3.10.4 LED Lighting

To avoid information clutter on the UI display, additional status information is displayed through a blue and an orange LED built into the rotary encoder. Table 3-1 shows the LED colors versus activity correspondence.

Table 3-1. LED Colors Versus System State
Color	Cold Plate Status
Breathing Purple	Standby
Breathing Blue	Actively Cooling
Solid Blue	At the Target Temperature
Solid Orange	Error

Both LEDs could be controlled via different slices of the same PWM signal, so controlling them was as simple as loading a new duty cycle into the correct register. The breathing effect was implemented using a simple state machine that loaded varying duty cycles into the PWM to create the illusion.