SW-32 - A modular ESP-32 e-stim device
About
The SW-32 is a modular e-stim unit, with the ESP-32 microcontroller at the core. It supports a max of 4 channels.
The modular output boards try to mimic the output stage of the well-known Erostec ET312 or better, the DIY reverse engineered MK-312. Hopefully by recreating this output stage, the same e-stim experience can be achieved as those devices.
The main board makes use of two ESP-32 modules. One for the main control/front panel IO and another for operating the output channels. They have separate ESPFlash 2x3 headers for programming and serial communication. A JTAG 2x5 header provides debugging support for both chips by use of JTAG chaining.
I chose to use two ESP-32 modules, instead of using additional I/O expanders and ADCs. Since two ESP-32 modules work out cheaper or roughly equal to the price of the other option, for one off assemblies. While also gaining additional functionality because microcontroller.
Everything is routed directly into the microcontroller as separate signals (e.g. the microphone and stereo line-in audio, L and R channels). Nothing is hardwired, allowing firmware to customize how the front I/O works. For example instead of having a MIC IN you could change the functionality to act as a trigger for some action, etc.
Structure
The project is split into multiple KiCad sub-projects:
- SW-3211M [Schematic] - An easy-to-use module board. Made to be used with external MCU and isn't considered a part of the modular design.
- SW-3240 [Schematic] - This is the core of the project, the main control board that can support up to four output channels.
Modules
- SW-32MO10 [Schematic] - A single output module, equivalent to the SW-3211M.
- SW-32MA1 [Schematic] - A basic audio module, supports a mono microphone and stereo line-in.
- SW-32MC1 [Schematic] - A front panel control module.
More detailed information about each can be found in the project specific READMEs.
Acknowledgments
The design of the output module board (SW-3211M) was based on the design by WendyTeslaburger/WT-312.
License
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License, available at http://creativecommons.org/licenses/by-nc/4.0/.
