OpenStim / Blog: Recent posts

OpenStim One

It's here! This is the first non-alpha, non-beta, actual "release"(whatever that means) of the OpenStim software and firmware. If you have Windows, you can download a nice executable package here, otherwise just check out the "openstim-one" branch on SVN.

OpenStim One has a lot of new features and tweaks of existing things, but the major changes are... read more

Posted by Nathan Whitmore 2013-01-29

OpenStim multi-channel preview

Ta da!

Today I'm releasing a preview version of what I've been working on for the last couple of weeks--a version of OpenStim capable of driving up to 5 electrodes at the same time with fully independent current regulation for each electrode.

OpenStim accomplishes this using time-domain multiplexing. Essentially, electrodes are switched on and off very rapidly, so that only two are connected to the circuit at any given time. By swithing between pairs of electrodes at a high frequency, OpenStim can safely stimulate multiple areas of the brain at the same time.... read more

Posted by Nathan Whitmore 2012-07-27

Technical difficulties

So as you might have noticed, updates have not exactly been forthcoming the last few weeks. This is due to a lot of things happening:

  • The Arduino board on my main testing device was damaged by an errant drop of salt water, which ended up disabling the SPI pins needed to communicate with the digital potentiometer. Unfortunately, the problem wasn't obvious, and it's taken several days of troubleshooting to find the source of the problem.... read more
Posted by Nathan Whitmore 2012-06-10


Whelp, AC stimulation is working. Mostly. In the spirit of "Release early, release often", I'm putting out an experimental* AC-capable version of OpenStim.

More specifically, I'm reasonable confident that the latest version will basically do what you tell it to do in terms of generating waveforms. Specifically, it implements the custom waveform settings described on the wiki page. This allows you to specify a waveform shape and frequency in the input file, and the the OpenStim will output that waveform. This is a very flexible system, because it allows you to implement a whole bunch of different protocols that rely on having the ability to do AC or custom DC waveforms(tRNS, single frequency AC, etc.). Right now, the absolute maximum frequency that the system can generate is 100 hz, though I'm working on increasing that.)... read more

Posted by Nathan Whitmore 2012-05-20

AC is hard

Actually it's not that hard in and of itself. Getting it to play nice with other stuff is hard.

The way OpenStim will implement AC is basically by building in an arbitrary waveform generator into the software. In other words, people writing imprint files will be able to specify the shape of the waveform, which then gets loaded into the OpenStim's memory. Once it's loaded, the OpenStim runs through the waveform at a certain speed, changing the "target" current as it goes. There's a bit of logic that handles switching the polarity appropriately, but all in all it's mostly based on the same current regulation algorithm it uses in DC mode.... read more

Posted by Nathan Whitmore 2012-05-16

I'm doing science and I'm still alive

A few updates on the OpenStim project

*There's been a lot of stuff added in the more recent versions. OpenStim can now do automatically timed runs, has a mode for double-blind sham stimulation(even on yourself!) better self-diagnostics, electrode quality monitoring, and better current regulation. There are also demo imprint files that give examples of how to configure things, and there should be some new documentation up shortly.... read more

Posted by Nathan Whitmore 2012-04-28

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