Trace the proposed PID retrofit through the Casa IV’s original controls, heater safety chain and the exact ProS3 header pins. Select a mode or click any component for its role, terminals and verification gate.
Each phase ends with recorded evidence and a stop/go gate. Phases 0–3 are de-energised or SELV-only. The stock machine is not altered electrically until its sensor baseline and every low-voltage failure path have passed.
Digital multimeter: useful for unplugged continuity/resistance and live SELV measurements. It is not enough to prove boot-time glitches, appliance insulation or protective-earth integrity, and this plan does not ask you to probe inside an energised machine.
Current-limited 0–6 V bench supply, rated for at least 1 A; a known-good USB supply or power bank; insulated clip leads; a reference thermometer; and optionally precision PT100 substitution resistors. Set the ProS3 rail to 5.0 V and never above 5.2 V.
Two-channel oscilloscope for the heartbeat/SSR-input proof and a contact thermocouple logger for the heatsink. Use a normal grounded scope only on the SELV bench while it is physically disconnected from mains. The electrician supplies appliance-safety and mains test instruments.
phase2_logic_sim. It runs the real state machine, PID, 5 s slow PWM, settings validation, mode-specific limits and RGB annunciation with serial-controlled temperature/mode, fixed simulated settings, a monotonic clock and an in-memory demand sink. IO15 and IO16 remain locked low.phase3_driver_bench, then add the independent IO15 heartbeat permit, IO16 demand gate, BC337/4.7 kΩ driver and only the G3NB input terminals 3+/4−. G3NB output terminals 1/2 stay physically empty. The provisional IO14 pull-up treats an open lead as steam/inhibit but cannot diagnose it; the final isolated detector must distinguish brew, steam and invalid open/short bands.arm driver-bench before each bounded permit, pulse, static-low, static-high or demand-only command. Capture power-up, reset, flash, static/missing heartbeat, IO16 demand-only and steam-mode interruption. The G3NB input must remain below 1 V when off, exceed 4 V only with valid heartbeat plus demand, and lose drive within the measured hardware timeout.phase4_stock_logger, mechanically retain the PT100 and its independent strain relief, and use the Phase 3-accepted isolated IO14 mode signal. The firmware stores one-second CSV records in onboard LittleFS; IO15/IO16 stay low and networking is absent. Reassemble the stock machine and run the protected logger from a power bank with ordinary USB disconnected.flush/dump, save the CSV and inspect the cold probe for movement or lead damage.scripts/analyze_phase4.py as a review aid before proposing initial setpoint, no-rise and rate-of-rise envelopes.phase5_install_lockout while unplugged; it has only read-only commands, repeatedly drives IO15/IO16 LOW and latches a GPIO readback HIGH. The electrician installs the fused IRM-05 PCB, barriers, steam detector, heartbeat gate, SSR/heatsink, high-temperature wiring, enclosure and service provision while retaining protective earth and all OEM thermostats.status confirms only input health and LOW GPIO readback. Separately record visual/clearance review, protective-earth continuity, polarity, insulation resistance using a method safe for connected electronics, fuse coordination, strain relief and leakage/appliance tests. Powered checks are only under the electrician's controlled procedure.phase6_commission uses the real sensor, isolated mode input, PID/interlocks, heartbeat gate, checksummed NVS settings and a supervised IO13 deadman: 10 kΩ pull-up to always-on LDO1 3V3 plus a remote normally-open switch and 10 kΩ series resistor to GND. The repository evidence gates remain false, so the current binary reports authorization-blocked and cannot heat. Networking and serial heat/fault-clear commands are absent.phase7_release replaces the Phase 6 session with normal local regulation after one second of valid released IO13 input. It restores a checksummed NVS record or an accepted compiled fallback, uses the same heartbeat-gated output and retains local fault acknowledgement. Four checked-in release gates remain false, so the current binary reports authorization-blocked and cannot heat. Networking, OTA and commissioning/settings-write commands are absent.The labels and physical header order below are transcribed from Unexpected Maker’s ProS3 pinout card. Gold rows are assigned by this project; red-edged IO0 and IO3 are boot-strapping pins and deliberately unused.
Purpose-drawn vector illustrations preserve the important physical distinctions and terminal labels without pretending an AliExpress listing photo proves the delivered part’s identity. Click a card for its acceptance checks.
Component identity and physical positions come from locally held ECM Casa IV research copies, which are intentionally not republished here. The ProS3 header order and proposed project assignments are checked against Unexpected Maker’s official card; the mains topology remains survey-dependent.
ECM support · Official ProS3 pinout cards · UM 5 V limits · Omron G3NB specifications · Mean Well IRM-05 · PlatformIO ProS3 · Adafruit MAX31865 · SafeWork NSW electrical testing