Gaal Laszlo Website

Live readings

Container sensors

Level updated 18 Apr, 20:33 · temps updated 19 Apr, 00:48

OnlineLast seen just nowUptime 11h 32m

Schematic is illustrative — not to scale.

Inlet temp

9.9°C

Container temp

9.2°C

Air temp

10.0°C

Temperatures · last 24 hours

147 × 10-min averages

Level history

100 state changes

Source: Raspberry Pi Pico W → ThingSpeakTelegram alert fires if the pump fails to refill the container

Project

Water Level & Temperature Sensor

A MicroPython project built on the Raspberry Pi Pico W that monitors water-container level and three temperature sensors (air, inlet, water), shows live readings on a 128×64 OLED, and uploads data to ThingSpeak over WiFi. The pump itself runs on its own automatic controller — this is a safety net: a ThingSpeak action pings me on Telegram if the container stays empty, meaning something has gone wrong and the pump isn't recovering on its own. The temperatures are mostly for curiosity, and for deciding when to add heating to the container over winter. Configuration can be changed from any browser on the local network — no re-flashing required.

Pipeline

Pico W

MicroPython

ThingSpeak

HTTP · channels

This page

live dashboard

pump-failure alert

Hardware

Raspberry Pi Pico W — WiFi-enabled microcontroller
3 × DS18B20 on a shared OneWire bus (4.7 kΩ pull-up)
2 × contact water-level sensors — HIGH when water present
SSD1306 128×64 I²C OLED display
Momentary push-button to toggle the OLED on/off

Pin map

GPIO	Function	Direction
5	Water level sensor 1 (lower)	Input, pull-down
6	Water level sensor 2 (upper)	Input, pull-down
9	DS18B20 OneWire data	—
10	Mode pin 1	Output
11	Mode pin 2	Output
13	OLED toggle button	Input, pull-up
26	OLED SDA (I²C1)	—
27	OLED SCL (I²C1)	—

How it works

Main loop

Runs every 100 ms. Feeds a 15-second hardware watchdog, reads temperatures and water level on separate intervals, uploads to ThingSpeak, checks the OLED button, and handles web-config requests.

OLED display

SSD1306 over I²C. Updates are batched into a single flush to minimise bus traffic and keep the main loop responsive.

Web config

A non-blocking HTTP server on port 80 exposes a form for WiFi credentials, API keys, and intervals. Submissions are written to config.json and the device reboots.

ThingSpeak + Telegram

Temperature values upload every cycle; water-level uploads only fire on state change. The pump runs on its own automatic controller — a ThingSpeak action pings Telegram only as a safety net when the container stays empty, i.e. the pump failed to recover on its own.

Reliability features

Hardware watchdog (15 s)Auto-reboot if the main loop freezes.
WiFi connect timeoutGives up after ~10 s instead of hanging forever.
HTTP request timeout (10 s)Slow ThingSpeak never blocks the loop.
Automatic WiFi reconnectRecovers on its own when the router restarts.
Sensor presence checkMissing DS18B20 sensors raise a clear error.
Overflow-safe timingticks_diff() handles the 12-day ticks_ms() wrap.

File structure

.
├── main.py           # Entry point — main loop, watchdog, button, scheduling
├── config.py         # Defaults + config.json override loader
├── networking.py     # WiFi connect + ThingSpeak HTTP uploads
├── sensors.py        # DS18B20 temperature + water-level sensors
├── oled_display.py   # SSD1306 rendering helpers
├── web_config.py     # HTTP server for browser-based configuration
└── README.md