61 lines
2.4 KiB
Python
61 lines
2.4 KiB
Python
#!/usr/bin/env python
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######################################################################## # GrovePi Library for using the Grove - CO2 Sensor(http://www.seeedstudio.com/depot/Grove-CO2-Sensor-p-1863.html)
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#
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# The GrovePi connects the Raspberry Pi and Grove sensors. You can learn more about GrovePi here: http://www.dexterindustries.com/GrovePi
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#
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# Have a question about this library? Ask on the forums here: http://forum.dexterindustries.com/c/grovepi
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#
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#
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# NOTES:
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# * Calibration and read of the CO2 sensor MH-Z16 according to the datasheet : http://www.seeedstudio.com/wiki/images/c/ca/MH-Z16_CO2_datasheet_EN.pdf
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# * output value directly in ppm
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# * Library derived from the inital controbution by Doms Genoud (@domsgen) here: http://www.dexterindustries.com/topic/how-to-use-co2-grove-sensor-with-serial-grovepi/
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#
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# History
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# ------------------------------------------------
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# Author Date Comments
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# Doms Genoud 13 Apr 15 Initial Authoring
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# Karan 07 Jan 16 Code cleanup and added to main Github repo
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#
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# These files have been made available online through a Creative Commons Attribution-ShareAlike 3.0 license.
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# (http://creativecommons.org/licenses/by-sa/3.0/)
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#
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########################################################################
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import serial, time
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class CO2:
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#inspired from c code of http://www.seeedstudio.com/wiki/Grove_-_CO2_Sensor
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#Gas concentration= high level *256+low level
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inp = []
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cmd_zero_sensor = b'\xff\x87\x87\x00\x00\x00\x00\x00\xf2'
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cmd_span_sensor = b'\xff\x87\x87\x00\x00\x00\x00\x00\xf2'
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cmd_get_sensor = b'\xff\x01\x86\x00\x00\x00\x00\x00\x79'
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def __init__(self):
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#To open the raspberry serial port
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ser = serial.Serial('/dev/serial0', 9600, timeout = 1) #Open the serial port at 9600 baud
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#init serial
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ser.flush()
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def read(self):
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try:
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ser.write(self.cmd_get_sensor)
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self.inp = ser.read(9)
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high_level = self.inp[2]
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low_level = self.inp[3]
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temp_co2 = self.inp[4] - 40
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#output in ppm, temp
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conc = high_level*256+low_level
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return [conc,temp_co2]
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except IOError:
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return [-1,-1]
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if __name__ == "__main__":
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c = CO2()
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while True:
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print(c.read())
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time.sleep(1)
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