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ESP8266 (NodeMCU / Wemos D1)

Budget WiFi microcontroller

Released 2014

Wikimedia Commons · CC BY-SA 4.0

The classic for budget projects: for a couple of dollars your sensor gets online. WiFi only (no Bluetooth) and fewer pins than the ESP32, but it handles most simple monitors.

Chip Espressif ESP8266 (Tensilica L106, single-core)

Clock 80 MHz (up to 160 MHz)

Memory ~80 KB usable RAM · 4 MB flash (NodeMCU)

Connectivity WiFi 2.4 GHz (b/g/n) — no Bluetooth

GPIO ~11 usable · 1 ADC (A0)

Logic level 3.3 V

Programmed in Arduino IDE (C++) · MicroPython

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Good to know A few GPIOs are boot pins — avoid D3/D4/D8 for sensors.

Sensors that pair well

Air temperature Air humidity Soil moisture Light level Any on / off

⚡ Generate my code View pinout ↗

source: Random Nerd Tutorials · Espressif datasheet ↗