# 3.28 Environment Monitoring

## 3.28.1 Overview

In this project, we use an OLED display to reveal the values of temperature, humidity, air pressure and altitude in the environment. It can be regarded as a mini environmental monitoring device. 

## 3.28.2 Test Code

**Code:**

In Files, open **3-28-environmentalMonitoring.py** and click ![](media/run.jpg).

```python
'''
 * Filename    : 3-28-environmentalMonitoring
 * Thonny      : Thonny 4.1.4
 * Author      : http://www.keyestudio.com
'''
import machine
#import I2C and Pin from machine module
from machine import I2C, Pin
#import AHT20 from aht20 library
from aht20 import AHT20
#import BMP388 from BMP388 library
from bmp388 import BMP388
from oled import OLED
import time

#create an I2C object and add SDA and SCL pins
i2c = I2C(scl=Pin(22), sda=Pin(21))
#create an AHT20 object and initialize I2C object to communicate with AHT20 sensor via I2C bus
sensor = AHT20(i2c)

# create a BMP388 object and set SDA and SCL pins, set IIC frequency to 100KHz
i2c = machine.SoftI2C(scl=machine.Pin(22), sda=machine.Pin(21), freq=100000)

# create a BMP388 object and send i2c object to it to communicate with the BMP388 sensor via the I2C bus, set the BMP388 IIC address to 0x76
bmp = BMP388(i2c, i2c_addr=0x76)

# create an OLED example
oled = OLED(i2c)
# clear oled
oled.clear()
'''
str() function converts a variable of type string from a variable of another type
int() function converts a variable of another type to a variable of type int. The reason for this conversion is that there is no data display after the decimal
pressure unit conversion：1 hPa = 1 × 100 Pa = 100 Pa

'''

while True:	
    try:
        #Store the values of temperature and humidity in the temperature and humidity variables
        temperature, humidity = sensor.read_temperature_humidity()
        # read the pressure
        pressure = bmp.read_pressure() // 100 #Convert Pa to hPa by dividing the pressure by 100        
        # clear display
        oled.clear()
        # show pressure
        oled.show_text("Pressure:", 0, 0)
        oled.show_text(str(int(pressure)), 70, 0)
        oled.show_text("hPa", 105, 0)
        # show temperature
        oled.show_text("Temperature:", 0, 15)
        oled.show_text(str(int(temperature)), 100, 15)
        oled.show_text("C", 120, 15)
        # show humidity
        oled.show_text("Humidity:", 0, 30)
        oled.show_text(str(int(humidity)), 75, 30)
        oled.show_text("%", 105, 30)

        # show oled
        oled.oled.show()
    # detect and read value, print “Failed to read from sensor:” if an error occurs
    except RuntimeError as e:
        print("Failed to read from sensor: ", e)
    time.sleep(1)	#delay 1S



```

**Result:**

After uploading code, you will see the values of temperature, humidity and air pressure on the OLED display.