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+-- ***************************************************************************
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+-- BH1750 module for ESP8266 with nodeMCU
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+-- BH1750 compatible tested 2015-1-22
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+--
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+-- Written by xiaohu
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+--
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+-- MIT license, http://opensource.org/licenses/MIT
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+-- ***************************************************************************
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+local moduleName = ...
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+ local M = {}
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+ _G[moduleName] = M
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+ --I2C slave address of GY-30
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+ local GY_30_address = 0X23
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+ -- i2c interface ID
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+ local id = 0
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+ --LUX
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+ local l
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+ --CMD
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+ local CMD = 0x10
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+ local init = false
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+ function M.init(sda, scl)
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+ i2c.setup(id, sda, scl, i2c.SLOW)
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+ --print("i2c ok..")
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+ init = true
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+ end
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+ local function read_data(ADDR, commands, length)
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+ i2c.start(id)
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+ i2c.address(id, ADDR, i2c.TRANSMITTER)
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+ i2c.write(id, commands)
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+ i2c.stop(id)
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+ i2c.start(id)
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+ i2c.address(id, ADDR,i2c.RECEIVER)
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+ tmr.delay(200000)
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+ c = i2c.read(id, length)
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+ i2c.stop(id)
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+ return c
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+ end
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+ local function read_lux()
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+ dataT = read_data(GY_30_address, CMD, 2)
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+ UT = string.byte(dataT, 1) * 256 + string.byte(dataT, 2)
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+ l = (UT*1000/12)
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+ return(l)
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+ end
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+ function M.read()
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+ if (not init) then
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+ print("init() must be called before read.")
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+ else
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+ read_lux()
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+ end
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+ end
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+ function M.getlux()
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+ return l
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+ end
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+ return M
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