Adam-EEG

India's first open-hardware 32-channel EEG / biopotential acquisition board — a quad-ADS1299 analog front end driven by a dual-ATmega328 controller, designed in EAGLE by Soul Scientific in 2015.

Adam-EEG packs four Texas Instruments ADS1299 24-bit, 8-channel simultaneous-sampling analog front ends onto one board — 32 truly simultaneous EEG channels, daisy-chained over a single SPI bus — with onboard microSD logging for fully standalone (untethered) recording. It's the original prototype in the Adam-EEG lineage: a from-scratch, low-cost, open alternative to research-grade EEG acquisition hardware.

Also published at: Hackaday.io · dev.to · NeuroTechX/awesome-bci (merged)

• Why this exists
• Technical specifications
• Connectors & pinout
• Passive component reference
• System architecture
• Repository contents
• Getting started
• Safety & disclaimer
• Roadmap
• Contributing
• License

Research-grade multichannel EEG hardware is expensive and closed. Adam-EEG set out to prove that a 32-channel, simultaneous-sampling, standalone-logging EEG acquisition board could be built from commodity parts, in a hobbyist CAD tool, at a fraction of the cost — fully open, so anyone can build on it rather than starting from a datasheet.

Extracted directly from the schematic's named nets — real signal names, not inferred from silkscreen alone.

Most-used passive values, pulled from the real value= attributes in the schematic (useful for a BOM sanity-check or respin):

flowchart LR
    subgraph AFE["Analog Front End"]
        A1["ADS1299 #1<br/>ch 1-8"]
        A2["ADS1299 #2<br/>ch 9-16"]
        A3["ADS1299 #3<br/>ch 17-24"]
        A4["ADS1299 #4<br/>ch 25-32"]
    end
    A1 -- "DOUT daisy" --> A2 -- "DOUT daisy" --> A3 -- "DOUT daisy" --> A4
    MCU["Dual ATmega328<br/>controller"]
    A1 <-- "shared SCLK / DIN / DRDY<br/>individual CS1-CS4" --> MCU
    A2 <-.-> MCU
    A3 <-.-> MCU
    A4 <-.-> MCU
    MCU --> SD["microSD<br/>standalone logging"]
    PWR["LM2663 charge pump<br/>+ LP5907 / TPS723xx LDOs"] --> AFE
    ISP["2x AVR ISP header"] --> MCU

Each ADS1299 samples 8 channels simultaneously; the four devices share one SPI bus in TI's standard multi-device daisy-chain topology, so all 32 channels are read out in lockstep with no channel-to-channel skew.

1. Install Autodesk EAGLE (a free tier is sufficient — this board's ≤80 cm², 2-layer, single-sheet design was scoped to fit within EAGLE's classic free-tier limits).
2. Clone this repo and unzip EEG_64_1.zip.
3. Open EEG_64.sch for the schematic or EEG_64_1.brd for the board layout — both are standard EAGLE XML and can also be inspected with eagle2kicad-style converters if you prefer KiCad.
4. Gerbers are not checked in — export them from the .brd via EAGLE's CAM processor if you're sending this to fab.

This is an open-hardware research/prototyping board, not a certified medical device. It has not undergone FDA/CE or equivalent regulatory clearance, and no formal patient-isolation or leakage-current certification has been performed on this design. If you build and use this board:

• Do not use it for clinical diagnosis or treatment decisions.
• Power it only from isolated, battery-backed supplies — never connect a build to mains-powered equipment while it is attached to a person.
• Treat it as you would any DIY biopotential-acquisition project: informed use, at your own risk.

This 2015 quad-ADS1299 board is the original Adam-EEG prototype. It remains a solid, low-cost 32-channel reference design for anyone building EEG/BCI acquisition hardware from scratch. Later Adam-EEG iterations explore denser single-chip AFE options; this repository stays focused on the original, fully-verified quad-ADS1299 design.

Issues and pull requests are welcome — see CONTRIBUTING.md. Whether it's a routing improvement, a KiCad conversion, a BOM/sourcing update, or a build log from your own fab run, please open an issue first so we can track it.

Apache License 2.0 — see LICENSE. You are free to use, modify, and distribute this design, including commercially, provided attribution is preserved.