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Updates readme to reflect the library better

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Simon Albinsson
2018-04-22 19:38:53 +00:00
parent f21f54f7cd
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README.md
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@@ -2,13 +2,29 @@
Program to read eCO_2 and TVOC from the [SGP30 sensor](https://www.sensirion.com/fileadmin/user_upload/customers/sensirion/Dokumente/9_Gas_Sensors/Sensirion_Gas_Sensors_SGP30_Datasheet_EN.pdf). Based on the smbus2 i2c library for ease of use.
It currently lacks support for many features features and is more of a crude demo than a proper library.
Quick usage-example:
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())
## Features that are known to be missing (listing in rough order of importance):
* Proper structuring of the code
* CRC support
* The handing of baseline values are 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 took care of all chip identification, polling intervals store baseline and so on.
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](https://pinout.xyz/pinout/i2c). You should then be able to find the SGP30 an address 0x58 using `i2cdetect -y 1`. If you get an error message you probbably need to enable i2c in the kernel using [`raspi-config` and reboot](https://learn.sparkfun.com/tutorials/raspberry-pi-spi-and-i2c-tutorial)
After 12 hours of run time the base-line data is saved once every hour as per the "device driver integration guide". The data is saved as json to ~/sgp_config_data.txt