← WTTC: control the Thermo Top C from your phone

Install WTTC from the browser

No Arduino IDE and nothing to install: plug the board into your computer over USB, click Install and the browser flashes the latest WTTC version. WTTC needs an ESP32-S3; the fake Webasto (below) works on any ESP32.

🖥️ Serial console: see the log nothing to install; both boards at once, in colour, saved as .txt or .md

This browser cannot flash over USB. Open this page with Chrome, Edge or Opera on a computer.
The page must be opened over https (as here) to flash over USB.

Version to be installed: 0.3.18

What you need

Steps

  1. Plug the board into the computer and click Install WTTC. Choose its port in the browser window (usually called “CP2102”, “USB Single Serial”, “CH343” or similar).
  2. Click Install and wait a minute without unplugging it. If it hangs at “Connecting”, hold the board's BOOT button until it starts.
  3. When it finishes, click Logs & Console and then the board's RST button: you will see a summary with the version, the Bluetooth PIN, the board's Wi-Fi and its password, and the web user and password (write them down; info shows it again). You can type status right there for the first test with the Webasto.
  4. Pair the app with that PIN, or join its WTTC Wi-Fi: the first time it asks you to change the factory password.

Good to know

The fake Webasto: a second ESP32 acting as the heater

To test WTTC on the bench, without a van or diesel: another ESP32 (a classic one or an S3) pretends to be the Thermo Top C on the W-Bus. It starts, ignites, regulates, runs the after-run and reports faults; from its USB console (115200) you trigger failures and speed up time. It installs like WTTC, on the other board. How to wire it, in the drawing below; its commands, in its README. By default it listens on IO16, answers on IO17 and returns the echo (direct wiring); for wiring through the bus, type eco no in its console, and pines 16 17 to change the pins.

A) Direct, without transceivers (the easiest) First remove the TJA1020 board from WTTC (or disconnect its TX and RX) · echo on (default) Fake ESP32 (any: classic or S3) TX · IO17 RX · IO16 GND USB to the PC: console 115200 WTTC · ESP32-S3 without the TJA1020 board IO16 (listens) IO17 (sends) GND 1 2 3 ① what the fake Webasto answers · ② what WTTC sends · ③ common ground all at 3.3 V: nothing else is needed (the fake Webasto returns the bus echo) Power: each ESP32 from its own USB (computer or charger). Do not join their 5 V: the ground ③ is enough. B) Over the real bus, with a second TJA1020 Also tests the transceiver and the W-Bus wire · TX and RX as in WTTC (the module TX terminal goes to the ESP32 RX) · in its console: eco no Fake ESP32 IO16 (RX) IO17 (TX) 3V3 GND TJA1020 TX RX SLP GND LIN 12V GND WTTC TJA1020 LIN 12V GND WTTC as in the van W-Bus (LIN to LIN) 12 V supply(+ and −) Power: both ESP32 from their USB. The 12 V supply only feeds the TJA1020s (the bus). WTTC can also take 5 V from its LM2596 on that supply, as in the van (and then without its USB). In both cases: the fake Webasto is driven from its USB console (faults, battery, temperature, faster time)
This browser cannot flash over USB. Open this page with Chrome, Edge or Opera on a computer.
The page must be opened over https (as here) to flash over USB.

Version to be installed: 0.3.18 · ESP32 / ESP32-S3

Seeing the log over USB (serial console)

Easiest: this site’s serial console (Chrome or Edge on a computer): connects both boards at once, knows which is which, colours every line and saves it as .txt or .md. Nothing to install.

Both boards (WTTC and the fake Webasto) report everything they do over their USB. To see it on Windows, with PuTTY:

  1. Plug the board into the computer over USB (on the ESP32-S3, the USB port marked UART or COM).
  2. In Device Manager → Ports (COM & LPT) check its number (e.g. COM5; usually called CP210x, CH340/CH343 or “USB Serial”). If it is missing, install its driver (CP210x or CH343).
  3. In PuTTY, Session: Connection type Serial, Serial line COM5 (yours) and Speed 115200.
  4. Connection → Serial: Flow control None.
  5. Terminal: Local echo and Local line editing set to Force on (you see what you type and it is sent on Enter).
  6. To save it to a file (and send it if something fails): Session → Logging → “All session output” and pick the file.
  7. Back in Session, give it a name (“Fake Webasto”, “WTTC”) and click Save; then Open. Type ayuda (fake Webasto) or info (WTTC) and Enter.

Opening the port restarts the board: that is normal. Only one program can use the port at a time: close the Arduino Serial Monitor or the installer window first. With both boards on the same computer, each has its own COM: open two PuTTY windows. On Linux or Mac: screen /dev/ttyUSB0 115200 (quit: Ctrl+A, then K).