MicroPython SI7021 Library¶

`micropython_si7021`¶

MicroPython Driver for the SI7021 Temperature and Humidity sensor

Author(s): Jose D. Montoya

Implementation Notes¶

Software and Dependencies:

This library depends on Micropython

class micropython_si7021.si7021.RegisterStructRW(form: str, cmd_read: int = None, cmd_write: int = None)[source]¶: Register Struct

class micropython_si7021.si7021.SI7021(i2c, address=0x40)[source]¶

Main class for the Sensor

Parameters:¶

i2c : I2C¶: The I2C bus the SI7021 is connected to.
address : int¶: The I2C device address. Defaults to 0x40

Raises:¶

RuntimeError – if the sensor is not found

Quickstart: Importing and using the device

Here is an example of using the micropython_si7021.SI7021 class. First you will need to import the libraries to use the sensor

from machine import Pin, I2C
import micropython_si7021 as si7021

Once this is done you can define your machine.I2C object and define your sensor object

i2c = I2C(sda=Pin(8), scl=Pin(9))
si = si7021.SI7021(i2c)

Now you have access to the temperature and humidity attributes

temp = si.temperature
hum = si.humidity

property resolution¶

Meassurement resolution. The resolution of the measures. This will return the temperature and humidity resolution. These values are linked so change the resolution in temperature will affect humidity’s resolution

Value	RH	Temp
00	12 bit	14 bit
01	8 bit	12 bit
10	10 bit	13 bit
11	11 bit	11 bit

When selecting the values use the following variables:

Mode	Value
`si7021.TEMP_14_RH_12`	`0b00000000`
`si7021.TEMP_12_RH_8`	`0b00000001`
`si7021.TEMP_13_RH_10`	`0b10000000`
`si7021.TEMP_11_RH_11`	`0b10000001`

Example¶

from machine import Pin, I2C
import micropython_si7021 as si7021

i2c = I2C(sda=Pin(8), scl=Pin(9))  # Correct I2C pins for UM FeatherS2
si = si7021.SI7021(i2c)

si.resolution = si7021.TEMP_13_RH_10

property temperature¶

Returns the temperature in Celsius. Temperature resolution can be adjusted with the temperature attribute

Example¶

from machine import Pin, I2C
import micropython_si7021 as si7021

i2c = I2C(sda=Pin(8), scl=Pin(9))  # Correct I2C pins for UM FeatherS2
si = si7021.SI7021(i2c)

print("Temperature: ", si.temperature)

property humidity¶

Returns the humidity in %. Temperature resolution can be adjusted with the: humidity attribute

Example¶

from machine import Pin, I2C
import micropython_si7021 as si7021

i2c = I2C(sda=Pin(8), scl=Pin(9))  # Correct I2C pins for UM FeatherS2
si = si7021.SI7021(i2c)

print("Relative Humidity: ", si.humidity)

property heater¶

Sensor Heater Status.

False : Off
True : ON

Example¶

from machine import Pin, I2C
import micropython_si7021 as si7021

i2c = I2C(sda=Pin(8), scl=Pin(9))  # Correct I2C pins for UM FeatherS2
si = si7021.SI7021(i2c)

# Turning ON the Heater
print("Status of the Sensor Heater: ", si.heater)
si.heater = si7021.HEATER_ON
print("Status of the Sensor Heater: ", si.heater)

MicroPython SI7021 Library¶