Affordable, stackable, open source, 32-channel EEG ADC powered by a Cortex-M7

Dec 06, 2021

Project update 6 of 8

Fulfillment Update

by Joshua Brewster

Hey everyone,

So, we are overdue for an update on everything that’s been going on with the FreeEEG32. We have good news and bad news. The bad news is the chip shortages around the AD7771 don’t look like they’ll begin to subside until at least mid-year next year, when some suppliers have expected stock dates listed. In order to for sure secure chips by third quarter next year, we would need to order a reel of 2500 fresh from the factory. To do that, we would need to raise another $20 grand or so to pay for that, on top of what we have currently raised (not including if we wanted to produce an extra 500 32-channel boards with all of those chips.)

That’s definitely not feasible for us right now, so instead we’ve been exploring another option of an alternate ADC chip that is currently in supply. We’re waiting for a factory test to confirm if it’s a feasible alternative for EEG (it’s good for everything else.) If it is, it will lower the cost of the board further, and be a bit easier to program - but only if we can get it to be as reliable as the AD7771. So to get an idea of the cost difference, we can make a 128-channel board for the same cost as a 32-channel AD7771-based board, and with marginal loss in signal fidelity. The only issue we are running into right now is that the input impedance is too low on this chip (1 MOhm, vs 10 MOhm on the AD7771), but we’re crossing our fingers that we can make use of analog filters to save the day so we’ll say more on that soon.

128-channel prototype:

Hand-soldered firmware test:

If anyone has more serious interest in our project for research or industry purposes, we can think of several ways to use up these chips if we got a reel order in, but it’s all a matter of funding - without damaging the integrity of the open source initiative while we do our part to socially engineer a more ethical society through shared infrastructure. We’re serious about that…

Even with crowdfunding, a lot still ends up out of pocket, because this is a passion project with zero marketing (intentionally) and we’re learning along the way. The funding you all provided has ensured that we can produce enough boards to start to get our work out there, but we still take on a lot of risks with our way of doing things, especially with all of the industry-wide shortages and our collective learning process as we navigate a rapidly evolving tech industry. However, we’re excited heading into the new year as a lot of work continues to come together, and ultimately this will lead to a higher quality, easier to use final product for the FreeEEG32 project and beyond. We’re just hoping we can get the boards out to you sooner than later, so we’ll keep you all updated on that, otherwise you can come chase us down on Discord:

So some of that was good news mixed in with the bad, I’m hopelessly optimistic here really. For more good news, Bernard has continued to refine his headsets for comfort and making them easier to produce. He’ll even start to offer a DB-25 connector option after he gets back from Columbia. He’s currently working with troubled students teaching transcendental meditation and taking EEG readings.

Check out their alpha brain waves (the big sine waves on the graph)!

Otherwise, we’re hammering away at the web software support with Brains@Play. We’re redoing it into a natively multi-threaded solution and building more on our GPU libraries. We’re even exploring WebRTC integration as it can safely stream data peer-2-peer along with video/audio chat (or even code to send programs back and forth) and add new layers of awesome to the web BCI experience. We’re going to resolve all of this software work into a free neurofeedback studio that will sit on the web and be compatible with many devices, in a way where we will be able to burgeon its features with community support. This is all AGPL, just like the FreeEEG32, as we are dedicated to growing the wisdom and tools available in the commons! We’ve also now partnered with a rehab facility in Los Angeles to create an AGPL bio-metric & medical communications tool along with an 8-channel hardware design we’ll be using to drive several projects. There’s a whole lot more brewing, but it’s getting hard to keep track of.

Thanks to everyone who’s been here on the ground and who’s supporting us all the way! We won’t let you down, thanks for your patience!


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