m_srv_dist.2.lua

hc_server_responce=("No command "..pl.." found\nOptions dist_[get]_[cont]_[stop]")	
if (pl=="dist_get") then --stop
 --measure()
hc_server_responce=("distance:"..distance);
elseif (pl=="dist_get_cont") then --stop
CONTINUOUS = true
measure()
m.dist_state="on"
hc_server_responce=("continuous enabled");
elseif (pl=="dist_get_cont_stop") then --stop
CONTINUOUS = false
m.dist_state="off"
hc_server_responce=("continuous disabled");
end


if m.dist=="enabled" then
	m.dist="started"
	READING_INTERVAL = math.ceil(((max_dist *2/ 340*1000) + TRIG_INTERVAL)*1.2)
-- initialize global variables
	time_start = 0
	time_stop = 0
	distance = 0
	readings = {}
-- start a measure cycle
	function measure()
		readings = {}
		tmr.start(0)
	end
-- called when measure is done
	function done_measuring()
--		print("Distance: "..string.format("%.3f", distance).." Readings: "..#readings)
		distance=distance*100
	--if distance_last and (distance >= distance_last+20 or distance <= distance_last-20) then 
	--	distance=distance_last 
	--else
	--	distance_last=distance 
	--end

--	print(distance)
	--if distance >100 then
	--remote_cmd("192.168.51.1","car_frwd")
	--remote_cmd("192.168.51.1","car_speed_99")
	--elseif distance <=55 then
	--remote_cmd("192.168.51.1","car_left")
	--elseif distance <=90 then
	--remote_cmd("192.168.51.1","car_speed_85")
	--end	
		if CONTINUOUS then
			node.task.post(measure)
		end
	end
-- distance calculation, called by the echo_callback function on falling edge.
	function calculate()
		-- echo time (or high level time) in seconds
		local echo_time = (time_stop - time_start) / 1000000
		-- got a valid reading
		if echo_time > 0 then
			-- distance = echo time (or high level time) in seconds* velocity of sound (340M/S) / 2
			distance = echo_time *340 / 2
			table.insert(readings, distance)
		end
		tmr.stop(0)
		node.task.post(done_measuring)
	end
-- echo callback function called on both rising and falling edges
	function echo_callback(level)
		if level == 1 then
			time_start = tmr.now()
		else
			time_stop = tmr.now()
			calculate()
		end
	end
-- send trigger signal
	function trigger()
		gpio.write(TRIG_PIN, gpio.HIGH)
		tmr.delay(TRIG_INTERVAL)
		gpio.write(TRIG_PIN, gpio.LOW)
	end
-- configure pins
	gpio.mode(TRIG_PIN, gpio.OUTPUT)
	gpio.mode(ECHO_PIN, gpio.INT)
-- trigger timer
	dist_tmr_trigger=tmr.create()
		tmr.register(dist_tmr_trigger, READING_INTERVAL,tmr.ALARM_AUTO, function() 	
        gpio.write(m.dist_trig_pin, gpio.HIGH)
		tmr.delay(m.dist_trig_interval)
		gpio.write(m.dist_trig_pin, gpio.LOW)
    end)
	tmr.register(0, READING_INTERVAL, tmr.ALARM_AUTO, trigger)
-- set callback function to be called both on rising and falling edges
	gpio.trig(ECHO_PIN, "both", echo_callback)
end