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the bare PCB is available as a single unit at papymakers.com — €15.
🆕 New (July 2026) — The weekly scheduler is now documented. It is enabled by fitting a 24C32 EEPROM as a direct replacement for the 24C02. See Weekly scheduler.
Electric "fil pilote" heating controller for 2 zones, based on the ESP32-C6.
Controls radiators over the French fil pilote signalling wire (5 useful orders), reads the Linky smart meter, manages EDF Tempo tariffs, with an embedded Web interface and MQTT.
⚠️ This board connects to 230 V mains. Its installation and wiring are reserved for people with the skills required to work safely on mains electricity. Read the Electrical safety section before doing anything.
TM1637 display (4-digit 7-segment) — PCB in production.
A companion PCB kit (TM1637 display + status LED bargraph + switches, in a 6-module DIN enclosure) is available in theheating-2z-display-boardrepository.
A note on "fil pilote": this is the French standard for controlling electric heaters through a dedicated low-current signalling wire. The controller sends coded half-wave mains signals that tell each radiator which setpoint mode to apply (off, frost protection, eco, comfort…). It is specific to the French/EU market.
- 2-zone fil pilote control — 5 orders: STOP, Frost-protection, ECO, COMFORT, Comfort -2°C (CM2)
(the Comfort -1°C order of the 6-order standard is deliberately omitted: redundant with the setpoint adjustment of modern radiators, it provides no useful load-shedding step in practice) - Linky TIC frame reading (historical mode)
- EDF Tempo management — Blue/White/Red days, with season counters (red/white days) saved in EEPROM
- Automatic load shedding when subscribed power is exceeded
- Embedded responsive Web interface (HTTP polling refresh)
- Full MQTT communication (status, commands, log)
- Weekly scheduler configurable from the WebUI (requires a 24C32 EEPROM — see note below)
- State persistence in I2C EEPROM (24C02 by default, or 24C32 for the scheduler)
- Physical buttons with multi-click and long-press handling
- RGB status LED
This board is powered from 230 V mains and switches radiators on the mains. The protections below are not optional.
The 230 V supply to the controller must be protected by a dedicated 2 A double-pole circuit breaker (simultaneous line + neutral disconnection). The low rating is intentional: the board only draws a few watts (HLK-10M05 module, 10 W max), so a 2 A breaker provides close-in protection against an internal fault — far finer than the heating circuit's main breaker. Double-pole disconnection guarantees that no terminal on the board stays live during maintenance.
Each fil pilote output is protected by a resettable fuse (PPTC / polyswitch)
230 V – 100 mA in series (reference F1, part 0ZRE0100FF1A). The fil pilote wire only
carries a very low-current signal: 100 mA is ample for normal operation, while still
tripping in case of an accidental short between the pilot wire and a power conductor.
This protection is complementary to the upstream breaker, not a substitute.
| Protection | Ref | Role |
|---|---|---|
| 2 A double-pole breaker (external) | — | Close-in board supply protection + line/neutral disconnection |
| Resettable PPTC fuse 230 V/100 mA | F1 | Fil pilote output protection |
| Input fuse | F2 | Primary protection of the power module |
| 560 V varistor | RV1 | Mains surge clamping |
| 1 MΩ discharge resistor | R16 | Discharges the X2 capacitor (C5) when unplugged |
⚠️ The 2 A double-pole breaker is an external component to be installed in the panel or enclosure: it is not part of the board. Never power the board without this protection in place.
All wiring work is done with the power off. Never work on the panel or the board while live.
- Main disconnection: open the service breaker (main switch), or failing that the dedicated 2 A double-pole breaker for the board.
- Verify absence of voltage (VAT): check with a voltage tester (multimeter or dedicated tester) that there is no more 230 V on the terminals before touching anything. Never rely on simply having switched off the breaker.
- Lockout: if possible, lock the breaker in the open position and mark the intervention, to prevent it being switched back on while you work.
- Only restore power once wiring is complete, checked, and the board is properly secured in its enclosure.
- Observe polarity at the input terminal block. The line (phase) from the breaker connects to the terminal marked Ph (fuse input F2); the neutral to terminal N.
- 230 V conductor cross-section: 1.5 mm² solid (H07V-U) for the supply.
- Tighten the terminals firmly and check that no strand protrudes.
- Each pilot wire (zone 1, zone 2) connects to its dedicated terminal block.
- Cross-section 1.5 mm² maximum, solid conductor. The fil pilote only carries a very low-current signal: a larger cross-section is unnecessary and makes terminal connection awkward.
- Each radiator's pilot wire (usually the black or marked conductor) goes to the corresponding zone output.
- Reminder: each output is protected by the PPTC 230 V/100 mA (F1).
- The link between the I1 / I2 terminals of the Linky meter and the board's TIC input uses a solid 0.5 mm², single-pair cable.
- Wiring direction is irrelevant on the Linky side: the two I1 and I2 terminals of the tele-information output are not polarised, so the two wires can be swapped without consequence.
- This is a low-level signal: keep this pair away from the 230 V power conductors as much as possible, to limit disturbance on the TIC frame.
| Component | Reference | Role |
|---|---|---|
| Microcontroller | ESP32-C6-DevKitC-1-N8 | CPU WiFi/MQTT/Web |
| Display | TM1637 4-digit | Zone/mode display |
| EEPROM | 24C02 (I2C, 0x50) — or 24C32 for the scheduler | State persistence |
| Optocouplers | 2× MOC3041 per zone | 230 V fil pilote drive |
| Mains detection | LTV-814S + C5 (470 nF X2) | Mains presence / sync |
| Power supply | HLK-10M05 (230 VAC → 5 V, 10 W) | Board supply |
| Output protection | PPTC 230 V / 100 mA (F1) | Fil pilote |
| C5 discharge | 1 MΩ (R16, bottom side) | Safety when unplugged |
The complete bill of materials is available: detailed BOM · importable version BOM.csv.
| Function | GPIO |
|---|---|
| Zone 1 — MOC positive | GPIO 3 |
| Zone 1 — MOC negative | GPIO 2 |
| Zone 2 — MOC positive | GPIO 11 |
| Zone 2 — MOC negative | GPIO 10 |
| Zone-select switch | GPIO 7 |
| Mode-change switch | GPIO 6 |
| Linky RX (TIC) | GPIO 4 |
| TM1637 CLK | GPIO 23 |
| TM1637 DIO | GPIO 22 |
| I2C SDA (EEPROM) | GPIO 18 |
| I2C SCL (EEPROM) | GPIO 19 |
| RGB LED | GPIO 8 |
| BOOT button | GPIO 9 |
| Order | MOC+ | MOC− |
|---|---|---|
| STOP | LOW | HIGH |
| Frost-protection | HIGH | LOW |
| ECO | LOW | LOW |
| COMFORT | HIGH | HIGH |
| CM2 | 7s/293s cycle | — |
Main board schematic:
Assembled main board:
- PlatformIO (VS Code or CLI)
- ESP32-C6-DevKitC-1 with 8 MB Flash
Copy and adapt include/config.h:
// WiFi network
inline constexpr char WIFI_SSID[] = "YOUR_SSID";
inline constexpr char WIFI_PASSWORD[] = "YOUR_PASSWORD";
// Static IP (adapt to your network)
inline const IPAddress LOCAL_IP (192, 168, 1, 50);
inline const IPAddress GATEWAY (192, 168, 1, 1);
// MQTT broker
inline constexpr char MQTT_BROKER[] = "192.168.1.x";Choose the EEPROM type in config.h:
#define EEPROM_TYPE_24C02 // 256 bytes (default) — no scheduler
// #define EEPROM_TYPE_24C32 // 4KB — enables the weekly scheduler24C02 (256 bytes) — sufficient for persisting zone states, Tempo settings and load-shedding. The weekly scheduler is disabled (not enough memory to store the hourly profiles).
24C32 (4 KB) — enables the weekly scheduler. Direct pin-to-pin replacement of the 24C02 (same 8-pin package, same I2C address 0x50, A0/A1/A2 to GND). Tested part: Microchip AT24C32E (PDIP-8 package:
AT24C32E-PUM). After swapping the chip and toggling the#define, erase the EEPROM on first boot (BOOT button held, or from the web page) to initialise the new memory layout.
pio run --target upload
pio device monitorAccess via http://<LOCAL_IP> from the local network.
- Manual control of each zone
- Real-time instantaneous power display
- Today's Tempo period (Blue/White/Red)
- Counters of Tempo days used this season (red/white)
- Automatic load-shedding settings
- Weekly scheduler (visible only with a 24C32 EEPROM)
The Heating calendar section of the web page only appears if the firmware detects a 24C32 EEPROM. With a 24C02, this section is automatically hidden.
The scheduler is based on reusable profiles: each profile defines a full day in 30-minute slots (48 slots), each assigned an order (STOP / FP / ECO / COMFORT / CM2). A profile is then assigned to each zone. The web editor lets you paint slots with the mouse (click = cycle order, drag = fill) and save profiles and their assignments.
The scheduler remains non-priority: a manual command (button, web or MQTT), a load-shed event or a Tempo rule takes precedence over the programmed order.
| Topic | Content |
|---|---|
heatingCtrl_v4/status |
JSON of the full system state |
heatingCtrl_v4/zone/N/mode |
Current mode of zone N |
heatingCtrl_v4/tempo |
Current Tempo period |
heatingCtrl_v4/linky |
Linky data (PAPP, PTEC…) |
heatingCtrl_v4/log |
Log messages |
| Topic | Payload | Action |
|---|---|---|
heatingCtrl_v4/zone/N/cmd |
STOP HG ECO CONF CM2 |
Command zone N |
esp32-heating-2z/
├── include/
│ ├── config.h # Configuration (pins, network, timings)
│ └── types.h # Shared types and structures
├── src/
│ └── main.cpp # Main orchestrator + system FSM
├── lib/
│ ├── ZoneManager/ # Heating zone management
│ ├── CommandHandler/ # MQTT/Web command handling
│ ├── LinkyReader/ # Linky TIC frame decoding
│ ├── TempoManager/ # EDF Tempo period management
│ ├── OverloadManager/ # Automatic load shedding
│ ├── ScheduleManager/ # Weekly scheduler
│ ├── DisplayManager/ # TM1637 display
│ ├── StorageManager/ # I2C EEPROM (24C02/24C32)
│ ├── Publisher/ # MQTT publication
│ ├── WebUI/ # Web interface + HTTP server
│ └── ErriezTM1637/ # TM1637 display driver (local copy, MIT)
├── index.html # WebUI (embedded in the firmware)
├── partitions.csv # 8MB Flash partition table
├── platformio.ini # PlatformIO configuration
├── CHANGELOG.md
└── LICENSE
lib_deps =
knolleary/PubSubClient @ ^2.8
bblanchon/ArduinoJson @ ^7.0.0The ErriezTM1637 library (display driver) is not declared in lib_deps: it is
provided as a local copy in the lib/ErriezTM1637/ folder (MIT license, source:
https://github.com/Erriez/ErriezTM1637). PlatformIO compiles it directly, with no
download.
⚠️ Possible loading issue with VS Code / PlatformIODepending on versions, PlatformIO may no longer resolve the library from the registry under the identifier
erriez/ErriezTM1637: dependency loading fails, or anotherTM1637library conflicts (compilation errors inDisplayManager: constructor,begin(),writeData).Fix: the library is already embedded in
lib/ErriezTM1637/— so there is nothing to install. If you had tried adding another TM1637 library during your tests, purge the dependency cache and recompile:rm -rf .pio/libdeps # Windows: rmdir /s /q .pio\libdeps pio runPlatformIO then only re-resolves
PubSubClientandArduinoJson, plus the local copy of ErriezTM1637 — with no conflict.
MIT — see LICENSE
Denis Mattera — 2025
The schematic, bill of materials (BOM) and a photo of the main board are provided in the
hardware/ folder. The Gerber fabrication files are not published in this repository;
the bare PCB is offered for order (see Ordering boards).
hardware/
├── hardware_README.md # Fabrication notes
├── BOM.md # Bill of materials (Mouser links)
├── BOM.csv # Bill of materials (importable)
└── main-board/
├── schematic_main_board.png # Schematic
└── Heating-Control_main-board.jpeg # Board photo
The schematic and BOM allow reproducing or adapting the board. To obtain a ready-to-use PCB, see the Ordering boards section.
This project represents 4 years of development, prototyping and real-world testing. The firmware is open source — if you would like to support the project or save time, boards are available to order.
| Option | Contents | Indicative price |
|---|---|---|
| Bare PCB | Main board | €15 |
| Display kit | 3 PCBs (front panel + TM1637/bargraph + link/switches), 6-module DIN enclosure — see heating-2z-display-board |
€15 |
Shipping included. Shipped from France.
⚠️ Reminder: the PCB is sold bare, without components. Its installation requires a 2 A double-pole circuit breaker upstream (not supplied) and compliance with the electrical safety rules. Sold as-is, for integration by a competent person.
📧 Orders and questions: support@papymakers.com - https://papymakers.com/
- Bug / technical question → open an Issue
- Orders → support@papymakers.com
- General discussion → Discussions tab