MQTT, topics and your token
| Setting | Value |
|---|---|
| Broker | chertiot.com |
| Port | 8883 (TLS). Plain 1883 is not exposed publicly |
| Username | your device's access token |
| Password | empty |
| Client id | anything unique; the starter code uses the device name |
| Telemetry topic | v1/devices/me/telemetry |
| Attributes topic | v1/devices/me/attributes (device metadata such as firmware version) |
Payload is JSON, either {"key": value, ...} (timestamped on arrival) or {"ts": 1700000000000, "values": {...}} to supply your own timestamp. Keys are free-form; numbers become charts, strings become labels.
Tokens are per device. A token can only write to its own device — it cannot read anything, and cannot reach another device or another student's data. Lost a token, or pasted it somewhere public? Open the device page and click Issue new token; the old one stops working immediately.
TLS: the certificate is a normal public one (Let's Encrypt). Most Arduino cores and MicroPython builds accept it by default; the ESP32 starter uses setInsecure() for simplicity — switch to setCACert() with the ISRG Root X1 certificate for anything beyond the lab.