Channel Map¶

The canonical source is controlunit/settings.yml — the developer's deliberate in-code data dictionary, written as a memory aid after long gaps in work. Channel names, ADC addresses, gains, descriptions, and conversion function identifiers all live there.

"I did that to not remember the modules. So I DID DOCUMENT THERE INTENTIONALLY." — Arseniy

Hardware documentation (board layouts, signal conditioning, pin numberings, datasheets) lives in the external hub: aklab-howto. Do not expect hardware build notes here.

ADC signal channels¶

Name	Signal	Sensor / notes
`Ip`	Plasma current	Hall-effect sensor: `5 * (v - 2.52) A`
`Pu`	Upstream pressure	Pfeiffer single gauge PKR251 (currently operating in Pirani mode — cold-cathode discharge not igniting)
`Pd`	Downstream pressure	Ionization gauge, with `Place: "downstream"` in the settings for the Control dock and the web Gauges card to show beside its short name. Its controller's mode (Torr linear or Pa log) and exponent are recorded per row as `IGmode` and `IGscale`, the columns the file has always had.
`Pu2`	Upstream pressure	Second ionization gauge, wired to channel 16 on 2026-09-15, with its own selector on the Control dock and the web Control tab, and `Place: "upstream"` in the settings for both to show beside its short name. Its mode and exponent are recorded per row as `IGmode_Pu2` and `IGscale_Pu2`, appended after the original columns so nothing an old reader counts on moves.
`Bu`	Upstream Baratron	MKS 627, FS = 1 Torr
`Bd`	Downstream Baratron	MKS 628B, FS = 0.1 Torr
`MFC1`	H₂ flow	20 SCCM range
`MFC2`	O₂ flow	10 SCCM range
`Ci`	Cathode current	Channel prepared in ADC map and on PCB; never actually measured. Conversion function exists for consistency.
`Cv`	Cathode voltage	Same as `Ci` — prepared but not deployed
`T`	Membrane temperature	Now read off-Pi (NI on Windows). Channel definition remains.
`QMS_signal`	Sync trigger state	Boolean — logs whether GPIO sync is active during each row

DAC outputs¶

Device	Signal	Notes
DAC8532 ch1	MFC1 (H₂) setpoint voltage
DAC8532 ch2	MFC2 (O₂) setpoint voltage
MCP4725	Plasma current (Ip) DAC	Behind galvanic I²C isolator since Apr 2026

Conversion functions¶

Conversion polynomials are defined in controlunit/devices/conversions.py with LaTeX in docstrings — physics inline with the code that uses it.

The polynomials come from external datasheets. The PKR251 datasheet, for example, lives in aklab-howto.

Dispatch is settings-driven: each channel in settings.yml carries a Conversion Function key that maps to a function in conversions.py via AdcChannelProps.set_conversion_function(). Adding a new instance of an existing sensor type means editing YAML, not code.

Settings versioning¶

The repo carries controlunit/settings.yml as canonical schema. The live rig runs ~/.controlunit/settings.yml with its own channel map. A Settings Version key prevents silent drift after a schema bump:

# controlunit/readsettings.py
if local_config["Settings Version"] == config["Settings Version"]:
    config = local_config