Coin-cell LED board

A CR2450 holder, a resistor, and an LED — the Power class, an ERC pass, and a board that lights up when you snap the cell in.

Click through the files — it's the whole project

What's going on

• The Power object marks the holder as a source: pin 1 becomes power_out, pin 2 becomes power_in, and the voltage and current travel with it. ERC on the built schematic uses those types.
• The LED and resistor are built-in passives — size picks the package, and the value is a string that lands on the schematic and in the BOM.
• A CR2450 tops out around 3 V, so a 100 Ω resistor keeps the LED at a sensible current — swap the value and rebuild; the schematic, netlist, and BOM all follow.
• Placement is all relative: the holder is centered, the resistor sits below it, and the LED follows the resistor — move the holder and the rest comes along at create().

Build

cd my-project/hw
	npx @typecad/pcb build

build/
	  coin_cell_led.kicad_pcb
	  coin_cell_led.kicad_sch
	  coin_cell_led.net
	  coin_cell_led.csv   ← the BOM

The runERC() call at the end of the entry file prints its findings on every build — the check runs against build/coin_cell_led.kicad_sch, so it sees what you see.

Where to go next

• Pins & Power — the Power class, direction, and what ERC does with pin types
• Passives — LEDs, resistors, and the other built-ins
• Checks & Export — runERC, runDRC, and the export functions