Power up an LED — on paper, then on a board
You now own the four ideas every schematic is built from: charge, current, voltage, and power, glued together by the passive sign convention. The capstone uses all four on the simplest real circuit there is — one LED — and then you build it as an actual board in PCB Studio and compare your paper analysis against the engine's validated schematic.
- On paper: a red LED drops about 2.0 V at its rated brightness and should carry about 10 mA. It will run from the Pico's 3.3 V rail. Compute the voltage that must appear across the series resistor.
- Compute the resistor value that sets 10 mA (you may use i = v/R — Ohm's law, formally introduced in CA-2). Then compute the power absorbed by the LED, the power absorbed by the resistor, and the power delivered by the 3.3 V rail. Verify Σp = 0.
- Open PCB Studio and build the board: add the Pico 2 W and one 5 mm LED on any free GPIO, then generate the schematic.
- Examine the generated schematic's handling of the LED's series resistance and compare it with your hand calculation. Where they differ, work out why (standard resistor values, chosen target current).
- Run "Generate + PCB layout" and look at the routed board — the copper traces are the wires your analysis assumed were ideal. In CA-2 you'll learn when that assumption holds.