Add SGTL5000 dacVolumeRamp functions & example

control_sgtl5000.cpp

@@ -694,6 +694,24 @@ unsigned short AudioControlSGTL5000::dacVolume(float left, float right)
 	return modify(CHIP_DAC_VOL,m,65535);
 }
 
+bool AudioControlSGTL5000::dacVolumeRamp()
+{
+	return modify(CHIP_ADCDAC_CTRL, 0x300, 0x300);
+}
+
+bool AudioControlSGTL5000::dacVolumeRampLinear()
+{
+	return modify(CHIP_ADCDAC_CTRL, 0x200, 0x300);
+}
+
+bool AudioControlSGTL5000::dacVolumeRampDisable()
+{
+	return modify(CHIP_ADCDAC_CTRL, 0, 0x300);
+}
+
+
+
+
 unsigned short AudioControlSGTL5000::adcHighPassFilterEnable(void)
 {
 	return modify(CHIP_ADCDAC_CTRL, 0, 3);

control_sgtl5000.h

@@ -60,6 +60,9 @@ public:
 	unsigned short lineOutLevel(uint8_t left, uint8_t right);
 	unsigned short dacVolume(float n);
 	unsigned short dacVolume(float left, float right);
+	bool dacVolumeRamp();
+	bool dacVolumeRampLinear();
+	bool dacVolumeRampDisable();
 	unsigned short adcHighPassFilterEnable(void);
 	unsigned short adcHighPassFilterFreeze(void);
 	unsigned short adcHighPassFilterDisable(void);

examples/HardwareTesting/SGTL5000/VolumeRamp/VolumeRamp.ino

@@ -0,0 +1,97 @@
+// The SGTL5000 has a secondard "dacVolume" setting, in addition to normal volume.
+// 
+// Normally dacVolume defaults to 1.0, to pass your sound directly to the normal
+// volume control.  The actual volume you hear depends on both settings.
+//
+// The dacVolume control has an option to gracefully ramp (change) its setting over
+// time, to prevent a sudden pop or click sound.  You could achieve this by adding
+// code to change the volume setting in very small steps over time, but the
+// SGTL5000 can do it for you automatically.
+
+#include <Audio.h>
+#include <Wire.h>
+#include <SPI.h>
+#include <SD.h>
+
+// GUItool: begin automatically generated code
+AudioSynthWaveformSine   sine1;          //xy=203,233
+AudioOutputI2S           i2s1;           //xy=441,233
+AudioConnection          patchCord1(sine1, 0, i2s1, 0);
+AudioConnection          patchCord2(sine1, 0, i2s1, 1);
+AudioControlSGTL5000     sgtl5000_1;     //xy=452,162
+// GUItool: end automatically generated code
+
+
+elapsedMillis msec;
+float vol;
+float inc;
+int rampType;
+const char *rampName[] = {
+  "No Ramp (instant)",  // loud pop due to instant change
+  "Normal Ramp",        // graceful transition between volume levels
+  "Linear Ramp"         // slight click/chirp
+};
+
+void setup(void) {
+  Serial.begin(9600);
+
+  AudioMemory(4);
+  vol = 0.0;
+  inc = 0.2;
+
+  rampType = 0;
+
+  sine1.amplitude(1.0);
+  sine1.frequency(440);
+
+  sgtl5000_1.enable();
+  sgtl5000_1.volume(0.5);     // set the main volume...
+  sgtl5000_1.dacVolume(0);    // set the "dac" volume (extra control)
+  sgtl5000_1.dacVolumeRampDisable();
+
+  Serial.println("setup done");
+}
+
+void loop(void) {
+  if (msec > 1000) { // change the volume every second
+
+    // increment or decrement the volume variable
+    vol += inc;
+    if (vol >= 1.0) {
+      vol = 1.0;
+      inc = -inc;
+    }
+    if (vol < 0.01) {
+      vol = 0.0;
+      inc = -inc;
+    }
+    Serial.print("Volume: ");
+    Serial.print(vol);
+    Serial.print("   ");
+    Serial.println(rampName[rampType]);
+
+    // configure which type of volume transition to use
+    if (rampType == 0) {
+      sgtl5000_1.dacVolumeRampDisable();
+    } else if (rampType == 1) {
+      sgtl5000_1.dacVolumeRamp();
+    } else {
+      sgtl5000_1.dacVolumeRampLinear();
+    }
+
+    // set the dacVolume.  The actual change make take place over time, if ramping
+    // this is a logarithmic volume,
+    // that is, the range 0.0 to 1.0 gets converted to -90dB to 0dB in 0.5dB steps
+    sgtl5000_1.dacVolume(vol);
+
+    // if we turned the volume off, advance to the next ramp type
+    if (vol < 0.01) {
+      rampType = rampType + 1;
+      if (rampType > 2) rampType = 0;
+    }
+    msec = 0;
+  }
+}
+
+
+