Introduction

elmo (ELectronics MOdeling, Schematics as a code) is a small text language for describing electronic circuits that render as schematics — in the spirit of Mermaid and PlantUML, but for electronics.

You write parts, pins, and connections in plain text; elmo lays them out and draws a schematic as SVG.

part U1 ic "ATtiny85" pkg=SOIC-8 {
  left 1:~RESET 2:PB3 3:PB4 right 8:VCC 7:PB2 6:PB1 5:PB0 bottom 4:GND
}
part R1 res 10k
part D1 led green
wire U1.PB0 -- R1.1
wire R1.2 -- D1.anode
power VCC = U1.VCC
gnd GND = U1.GND D1.cathode

Why a language?

• Diffable & reviewable — schematics live in git as text, not binary.
• Generatable — emit elmo from scripts, BOMs, or config.
• Embeddable — drop diagrams into Markdown docs, wikis, and MDX.
• Downstream-ready — the same source exports a netlist and a BOM.

How it works

The pipeline is: parse the DSL into an intermediate representation, merge shared connections into electrical nets, place components with elkjs, route signal nets orthogonally, and emit themeable SVG. Power and ground render as symbols (never routed); signal nets route as wires or collapse to net labels by fan-out.

Continue to Install and Getting started.