linker Kühlschrank, Temperatursensor

ds1621.lua

id  = 0                                             
sda = 7
scl = 6

m = mqtt.Client("kuehlschrank", 120, nil, nil)

i2c.setup(id, sda, scl, i2c.SLOW)

function mqtt_init()
	print("mqtt_init()")
	m:on("connect", function(client) print("subscribed") tmr.start(0) end )
	m:connect("172.22.26.64")
end

function wlan_init()
	print("wlan_init()")
	wifi.sta.eventMonReg(wifi.STA_GOTIP, function() mqtt_init() end)

	wifi.setmode(wifi.STATION)
	wifi.sta.config("chaosdorf-legacy", "7Aaagghnox")
	wifi.sta.eventMonStart()
	print(wifi.sta.getip())
end

function write_command(dev_addr, reg_addr)
	i2c.start(id)
	i2c.address(id, dev_addr, i2c.TRANSMITTER)
	i2c.write(id, reg_addr)
	i2c.stop(id)
end

function read_command(dev_addr, reg_addr)
	i2c.start(id)
	i2c.address(id, dev_addr, i2c.TRANSMITTER)
	i2c.write(id, reg_addr)
	i2c.stop(id)
	i2c.start(id)
	i2c.address(id, dev_addr, i2c.RECEIVER)
	local a = i2c.read(id, 1)
	i2c.stop(id)
	return a
end


local function twoCompl(value)
	local a = string.byte(value)
	if a > 127 then
		a = -(255 - a + 1)
	end
	return a
end

function gettemp()
	local temp = twoCompl(read_command(0x48, 0xAA)) * 10000
	local cperc = string.byte(read_command(0x48, 0xA9))
	local cremain = string.byte(read_command(0x48, 0xA8))
	local result = temp - 2500 + (cperc*10000 - cremain*10000)/cperc
	return string.format("%d.%04d", result/10000, result%10000)
end

function ds1621_senddata()
	m:publish("sensors/lfridge/temperature", gettemp(), 0, 0)
end

write_command(0x48, 0xEE)
wlan_init()

tmr.register(0, 1000, tmr.ALARM_AUTO, ds1621_senddata)