COSMIIC Pulse Generator (PG4)

The PG4 is a four-channel implantable pulse generator for electrical stimulation of nerve and muscle tissue. It delivers programmable monopolar stimulation through four independent electrodes, using the device case as the common return path.

How it works

The PG4 receives stimulation parameters over the CANopen network from the Power Module. Its Atmel AT90CAN128 processor converts control signals into precise charge-balanced stimulus pulses according to pre-programmed patterns or real-time commands. The SYNC message from the PM controls pulse frequency.

Three independent failsafe mechanisms protect against overstimulation:

1. Hardware limits on total charge per pulse
2. Software limits on stimulation parameters
3. Magnetic shutdown switches in both PG4 and PM

Hardware

Stimulation Modes

• Direct PM parameter setting — ~50 Hz update, up to 24 channels
• SDO direct setting — ~4 Hz for 12 channels, ~50 Hz single channel (recommended for testing)
• Pattern-based lookup tables — preloaded, up to 48 patterns per PG4 (recommended for permanent systems)

MATLAB Control

nnp.networkOn;
nnp.setSync(50);            % 50ms = 20 Hz
nnp.enterTestStim;
nnp.write(node, '3212', ch, [PW, PA*10]);  % pulse width, amplitude
nnp.write(node, '3212', ch, [0, 0]);       % stop
nnp.enterWaiting;

Design source

This page publishes the Fusion 360 Electronics molecule for the PG4 (PG4 FRAME MOL). Fusion Electronics is EAGLE underneath, so the board and schematic ship as EAGLE-format .brd/.sch, which the Adom viewers render natively — the interactive schematic, PCB and 3D shown on this page (and in Adom Nucleus) all come from this Fusion export.

• Upstream hardware: COSMIIC-Community/Implantables-PG4-Hardware (Aug 2025)
• Firmware: COSMIIC-Community/Implantables-PG4-App (C, AVR toolchain)
• License: open source under CERN-OHL-P-2.0 (hardware) and MIT (firmware).

Files

Created by: COSMIIC · Fusion 360 Electronics export