COSMIIC Remote Module Network Interface

Creator Chris Rexroth

Tools tscircuit

Version 1.0.0

Assets 1 files

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Add a CAN network interface to my remote module

What is the COSMIIC network interface circuit?

Connect a remote module to the COSMIIC implant bus

Show me the CAN transceiver circuit for an implantable device

How does the COSMIIC 2-conductor network carry power and CAN?

⚡ Install this molecule

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Search the Adom Wiki for the molecule "COSMIIC Remote Module Network Interface" (slug: cosmiic-remote-module-network-interface) at https://wiki-ufypy5dpx93o.adom.cloud/wiki/molecules/cosmiic-remote-module-network-interface. Download its symbol (.kicad_sym), footprint (.kicad_mod), and 3D model (.glb/.step) assets into my current KiCad project under symbols/, footprints/, and 3dmodels/ directories. Register them in the project library tables. Show me the files once installed.

The Remote Module Network Interface is the shared circuit block present on every COSMIIC remote module (PG4, BP2, and derivatives). It bridges the AT90CAN128's built-in CAN controller to the implanted 2-conductor network, extracts regulated 5V from the network supply, and fans out to 4 ports (1 upstream in + 3 downstream out) for branching tree topology.

How it works

Every remote module connects to the COSMIIC implanted network through a single 2-conductor cable. That cable carries both the CANopen differential bus and the DC supply voltage on the same conductors (NET_P = CANH / supply+, NET_N = CANL / supply return). The network interface circuit:

Extracts regulated 5V — NET_P (4.7–9.6 V from the PM) feeds the U2 LDO; regulated 5V powers the AT90CAN128 and the CAN transceiver
Transceives CAN — U1 (TJA1050T) bridges the AT90CAN128's digital CANTX/CANRX pins to the physical CANH/CANL bus
Fans out to 4 ports — J1–J4 connectors branch the same CAN bus to 1 upstream input + 3 downstream outputs
Hardware node addressing — MC_ANODE exposes the hardware node address line to the AT90CAN128

U1's Rs pin is pulled low through R1 (10 kΩ) for slope-controlled mode, which limits dV/dt on the bus edges and reduces EMI — important for implantable devices.

Hardware

Parameter	Value
CAN Controller	AT90CAN128 built-in (ISO 11898, CAN 2.0B)
CAN Transceiver	NXP TJA1050T (SOIC-8, 1 Mbps, 5V)
LDO Regulator	MIC5205-5.0YM5 (SOT-23-5, 5V, 150 mA)
Network Cable	2-conductor (CAN differential + power superimposed)
Network Ports	4 total — J1 upstream in, J2–J4 downstream out
Topology	Branching tree (up to 24 nodes from a single PM)
Network Voltage	4.7–9.6 V (adjustable from PM)
Output Voltage	5 V regulated
Protocol	CANopen
Node Addressing	Hardware-configured (MC_ANODE)
PCB Size	32 × 24 mm Adom molecule

Components

Ref	Part	Value	Package	JLCPCB
U1	NXP TJA1050T	CAN transceiver, 1 Mbps	SOIC-8	C6952
U2	MIC5205-5.0YM5	5V LDO, 150 mA, 16V max in	SOT-23-5	C89758
J1–J4	2-pin header	COSMIIC network port	2.54mm pitch	—
C1	100nF	TJA1050T VCC decoupling	0402	C1525
C2	10µF	LDO input cap	0805	—
C3	22µF	LDO output cap (stability)	0805	—
C4	100nF	TJA1050T VREF bypass	0402	C1525
R1	10 kΩ	TJA1050T slope control (Rs)	0402	C25744

Production note: For the full 4.7–9.6 V network range, replace U2 with LM1117S-5.0 (C126028, SOT-223-3, 800 mA) which handles up to 15 V input.

Signal Net Names

Net	Description
`NLTXCAN` / MC_CANTX	CAN TX from AT90CAN128 to U1.TXD
`NLRXCAN` / MC_CANRX	CAN RX from U1.RXD to AT90CAN128
`NLTXCANBUS` / CANH	CAN bus positive on network cable
`NLTXCANBUS` / CANL	CAN bus negative on network cable
`NLANODE` / MC_ANODE	Hardware node address input

Machine Contacts

Contact	Side	Function
MC_CANTX	Left	CAN TX from AT90CAN128 → U1.TXD
MC_CANRX	Left	CAN RX from U1.RXD → AT90CAN128
MC_VCC5V	Left	5V regulated output to module
MC_GND	Left	Ground reference
MC_VIN	Right	Network supply input (4.7–9.6V)
MC_CANH	Right	CAN bus positive
MC_CANL	Right	CAN bus negative
MC_ANODE	Right	CANopen node address

Architecture

        Network Cable (2-wire: NET_P/CANH and NET_N/CANL)
                │
    ┌───────────▼─────────────┐
    │   J1 — Port 1 (in)      │
    └───────────┬─────────────┘
                │
    ┌───────────▼──────────────────────────────────┐
    │        Network Interface (32×24mm)           │
    │                                              │
    │  ┌──────────────┐   ┌────────────────────┐  │
    │  │ U2 MIC5205   │   │ U1 TJA1050T        │  │
    │  │ 5V LDO       │   │ CAN Transceiver    │  │
    │  │ NET_P → 5V   │   │ CANTX/CANRX (MCU)  │  │
    │  └──────┬───────┘   │ CANH/CANL (bus)    │  │
    │         │ VCC       └──────┬──────────────┘  │
    │         └──────────────────┤                 │
    │                            │ CANH / CANL     │
    └────────────────────────────┼─────────────────┘
                │          │          │
    ┌───────────▼─┐ ┌───────▼──┐ ┌───▼────────┐
    │ J2 (out 1)  │ │J3 (out 2)│ │J4 (out 3)  │
    └─────────────┘ └──────────┘ └────────────┘

CANopen Protocol

The PM acts as NMT master; remote modules are NMT slaves.

Message Type	Direction	Purpose
NMT	PM → Module	State machine transitions (Operational, Pre-op, Reset)
SYNC	PM → All	Cyclic timing reference (controls stimulation frequency, data windows)
SDO	Bidirectional	Point-to-point Object Dictionary read/write (configuration, testing)
PDO	Module → PM	High-speed broadcast of sensor data / stimulation status
Emergency	Module → PM	Fault reporting

Build

EDA: tscircuit (TSX) — source bundle included in Files below.

LDO note: Production modules use LM1117S-5.0 (C126028, SOT-223) which handles the full 4.7–9.6V network range. The SOT-23-5 MIC5205 in this reference design targets bench testing where network voltage is kept ≤6V.

Firmware: COSMIIC-Community/Implantables-PG4-App / Implantables-BP2-App — C, AVR toolchain

Source

All design files are open source under CERN-OHL-P-2.0 (hardware) and MIT (firmware).

Files

File	Description
`cosmiic-network-interface-source.tar.gz`	tscircuit project source (lib/index.tsx, package.json, config)
`schematic.svg`	Circuit schematic (all connections)
`pcb.svg`	PCB layout (32×24mm, component placement)
`3d.glb`	3D board model

Reference Implementation

The equivalent analog circuit appears as a dedicated schematic sheet in every remote module Altium project:

PG4 — page 4 of 8 ("CAN Interface") in COSMIIC-Community/Implantables-PG4-Hardware
BP2 — page 4 of 6 ("Network Interface") in COSMIIC-Community/Implantables-BP2-Hardware

NSF Relevance

The standardized remote module network interface enables multi-node implantable research systems with a single power and communication cable per branch. Researchers can add sensing or stimulation nodes to a running implant without architectural changes, enabling adaptive closed-loop protocols with real-time bidirectional data flow.

Science Drivers

implantable_healthcare

Created by: noah Version: v1 Category: other

Source files

GZ	cosmiic-network-interface-source.tar.gz tscircuit project source (lib/index.tsx, package.json, config)	file	39.4 KB
SVG	pcb.svg PCB layout (32×24mm, component placement)	file	164.1 KB
GLB	3d.glb 3D board model	glb	1.1 MB
SVG	schematic.svg Circuit schematic (all connections)	file	153.0 KB

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0 revisions · Molecule # · Updated 2026-05-22 20:37:43