Added DAC & HP balance examples

Changed method for setting level/gains for left & right from
'item_left(..); item_right(..);' style to 'volume(left,right)' style
instead.

examples/SGTL5000_Specific/balanceDAC/balanceDAC.ino

+// DAC balance example: Will influence both HP & LO outputs.
+
+#include <Audio.h>
+#include <Wire.h>
+#include <SD.h>
+
+#define PIN_VOLUME 0
+#define PIN_BALANCE 15
+
+const int myInput = AUDIO_INPUT_LINEIN;
+// const int myInput = AUDIO_INPUT_MIC;
+
+// Create the Audio components.  These should be created in the
+// order data flows, inputs/sources -> processing -> outputs
+//
+
+AudioInputI2S       audioInput;         // audio shield: mic or line-in
+AudioOutputI2S      audioOutput;        // audio shield: headphones & line-out
+
+
+
+// Create Audio connections between the components
+//
+AudioConnection c1(audioInput, 0, audioOutput, 0); // left passing through
+AudioConnection c2(audioInput, 1, audioOutput, 1); // right passing through
+
+// Create an object to control the audio shield.
+// 
+AudioControlSGTL5000 audioShield;
+
+void setup() {
+  // Audio connections require memory to work.  For more
+  // detailed information, see the MemoryAndCpuUsage example
+  AudioMemory(6);
+  // Enable the audio shield and set the output volume.
+  audioShield.enable();
+  audioShield.inputSelect(myInput);
+  audioShield.volume(90);
+  audioShield.unmuteLineout();
+}
+
+elapsedMillis chgMsec=0;
+float lastVol=1024;
+float lastBal=1024;
+
+void loop() {
+  // every 10 ms, check for adjustment the balance & vol
+  if (chgMsec > 10) { // more regular updates for actual changes seems better.
+#if PIN_BALANCE
+    float bal1=analogRead(PIN_BALANCE);
+#else
+    float bal1=0; // middle will be default if analog pin is not supplied
+#endif
+    bal1=((bal1-512)/512)*100;
+    bal1=(int)bal1;
+    if(lastBal!=bal1)
+    {
+      if(bal1<0)
+      { // leaning toward left...
+        audioShield.dac_vol(100,100+bal1);
+      } else if(bal1>0) { // to the right
+        audioShield.dac_vol(100-bal1,100);
+      } else { // middle
+        audioShield.dac_vol(100);
+      }
+      lastBal=bal1;
+    }
+
+#if PIN_VOLUME
+    float vol1=analogRead(PIN_VOLUME)/10.23; // 0 - 100
+#else
+    float vol1=70; // 70% output will be default if analog pin is not supplied.
+#endif
+    vol1=(int)vol1;
+    if(lastVol!=vol1)
+    {
+      audioShield.volume(vol1);
+      lastVol=vol1;
+    }
+    chgMsec = 0;
+  }
+}
+

examples/SGTL5000_Specific/balanceHP/balanceHP.ino

+// HP balance example: Will influence both HP & LO outputs.
+
+#include <Audio.h>
+#include <Wire.h>
+#include <SD.h>
+
+#define PIN_VOLUME 0
+#define PIN_BALANCE 15
+
+const int myInput = AUDIO_INPUT_LINEIN;
+// const int myInput = AUDIO_INPUT_MIC;
+
+// Create the Audio components.  These should be created in the
+// order data flows, inputs/sources -> processing -> outputs
+//
+
+AudioInputI2S       audioInput;         // audio shield: mic or line-in
+AudioOutputI2S      audioOutput;        // audio shield: headphones & line-out
+
+
+
+// Create Audio connections between the components
+
+// Just connecting in to out
+AudioConnection c1(audioInput, 0, audioOutput, 0); // left connection
+AudioConnection c2(audioInput, 1, audioOutput, 1); // right connection
+
+// Create an object to control the audio shield.
+// 
+AudioControlSGTL5000 audioShield;
+
+void setup() {
+  // Audio connections require memory to work.  For more
+  // detailed information, see the MemoryAndCpuUsage example
+  AudioMemory(12);
+  // Enable the audio shield and set the output volume.
+  audioShield.enable();
+  audioShield.inputSelect(myInput);
+  audioShield.volume(60);
+  audioShield.unmuteLineout();
+}
+
+elapsedMillis chgMsec=0;
+
+float lastVol=1024;
+float lastBal=1024;
+
+void loop() {
+  // every 10 ms, check for adjustment the balance & vol
+  if (chgMsec > 10) { // more regular updates for actual changes seems better.
+
+#if PIN_VOLUME
+    float vol1=analogRead(PIN_VOLUME)/10.23; // 0 - 1000
+#else
+    float vol1=70; // 70% output will be default if analog pin is not supplied.
+#endif
+    vol1=(int)vol1;
+
+#if PIN_BALANCE
+    float bal1=analogRead(PIN_BALANCE);
+#else
+    float bal1=0; // middle will be default if analog pin is not supplied
+#endif
+    bal1=((bal1-512)/512)*100;
+    bal1=(int)bal1;
+    if((lastVol!=vol1)||(lastBal!=bal1))
+    {
+      if(bal1<0)
+      {
+        audioShield.volume(vol1,(vol1/100)*(100+bal1));
+      } else {
+        audioShield.volume((vol1/100)*(100-bal1),vol1);
+      }
+      lastVol=vol1;
+      lastBal=bal1;
+    }
+    chgMsec = 0;
+  }
+}
+