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70 lines
2.1 KiB
70 lines
2.1 KiB
#!/usr/bin/python
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#---------------------------------------------------------------------
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# ___ ___ _ ____
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# / _ \/ _ \(_) __/__ __ __
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# / , _/ ___/ /\ \/ _ \/ // /
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# /_/|_/_/ /_/___/ .__/\_, /
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# /_/ /___/
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#
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# bh1750.py
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# Read data from a BH1750 digital light sensor.
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#
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# Author : Matt Hawkins
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# Date : 26/06/2018
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#
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# For more information please visit :
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# https://www.raspberrypi-spy.co.uk/?s=bh1750
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#
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#---------------------------------------------------------------------
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import smbus
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import time
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# Define some constants from the datasheet
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DEVICE = 0x23 # Default device I2C address
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POWER_DOWN = 0x00 # No active state
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POWER_ON = 0x01 # Power on
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RESET = 0x07 # Reset data register value
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# Start measurement at 4lx resolution. Time typically 16ms.
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CONTINUOUS_LOW_RES_MODE = 0x13
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# Start measurement at 1lx resolution. Time typically 120ms
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CONTINUOUS_HIGH_RES_MODE_1 = 0x10
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# Start measurement at 0.5lx resolution. Time typically 120ms
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CONTINUOUS_HIGH_RES_MODE_2 = 0x11
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# Start measurement at 1lx resolution. Time typically 120ms
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# Device is automatically set to Power Down after measurement.
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ONE_TIME_HIGH_RES_MODE_1 = 0x20
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# Start measurement at 0.5lx resolution. Time typically 120ms
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# Device is automatically set to Power Down after measurement.
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ONE_TIME_HIGH_RES_MODE_2 = 0x21
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# Start measurement at 1lx resolution. Time typically 120ms
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# Device is automatically set to Power Down after measurement.
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ONE_TIME_LOW_RES_MODE = 0x23
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#bus = smbus.SMBus(0) # Rev 1 Pi uses 0
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bus = smbus.SMBus(1) # Rev 2 Pi uses 1
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def convertToNumber(data):
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# Simple function to convert 2 bytes of data
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# into a decimal number. Optional parameter 'decimals'
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# will round to specified number of decimal places.
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result=(data[1] + (256 * data[0])) / 1.2
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return (result)
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def readLight(addr=DEVICE):
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# Read data from I2C interface
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data = bus.read_i2c_block_data(addr,ONE_TIME_HIGH_RES_MODE_1)
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return convertToNumber(data)
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def main():
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while True:
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lightLevel=readLight()
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print("Light Level : " + format(lightLevel,'.2f') + " lx")
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time.sleep(0.5)
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if __name__=="__main__":
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main()
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