esp32_alecto

ESP32 sketch that listens for an Alecto V1 wireless weather sensor on a GPIO line and forwards each new reading to an HTTP endpoint as a form POST.

What it does

The Alecto V1 sensor broadcasts on 433 MHz. With a cheap receiver wired into GPIO 5, the WeatherStationDataRx library decodes the packets. This sketch keeps the last forwarded reading in memory, de-duplicates incoming packets, and POSTs the new ones to a URL of your choice (id, ch, t, h, bat as form fields). A reference PHP receiver is included below.

It's a one-evening project — no OTA, no MQTT, no TLS. Use it on a trusted LAN.

Hardware

Part	Notes	Approx. cost
ESP32 dev board (any Arduino-core variant)	DevKitC, Wemos, NodeMCU-32	$5
Alecto V1 outdoor sensor	Temperature + humidity, 433 MHz	$15
433 MHz RX module (RXB6 or similar)	Superheterodyne preferred over regen	$3

Wiring:

Alecto V1 (433 MHz)  ))) ))) (((  RXB6 DATA ──► GPIO 5 (ESP32)
                                       VCC ──► 3.3 V
                                       GND ──► GND

Quickstart (PlatformIO)

git clone https://github.com/egerkuzma/esp32_alecto.git
cd esp32_alecto
cp include/secrets.h.example include/secrets.h
# edit include/secrets.h with your Wi-Fi + server URL
pio run -t upload
pio device monitor

Or in Arduino IDE: install the WeatherStationDataRx library via Library Manager, open src/main.cpp as a sketch (rename to .ino), and create a secrets.h next to it.

Configuration

Edit include/secrets.h (gitignored). Three values:

Define	Meaning
WIFI_SSID	Your network SSID
WIFI_PASS	Your network password
SERVER_URL	HTTP endpoint to POST readings to

How it works

1. WeatherStationDataRx::readData() returns a packet type ('T' = temp + humidity, others ignored here).
2. The sketch compares ID, temperature (±0.05 °C), humidity, and battery flag against the last forwarded reading.
3. If anything changed, it POSTs id=…&ch=0&t=…&h=…&bat=… to SERVER_URL.
4. Wi-Fi is checked before every POST and reconnected if dropped.

Example PHP receiver

<?php
// weather_log.php — minimal MySQL receiver.
$conn = new mysqli('localhost', getenv('DB_USER'), getenv('DB_PASS'), 'weather_db');
if ($conn->connect_error) { http_response_code(500); exit('DB down'); }

$fields = ['id','ch','t','h','bat'];
foreach ($fields as $f) if (!isset($_POST[$f])) { http_response_code(400); exit("missing $f"); }

$stmt = $conn->prepare(
  'INSERT INTO weather_log (sensor_id, channel, temperature, humidity, battery)
   VALUES (?, ?, ?, ?, ?)'
);
$stmt->bind_param('iidii',
  $_POST['id'], $_POST['ch'], $_POST['t'], $_POST['h'], $_POST['bat']
);
$stmt->execute();
echo 'OK';

Matching schema:

CREATE TABLE weather_log (
  id INT AUTO_INCREMENT PRIMARY KEY,
  sensor_id SMALLINT NOT NULL,
  channel TINYINT NOT NULL,
  temperature FLOAT NOT NULL,
  humidity TINYINT NOT NULL,
  battery TINYINT NOT NULL,
  ts TIMESTAMP DEFAULT CURRENT_TIMESTAMP
);

Limitations

• Plain HTTP only — anyone on the LAN can read your readings or fake them.
• No persistence: a reboot resets the de-dup state, so the first packet after boot is always forwarded.
• WeatherStationDataRx receiving is timing-sensitive; cheap regen RX modules sometimes drop packets.
• Only 'T' (temperature + humidity) packets are forwarded — wind/rain/button events are ignored.

Credits

• WeatherStationDataRx — Alecto V1 decoder
• arduino-esp32 — Arduino core for ESP32

License

MIT — see LICENSE.