Aurora 18 prototype
New project using RGB/tricolor LEDs. Tricolor means triple the number of LEDs to control – more load on the processor. I decided to move up to 16 bit PIC, 24F series for the increased processing speed (MIPS) and memory. 16 MIPS and 4 KB of RAM and still had to resort to multiplexing RGB channels. 18 LEDs color/brightness individually controlled in gamma-corrected 8 bit levels (equivalent to about 14 bit linear PWM).
Countless software tweaks later I’m getting 200 Hz refresh rate. Hard to tell from the video, but the fades are truly smooth.
The circuit is quite simple. Besides the PIC and the LEDs, 6 transistors and a few resistors & caps. No current driver ICs or shift-registers.
Here’s the schematic for anyone interested. LED to PIC connections can be rearranged – mine was dictated by the PCB layout. I wanted to route the I/O pins to the nearest LED on the PCB (being fabricated right now – stay tuned for the update).