brainmaster

A Rust library and terminal UI for BrainMaster Discovery 20/24E EEG amplifiers over USB serial (FTDI).

Dual backend: runtime-loaded bmrcm.dll FFI on Windows (18/18 functions) + pure-Rust serial protocol on all OS. Frame decoding, sync detection, impedance extraction, and conversion factors derived from the neuromore studio open-source integration.

Installation

cargo add brainmaster

Supported hardware

Device	Channels	Sampling Rate	Connection	Impedance
Discovery 20	20 EEG + 4 AUX (24 total)	256 Hz	USB serial (FTDI, 460800 baud)	✅
Discovery 24E	20 EEG + 4 AUX (24 total)	256 Hz	USB serial (FTDI, 460800 baud)	✅

Channel layout (10-20 system)

Ch01 Fp1    Ch07 T3     Ch13 P4     Ch19 Pz
Ch02 F3     Ch08 T5     Ch14 O2     Ch20 A2
Ch03 C3     Ch09 Fz     Ch15 F8     Ch21 Fpz
Ch04 P3     Ch10 Fp2    Ch16 T4     Ch22 Oz
Ch05 O1     Ch11 F4     Ch17 T6     Ch23 AUX23
Ch06 F7     Ch12 C4     Ch18 Cz     Ch24 AUX24

Cross-platform

Works on Windows, Linux, and macOS.

Platform	bmrcm.dll FFI	Pure-Rust serial	Requirements
Windows x86	✅ 18/18 functions	✅	FTDI drivers
Windows x64	❌ (32-bit DLL)	✅	FTDI drivers
Windows ARM64	❌ (32-bit DLL)	✅	FTDI drivers
Linux x64	❌	✅	ftdi_sio kernel module
Linux ARM64	❌	✅	ftdi_sio kernel module
macOS x64	❌	✅	FTDI VCP (built-in)
macOS ARM64	❌	✅	FTDI VCP (built-in)

bmrcm.dll is a legacy Windows 32-bit DLL from BrainMaster Technologies. The pure-Rust serial backend provides identical functionality on all platforms — it implements the complete Discovery frame protocol directly over the FTDI USB-serial interface.

The pure-Rust backend uses the serialport crate and requires no DLL. It implements the complete Discovery serial frame protocol:

Frame format (78 bytes at 256 Hz)

[0]     Sync byte (cycles: 0x20 → 0x40 → 0x60 → 0x80 → 0xA0 → 0xC0 → 0xE0)
[1-2]   Unused
[3]     Steering (impedance channel selector, 1-28)
[4-5]   Special data (impedance raw, 16-bit signed LE)
[6-77]  24 channels × 3 bytes (24-bit signed LE)

Conversion factors

• EEG: raw_24bit × 0.01658 = µV
• Impedance: raw_16bit × 0.005 = kΩ

bmrcm.dll API (Windows, 18 functions)

Function	Purpose
AtlOpenPort	Open COM port at baud rate
AtlClosePort	Close COM port
AtlSetBaudRate	Set baud rate (0x10=460800, 0x20=115200, 0x30=9600)
AtlWriteSamplingRate	Set device sampling rate
AtlReadSamplingRate	Read device sampling rate
AtlClearSpecials	Clear all special selections
AtlFlush	Flush serial buffers
BmrLoginDevice	Authenticate with codekey/serial/passkey
DiscStartModule	Start data acquisition
DiscStopModule	Stop data acquisition
AtlGetBytesInQue	Get bytes available in receive buffer
AtlReadData	Read raw bytes from buffer
AtlSelectImpedanceChans	Select impedance measurement channels
AtlSelectSpecial	Select special data mode
AtlSetNotchFilters	Configure notch filters
AtlPeek	Read device memory location
AtlPoke	Write device memory location
AtlQueryFirmware	Query firmware version

Quick start

use brainmaster::prelude::*;

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let ports = DiscoveryDevice::find()?;
    let mut device = DiscoveryDevice::open(&ports[0])?;
    device.start()?;

    for _ in 0..SAMPLING_RATE as usize * 4 {
        if let Some(_frame) = device.read_frame()? {
            let ch = device.channels();
            println!("Fp1={:.2}µV O1={:.2}µV O2={:.2}µV",
                ch.data[0], ch.data[4], ch.data[13]);
        }
    }

    device.stop()?;
    device.close();
    Ok(())
}

Project layout

brainmaster-rs/
├── Cargo.toml
├── README.md
├── CHANGELOG.md
├── LICENSE
└── src/
    ├── lib.rs            # Crate root + prelude
    ├── main.rs           # CLI binary
    ├── bin/tui.rs        # ratatui TUI (8-channel EEG charts)
    ├── ffi.rs            # Runtime-loaded bmrcm.dll (Windows, 18 functions)
    ├── protocol.rs       # Pure-Rust serial protocol (all OS)
    ├── types.rs          # Frame format, channels, sync, conversion
    ├── device.rs         # High-level device API
    └── error.rs          # Error types
├── examples/
│   ├── scan.rs           # Port discovery
│   ├── read_eeg.rs       # 4-second EEG capture
│   └── read_impedance.rs # Impedance measurement
└── tests/
    └── protocol_tests.rs # Frame decode, sync, conversion tests

Dependencies

Crate	Purpose
serialport	Cross-platform serial I/O (FTDI USB)
libloading	Runtime DLL loading (Windows, optional)
thiserror	Error types
log	Logging facade
env_logger	Log output
ratatui	Terminal UI (optional)
crossterm	Terminal backend (optional)

Running tests

cargo test

License

MIT