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README.md

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+# CO2Meter
+Python Module to use co2meters like the 'AirCO2ntrol Mini' from TFA Dostmann with USB ID 04d9:a052. There are also other modules using the same interface.
+
+This module supports Python 2.7 and 3.x.
+
+## Attribution
+Reverse Engineering of the protocol and initial code done by [Henryk Plötz](https://github.com/henryk). 
+
+Read all about it at [hackaday](https://hackaday.io/project/5301-reverse-engineering-a-low-cost-usb-co-monitor)
+
+Code derived from [this article](https://hackaday.io/project/5301-reverse-engineering-a-low-cost-usb-co-monitor/log/17909-all-your-base-are-belong-to-us)
+
+## Install
+
+With pip:
+```bash
+pip install git+https://github.com/heinemml/CO2Meter
+```
+
+Without pip:
+```bash
+python setup.py install
+```
+Remark: you don't need to install, you can also just copy the CO2Meter.py into your project.
+
+If you don't want to run your script as root make sure you have sufficient rights to access the device file.
+
+This udev rule can be used to set permissions.
+```
+ACTION=="remove", GOTO="co2mini_end"
+
+SUBSYSTEMS=="usb", KERNEL=="hidraw*", ATTRS{idVendor}=="04d9", ATTRS{idProduct}=="a052", GROUP="plugdev", MODE="0660", SYMLINK+="co2mini%n", GOTO="co2mini_end"
+
+LABEL="co2mini_end"
+```
+save it as `/etc/udev/rules.d/90-co2mini.rules` and add the script user to the group `plugdev`.
+
+This rules make the device also available as co2mini0 (increase trailing number for each additional device).
+
+## Usage
+```python
+from CO2Meter import *
+import time
+sensor = CO2Meter("/dev/hidraw0")
+while True:
+    time.sleep(2)
+    sensor.get_data()
+```
+
+The device writes out one value at a time. So we need to parse some data until we have co2 and temperature. Thus the get_data() method will initially return none or only one value (whichever comes first). 
+When you just need one measurement you should wait some seconds or iterate until you get a full reading. If you just need co2 a call to `get_co2` might speed things up.
+
+### Callback
+You can pass a callback to the constructor. It will be called when any of the values is updated. The parameters passed are `sensor` and `value`. `sensor` contains one of these constants:
+
+```python
+CO2METER_CO2 = 0x50
+CO2METER_TEMP = 0x42
+CO2METER_HUM = 0x41
+```
+
+
+### Error handling
+In Case the device can't be read anymore (e.g. it was unplugged) the worker thread will end in the background. Afterwards calls to any of the `get_*` functions will throw an `IOError`. You will need to handle any resetup, making sure that the device is there etc yourself.