- most px4_io-v2 boards have a blue LED that breathes for status
- the pixhawk 2.1 (hex) re-used this blue LED for as an IMU heater (active low), but kept the same board id (so we have to detect at runtime)
- the new cubepilot boards (yellow, orange) inverted the polarity of this heater pin
- untangle the mess slightly so that things we know statically (eg cubepilot cubeorange LEDs and heater polarity) are handled at build time.
co63oc