Arduino Uno

What it is

A small open-source microcontroller board. Programs run bare-metal — no operating system, no scheduler, deterministic timing. You write a setup() and a loop() in C/C++ via the Arduino IDE; the loop runs forever at microcontroller speed.

Inputs / outputs

• Digital I/O: 14 pins, 5V logic, ~20 mA per pin sink/source (40 mA absolute max). 6 of those are PWM-capable (pins 3, 5, 6, 9, 10, 11).
• Analog input: 6 pins, 10-bit ADC, 0–5V range, ~10 kS/s.
• Serial: UART (pins 0/1, also USB), I²C (A4/A5), SPI (10–13).
• Power: 5V via USB or 7–12V via barrel jack with onboard regulator. Active draw ~50 mA; sleep mode ~10 µA.

Combines with

The full sensor-and-actuator pantry — see relations above. The Uno is the universal solvent of farm-electronics prototyping; nearly every commodity sensor has Arduino library support.

Solves / unlocks

• Threshold-driven irrigation (read soil moisture → open solenoid)
• Greenhouse environmental logging (temp, humidity, lux)
• Hydroponic nutrient dosing (pump pulse on EC reading)
• Coop / barn door automation (servo or [[stepper-motor|stepper]] on light-time)
• Standalone weather stations (offline data logging to SD)

Constraints

• No networking out of the box (add ethernet/WiFi shield, ESP module, or LoRa).
• No filesystem (add SD card module if logging is needed).
• 5V logic only — many newer sensors are 3.3V; needs level shifters.
• Single-threaded — the loop is sequential; complex multi-task work needs an RTOS or a more capable board.
• 2 KB SRAM — too small for image processing, ML, or large datasets.

Source

• Reference design: https://store.arduino.cc/products/arduino-uno-rev3 (open hardware)
• Schematic, PCB, BOM published under CC-BY-SA
• Software: https://www.arduino.cc/en/software (open-source IDE)
• Library registry: https://www.arduino.cc/reference/en/libraries/

See also

Auto-generated from this entry’s typed relations: frontmatter, grouped by relation type so the editorial signal isn’t flattened.

• Parallels: [[esp32]]
• Member of: [[ingredient]]
• Combines with: [[capacitive-soil-moisture-sensor]] · [[dht22-temperature-humidity]] · [[bme280-environmental-sensor]] · [[solenoid-valve]] · [[peristaltic-pump]] · [[servo-motor]] · [[lorawan]]