A small debug logging setup I put together for WiFi microcontroller projects. When the device is wireless or across the room, log() sends the message over HTTP to a Node-RED hub — you can watch it live in the browser. Serial output is mirrored by default so the existing workflow stays intact. Libraries for Arduino (ESP8266/ESP32) and MicroPython (Pico W).
[Your Device] → HTTP POST plain text → [Node-RED Hub] → WebSocket → [Browser UI]
The library formats each message automatically before sending:
DEVICENAME: your message here
DEVICENAME(-2): something to warn about
The device name and log level are added by the library — you only pass the message string and an optional level integer to log().
| Level | Name | Color |
|---|---|---|
| 0 | (plain) | white |
| 1 | INFO | green |
| 2 | WARN | yellow |
| 3 | ERROR | red |
| 4 | CRITICAL | purple |
Node-RED receives it, parses the device name and level, timestamps it, and stores it in memory. Logs can be observed live at http://<node-red-host>:1880/logfire. Per-device logs are capped at 3 MB — oldest entries are evicted when the limit is reached. The browser UI shows a live tab per device with a filter dropdown.
For a step-by-step guide see HOWTO.md.
Run python nodered/build.py to embed the UI into the flow, then import nodered/flow.json into Node-RED. The flow serves the UI at GET /logfire.
Logs persist to /data/logfire_logs.json inside the Docker container and survive restarts.
Copy arduino/LogFire/ into your project's lib/ directory.
#include <LogFire.h>
LogFire.begin("MyDevice", "192.168.1.100", 1880);
LogFire.log("Device booted"); // level 0 (plain)
LogFire.log("Sensor timeout", 2); // level 2 (WARN)
// LogFire.mirrorSerial(false); // disable Serial echo (on by default)
// LogFire.localOnly(true); // Serial only, no networkSee arduino/LogFire/examples/ for full examples.
Copy micropython/logfire.py to your Pico W:
import logfire
logfire.init("MyPico", "192.168.1.100", 1880)
logfire.log("Device booted") # level 0 (plain)
logfire.log("Sensor timeout", 2) # level 2 (WARN)
# logfire.mirror_serial(False) # disable print echo (on by default)
# logfire.local_only(True) # Serial only, no networkSee micropython/example/main.py for a full example.
- Hub: Node-RED (any machine on your local network)
- Arduino: ESP8266 or ESP32 with WiFi connected
- MicroPython: Raspberry Pi Pico W or Pico W2
MIT