SW32

SW32 - 4 Channel E-Stim

This project is a work in-progress. Changes to the design might occur. Order PCBs at your own risk..

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About

The SW32 is a 4-channel E-Stim box based around the MK312 box. Focusing on a modern and compact redesign. It supports USB Type-C PD charging with a variety of batteries such as Li-Ion, Li-Poly, or Lead Acid.

Controlling and interacting with the box can be achieved in numerous ways. Such as the front panel controls, USB, Bluetooth/A2DP, or via Wi-Fi using the internally hosted web app.

An RP2040 microcontroller was picked since it has dual cores and the PIO hardware peripheral. An active community and well documented SDK is also a bonus.

Features

• 1.8" 160x128 Color Display
• 4x Isolated Output Channels
  • Triphase Support
  • Tri-polar (+, GND, -) Support
• Stereo Line-In and Mono Microphone Input (with programmable gain)
• Internal Microphone
• 4x Trigger Channels
• USB Type-C PD Charging
• Multi-chemistry Battery Pack Support (Li-Ion/Li-Poly/Lead Acid)

Overview

The SW32 consists of following PCBs:

• Main Board - Provides the core functionality of the SW32.
• Output Board - Generates the isolated E-Stim output for each channel. Driven by the main board.
• Front Control Board - The PCB with all the front panel controls (e.g. pots, buttons, LEDs).
• Front Panel - A cosmetic silkscreen PCB for the front control board.
• Display Module* - 1.8" 160x128 TFT SPI color display.

The reason for having a separate output board is primarily for flexibility, space savings (expand vertically instead of horizontally), and long-term cost savings. Most of the cost is in the main board. So being able to reuse the main board when changing the output design will help keep costs down.

Fabrication

This build is mostly SMT with THT for connectors and front panel components. PCBs have been designed specifically for JLCPCB fabrication and assembly.

Schematics can be found in /schematics, and PCB fabrication files (gerbers, BoMs, CPL, etc.) can be found in /pcb.

Disclaimer

The SW32 comes with absolutely no warranty of any kind. The designs are free to use, under the conditions defined in the LICENSE. Using the designs in original or modified form, implies acceptance of any and all associated risks and liabilities.

• Use it entirely at your own risk.
• Do not use it for anything safety-critical, medical, industrial, military, or illegal.
• Do not use it on anyone without explicit and informed consent.
• Keep any and all electrodes below the chest.
• Do not use Li-Ion battery packs without a BMS.

Safety

SW32 can generate potentially lethal voltages and currents on its outputs and on internal components, even when powered from a battery. The risks associated with building, testing and using this device can be reduced but not eliminated.