1 files changed, 73 insertions, 0 deletions
diff --git a/src/drivers/include/dac.hpp b/src/drivers/include/dac.hpp
new file mode 100644
index 00000000..6d025384
--- /dev/null
+++ b/src/drivers/include/dac.hpp
@@ -0,0 +1,73 @@
+#pragma once
+
+#include "gpio-expander.hpp"
+
+#include <stdint.h>
+#include <functional>
+
+#include "esp_err.h"
+#include "result.hpp"
+
+namespace gay_ipod {
+
+/**
+ * Interface for a PCM5122PWR DAC, configured over I2C.
+ */
+class AudioDac {
+ public:
+  enum Error {
+    FAILED_TO_BOOT,
+    FAILED_TO_CONFIGURE,
+  };
+  static auto create(GpioExpander* expander)
+      -> cpp::result<std::unique_ptr<AudioDac>, Error>;
+
+  AudioDac(GpioExpander* gpio);
+  ~AudioDac();
+
+  /**
+   * Sets the volume on a scale from 0 (loudest) to 254 (quietest). A value of
+   * 255 engages the soft mute function.
+   */
+  void WriteVolume(uint8_t volume);
+
+  enum PowerState {
+    POWERDOWN = 0b0,
+    WAIT_FOR_CP = 0b1,
+    CALIBRATION_1 = 0b10,
+    CALIBRATION_2 = 0b11,
+    RAMP_UP = 0b100,
+    RUN = 0b101,
+    SHORT = 0b110,
+    RAMP_DOWN = 0b111,
+    STANDBY = 0b1000,
+  };
+
+  /* Returns the current boot-up status and internal state of the DAC */
+  std::pair<bool, PowerState> ReadPowerState();
+
+  // Not copyable or movable.
+  AudioDac(const AudioDac&) = delete;
+  AudioDac& operator=(const AudioDac&) = delete;
+
+ private:
+  GpioExpander* gpio_;
+
+  /*
+   * Pools the power state for up to 10ms, waiting for the given predicate to
+   * be true.
+   */
+  bool WaitForPowerState(std::function<bool(bool, PowerState)> predicate);
+
+  enum Register {
+    PAGE_SELECT = 0,
+    DE_EMPHASIS = 7,
+    DIGITAL_VOLUME_L = 61,
+    DIGITAL_VOLUME_R = 62,
+    DSP_BOOT_POWER_STATE = 118,
+  };
+
+  void WriteRegister(Register reg, uint8_t val);
+};
+
+}  // namespace gay_ipod