Mission Statement

In this post, I'm going to summarize the objectives of this project. I'm trying to develop an e-stim unit that puts the expensive commercially available boxes in their proper place. What makes me think I'm up to the challenge? I have an academic background, I'm an excellent coder, I have plenty of experience in programming close to hardware, and I have reasonable experience with microelectronics. However, only time will tell, and you may judge.

While working on this project, I will

• share my thoughts,
• talks about obstacles encountered and solutions found,
• put my Eagle hardware designs up as free (as in beer) download,
• share pictures of through-hole soldering jobs,
• and put source code up as free (as in beer) download.

I will try to add the following features to my unit:

• Four independent output channels.
• Low-current pulse-width modulated (PWM) operation.
• Minimalist user interface: Rotary encoder and push button (think of a BMW, Audi central console). En plus, a wealth of mechanical knobs adds unnecessary hardware complexity and cost where everything could be done in software in a much more convenient and reliable way.
• A small TFT display for a user menu and status information.
• Powered from a rechargeable battery pack. I won't discuss powering from anything that is, even indirectly, connected to the mains.
• Great connectivity: I'm thinking about Line-in audio, USB, WiFi, or Bluetooth. I dream about how this would enable client-server operation, remote operation, a web interface, a mobile phone app, etc. I don't like how commercial boxes lock users out, and how vendors make a big secret of trivial communication protocols and charge big time for standard cables and whatnot.
• Stim modes that can be programmed by, and shared among, users.
• Interfacing the box with sensors for interactivity. Just picture the scenarios possible if push buttons, microphone, inclination, movement, or pressure sensors could be processed by the stim programs.
• Cost: I will try to stay significantly below the cost of upscale commercial boxes, which range from USD 400 to USD 600. I'm not stupid and realize that vendors have to charge for development time, support, and profit. As a DIY community project, we should have a margin.
• Your ideas and wishes are welcome!

This list will be updated from time to time, and I will link to blog posts discussing these points. The box will be based on the Arduino Due as central processor, for several reasons:

• large number of PWM output channels
• large number of ADC input channels
• easily programmable in C or C++

Above all, an enthusiastic community that continues to create fantastic resources on PWM, TFT displays, Audio, Serial, USB, SPI, I2C, WiFi, Bluetooth, and all kinds of sensors is already out there. Whenever I build upon something I found out there, I will cite and give credit where credit is due.