elixir-sensors / sgp40

Use Sensirion SGP40 air quality sensor in Elixir

SGP40

Use Sensirion SGP40 air quality sensor in Elixir.

The raw signal from the SGP40 sensor is processed using Sensirion's software algorithm to give the VOC Index that represents an air quality value on a scale from 0 to 500 where a lower value represents cleaner air.

Usage

iex> {:ok, sgp} = SGP40.start_link(bus_name: "i2c-1")
{:ok, #PID<0.1407.0>}

iex> SGP40.measure(sgp)
{:ok, %SGP40.Measurement{voc_index: 123, timestamp_ms: 885906}}

For better accuracy, you can provide the SGP40 sensor with relative ambient humidity and ambient temperature from an external humidity sensor periodically.

iex> SGP40.update_rht(sgp, humidity_rh, temperature_c)
:ok

Depending on your hardware configuration, you may need to modify the call to SGP40.start_link/1. See t:SGP40.options/0 for parameters.

sgp40's Issues

VOC index jump to 500

I'm wondering why this happened, I just read the value every 2 minutes.

Brief doc for get/set states

Back up state periodically if possible

That would be nice if we can load past state on start_link.

Embed Sensirion's original source as a git submodule if possible