R4 pre-emptive bringup

Includes stripping out the IC-specific I2S stuff, and doing more manual
volume control using pots

1 files changed, 85 insertions, 0 deletions

diff --git a/src/drivers/digital_pot.cpp b/src/drivers/digital_pot.cpp
new file mode 100644
index 00000000..b20d982d
--- /dev/null
+++ b/src/drivers/digital_pot.cpp
@@ -0,0 +1,85 @@
+/*
+ * Copyright 2023 jacqueline <me@jacqueline.id.au>
+ *
+ * SPDX-License-Identifier: GPL-3.0-only
+ */
+
+#include "digital_pot.hpp"
+
+#include <cstdint>
+
+namespace drivers {
+
+using GpioExpander::VOL_LEFT;
+using GpioExpander::VOL_RIGHT;
+using GpioExpander::VOL_UP_DOWN;
+using GpioExpander::VOL_Z_CROSS;
+
+DigitalPot::DigitalPot(GpioExpander* gpios) : gpios_(gpios) {
+  gpios_->set_pin(VOL_Z_CROSS, true);  // Active-low
+  gpios_->set_pin(VOL_UP_DOWN, true);
+  gpios_->set_pin(VOL_LEFT, false);
+  gpios_->set_pin(VOL_RIGHT, false);
+  gpios_->Write();
+
+  // Power-on reset sets attenuation to maximum anyway, but we want to be safe
+  // and not blow anyone's ears out.
+  for (int i = 0; i < 32; i++) {
+    gpios_->set_pin(VOL_LEFT, true);
+    gpios_->set_pin(VOL_RIGHT, true);
+    gpios_->Write();
+    gpios_->set_pin(VOL_LEFT, false);
+    gpios_->set_pin(VOL_RIGHT, false);
+    gpios_->Write();
+  }
+}
+
+auto DigitalPot::SetRelative(int_fast8_t change) -> void {
+  if (change == 0) {
+    return;
+  }
+
+  gpios_->set_pin(VOL_UP_DOWN, change > 0);
+  gpios_->Write();
+
+  for (int i = 0; i < std::abs(change); i++) {
+    gpios_->set_pin(VOL_LEFT, true);
+    gpios_->set_pin(VOL_RIGHT, true);
+    gpios_->Write();
+    gpios_->set_pin(VOL_LEFT, false);
+    gpios_->set_pin(VOL_RIGHT, false);
+    gpios_->Write();
+  }
+}
+
+auto DigitalPot::SetRelative(Channel ch, int_fast8_t change) -> void {
+  if (change == 0) {
+    return;
+  }
+
+  GpioExpander::Pin pin = (ch == Channel::kLeft) ? VOL_LEFT : VOL_RIGHT;
+  gpios_->set_pin(VOL_UP_DOWN, change > 0);
+  gpios_->Write();
+
+  for (int i = 0; i < std::abs(change); i++) {
+    gpios_->set_pin(pin, true);
+    gpios_->Write();
+    gpios_->set_pin(pin, false);
+    gpios_->Write();
+  }
+}
+
+auto DigitalPot::SetZeroCrossDetect(bool enabled) -> void {
+  gpios_->set_pin(VOL_Z_CROSS, !enabled);  // Active-low
+  gpios_->Write();
+}
+
+auto DigitalPot::GetMaxAttenuation() -> int_fast8_t {
+  return 31;
+}
+
+auto DigitalPot::GetMinAttenuation() -> int_fast8_t {
+  return 0;
+}
+
+}  // namespace drivers