HTTP Server for LED/Servo

A simple yet robust HTTP server that can parse GET parameters and turn on/off a light or set the position of a servo.

lua_examples/http_server

@@ -0,0 +1,121 @@
+--
+-- Simple NodeMCU web server (done is a not so nodeie fashion :-)
+--
+-- Highly modified by Bruce Meacham, based on work by Scott Beasley 2015
+-- Open and free to change and use. Enjoy. [Beasley/Meacham 2015]
+--
+-- Meacham Update: I streamlined/improved the parsing to focus on simple HTTP GET request and their simple parameters
+--  Also added the code to drive a servo/light.  Comment out as you see fit.
+--
+-- Usage: 
+--  Change SSID and SSID_PASSPHRASE for your wifi network
+--  Download to NodeMCU
+--  node.compile("http_server.lua")
+--  dofile("http_server.lc")
+--  When the server is esablished it will output the IP address.
+--  	http://{ip address}/?s0=1200&light=1
+--  s0 is the servo position (actually the PWM hertz), 500 - 2000 are all good values
+--   light chanel high(1)/low(0), some evaluation boards have LEDs pre-wired in a "pulled high" confguration, so '0' ground the emitter and turns it on backwards.
+-- 
+--  Add to init.lua if you want it to autoboot.
+--
+
+-- Your Wifi connection data
+local SSID = "YOUR WIFI SSID"
+local SSID_PASSWORD = "YOUR SSID PASSPHRASE"
+
+-- General setup
+local pinLight = 2 -- this is GPIO4
+gpio.mode(pinLight,gpio.OUTPUT)
+gpio.write(pinLight,gpio.HIGH)
+
+servo = {}
+servo.pin = 4 --this is GPIO2
+servo.value = 1500
+servo.id = "servo"
+gpio.mode(servo.pin, gpio.OUTPUT)
+gpio.write(servo.pin, gpio.LOW)
+
+-- This alarm drives the servo
+tmr.alarm(0,10,1,function() -- 50Hz 
+    if servo.value then -- generate pulse
+        gpio.write(servo.pin, gpio.HIGH)
+        tmr.delay(servo.value)
+        gpio.write(servo.pin, gpio.LOW)
+    end
+end)
+
+local function connect (conn, data)
+   local query_data
+
+   conn:on ("receive",
+   	function (cn, req_data)
+	  params = get_http_req (req_data)
+         cn:send("HTTP/1.1 200/OK\r\nServer: NodeLuau\r\nContent-Type: text/html\r\n\r\n")
+	  cn:send ("<h1>ESP8266 Servo &amp; Light Server</h1>\r\n")
+	  if (params["light"] ~= nil) then
+	         if ("0" == params["light"]) then
+	         	gpio.write(pinLight, gpio.LOW)
+	         else
+			gpio.write(pinLight, gpio.HIGH)	         
+	         end
+         end
+         
+         if (params["s0"] ~= nil) then
+         	servo.value = tonumber(params["s0"]);
+         end
+
+	  -- Close the connection for the request
+         cn:close ( )
+      end)
+end
+
+-- Build and return a table of the http request data
+function get_http_req (instr)
+	local t = {}
+	local str = string.sub(instr, 0, 200)
+	local v = string.gsub(split(str, ' ')[2], '+', ' ')
+	parts = split(v, '?')
+	local params = {}
+	if (table.maxn(parts) > 1) then
+		for idx,part in ipairs(split(parts[2], '&'))  do
+			parmPart = split(part, '=')
+			params[parmPart[1]] = parmPart[2]
+		end
+	end
+	return params
+end
+
+-- Source: http://lua-users.org/wiki/MakingLuaLikePhp
+-- Credit: http://richard.warburton.it/
+function split(str, splitOn)
+    if (splitOn=='') then return false end
+    local pos,arr = 0,{}
+    for st,sp in function() return string.find(str,splitOn,pos,true) end do
+        table.insert(arr,string.sub(str,pos,st-1))
+        pos = sp + 1
+    end
+    table.insert(arr,string.sub(str,pos))
+    return arr
+end
+
+-- Configure the ESP as a station (client)
+wifi.setmode (wifi.STATION)
+wifi.sta.config (SSID, SSID_PASSWORD)
+wifi.sta.autoconnect (1)
+
+-- Hang out until we get a wifi connection before the httpd server is started.
+tmr.alarm (1, 800, 1, function ( )
+  if wifi.sta.getip ( ) == nil then
+     print ("Waiting for Wifi connection")
+  else
+     tmr.stop (1)
+     print ("Config done, IP is " .. wifi.sta.getip ( ))
+  end
+end)
+
+-- Create the httpd server
+svr = net.createServer (net.TCP, 30)
+
+-- Server listening on port 80, call connect function if a request is received
+svr:listen (80, connect)