ADS1299 Register Configuration

PiEEG-server exposes real-time ADS1299 register configuration over WebSocket. Change channel input modes, run noise diagnostics, and apply presets — all live, without restarting the stream.

This feature works on PiEEG boards (SPI). IronBCI boards use Bluetooth LE and do not expose register writes.

Capabilities

Switch input modes on the fly — normal electrodes, input shorted (noise floor test), test signal, temperature sensor
Run noise diagnostics — built-in test with per-channel RMS and automated pass/fail verdict
Apply named presets — one command to configure all 8 channels at once
Automate from any language — plain WebSocket JSON commands

Configurable registers

Channel registers CH1SET–CH8SET (addresses 0x05–0x0C) can be written at runtime. Configuration registers (CONFIG1–CONFIG3) are protected to prevent accidental sample-rate or reference changes.

Input modes

Value	Mode	Description
`0x00`	Normal electrode	Standard EEG measurement — default after startup
`0x01`	Input shorted	Both inputs tied together internally — measures baseline noise
`0x02`	Bias measurement	Routes bias signal to channel — verify bias drive circuit
`0x04`	Temperature sensor	On-chip temperature sensor — useful for thermal diagnostics
`0x05`	Test signal	Internal 1× amplitude square wave from CONFIG2 — verify signal chain

WebSocket commands

Read current register state


{"cmd": "reg_read"}

Response:


{"reg_config": {"regs": {"0x05": "0x0", "0x06": "0x0", ...}, "status": "ok"}}

Write individual registers


{"cmd": "reg_write", "regs": {"0x05": "0x00", "0x06": "0x01", "0x07": "0x05"}}

This sets CH1 to normal, CH2 to input shorted, and CH3 to test signal. Other channels remain unchanged.

Apply a preset


{"cmd": "reg_preset", "preset": "internal_short"}

Preset	Value	Use case
`normal`	`0x00` all channels	Resume standard measurement
`internal_short`	`0x01` all channels	Measure noise floor — no electrodes needed
`test_signal`	`0x05` all channels	Verify full signal chain with known waveform
`temp_sensor`	`0x04` all channels	Read on-chip temperature

Run noise test


{"cmd": "noise_test", "duration": 3}

Switches all channels to input-shorted mode, collects samples for the specified duration, computes per-channel RMS, then restores the previous configuration.

Response:


{
  "noise_test_result": {
    "rms": [2.5, 2.3, 3.1, 2.8, 2.6, 2.4, 2.9, 3.0],
    "max_rms": 3.1,
    "verdict": "good",
    "recommendation": "Electrodes OK",
    "duration": 3.0,
    "samples_collected": 750
  }
}

Verdict	Meaning
`good`	All channels below 5 µV RMS — normal
`warning`	Some channels 5–15 µV — check electrode contact
`bad`	Channels above 15 µV — likely loose or disconnected electrodes

Dashboard register panel

The dashboard includes a visual Register panel for register configuration without writing code:

Per-channel input mode selector (dropdown)
One-click presets (Normal, Shorted, Test Signal, Temperature)
Noise test button with live progress and color-coded results
Current register state display

How it works internally

Dashboard or client sends a WebSocket command
Server validates — only CHnSET registers (0x05–0x0C) are allowed
Acquisition thread pauses gracefully
SPI sequence: STOP → SDATAC → register writes → RDATAC → START
First 25 frames (~100 ms) discarded for ADC settling
Spike filter baseline resets to avoid false rejections
Updated register state broadcast to all connected clients

Example: automated noise check in Python


import asyncio, json, websockets
 
async def noise_check():
    async with websockets.connect("ws://raspberrypi.local:1616") as ws:
        await ws.send(json.dumps({"cmd": "noise_test", "duration": 3}))
        async for msg in ws:
            data = json.loads(msg)
            if "noise_test_result" in data:
                result = data["noise_test_result"]
                print(f"Verdict: {result['verdict']}")
                for i, rms in enumerate(result["rms"]):
                    print(f"  CH{i+1}: {rms:.1f} µV RMS")
                break
 
asyncio.run(noise_check())