The scenario
A Raspberry Pi drives a dual-color LED with common anode from two GPIO pins, using low-side switching through current-limiting resistors.
What is in this drawing
Read the decisions behind it.
01
Use common-anode LED with both anodes tied to the 3.3V rail
02
Connect each cathode to a GPIO pin through a 330 Ω resistor to set LED current
03
Tie Raspberry Pi ground to the 3.3V supply return
Reuse for any 3.3V microcontroller driving common-anode LEDs where GPIO sinks current to turn each color on.
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