Pinout

MPU6050 accelerometer/gyro module (GY-521, I2C) pinout

Pins

Board supply	3.3–5 V (onboard 3.3 V regulator)
Chip supply	2.375–3.46 V
Interface	I2C, up to 400 kHz
I2C address	0x68 (0x69 with AD0 HIGH)
Accelerometer ranges	±2 / ±4 / ±8 / ±16 g
Gyroscope ranges	±250 / ±500 / ±1000 / ±2000 °/s
ADC resolution	16 bit per axis
Axes	6 (3 accel + 3 gyro) + on-chip temperature sensor
Supply current	3.9 mA (accel + gyro active)
Extras	Digital Motion Processor (DMP), 1024-byte FIFO

HC-SR04 ultrasonic distance sensor (4-pin)Supply voltage: 5 V DC; Working current: 15 mA; Logic level: 5 V (TRIG and ECHO)
DHT11 / DHT22 temperature & humidity sensor (4-pin)Supply voltage: DHT11: 3–5.5 V; DHT22: 3.3–6 V; Interface: Single-wire digital (proprietary, not 1-Wire); Pull-up on DATA: 4.7–10 kΩ to VCC
PIR motion sensor (HC-SR501, 3-pin)Supply voltage: 4.5–20 V DC (5 V typical, onboard 3.3 V regulator); Quiescent current: < 50 µA; Output level: 3.3 V HIGH / 0 V LOW
Hall effect sensor module (KY-003, A3144, 3-pin)Sensor IC: A3144 unipolar Hall-effect switch; Supply voltage: 4.5–24 V (A3144 rating; 5 V typical); Supply current: ≈4.4 mA typical (chip)
DS18B20 temperature sensor (1-Wire, TO-92)Supply voltage: 3.0–5.5 V (or parasite power from DQ); Interface: 1-Wire, unique 64-bit ROM code per sensor; Pull-up on DQ: 4.7 kΩ to VDD
Rotary encoder module (KY-040, 5-pin)Supply voltage: 3.3–5 V; Output: 2-channel quadrature (CLK, DT); Pull-ups: 10 kΩ on CLK and DT; none on SW
BMP280 / BME280 barometric module (GY-BMP280, I2C/SPI)Board supply: GY-BMP280-3.3: 3.3 V only; boards with LDO: 3.3–5 V; Chip supply: 1.71–3.6 V; Interface: I2C (up to 3.4 MHz) or SPI (up to 10 MHz)
MQ-2 gas sensor module (4-pin)Supply voltage: 5 V; Heater resistance: 33 Ω ±5 %; Heater current: ≈150 mA