Team11 temperature and humidity sensor

SENS BME680 Temperature, Humidity, Air Pressure & Gas Sensor

The SENS BME680 is a temperature, humidity, air pressure and gas (air quality) sensor. The breakout board is equipped with a 3.3V regulator and I2C as well as SPI digital interface. This lets you use it safely with any kind of microcontroller with 3.3V-5V power or logic.

• Temperature - operation range from -40 to 85°C with an accuracy of ±1°C (full accuracy from 0 to 65°C)
• Humidity - operation range from 0 to 100% with an accuracy of ±3%
• Air pressure - operation range from 300 to 1100 hPa with an accuracy of ±1 hPa
• Air quality - a MOX (Metal-oxide) sensor that detects VOCs (like ethanol and carbon monoxide) in the air

Technical Specifications

The SENS BME680 is an I2C and SPI sensor. That means it uses the two I2C/SPI data/clock wires available on most microcontrollers and can share those pins with other sensors as long as they don't have an address collision.

Pinout

• VCC – power pin which can take 3-5VDC and safely converts it down using the built-in voltage regulator
• GND
• SCL - SCL pin for I2C communication / SCK pin for SPI communication
• SDA - SDA pin for I2C communication / SDI (MOSI) pin for SPI communication
• SDO - SDO (MISO) pin for SPI communication
• CS - Chip select pin for SPI communication

Advantages and Disadvantages

Advantages

• Best alternative to the DHT22 sensor which is a popular standard. However, it would be too large/clunky as a smartwatch component
• I2C and SPI bus interface
• 4-in-1 digital sensor

Disadvantages

• Size 30 x 14 x 10mm
• Relatively heavy (10g) in comparison to similar sensors

How to get it to work

Wiring with an ESP8266

• Connect VCC to the power supply (3-5V is fine) - 3V
• Connect GND to common power/data ground - G
• Connect SCL to the I2C clock SCL pin on your microcontroller - GPIO5 (D1)
• Connect SDA to the I2C data SDA pin on your microcontroller - GPIO4 (D2)

See schematic wiring diagram

Required Library

• Download and save following code as bme680.py
• upload library to your microcontroller

Code Example

 1 # import modules
 2 from machine import Pin, I2C
 3 from time import sleep
 4 from bme680 import *
 5 
 6 # Create sensor object, communicating over the board's default I2C bus
 7 i2c = I2C(scl=Pin(5), sda=Pin(4))
 8 bme = BME680_I2C(i2c=i2c)
 9 
10 # Print out temperature, humidity, air pressure and air quality values
11 while True:
12     temp = str(round(bme.temperature, 2)) + ' °C'
13     hum = str(round(bme.humidity, 2)) + ' %'
14     pres = str(round(bme.pressure, 2)) + ' hPa'
15     gas = str(round(bme.gas/1000, 2)) + ' KOhms'
16 
17     print('Temperature:', temp)
18     print('Humidity:', hum)
19     print('Pressure:', pres)
20     print('Gas:', gas)
21     print('----------')
22 
23     sleep(5)