Add support for lm92 temperature sensor

Added LUA module for the lm92 +-0.33C 12bit+sign temperature sensor.

lua_modules/lm92/README.md

@@ -0,0 +1,98 @@
+# LM92 module
+This module adds basic support for the LM92 +-0.33C 12bit+sign temperature sensor. More details in the [datasheet](http://www.ti.com/lit/ds/symlink/lm92.pdf).
+Works:
+- getting the temperature
+- entering the chip's to shutdown mode (350uA -> 5uA power consumption)
+- waking up the chip from shutdown
+
+##Require
+```lua
+LM92 = require("lm92")
+```
+## Release
+```lua
+LM92 = nil
+package.loaded["lm92"]=nil
+```
+
+##init()
+####Description
+Setting the i2c pins and address for lm92.
+
+####Syntax
+init(sda, scl, address)
+
+####Parameters
+sda: 1~12, IO index.<br />
+scl: 1~12, IO index.<br />
+address: 0x48~0x4b, i2c address (depends on tha A0~A1 pins)
+####Returns
+nil
+
+####Example
+```lua
+LM92 = require("lm92")
+gpio0 = 3
+gpio2 = 4
+sda = gpio0
+scl = gpio2
+addr = 0x48
+LM92.init(sda, scl,addr)
+```
+##getTemperature()
+####Description
+Returns the temperature register's content.
+
+####Syntax
+getTemperature()
+
+####Parameters
+-
+
+####Returns
+Temperature in degree Celsius.
+
+####Example
+```lua
+t = LM92.getTemperature()
+print("Got temperature: "..t.." C")
+```
+
+##wakeup()
+####Description
+Makes the chip exit the low power shutdown mode.
+
+####Syntax
+wakeup()
+
+####Parameters
+-
+
+####Returns
+-
+
+####Example
+```lua
+LM92.wakeup()
+tmr.delay( 1 * 1000 * 1000 )
+```
+
+##shutdown()
+####Description
+Makes the chip enter the low power shutdown mode.
+
+####Syntax
+shutdown()
+
+####Parameters
+-
+
+####Returns
+-
+
+####Example
+```lua
+LM92.shutdown()
+```
+#### TODO:
+- add full support of the features, including interrupt and critical alert support

lua_modules/lm92/lm92.lua

@@ -0,0 +1,94 @@
+-- ******************************************************
+-- LM92 module for ESP8266 with nodeMCU
+--
+-- Written by Levente Tamas <levente.tamas@navicron.com>
+--
+-- GNU LGPL, see https://www.gnu.org/copyleft/lesser.html
+-- ******************************************************
+
+-- Module Bits
+local moduleName = ...
+local M = {}
+_G[moduleName] = M
+
+-- Default ID
+local id = 0
+
+-- Local vars
+local address = 0
+
+-- read regs for len number of bytes
+-- return table with data
+local function read_reg(reg_addr, len)
+	local ret={}
+	local c
+	local x
+	i2c.start(id)
+	i2c.address(id, address ,i2c.TRANSMITTER)
+	i2c.write(id,reg_addr)
+	i2c.stop(id)
+	i2c.start(id)
+	i2c.address(id, address,i2c.RECEIVER)
+	c=i2c.read(id,len)
+	for x=1,len,1 do
+		tc=string.byte(c,x)
+		table.insert(ret,tc)
+	end
+	i2c.stop(id)
+	return ret
+end 
+
+--write reg with data table
+local function write_reg(reg_addr, data)
+	i2c.start(id)
+	i2c.address(id, address, i2c.TRANSMITTER)
+	i2c.write(id, reg_addr)
+	i2c.write(id, data)
+	i2c.stop(id)
+end 
+
+-- initialize i2c
+-- d: sda
+-- c: scl
+-- a: i2c addr 0x48|A1<<1|A0 (A0-A1: chip pins)
+function M.init(d,c,a)
+if (d ~= nil) and (c ~= nil) and (d >= 0) and (d <= 11) and (c >= 0) and ( c <= 11) and (d ~= l) and (a ~= nil) and (a >= 0x48) and (a <= 0x4b ) then
+		sda = d
+		scl = c 
+		address = a
+		i2c.start(id)
+		res = i2c.address(id, address, i2c.TRANSMITTER) --verify that the address is valid
+		i2c.stop(id)
+		if (res == false) then
+			print("device not found")
+			return nil
+		end
+		else 
+        print("i2c configuration failed") return nil
+      end
+	i2c.setup(id,sda,scl,i2c.SLOW)
+end
+
+-- Return the temperature data
+function M.getTemperature()
+	local temperature
+	local tmp=read_reg(0x00,2) --read 2 bytes from the temperature register
+	temperature=bit.rshift(tmp[1]*256+tmp[2],3) --lower 3 bits are status bits
+	if (temperature>=0x1000) then
+		temperature= temperature-0x2000 --convert the two's complement
+	end
+	return temperature * 0.0625
+end
+
+-- Put the LM92 into shutdown mode
+function M.shutdown()
+	write_reg(0x01,0x01)
+end
+
+-- Bring the LM92 out of shutdown mode
+function M.wakeup()
+	write_reg(0x01,0x00)
+end
+
+
+return M