Tuesday, March 3, 2015

ESP8266 - PIR Motion sensor detection

  First, The Question: What is a PIR sensor?

PIR Sensor with mounted Fresnel Lens

    A PIR module is basically made of a pyroelectric sensor (see it below as the round metal can with a rectangular crystal in the center), which can detect levels of infrared radiation. Everything emits some low level radiation, and the hotter something is, the more radiation is emitted. The sensor in a motion detector is actually split in two halves. The reason for that is that we are looking to detect motion (change) not average IR levels. The two halves are wired up so that they cancel each other out. If one half sees more or less IR radiation than the other, the output will swing high or low. 

PIR Sensor uncovered
    Along with the pyroelectic sensor is a bunch of supporting circuitry, resistors and capacitors. It seems that most small hobbyist sensors use the Micro Power PIR Motion Detector IC BISS0001 . This chip takes the output of the sensor and does some minor processing on it to emit a digital output pulse from the analog sensor.

Bottom Side
Micro Power PIR Motion Detector IC
    In PIR module description you can find that it's powered at 5V!  And as you know already ESP8266 it's a 3V only chip. This thing can be a joy-breaker.  

    The good thing is that if you look in the BISS0001 datasheet you will see that it's working ok also at 3V level. So maybe we are lucky today.

   Looking deeper on the PIR Module board we can find even better news: The board it's actually already a 3V one! The 5V voltage from the power pin is going only to the onboard power regulator! Output is at 3V logic levels. No level shifting or anything else needed ! Neat!

Holtek 3.3V LDO power regulator
     This give us 2 options for powering it up: using the existing 5V pin or if you want to use it in a 3V only setup, just bypass or remove the regulator and that's it.

     Connecting the PIR sensor module is pretty trivial, as it has only 3 PIN: GND, DOUT and VCC. The PIR acts as a digital output so all you need to do is listen for the pin status change to HIGH (motion detected) or LOW (no motion detected).

What we will need:


PIR Motion Detection Software

For programming CBDB Board and uploading the driver and the software we will continue to use the LuaUploader as before.


First test program: Blink a LED when movement detected

PIR "Blinky" running
1. Initialise used PINs:
 
       outpin=3                       -- Select output pin - GPIO0
       gpio.mode(outpin,gpio.OUTPUT)

       inpin=6                        -- Select input pin - GPIO12 
       gpio.mode(inpin,gpio.INT,gpio.PULLUP)  -- attach interrupt to inpin

2. Motion Detection function - called by the trigger on rising edge
      
      function motion()
           print("Motion Detected!")
          gpio.write(outpin,gpio.HIGH)  -- Led ON - Motion detected
          tmr.delay(5000000)           -- delay time for marking the movement
         gpio.write(outpin,gpio.LOW)   -- Led OFF
      end

3. Trigger INPIN on rising edge - based on internal interrupt mechanism 

       gpio.trig(6,"up",motion)


Save the code on ESP as 'pir.lua', restart ESP and run:      
        dofile(pir.lua")  -- Start PIR Program


First Test video: 



If everything looks great we can move to the next part

Example 2: Web enabled PIR Motion detection

  To be able to see online the PIR sensor status we will add a Web Server component to our program

2.1. Web Server 

srv=net.createServer(net.TCP)
  srv:listen(80,
     function(conn)
        conn:on("receive",function(conn,payload) print(payload)
        conn:send("HTTP/1.1 200 OK\n\n")
        conn:send("<META HTTP-EQUIV=\"REFRESH\" CONTENT=\"2\">")
        conn:send("<html><title>PIR Motion Detector Server - ESP8266</title><body>")
        conn:send("<h1>PIR Motion Detector Server - ESP8266</h1><BR>")
        conn:send('Status: ')
            if (stat == "ON") then conn:send('<B><font color=red>Movement Detected!</font></B>')
            elseif (stat == "OFF") then conn:send('<B><font color=green>No Movement</font></B>')
              else                     
                conn:send(stat)
                conn:send('%')
            end
           conn:send("<BR><BR><br>Node.HEAP : <b>" .. node.heap() .. "</b><BR><BR>")
           conn:send("IP ADDR    : <b>".. wifi.sta.getip() .. "</b><BR>")
           conn:send("TMR.NOW    : <b>" .. tmr.now() .. "</b><BR<BR><BR>")
           conn:send("</html></body>")
           conn:on("sent",function(conn) conn:close() end)
      end)
end)

2.2 Motion Detection function.

Splitted in 2 separate functions, to easier understand the mechanism behind:

2.2.1  Trigger on rising edge
  
        function motion()
           print("Motion Detection : ON!")
          stat = "ON"
          gpio.write(outpin,gpio.HIGH)  -- Led ON - Motion detected
         gpio.trig(6,"down",nomotion)  -- trigger on falling edge
        return stat
     end



2.2.2  Trigger on falling edge

     function nomotion()
         print("Motion Detection : OFF!")
         stat = "OFF"
        gpio.write(outpin,gpio.LOW)   -- Led OFF
        gpio.trig(6,"up",motion)  -- trigger on rising edge
       return stat
   end

 Save the code on ESP as 'pir.lua', restart ESP and run:      
        dofile(pir.lua")  -- Start PIR Program


Example 2 Video:



Now, if all OK, you can replace the output LED with the Main power switch module.
Take a look on the previous project for connections. After properly connecting it, rerun Example 2. 
You have a fully functional MAINS power switch with motion detection: 




That's all for today, thank you for your great feedback and looking forward for your suggestions!
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Monday, March 2, 2015

WIFI Web Power Switch for MAINS - ESP8266 - CBDB Board

 

WARNING!! You will play with LIVE MAINS!! Deadly zone!! 


 If you don't have any experience and are not qualified for working with MAINS power I will not ecourage you to play arround!

 The story behind:

  Somebody was asking few days ago on ESP8266.com forum for the easiest way to turn OFF his tube amplifier remotely. A W2MPS (Wifi Web Mains Power Switch) sounds great for this job?

The Question: How? 

   Because of the extensive work done before with such modules, the easiest way that I can see it to be done is a classical setup: Zero voltage crossing bilateral Triac driver + Triac combination, as a added module to our CBDB Board.

 What we will need:
  • USB adapter (take a look on Part 1 for details how to connect them together)
  • Main Power Switch module (details below) 

Main Power Switch Module (MPSM)

   General considerations:   For resistive loads ON-OFF only jobs (no dimming required) a winning combination is between  MOC304X for  Triac driver (Zero voltage crossing one) and a good quality Triac, decently sized by the power needs.  A 25A one usually fits mostly of the needs in a domestic project, with proper heatsink for power disipation. For standard home lighting, 8A is 99% of the times more than enough for one channel. If your house is a Castle with huge chandeliers, probably not :). 

     Triacs are the most common used semiconductor devices for power control and switching applications. Such power control circuits can be used to remotelly switch power to electrical devices or to switch power automatically when parameters such as temperature or light intensities go beyond preset level.

  BT1XX class from NXP never dissapointed. Be sure they are genuine, from a trustable source. I know, shit happens in the supply chains even to big houses from time to time but, as a good practice, a good traceability for the parts you are using is desirable.
And don't forget :LIVE MAINS Switching!!




Available models that also can be used:
   BT 136 600V – 4A 
   BT 138 600V – 12A
   BT 139 600V – 16A
   BTA 23 800V – 12A
   BTA 22 800V – 10A
   BTA 40 800V – 40A
   BTA 41 800V – 40A 
A typical circuit for use when hot line switching is required:
MPSM schematic - 1
    In this circuit the “hot” side of the line is switched and the load connected to the cold or neutral side. The load may be connected to either the neutral or hot line.
    This type of circuit from above is good enough for resitive loads only. When a TRIAC controls inductive loads, the mains voltage and the load current are not in phase. To limit the slope of the reapplied voltage and ensure right TRIAC turn-off, usually is used a "snubber circuit" connected in parallel with the TRIAC. This circuit can also be used to improve TRIAC immunity to fast transient voltages.
MPSM Schematic - 2
 The 100Ω resistor and 0.01μF capacitor are for snubbing of the triac and is often, but not always,
necessary depending upon the particular triac and load used, generally for inductive ones.

Connection of the CBDB Board with W2MPS Module


W2MPS Software

For programming CBDB Board and uploading the driver and the software we will continue to use the LuaUploader as before. 

1. Define used GPIO pin:

       outpin=3       -- Select IO - GPIO0 
       gpio.mode(outpin,gpio.OUTPUT)
       gpio.write(outpin,gpio.LOW)

 2. Power Switch function, acting based on received command:

      function PwrSW(swstat,payload)
         gpio.mode(outpin,gpio.OUTPUT)
         newstat=string.sub(payload,swstat[2]+1,#payload)
         status = newstat
         if newstat=="ON"  then gpio.write(outpin,gpio.HIGH) return end
         if newstat=="OFF" then gpio.write(outpin,gpio.LOW) return end
      end 

3. Send Page function based on request:

function sendPage(conn)
   conn:send('HTTP/1.1 200 OK\n\n')
   conn:send("<META HTTP-EQUIV=\"REFRESH\" CONTENT=\"5\">")
   conn:send('<!DOCTYPE HTML>')
   conn:send('<html>')
   conn:send('<head><meta content="text/html; charset=utf-8"><style>input{width: 100px; height: 100px;}</style>')
   conn:send('<title>ESP8266 - Power Switch Controller</title></head>')
   conn:send('<body><h1>Power Switch Controller</h1>')
   conn:send('Status: <b>')
   if (status == "ON") then      conn:send('<B><font color=red>ON</font></B>')
   elseif (status == "OFF") then    conn:send('<B><font color=green>OFF</font></B>')
   else                     
      conn:send(status)
      conn:send('%')
   end
   conn:send('</b><br /><br />')
   conn:send('<form action="/" method="POST">')
   conn:send('<input type="submit" name="cmd1" value="OFF"/>')
   conn:send('<input type="submit" name="cmd1" value="ON"/><br /><br /></form>')
   conn:send('</body></html>')
end

4. Web Server:

srv=net.createServer(net.TCP)
srv:listen(80,function(conn)
   conn:on("receive", function(conn,payload)
      --next row is for debugging output only
      --print(payload)
      if (string.find(payload, "GET / HTTP/1.1") ~= nil) then
         print("GET received")
         sendPage(conn)
      else
         swstat={string.find(payload,"cmd1=")}
         --If POST value exist, set LED power
         if swstat[2]~=nil then
            print("Command received: " .. payload)
            PwrSW(swstat,payload)
            sendPage(conn)
         end
      end
   end)
   conn:on("sent", function(conn)
      conn:close()
      print("Connection closed")
   end)
end) 

 Save the code on ESP as 'web_switch.lua', restart ESP and run:   

        =wifi.sta.getip()                -- find the IP Address where your Web Server will be
        dofile("web_switch.lua")  -- Start the Web Server




   If this is your first project with a new ESP module that was never used in your WIFI Network, don't forget to run also (one time only) :

       wifi.setmode(wifi.STATION)
       wifi.sta.config("<YOUR WIFI Network SSID>","<password>")

Open your favorite Web browser and type your new Web Server IP address. If all ok, should look something like below :


And a short video demonstration :


 
If you want the Web Power Switch software to start automatically when your CBDB module starts or reboots, then you neet to create and add some lines in your 'init.lua' file:

tmr.now()                         -- for debug only, you can skip it
wifi.sta.getmac()              -- for debug only, you can skip it       
wifi.sta.getip()                 -- for debug only, you can skip itnode.heap()
dofile("web_switch.lua")   -- needed to start Web Server for command input

Save the code on ESP as 'init.lua', restart ESP. It should reboot and restart the program and reinitialize the Web Server:

Step-by-step run for testing
  

   As I said from the beginning, this is a experimental W2MPS module example for a Web Controlled Power ON-OFF switch only. Dimming is another story, but if you are interrested about we can talk about it. 

As usual, waiting  your comments and suggestions. If is anybody interested I have available few of them from previous projects and can easily respin more as the parts are already available.

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