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4x4x4 RGB Cube+Pics TLC5940, Fixed Multiplexing...
Topic: 4x4x4 RGB Cube+Pics TLC5940, Fixed Multiplexing...
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Re: 4x4x4 RGB Cube+Pics TLC5940, Fixed Multiplexing...
Nov 21, 2010, 11:03 pm
Brightness is relatively linear throughout the PWM range with the MOSFET drivers blocks that manage the cube's multiplexed power.
Do you still have the 512 PWM boundary if you disable multiplexing (ie. hold power constant on just one row / plane)? What is your multiplexing frequency?
I use the MOSFET driver blocks to multiplex power. The driver blocks are directly controlled by non-PWM'd arduino ports, in a 1 port to 1 power plane (4x4 LEDs) configuration. The multiplexing frequency is approximately 1Khz while the PWM frequency is much higher (have to check the TLC5940 lib docs for the exact number). This gives each plane of LEDs 1 ms of uninterrupted power which seems sufficient to see PWM across the range.
I sketched most of my schematics on paper or figured things out on breadboards. Was there something specific you wanted to see (eg. charge pump, power drivers, etc.)? I'll beef up the comments in my code and post it here.