SHT31 Description:  Sensiron Temperature/Humidity sensors are some of the finest & highest-accuracy devices you can get. And, finally we have some that have a true I2C interface for easy reading. The SHT31-D sensor has an excellent ±2% relative humidity and ±0.3°C accuracy for most uses. Unlike earlier SHT sensors, this sensor has a true I2C interface, and (bonus ) even with two address options. It also is 3V or 5V compliant, so you can power and communicate with it using just about any microcontroller or microcomputer. Such a lovely chip - so we spun up a breakout board with the SHT31-D and some supporting circuitry such as pullup resistors and capacitors. Each order comes with one fully assembled and tested PCB breakout and a small piece of header. You'll need to solder the header onto the PCB but it's fairly easy and takes only a few minutes even for a beginner. Power Pins: Vin - this is the power pin. The chip can use 2.5-5VDC for power. To power the board, give it the same power as the logic level of your microcontroller - e.g. for a 5V micro like for Arduino, use 5V. For a 3.3V controller like a Raspbery Pi, connect to 3.3V GND - common ground for power and logic I2C Logic pins: SCL - I2C clock pin, connect to your microcontrollers I2C clock line. This pin has a 10K pullup resistor to Vin SDA - I2C data pin, connect to your microcontrollers I2C data line. This pin has a 10K pullup resistor to Vin Other Pins: ADR - This is the I2C address selection pin. This pin has a 10K pull down resistor to make the default I2C address 0x44. You can tie this pin to Vin to make the address 0x45 RST - Hardware reset pint. Has a 10K pullup on it to make the chip active by default. Connect to ground to do a hardware reset ALR - Alert/Interrupt output. You can set up the sensor to alert you when an event has occured. Check the datasheet for how you can set up the alerts