JonoThora: Phase F1: foundations (templates + theory stubs + HelmKit Architecture bus/power)

2026-05-12T03:04:06Z

Phase F1: foundations (templates + theory stubs + HelmKit Architecture bus/power)

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 * [[Near_Field_Electromagnetics]]
 * [[Caduceus_Coil]]
 * [[Bifilar_Coil]]
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 * ICNIRP (2020). "Guidelines for limiting exposure to electromagnetic fields (100 kHz to 300 GHz)." ''Health Physics'' 118: 483–524.
 * IEEE C95.1-2019 — IEEE Standard for Safety Levels.
 [[Category:Psionics]]
 [[Category:Hardware]]
 [[Category:Functional Safety]]

JonoThora: Psionics expansion (01a + 01b): content authored / LaTeX-restored per local submodule; lint-clean.

2026-05-11T20:49:39Z

Psionics expansion (01a + 01b): content authored / LaTeX-restored per local submodule; lint-clean.

New page

= HelmKit Architecture =

{{Audience_Sidebar
| difficulty = Intermediate
| reading_time = 8 minutes
| prerequisites = Basic embedded-systems knowledge; some RF design vocabulary; safety-critical-systems awareness helpful.
| if_too_advanced_see = [[HelmKit]]; [[Psionic_Device_Overview]]
| if_you_want_the_math_see = [[Near_Field_Electromagnetics]]; [[SAR_Calculation_for_Psionic_Devices]]
}}

'''HelmKit Architecture''' specifies the hardware and firmware design of the [[HelmKit]] — a head-worn near-field psionic device. The architecture is built around a '''dual-MCU checker-doer pattern''' inherited from aerospace and industrial functional-safety standards (DO-178C DAL-A, IEC 61508 SIL-3), adapted for a consumer-grade wearable.

The central design constraint: '''no single software fault may cause an overexposure event'''. This is achieved by hardware-enforced safety oversight running on an independent MCU.

== Block diagram ==

┌──────────────────────────────────────────────────┐
│ Battery + PMIC │
└──────────────────────────────────────────────────┘
│ │
▼ ▼
┌──────────────┐ ┌──────────────┐
│ MCU-A │ │ MCU-B │
│ ("doer") │ │ ("checker") │
│ │ │ │
│ RF gen │ │ Sensors │
│ Modulation │ │ Blacklist │
│ UI / BLE │ │ Auth/cutoff │
└──────────────┘ └──────────────┘
│ │
│ RF drive │ Opto-isolated relay (cuts RF)
▼ ▼
┌──────────────────────────────────────────────────┐
│ Power Amplifier │
└──────────────────────────────────────────────────┘
│
▼
┌──────────────────────────────────────────────────┐
│ Matching network + [[Caduceus_Coil]] / [[Bifilar_Coil]] │
└──────────────────────────────────────────────────┘

== MCU-A ("doer") ==

The doer MCU is responsible for primary device functionality:

* '''RF signal generation''' — synthesises the drive waveform (CW or modulated).
* '''Modulation control''' — frequency, amplitude, phase, pulse-shape.
* '''User interface''' — buttons, display, BLE / WiFi link for telemetry.
* '''Mode selection''' — selects between operating presets stored in firmware.
* '''Logging''' — records session parameters and sensor readings.

Hardware: typical mid-range ARM Cortex-M (M4 / M7) or ESP32-class part. Standard development environment, standard firmware update mechanism.

== MCU-B ("checker") ==

The checker MCU runs independent of MCU-A:

* '''Independent power supply''' (separate LDO from battery).
* '''Independent clock''' (separate crystal oscillator).
* '''Independent firmware''' (developed and audited separately).
* '''Read-only authority over RF cutoff''' (opto-isolated relay).

Responsibilities:

* '''RF power monitoring''' — calibrated directional coupler reads forward/reflected power.
* '''Coil temperature monitoring''' — thermistor or PT100 on coil former.
* '''Body-proximity sensing''' — capacitive sensor confirms device-on-head condition.
* '''Ambient field monitoring''' — independent E-probes verify the field amplitude vs. MCU-A's target.
* '''Blacklist enforcement''' — hardware-fuse-stored frequency/modulation prohibitions (see below).
* '''Watchdog''' — MCU-A must heartbeat MCU-B every N ms or RF is cut.

Hardware: a smaller, dedicated MCU (e.g. ARM Cortex-M0, MSP430). Simple deterministic firmware, formally audited (target: < 5 kLOC).

== Safety blacklist ==

MCU-B holds a '''hardware-fuse-stored blacklist''' of forbidden frequency/modulation combinations. If MCU-A requests a configuration that violates the blacklist, MCU-B refuses to enable the RF power stage. The blacklist is set at factory time and is not modifiable in the field.

See [[Psionic_Device_Safety]] for the full blacklist contents. Highlights:

* '''Cardiac stimulation risk''' — DC pulses with rise time < 1 ms applied near thorax; 10-100 Hz pulse trains > 1 mA into chest area.
* '''Brain stimulation / seizure risk''' — 3-8 Hz photic-frequency RF at > 100 V/m head-field; strong 1 Hz pulse trains; modulation envelopes matching cardiac or respiratory rates at > 5% depth.
* '''[[Microwave_Auditory_Effect|Frey effect]]''' — pulsed RF 200-3000 MHz with peak power density > 40 mW/cm<sup>2</sup> and pulse widths < 1 ms.
* '''ICNIRP violations''' — continuous-wave near-field > 50 V/m rms at the wearer's head; peak pulsed E-field > 300 V/m.

== Fail-safe state ==

On any MCU-B alert:

# RF power is '''cut immediately''' via the opto-isolated relay.
# The system enters a '''non-resetable lockout''' state.
# Lockout requires '''physical key release''' (a manual reset switch inside the device).
# The event is logged in tamper-evident memory.
# User notification via display and BLE.

This eliminates the possibility of a single-software-fault causing overexposure.

== RF chain ==

# '''Crystal oscillator''' — provides stable RF reference (e.g. 2.45 GHz).
# '''VCO + PLL''' (optional) — for tuneable operation.
# '''Modulator''' — applies AM / FM / pulse modulation as commanded by MCU-A.
# '''Power amplifier''' — Class-E for efficiency; output ≲ 1 W.
# '''Directional coupler''' — taps a small fraction for MCU-B monitoring.
# '''Matching network''' — impedance transform to the [[Caduceus_Coil]] / [[Bifilar_Coil]] / [[Double-Helix_Antenna]].
# '''Coil''' — the primary near-field emitter.

== Body-aware operation ==

Because tissue loading detunes the coil's impedance (5-20% downward), the matching network is dynamic:

* '''Body-proximity sensor''' detects device-on-head.
* '''Reflectometer''' (the same directional coupler used for safety) measures the antenna VSWR.
* '''Tuneable matching network''' adjusts capacitor/inductor values to restore match.
* '''MCU-A''' adapts the drive frequency or matching state to keep the operating point in the desired regime.

If the body is removed mid-session, the coil's impedance jumps and the matching is lost. MCU-A detects this via reflectometry; MCU-B independently confirms via the proximity sensor.

== Reference architectures ==

The dual-MCU pattern is inherited from:

* '''DO-178C''' — "Software Considerations in Airborne Systems and Equipment Certification" — Design Assurance Level A (DAL-A) requires independent verification of safety-critical functions.
* '''IEC 61508''' — "Functional Safety of Electrical/Electronic/Programmable Electronic Safety-related Systems" — Safety Integrity Level 3 (SIL-3) is the target for medical-device-grade safety.
* '''ISO 26262''' — automotive functional safety (ASIL-D) — similar dual-channel pattern.

HelmKit does not target medical-device certification (which would require clinical trials beyond the framework's current scope). But the architectural pattern is the same: '''safety is enforced by an independent channel''', not by trust in the primary firmware.

== Firmware development discipline ==

For MCU-B specifically:

* '''Formal verification''' of the safety logic (using e.g. Frama-C, SPARK, TLA+).
* '''Code review''' by an independent reviewer not on the MCU-A team.
* '''No dynamic memory allocation'''; static buffers only.
* '''No external code dependencies''' beyond the MCU vendor's HAL.
* '''Tamper-evident builds''' (signed firmware, hardware-fused public key).
* '''No remote update path''' — MCU-B firmware updates require physical access.

== See Also ==

* [[HelmKit]]
* [[Psionic_Device_Overview]]
* [[Psionic_Device_Safety]]
* [[SAR_Calculation_for_Psionic_Devices]]
* [[Microwave_Auditory_Effect]]
* [[Near_Field_Electromagnetics]]
* [[Caduceus_Coil]]
* [[Bifilar_Coil]]

== References ==

* RTCA DO-178C (2011). "Software Considerations in Airborne Systems and Equipment Certification."
* IEC 61508 (2010). "Functional Safety of Electrical/Electronic/Programmable Electronic Safety-related Systems."
* ICNIRP (2020). "Guidelines for limiting exposure to electromagnetic fields (100 kHz to 300 GHz)." ''Health Physics'' 118: 483–524.
* IEEE C95.1-2019 — IEEE Standard for Safety Levels.

[[Category:Psionics]]
[[Category:Hardware]]
[[Category:Functional Safety]]

HelmKit Architecture - Revision history

JonoThora: Phase F1: foundations (templates + theory stubs + HelmKit Architecture bus/power)

JonoThora: Psionics expansion (01a + 01b): content authored / LaTeX-restored per local submodule; lint-clean.