Improve DAC power+mute management to reduce clicks and pops

src/drivers/gpios.cpp

@@ -43,7 +43,7 @@ static const uint8_t kPortADefault = 0b00111110;
 // 6 - NC
 // 7 - NC
 // Default inputs high, amp off.
-static const uint8_t kPortBDefault = 0b00001101;
+static const uint8_t kPortBDefault = 0b00011111;
 
 /*
  * Convenience mehod for packing the port a and b bytes into a single 16 bit

src/drivers/i2s_dac.cpp

@@ -137,54 +137,43 @@ I2SDac::I2SDac(IGpios& gpio, PcmBuffer& buf, i2s_chan_handle_t i2s_handle)
                                                        I2S_SLOT_MODE_STEREO)) {
   clock_config_.clk_src = I2S_CLK_SRC_APLL;
 
-  // The amplifier's power rails ramp unevenly, with the negative rail coming
-  // up ~5ms after the positive rail. Ensure that headphone output is muted
-  // during this to avoid a loud pop during power up.
-  gpio_.WriteSync(IGpios::Pin::kAmplifierMute, true);
-  vTaskDelay(pdMS_TO_TICKS(1));
-
-  gpio_.WriteSync(IGpios::Pin::kAmplifierEnable, true);
+  // Power up the DAC.
+  wm8523::WriteRegister(wm8523::Register::kPsCtrl, 0b01);
 
   // Reset all registers back to their default values.
   wm8523::WriteRegister(wm8523::Register::kReset, 1);
 
-  // Wait for DAC reset + analog rails ramp.
+  // Wait for DAC to reset.
   vTaskDelay(pdMS_TO_TICKS(10));
 
-  wm8523::WriteRegister(wm8523::Register::kPsCtrl, 0b0);
-  // Use zero-cross detection for volume changes.
-  wm8523::WriteRegister(wm8523::Register::kDacCtrl, 0b10000);
+  // Enable zero-cross detection and ramping for volume changes.
+  wm8523::WriteRegister(wm8523::Register::kDacCtrl, 0b10011);
+
+  // Ready to play!
+  wm8523::WriteRegister(wm8523::Register::kPsCtrl, 0b10);
 }
 
 I2SDac::~I2SDac() {
-  Stop();
-  i2s_del_channel(i2s_handle_);
-
-  gpio_.WriteSync(IGpios::Pin::kAmplifierMute, true);
-  vTaskDelay(pdMS_TO_TICKS(1));
-  gpio_.WriteSync(IGpios::Pin::kAmplifierEnable, false);
-}
+  if (i2s_active_) {
+    SetPaused(true);
+  }
 
-auto I2SDac::Start() -> void {
-  std::lock_guard<std::mutex> lock(configure_mutex_);
-  wm8523::WriteRegister(wm8523::Register::kPsCtrl, 0b11);
-}
+  // Power down the DAC.
+  wm8523::WriteRegister(wm8523::Register::kPsCtrl, 0b01);
+  wm8523::WriteRegister(wm8523::Register::kPsCtrl, 0b00);
 
-auto I2SDac::Stop() -> void {
-  std::lock_guard<std::mutex> lock(configure_mutex_);
-  set_channel(false);
-  wm8523::WriteRegister(wm8523::Register::kPsCtrl, 0b0);
+  i2s_del_channel(i2s_handle_);
 }
 
 auto I2SDac::SetPaused(bool paused) -> void {
   if (paused) {
-    gpio_.WriteSync(IGpios::Pin::kAmplifierUnmuteLegacy, false);
+    wm8523::WriteRegister(wm8523::Register::kPsCtrl, 0b10);
     gpio_.WriteSync(IGpios::Pin::kAmplifierMute, true);
     set_channel(false);
   } else {
     set_channel(true);
-    gpio_.WriteSync(IGpios::Pin::kAmplifierUnmuteLegacy, true);
     gpio_.WriteSync(IGpios::Pin::kAmplifierMute, false);
+    wm8523::WriteRegister(wm8523::Register::kPsCtrl, 0b11);
   }
 }
 
@@ -250,6 +239,8 @@ auto I2SDac::Reconfigure(Channels ch, BitsPerSample bps, SampleRate rate)
   if (i2s_active_) {
     i2s_channel_enable(i2s_handle_);
     wm8523::WriteRegister(wm8523::Register::kPsCtrl, 0b11);
+  } else {
+    wm8523::WriteRegister(wm8523::Register::kPsCtrl, 0b10);
   }
 }
 

src/drivers/include/drivers/i2s_dac.hpp

@@ -45,8 +45,6 @@ class I2SDac {
   I2SDac(IGpios& gpio, PcmBuffer&, i2s_chan_handle_t i2s_handle);
   ~I2SDac();
 
-  auto Start() -> void;
-  auto Stop() -> void;
   auto SetPaused(bool) -> void;
 
   enum Channels {

src/tangara/audio/i2s_audio_output.cpp

@@ -41,8 +41,6 @@ static constexpr uint16_t kMaxVolumeBeforeClipping = 0x185;
 static constexpr uint16_t kLineLevelVolume = 0x13d;
 static constexpr uint16_t kDefaultVolume = 0x100;
 
-static constexpr size_t kDrainBufferSize = 8 * 1024;
-
 I2SAudioOutput::I2SAudioOutput(drivers::IGpios& expander,
                                drivers::PcmBuffer& buffer)
     : IAudioOutput(),
@@ -55,10 +53,6 @@ I2SAudioOutput::I2SAudioOutput(drivers::IGpios& expander,
       current_volume_(kDefaultVolume),
       max_volume_(0) {}
 
-I2SAudioOutput::~I2SAudioOutput() {
-  dac_->Stop();
-}
-
 auto I2SAudioOutput::changeMode(Modes mode) -> void {
   if (mode == current_mode_) {
     return;
@@ -70,7 +64,6 @@ auto I2SAudioOutput::changeMode(Modes mode) -> void {
     // Turning off this output. Ensure we clean up the I2SDac instance to
     // reclaim its valuable DMA buffers.
     if (dac_) {
-      dac_->Stop();
       dac_.reset();
     }
     return;
@@ -87,7 +80,6 @@ auto I2SAudioOutput::changeMode(Modes mode) -> void {
     }
     // Set up the new instance properly.
     SetVolume(GetVolume());
-    dac_->Start();
   }
 
   current_mode_ = mode;

src/tangara/audio/i2s_audio_output.hpp

@@ -22,7 +22,6 @@ namespace audio {
 class I2SAudioOutput : public IAudioOutput {
  public:
   I2SAudioOutput(drivers::IGpios&, drivers::PcmBuffer&);
-  ~I2SAudioOutput();
 
   auto SetMaxVolume(uint16_t) -> void;
   auto SetVolumeDb(uint16_t) -> void;