About¶
The SW32 is a 4-channel E-Stim box based around the MK312-BT. Focusing on a design that adds modern conveniences like USB Type-C PD and Li-Ion battery support.
Controlling and interacting with the box can be achieved in numerous ways. This includes the front panel inferface, Bluetooth, 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
- 4x Trigger Channels
- Stereo Line-In and Mono Microphone In (with programmable gain)
- Internal Microphone
- USB Type-C PD Charging
- Li-Ion / SLA Battery Pack Support
Overview¶
The SW32 consists of following PCBs:
| PCB | Description |
|---|---|
| Main Board | Provides the core functionality of the SW32. |
| Output Board | Generates 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). Provides wireless features. |
| 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.
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.