. Increased bit depth to 13(14) bit and PWM speed (refresh rate) to 610Hz on 18F for better perfomance.