rpi_sgp30's Introduction

RPI_SGP30

Library to read eCO₂ and TVOC from the SGP30 sensor. Based on the smbus2 i2c library for ease of use.

It should be compatible with both python 2 and 3 but is currently only tested under Python 2.7

Quick usage-example:

from smbus2 import SMBusWrapper
from sgp30 import Sgp30
import time
with SMBusWrapper(1) as bus:
    sgp=Sgp30(bus,baseline_filename="/tmp/mySGP30_baseline") #things thing with the baselinefile is dumb and will be changed in the future
    print("resetting all i2c devices")
    sgp.i2c_geral_call() #WARNING: Will reset any device on teh i2cbus that listens for general call
    print(sgp.read_features())
    print(sgp.read_serial())
    sgp.init_sgp()
    print(sgp.read_measurements())
    print("the SGP30 takes at least 15 seconds to warm up, 12 hours before the readigs become really stable"
      for i in range(20):
          time.sleep(1)
          print(".",end="")
      print()
       print(sgp.read_measurements())

Current design considerations:

The class strives to to be light-weight and portable. It is currently a bit to tightly bound to the smbus2 class. In most cases I try to ease of readability rather than purity or speed.

Features that are known to be missing (listing in rough order of importance):

The handing of baseline values is not that great, it should probably be up to the end user to save and restore them as needed.
Write doc-strings for all or at least most methods.
reading raw-values.
A more "driver like" class that takes care of all chip identification, polling at regular intervals, restoring baseline and so on.
Run real hardware tests under Python3

Hardware notices:

If you have the Adafruit board with built in level shifters and voltage regulator it is should work if you just plug in SDA to pin 3, SCL to pin 5, VCC to pin 17 and GND to pin 20. You should then be able to find the SGP30 an address 0x58 using i2cdetect -y 1. If you get an error message you probably need to enable i2c in the kernel using raspi-config and reboot

Feel free to contact me with bugs, questions or issues.

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