109 lines
2.6 KiB
Lua
109 lines
2.6 KiB
Lua
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-------------------------------------------------------
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-- This library was written for the Texas Instruments
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-- HDC1000 temperature and humidity sensor.
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-- It should work for the HDC1008 too.
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-- Written by Francesco Truzzi (francesco@truzzi.me)
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-- Released under GNU GPL v2.0 license.
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-------------------------------------------------------
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-------------- NON-DEFAULT CONFIG VALUES --------------
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------------- config() optional arguments -------------
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-- HDC1000_HEAT_OFF 0x00 (heater)
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-- HDC1000_TEMP_11BIT 0x40 (resolution)
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-- HDC1000_HUMI_11BIT 0x01 (resolution)
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-- HDC1000_HUMI_8BIT 0x20 (resolution)
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-------------------------------------------------------
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local modname = ...
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local M = {}
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_G[modname] = M
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local id = 0
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local i2c = i2c
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local delay = 20000
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local _drdyn_pin
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local HDC1000_ADDR = 0x40
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local HDC1000_TEMP = 0x00
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local HDC1000_HUMI = 0x01
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local HDC1000_CONFIG = 0x02
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local HDC1000_HEAT_ON = 0x20
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local HDC1000_TEMP_HUMI_14BIT = 0x00
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-- reads 16bits from the sensor
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local function read16()
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i2c.start(id)
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i2c.address(id, HDC1000_ADDR, i2c.RECEIVER)
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local data_temp = i2c.read(0, 2)
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i2c.stop(id)
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local data = bit.lshift(string.byte(data_temp, 1, 1), 8) + string.byte(data_temp, 2, 2)
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return data
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end
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-- sets the register to read next
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local function setReadRegister(register)
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i2c.start(id)
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i2c.address(id, HDC1000_ADDR, i2c.TRANSMITTER)
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i2c.write(id, register)
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i2c.stop(id)
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end
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-- writes the 2 configuration bytes
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local function writeConfig(config)
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i2c.start(id)
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i2c.address(id, HDC1000_ADDR, i2c.TRANSMITTER)
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i2c.write(id, HDC1000_CONFIG, config, 0x00)
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i2c.stop(id)
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end
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-- returns true if battery voltage is < 2.7V, false otherwise
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function M.batteryDead()
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setReadRegister(HDC1000_CONFIG)
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return(bit.isset(read16(), 11))
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end
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-- setup i2c
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function M.setup(drdyn_pin)
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_drdyn_pin = drdyn_pin
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end
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function M.config(addr, resolution, heater)
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-- default values are set if the function is called with no arguments
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HDC1000_ADDR = addr or HDC1000_ADDR
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resolution = resolution or HDC1000_TEMP_HUMI_14BIT
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heater = heater or HDC1000_HEAT_ON
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writeConfig(bit.bor(resolution, heater))
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end
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-- outputs temperature in Celsius degrees
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function M.getHumi()
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setReadRegister(HDC1000_HUMI)
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if(_drdyn_pin ~= false) then
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gpio.mode(_drdyn_pin, gpio.INPUT)
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while(gpio.read(_drdyn_pin)==1) do
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end
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else tmr.delay(delay) end
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return(read16()/65535.0*100)
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end
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-- outputs humidity in %RH
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function M.getTemp()
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setReadRegister(HDC1000_TEMP)
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if(_drdyn_pin ~= false) then
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gpio.mode(_drdyn_pin, gpio.INPUT)
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while(gpio.read(_drdyn_pin)==1) do
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end
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else tmr.delay(delay) end
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return(read16()/65535.0*165-40)
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end
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return M
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