§ E1M™ open standard · v1.0
One pinout, every module.
The E1M specification fixes the carrier-board pinout, mechanical envelope, and electrical interface of two SoM form factors — so a single base board can host any silicon that conforms. Published under CC BY-SA 4.0. No NDA.
§ Two form factors
Fixed footprints. Silicon-agnostic.
E1M
35 × 35 mm
312 pads · LGA · "Normal"
Compact footprint optimized for always-on MCU-class compute, smart cameras, and ultra-low-power sensors. Hosts the Alif Ensemble and i.MX 93 reference SoMs.
Modules: E1M-AEN · E1M-N93
E1M-X
45 × 65 mm
496 pads · LGA · "Extended"
Higher pad density to expose additional controllers (more PCIe ports, more MIPI CSI lanes, parallel LCD) than fit on E1M. Hosts the Renesas RZ/V2N and RZ/V2H reference SoMs, with optional DeepX M1.
Modules: V2N · V2N+M1 · V2H · V2H+M1
§ Interface count overview
Every peripheral, by form factor.
From §7.2 of the spec — the peripheral count guaranteed by each footprint. Counts are minimum guarantees: a conformant SoM may repurpose digital pads as GPIO beyond the default-function rows below.
| Interface | E1M | E1M-X |
|---|---|---|
| Ethernet 1 GbE | 2 | 2 |
| USB 2.0 | 1 | 1 |
| USB 3.x | 1 | 2 |
| UART | 2 | 2 |
| SPI | 2 | 3 |
| I²C | 2 | 4 |
| I³C | 1 | 1 |
| I²S | 2 | 2 |
| SDIO / SD card (4-bit) | 1 | 1 |
| CAN-BUS | 1 | 2 |
| JTAG / SWD | 1 | 1 |
| GPIO (default-function) | 25 | 34 |
| PDM microphone | 2 | 2 |
| Audio master clock | 1 | 1 |
| Interface | E1M | E1M-X |
|---|---|---|
| RTC clock output | 1 | 1 |
| Boot-strap pins | 4 | 4 |
| Analogue input (ADC) | 8 | 8 |
| Analogue output (DAC) | 2 | 2 |
| Quadrature encoder | 4 | 4 |
| PWM | 8 | 8 |
| MIPI CSI-2 4-lane | 2 | 4 |
| MIPI DSI 4-lane | 2 | 2 |
| Parallel camera | 1 (8-bit) | 1 (16-bit) |
| Parallel LCD (24-bit RGB) | — | 1 |
| PCIe 4-lane | 1 | 2 |
| Reserved (RSVD) | 36 | 22 |
| Not connected (NC) | 0 | 35 |
§ What it fixes
A contract between the SoM and the carrier board.
Mechanical
Outline, height envelope, component placement areas, soldering guidance, packaging.
Electrical
Power architecture, voltage rails, reset, boot strap, electrical characteristics. Single-supply input.
Pinout
Every pad's default function + GPIO secondary. Compound-function pins and per-SoM tertiary functions.
Boot policy
Mandatory on-module components, normative boot configuration, peripheral-instance naming.
What the spec does not cover: the internal design of any SoM (silicon, on-module components, firmware) — those are vendor-specific and live outside the standard.
§ Versioning
Major bumps stay rare on purpose.
- Major — bumps for any backwards-incompatible pad change (pad removed, signal-set narrowed, position shifted).
- Minor — additions only (new alt-function on an existing pad, new pad in a previously reserved location).
- Releases tagged v<major>.<minor> (e.g. v1.0).
§ Licensing
CC BY-SA 4.0 — share, modify, build.
The specification text and pinout files are licensed under Creative Commons Attribution-ShareAlike 4.0 International. Build a conformant SoM, design a carrier, or fork the spec — just preserve the attribution and license downstream.
The proprietary SoM designs that implement E1M (E1M-AEN, E1M-X V2N, E1M-X V2N+M1, etc.) are not part of the spec and not covered by CC BY-SA 4.0.
§ Repository layout
Everything is in one place.
| Path | Purpose |
|---|---|
| STANDARD.md | Prose specification. The normative document. |
| pinout/v1.json | Canonical machine-readable E1M pinout (Loom v1). |
| pinout/x-v1.json | Canonical machine-readable E1M-X pinout (Loom v1). |
| pinout/schema/loom-v1.schema.json | JSON Schema validating both pinout files. |
| images/ | Pinout drawings, mechanical footprints, placement diagrams. |
| examples/ | Reference SoM manifest snippets. |
| source/altium-*.tsv | Authoritative pin-list exports from Altium. |
| CHANGELOG.md | Version history. |
§ Build with the spec
Designing a carrier board, or your own E1M SoM?
Grab the pinout JSON, drop the Altium symbol-and-footprint into your project, and you're done. Questions about conformance? We review third-party SoM designs.