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#!/usr/bin/python3
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# -*- coding: utf-8 -*-
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#
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# sensors/light.py
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#
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# Copyright 2020 Ron Wellsted <ron@wellsted.org.uk>
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#
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 2 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program; if not, write to the Free Software
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# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
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# MA 02110-1301, USA.
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#
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#
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from sensors import i2cbus, bh1750_address
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import smbus
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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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ONE_TIME_HIGH_RES_MODE = 0x20
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bus = smbus.SMBus(i2cbus) # 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
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return ((data[1] + (256 * data[0])) / 1.2)
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def read_light():
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data = bus.read_i2c_block_data(bh1750_address,ONE_TIME_HIGH_RES_MODE)
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return convertToNumber(data)
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