Arduino speaker controller

I've had this project in mind for a while, and finally got around to it. I wanted a way to turn on or off the various speakers around the house. In addition to the front room, where the main stereo is, we have speakers in the dining room, hot tub area, and back patio. Previously, I could turn on the amp, pick a playlist from Kodi, and make it play all from my phone, but if I was outside on the patio, I had to go back in the house and push a button to turn on the speakers. No more! Now I have a simple web app and an Arduino controller to turn on the speakers.

 I got a lot of inspiration and ideas for this project from http://www.33snowflakes.com/blog/arduino-android-speaker-selector/. There is even a link to a nice looking Android app to control the speaker relays, but I couldn't get it to work, so I just did a little web app that runs on Arduino to control the speakers. I got just about all the parts from Amazon:

• Hammond 1591ESBK ABS Project Box Black $10
• Phantom YoYo 40P dupont cable 200mm male to female $7
• Single Row 4 Position Cable Clip Socket Push Type Speaker Terminals 5PCS $6
• SainSmart 8-Channel Relay Module $11
• Ethernet W5100 Shield Network Expansion Board w/ Micro SD Card Slot for Arduino $11
• Arduino that I already had
• some speaker wire

Here is the wiring to control the relay board. The brown wire on the left connects to the 9V output on the Arduino to power the relays themselves. The black wire on the right is the ground, and is common to the board and the relays. The white wire connects to the 5V output on the Arduino to power the relay circuit board.

A close up of the connections on the relay board. Again, the brown wire on the right is connected to the 9V output on the Arduino and powers the relays themselves, while the white wire is connected to the 5V output on the Arduino to power the relay circuit board. The other wires are connected to pins 2 through 9 on the Arduino to actually trigger the relays.

Here are the connections on the Arduino side. You can see the 5V white wire, the black ground wire, and the 9V brown wire. The other wires are connected to pins 2 though 9 to control the 8 relays.

Just a big picture of the completed wiring between the Arduino and the relay board

A shot of everything in the box. My dremel skills aren't the best, but this will be in a cabinet and essentially hidden from view, so it's okay. There are cut outs for the ethernet, USB, and power connections.

The speakers will connect here. It might have been better if I'd found similar connectors that were all black. For this use, each speaker gets two connectors. The negative wire is cut, then one of the cut ends goes in the top row of connectors and the other cut end connects to the corresponding connector in the bottom row. The relay then completes the circuit. These are installed right to left, so the right most connector is controlled by relay 1, and the left most connector is controlled by relay 8. I did it this way so it would be easier to wire into my stereo cabinet. Note that this piece is one of about 6 that make all the speakers work. 

A shot of the inside. It looks messy, but it's pretty straightforward.

The code is a simple web server. The IP address is hard-coded to 192.168.2.251 so it's easy to bookmark in my phone's browser. The web page it produces looks like this, both on my phone and on my desktop browser:

Pretty plain, but it does the right thing.

/*
Simple web server to serve a form to turn on or off digital pins. In this case,
the pins are connected to relays to turn speakers on or off. This uses pins
2 through 9 in pairs, so 2 and 3 control the hot tub speakers, 4 and 5 control
the dining room speakers, and 6 and 7 control the portico speakers. 8 and 9 are
available in case I ever find a need to connect one more pair of speakers.
*/

#include <SPI.h>
#include <Ethernet.h>
#include <string.h>

// MAC address can be anything that is unique within the local network.
byte mac[] = {0x00, 0x1E, 0x2A, 0x77, 0x24, 0x02 };

// Some unused IP address on the local network.
byte ip[] = {192, 168, 2, 251 }; 

// web server, nothing fancy, just port 80 for http
EthernetServer server( 80 ); 

#define RELAY_ON 0
#define RELAY_OFF 1


// true, just show speaker status or false, actually change the speaker states
boolean showStatus = false;

// which zones are on or off, initially, all are off
boolean zone1 = false;
boolean zone2 = false;
boolean zone3 = false;
boolean zone4 = false;

// pin definition, one pin per speaker, 
// so the left speaker in zone 1 is pin 2, etc
static const int zone1L = 2;
static const int zone1R = 3;
static const int zone2L = 4;
static const int zone2R = 5;
static const int zone3L = 6;
static const int zone3R = 7;
static const int zone4L = 8;
static const int zone4R = 9;


// set up pins, initially all speakers in all zones are off
void setupPins() {
    digitalWrite(zone1L, RELAY_OFF);
    digitalWrite(zone1R, RELAY_OFF);
    digitalWrite(zone2L, RELAY_OFF);
    digitalWrite(zone2R, RELAY_OFF);
    digitalWrite(zone3L, RELAY_OFF);
    digitalWrite(zone3R, RELAY_OFF);
    digitalWrite(zone4L, RELAY_OFF);
    digitalWrite(zone4R, RELAY_OFF);

    pinMode( zone1L, OUTPUT );
    pinMode( zone1R, OUTPUT );
    pinMode( zone2L, OUTPUT );
    pinMode( zone2R, OUTPUT );
    pinMode( zone3L, OUTPUT );
    pinMode( zone3R, OUTPUT );
    pinMode( zone4L, OUTPUT );
    pinMode( zone4R, OUTPUT );
    
    delay(4000);
}

void setup() {
    Ethernet.begin( mac, ip );
    server.begin();

    setupPins();
}

// set up buffer for reading web requests
static const int bufferMax = 128;
int bufferSize;
char buffer[ bufferMax ];

void loop() {
    EthernetClient client = server.available();
    if ( client ) {
        waitForRequest( client );
        handleRequest();
        client.stop();
    }
}

void waitForRequest( EthernetClient client ) 
{
    bufferSize = 0;

    while ( client.connected() ) {
        if ( client.available() ) {
            char c = client.read();
            if ( c == '\n' ) {
                break;
            }
            else {
                if ( bufferSize < bufferMax ) {
                    buffer[ bufferSize++ ] = c;
                }
                else {
                    break;
                }
            }
        }
    }
}

void handleRequest() {
    // Received buffer contains a standard HTTP GET line, something like
    // "GET /?X=X&Y=Y HTTP/1.1". 
    // Could have up to 4 parameters, 1=on&2=on&3=on&4=on,
    // one for each set of speakers. All that is necessary here is to

    // extract the query string and check for each of the zone numbers.

    String request = String(buffer);
    int firstSpace = request.indexOf(" ");   // right after GET
    int lastSpace = request.indexOf(" ", firstSpace + 1); // just after the query string
    request = request.substring(firstSpace, lastSpace);
    
    showStatus = request.indexOf("?") == -1;
    zone1 = request.indexOf("1") > -1;
    zone2 = request.indexOf("2") > -1;
    zone3 = request.indexOf("3") > -1;
    zone4 = request.indexOf("4") > -1;

    if (request.indexOf("1=on") > -1) {
      zone1 = true;
    }
    else if (request.indexOf("1=off") > -1) {
      zone1 = false;
    }
    if (request.indexOf("2=on") > -1) {
      zone2 = true;
    }
    else if (request.indexOf("2=off") > -1) {
      zone2 = false;
    }
    if (request.indexOf("3=on") > -1) {
      zone3 = true;
    }
    else if (request.indexOf("3=off") > -1) {
      zone3 = false;
    }
    if (request.indexOf("4=on") > -1) {
      zone4 = true;
    }
    else if (request.indexOf("4=off") > -1) {
      zone4 = false;
    }


    if (!showStatus) {
        setSpeakerState();
    }
    sendPage();
}

void setSpeakerState() {
    digitalWrite(zone1L, zone1 ? RELAY_ON : RELAY_OFF);
    digitalWrite(zone1R, zone1 ? RELAY_ON : RELAY_OFF);
    digitalWrite(zone2L, zone2 ? RELAY_ON : RELAY_OFF);
    digitalWrite(zone2R, zone2 ? RELAY_ON : RELAY_OFF);
    digitalWrite(zone3L, zone3 ? RELAY_ON : RELAY_OFF);
    digitalWrite(zone3R, zone3 ? RELAY_ON : RELAY_OFF);
    digitalWrite(zone4L, zone4 ? RELAY_ON : RELAY_OFF);
    digitalWrite(zone4R, zone4 ? RELAY_ON : RELAY_OFF);
}

void sendPage() {
    printHead();
    printForm();
    printTail();
}

// the 'bootstrap' css makes the page look good in desktop browsers and on phones
void printHead() {
    server.print("<html>\n<head>\n<title>Speaker Control</title>\n");
    server.print("<meta name='viewport' content='width=device-width, initial-scale=1'>\n");
    server.print("<link rel='stylesheet' href='http://maxcdn.bootstrapcdn.com/bootstrap/3.3.4/css/bootstrap.min.css'>\n");
    server.print("</head>\n<body>\n"); 
}

void printForm() {
   server.print("<div class='container'>\n");
   server.print("<h2>Speaker Control</h2><br/>\n");
   server.print("<form action='/' role='form'>\n");
   
   int pinState = digitalRead(zone4L);                                           
   server.print("<div class='checkbox'><label><input type='checkbox' name='4'");
   server.print(pinState == RELAY_ON ? " checked='checked'" : "");
   server.print(">Hot tub</label></div><br/>\n");

   pinState = digitalRead(zone3L);                                           
   server.print("<div class='checkbox'><label><input type='checkbox' name='3'");
   server.print(pinState == RELAY_ON ? " checked='checked'" : "");               
   server.print(">Dining room</label></div><br/>\n");                            
                                                                             
   pinState = digitalRead(zone2L);                                           
   server.print("<div class='checkbox'><label><input type='checkbox' name='2'");
   server.print(pinState == RELAY_ON ? " checked='checked'" : "");               
   server.print(">Portico</label></div><br/>\n");                        
                                                                             
   pinState = digitalRead(zone1L);
   server.print("<div class='checkbox'><label><input type='checkbox' name='1'");
   server.print(pinState == RELAY_ON ? " checked='checked'" : "");               
   server.print(">(Empty)</label></div><br/>\n");                            
                                                                             
   server.print("<br/>\n");
   server.print("<button type='submit' class='btn btn-default'>Save</button>\n");
   server.print("</form>\n");
   
   server.print("</div>\n");
}

void printTail() {
   server.print("</body>\n</html>\n"); 
}