Merge branch 'main' into jqln/tts

16 files changed, 520 insertions, 201 deletions

diff --git a/src/drivers/CMakeLists.txt b/src/drivers/CMakeLists.txt
index 33d25894..fea5780f 100644
--- a/src/drivers/CMakeLists.txt
+++ b/src/drivers/CMakeLists.txt
@@ -8,5 +8,5 @@ idf_component_register(
   "samd.cpp" "wm8523.cpp" "nvs.cpp" "haptics.cpp" "spiffs.cpp" "pcm_buffer.cpp"
   INCLUDE_DIRS "include"
   REQUIRES "esp_adc" "fatfs" "result" "lvgl" "nvs_flash" "spiffs" "bt"
-  "tasks" "tinyfsm" "util" "libcppbor")
+  "tasks" "tinyfsm" "util" "libcppbor" "driver")
 target_compile_options(${COMPONENT_LIB} PRIVATE ${EXTRA_WARNINGS})
diff --git a/src/drivers/bluetooth.cpp b/src/drivers/bluetooth.cpp
index acb38ce4..3da5dd0c 100644
--- a/src/drivers/bluetooth.cpp
+++ b/src/drivers/bluetooth.cpp
@@ -4,6 +4,7 @@
 
 #include <algorithm>
 #include <atomic>
+#include <iterator>
 #include <mutex>
 #include <ostream>
 #include <sstream>
@@ -116,93 +117,111 @@ IRAM_ATTR auto a2dp_data_cb(uint8_t* buf, int32_t buf_size) -> int32_t {
   return buf_size;
 }
 
-Bluetooth::Bluetooth(NvsStorage& storage, tasks::WorkerPool& bg_worker) {
+Bluetooth::Bluetooth(NvsStorage& storage,
+                     tasks::WorkerPool& bg_worker,
+                     EventHandler cb)
+    : nvs_(storage) {
   sBgWorker = &bg_worker;
-  bluetooth::BluetoothState::Init(storage);
+  bluetooth::BluetoothState::Init(storage, cb);
 }
 
-auto Bluetooth::Enable() -> bool {
-  auto lock = bluetooth::BluetoothState::lock();
-  tinyfsm::FsmList<bluetooth::BluetoothState>::dispatch(
-      bluetooth::events::Enable{});
+auto Bluetooth::enable(bool en) -> void {
+  if (en) {
+    auto lock = bluetooth::BluetoothState::lock();
+    tinyfsm::FsmList<bluetooth::BluetoothState>::dispatch(
+        bluetooth::events::Enable{});
+  } else {
+    // FIXME: the BT tasks unfortunately call back into us while holding an
+    // internal lock, which then deadlocks with our fsm lock.
+    // auto lock = bluetooth::BluetoothState::lock();
+    tinyfsm::FsmList<bluetooth::BluetoothState>::dispatch(
+        bluetooth::events::Disable{});
+  }
+}
 
+auto Bluetooth::enabled() -> bool {
+  auto lock = bluetooth::BluetoothState::lock();
   return !bluetooth::BluetoothState::is_in_state<bluetooth::Disabled>();
 }
 
-auto Bluetooth::Disable() -> void {
-  // FIXME: the BT tasks unfortunately call back into us while holding an
-  // internal lock, which then deadlocks with our fsm lock.
-  // auto lock = bluetooth::BluetoothState::lock();
+auto Bluetooth::sources(OutputBuffers* src) -> void {
+  auto lock = bluetooth::BluetoothState::lock();
+  if (src == sStreams) {
+    return;
+  }
+  sStreams = src;
   tinyfsm::FsmList<bluetooth::BluetoothState>::dispatch(
-      bluetooth::events::Disable{});
+      bluetooth::events::SourcesChanged{});
 }
 
-auto Bluetooth::IsEnabled() -> bool {
-  auto lock = bluetooth::BluetoothState::lock();
-  return !bluetooth::BluetoothState::is_in_state<bluetooth::Disabled>();
+auto Bluetooth::softVolume(float f) -> void {
+  sVolumeFactor = f;
 }
 
-auto Bluetooth::IsConnected() -> bool {
+auto Bluetooth::connectionState() -> ConnectionState {
   auto lock = bluetooth::BluetoothState::lock();
-  return bluetooth::BluetoothState::is_in_state<bluetooth::Connected>();
+  if (bluetooth::BluetoothState::is_in_state<bluetooth::Connected>()) {
+    return ConnectionState::kConnected;
+  } else if (bluetooth::BluetoothState::is_in_state<bluetooth::Connecting>()) {
+    return ConnectionState::kConnecting;
+  }
+  return ConnectionState::kDisconnected;
 }
 
-auto Bluetooth::ConnectedDevice() -> std::optional<bluetooth::MacAndName> {
+auto Bluetooth::pairedDevice() -> std::optional<bluetooth::MacAndName> {
   auto lock = bluetooth::BluetoothState::lock();
-  if (!bluetooth::BluetoothState::is_in_state<bluetooth::Connected>()) {
-    return {};
-  }
-  return bluetooth::BluetoothState::preferred_device();
+  return bluetooth::BluetoothState::pairedDevice();
 }
 
-auto Bluetooth::KnownDevices() -> std::vector<bluetooth::Device> {
+auto Bluetooth::pairedDevice(std::optional<bluetooth::MacAndName> dev) -> void {
   auto lock = bluetooth::BluetoothState::lock();
-  std::vector<bluetooth::Device> out = bluetooth::BluetoothState::devices();
-  std::sort(out.begin(), out.end(), [](const auto& a, const auto& b) -> bool {
-    return a.signal_strength < b.signal_strength;
-  });
-  return out;
+  bluetooth::BluetoothState::pairedDevice(dev);
 }
 
-auto Bluetooth::SetPreferredDevice(std::optional<bluetooth::MacAndName> dev)
-    -> void {
-  auto lock = bluetooth::BluetoothState::lock();
-  auto cur = bluetooth::BluetoothState::preferred_device();
-  if (dev && cur && dev->mac == cur->mac) {
-    return;
-  }
-  ESP_LOGI(kTag, "preferred is '%s' (%u%u%u%u%u%u)", dev->name.c_str(),
-           dev->mac[0], dev->mac[1], dev->mac[2], dev->mac[3], dev->mac[4],
-           dev->mac[5]);
-  bluetooth::BluetoothState::preferred_device(dev);
-  tinyfsm::FsmList<bluetooth::BluetoothState>::dispatch(
-      bluetooth::events::PreferredDeviceChanged{});
+auto Bluetooth::knownDevices() -> std::vector<bluetooth::MacAndName> {
+  return nvs_.BluetoothNames();
 }
 
-auto Bluetooth::PreferredDevice() -> std::optional<bluetooth::MacAndName> {
-  auto lock = bluetooth::BluetoothState::lock();
-  return bluetooth::BluetoothState::preferred_device();
+auto Bluetooth::forgetKnownDevice(const bluetooth::mac_addr_t& mac) -> void {
+  nvs_.BluetoothName(mac, {});
 }
 
-auto Bluetooth::SetSources(OutputBuffers* src) -> void {
+auto Bluetooth::discoveryEnabled(bool en) -> void {
   auto lock = bluetooth::BluetoothState::lock();
-  OutputBuffers* cur = bluetooth::BluetoothState::sources();
-  if (src == cur) {
-    return;
-  }
-  bluetooth::BluetoothState::sources(src);
-  tinyfsm::FsmList<bluetooth::BluetoothState>::dispatch(
-      bluetooth::events::SourcesChanged{});
+  bluetooth::BluetoothState::discovery(en);
 }
 
-auto Bluetooth::SetVolumeFactor(float f) -> void {
-  sVolumeFactor = f;
+auto Bluetooth::discoveryEnabled() -> bool {
+  auto lock = bluetooth::BluetoothState::lock();
+  return bluetooth::BluetoothState::discovery();
 }
 
-auto Bluetooth::SetEventHandler(std::function<void(bluetooth::Event)> cb)
-    -> void {
-  auto lock = bluetooth::BluetoothState::lock();
-  bluetooth::BluetoothState::event_handler(cb);
+auto Bluetooth::discoveredDevices() -> std::vector<bluetooth::MacAndName> {
+  std::vector<bluetooth::Device> discovered;
+  {
+    auto lock = bluetooth::BluetoothState::lock();
+    discovered = bluetooth::BluetoothState::discoveredDevices();
+  }
+
+  // Show devices with stronger signals first, since they're more likely to be
+  // physically close (and therefore more likely to be what the user wants).
+  std::sort(discovered.begin(), discovered.end(),
+            [](const auto& a, const auto& b) -> bool {
+              return a.signal_strength < b.signal_strength;
+            });
+
+  // Convert to the right format.
+  std::vector<bluetooth::MacAndName> out;
+  out.reserve(discovered.size());
+  std::transform(discovered.begin(), discovered.end(), std::back_inserter(out),
+                 [&](const bluetooth::Device& dev) {
+                   return bluetooth::MacAndName{
+                       .mac = dev.address,
+                       .name = {dev.name.data(), dev.name.size()},
+                   };
+                 });
+
+  return out;
 }
 
 static auto DeviceName() -> std::pmr::string {
@@ -255,6 +274,10 @@ auto Scanner::StopScanningNow() -> void {
   }
 }
 
+auto Scanner::enabled() -> bool {
+  return enabled_;
+}
+
 auto Scanner::HandleGapEvent(const events::internal::Gap& ev) -> void {
   switch (ev.type) {
     case ESP_BT_GAP_DISC_RES_EVT:
@@ -347,16 +370,18 @@ NvsStorage* BluetoothState::sStorage_;
 Scanner* BluetoothState::sScanner_;
 
 std::mutex BluetoothState::sFsmMutex{};
-std::map<mac_addr_t, Device> BluetoothState::sDevices_{};
-std::optional<MacAndName> BluetoothState::sPreferredDevice_{};
-std::optional<MacAndName> BluetoothState::sConnectingDevice_{};
+std::map<mac_addr_t, Device> BluetoothState::sDiscoveredDevices_{};
+std::optional<MacAndName> BluetoothState::sPairedWith_{};
+std::optional<MacAndName> BluetoothState::sConnectingTo_{};
 int BluetoothState::sConnectAttemptsRemaining_{0};
 
 std::function<void(Event)> BluetoothState::sEventHandler_;
 
-auto BluetoothState::Init(NvsStorage& storage) -> void {
+auto BluetoothState::Init(NvsStorage& storage, Bluetooth::EventHandler cb)
+    -> void {
   sStorage_ = &storage;
-  sPreferredDevice_ = storage.PreferredBluetoothDevice();
+  sEventHandler_ = cb;
+  sPairedWith_ = storage.PreferredBluetoothDevice();
   tinyfsm::FsmList<bluetooth::BluetoothState>::start();
 }
 
@@ -364,68 +389,85 @@ auto BluetoothState::lock() -> std::lock_guard<std::mutex> {
   return std::lock_guard<std::mutex>{sFsmMutex};
 }
 
-auto BluetoothState::devices() -> std::vector<Device> {
-  std::vector<Device> out;
-  for (const auto& device : sDevices_) {
-    out.push_back(device.second);
-  }
-  return out;
+auto BluetoothState::pairedDevice() -> std::optional<MacAndName> {
+  return sPairedWith_;
 }
 
-auto BluetoothState::preferred_device() -> std::optional<MacAndName> {
-  return sPreferredDevice_;
-}
+auto BluetoothState::pairedDevice(std::optional<MacAndName> dev) -> void {
+  auto cur = sPairedWith_;
+  if (dev && cur && dev->mac == cur->mac) {
+    return;
+  }
+  if (dev) {
+    ESP_LOGI(kTag, "pairing with '%s' (%u%u%u%u%u%u)", dev->name.c_str(),
+             dev->mac[0], dev->mac[1], dev->mac[2], dev->mac[3], dev->mac[4],
+             dev->mac[5]);
+  }
+  sPairedWith_ = dev;
+  std::invoke(sEventHandler_, SimpleEvent::kDeviceDiscovered);
 
-auto BluetoothState::preferred_device(std::optional<MacAndName> addr) -> void {
-  sPreferredDevice_ = addr;
+  tinyfsm::FsmList<bluetooth::BluetoothState>::dispatch(
+      bluetooth::events::PairedDeviceChanged{});
 }
 
-auto BluetoothState::sources() -> OutputBuffers* {
-  return sStreams;
+auto BluetoothState::discovery() -> bool {
+  return sScanner_->enabled();
 }
 
-auto BluetoothState::sources(OutputBuffers* src) -> void {
-  sStreams = src;
+auto BluetoothState::discovery(bool en) -> void {
+  if (en) {
+    if (!sScanner_->enabled()) {
+      sDiscoveredDevices_.clear();
+    }
+    sScanner_->ScanContinuously();
+  } else {
+    sScanner_->StopScanning();
+  }
 }
 
-auto BluetoothState::event_handler(std::function<void(Event)> cb) -> void {
-  sEventHandler_ = cb;
+auto BluetoothState::discoveredDevices() -> std::vector<Device> {
+  std::vector<Device> out;
+  for (const auto& device : sDiscoveredDevices_) {
+    out.push_back(device.second);
+  }
+  return out;
 }
 
 auto BluetoothState::react(const events::DeviceDiscovered& ev) -> void {
-  bool is_preferred = false;
-  bool already_known = sDevices_.contains(ev.device.address);
-  sDevices_[ev.device.address] = ev.device;
+  bool is_paired = false;
+  bool already_known = sDiscoveredDevices_.contains(ev.device.address);
+  sDiscoveredDevices_[ev.device.address] = ev.device;
 
-  if (sPreferredDevice_ && ev.device.address == sPreferredDevice_->mac) {
-    is_preferred = true;
+  if (sPairedWith_ && ev.device.address == sPairedWith_->mac) {
+    is_paired = true;
   }
 
-  if (sEventHandler_ && !already_known) {
-    std::invoke(sEventHandler_, SimpleEvent::kKnownDevicesChanged);
+  if (!already_known) {
+    std::invoke(sEventHandler_, SimpleEvent::kDeviceDiscovered);
   }
 
-  if (is_preferred && sPreferredDevice_) {
-    connect(*sPreferredDevice_);
+  if (is_paired && sPairedWith_) {
+    connect(*sPairedWith_);
   }
 }
 
 auto BluetoothState::connect(const MacAndName& dev) -> bool {
-  if (sConnectingDevice_ && sConnectingDevice_->mac == dev.mac) {
+  if (sConnectingTo_ && sConnectingTo_->mac == dev.mac) {
     sConnectAttemptsRemaining_--;
   } else {
     sConnectAttemptsRemaining_ = 3;
   }
 
   if (sConnectAttemptsRemaining_ == 0) {
+    sConnectingTo_ = {};
     return false;
   }
 
-  sConnectingDevice_ = dev;
+  sConnectingTo_ = dev;
   ESP_LOGI(kTag, "connecting to '%s' (%u%u%u%u%u%u)", dev.name.c_str(),
            dev.mac[0], dev.mac[1], dev.mac[2], dev.mac[3], dev.mac[4],
            dev.mac[5]);
-  if (esp_a2d_source_connect(sConnectingDevice_->mac.data()) != ESP_OK) {
+  if (esp_a2d_source_connect(sConnectingTo_->mac.data()) != ESP_OK) {
     ESP_LOGI(kTag, "Connecting failed...");
     if (sConnectAttemptsRemaining_ > 1) {
       ESP_LOGI(kTag, "Will retry.");
@@ -489,7 +531,7 @@ void Disabled::react(const events::Enable&) {
 
   // Set a reasonable name for the device.
   std::pmr::string name = DeviceName();
-  esp_bt_dev_set_device_name(name.c_str());
+  esp_bt_gap_set_device_name(name.c_str());
 
   // Initialise GAP. This controls advertising our device, and scanning for
   // other devices.
@@ -553,36 +595,31 @@ void Disabled::react(const events::Enable&) {
   esp_bt_gap_set_scan_mode(ESP_BT_NON_CONNECTABLE, ESP_BT_NON_DISCOVERABLE);
 
   ESP_LOGI(kTag, "bt enabled");
-  if (sPreferredDevice_) {
-    ESP_LOGI(kTag, "connecting to preferred device '%s'",
-             sPreferredDevice_->name.c_str());
-    connect(*sPreferredDevice_);
+  if (sPairedWith_) {
+    ESP_LOGI(kTag, "connecting to paired device '%s'",
+             sPairedWith_->name.c_str());
+    connect(*sPairedWith_);
   } else {
-    ESP_LOGI(kTag, "scanning for devices");
     transit<Idle>();
   }
 }
 
 void Idle::entry() {
   ESP_LOGI(kTag, "bt is idle");
-  sScanner_->ScanContinuously();
+  std::invoke(sEventHandler_, SimpleEvent::kConnectionStateChanged);
 }
 
 void Idle::exit() {
-  sScanner_->StopScanning();
+  std::invoke(sEventHandler_, SimpleEvent::kConnectionStateChanged);
 }
 
 void Idle::react(const events::Disable& ev) {
   transit<Disabled>();
 }
 
-void Idle::react(const events::PreferredDeviceChanged& ev) {
-  bool is_discovered = false;
-  if (sPreferredDevice_ && sDevices_.contains(sPreferredDevice_->mac)) {
-    is_discovered = true;
-  }
-  if (is_discovered) {
-    connect(*sPreferredDevice_);
+void Idle::react(const events::PairedDeviceChanged& ev) {
+  if (sPairedWith_) {
+    connect(*sPairedWith_);
   }
 }
 
@@ -604,36 +641,32 @@ void Connecting::entry() {
   sTimeoutTimer = xTimerCreate("bt_timeout", pdMS_TO_TICKS(15000), false, NULL,
                                timeoutCallback);
   xTimerStart(sTimeoutTimer, portMAX_DELAY);
-
-  sScanner_->StopScanning();
-  if (sEventHandler_) {
-    std::invoke(sEventHandler_, SimpleEvent::kConnectionStateChanged);
-  }
 }
 
 void Connecting::exit() {
   xTimerDelete(sTimeoutTimer, portMAX_DELAY);
-
-  if (sEventHandler_) {
-    std::invoke(sEventHandler_, SimpleEvent::kConnectionStateChanged);
-  }
 }
 
 void Connecting::react(const events::ConnectTimedOut& ev) {
   ESP_LOGI(kTag, "timed out awaiting connection");
-  esp_a2d_source_disconnect(sConnectingDevice_->mac.data());
-  if (!connect(*sConnectingDevice_)) {
+  esp_a2d_source_disconnect(sConnectingTo_->mac.data());
+  if (!connect(*sConnectingTo_)) {
     transit<Idle>();
   }
 }
 
 void Connecting::react(const events::Disable& ev) {
-  // TODO: disconnect gracefully
+  esp_a2d_source_disconnect(sConnectingTo_->mac.data());
   transit<Disabled>();
 }
 
-void Connecting::react(const events::PreferredDeviceChanged& ev) {
-  // TODO. Cancel out and start again.
+void Connecting::react(const events::PairedDeviceChanged& ev) {
+  esp_a2d_source_disconnect(sConnectingTo_->mac.data());
+  if (sPairedWith_) {
+    connect(*sPairedWith_);
+  } else {
+    transit<Idle>();
+  }
 }
 
 void Connecting::react(events::internal::Gap ev) {
@@ -704,29 +737,41 @@ void Connected::entry() {
   ESP_LOGI(kTag, "entering connected state");
 
   transaction_num_ = 0;
-  connected_to_ = sConnectingDevice_->mac;
-  sPreferredDevice_ = sConnectingDevice_;
-  sConnectingDevice_ = {};
+  connected_to_ = sConnectingTo_->mac;
+  sPairedWith_ = sConnectingTo_;
+
+  sStorage_->BluetoothName(sConnectingTo_->mac, sConnectingTo_->name);
+  std::invoke(sEventHandler_, SimpleEvent::kKnownDevicesChanged);
+
+  sConnectingTo_ = {};
 
   auto stored_pref = sStorage_->PreferredBluetoothDevice();
-  if (!stored_pref || (sPreferredDevice_->name != stored_pref->name ||
-                       sPreferredDevice_->mac != stored_pref->mac)) {
-    sStorage_->PreferredBluetoothDevice(sPreferredDevice_);
+  if (!stored_pref || (sPairedWith_->name != stored_pref->name ||
+                       sPairedWith_->mac != stored_pref->mac)) {
+    sStorage_->PreferredBluetoothDevice(sPairedWith_);
   }
+
+  std::invoke(sEventHandler_, SimpleEvent::kConnectionStateChanged);
+
+  // TODO: if we already have a source, immediately start playing
 }
 
 void Connected::exit() {
   ESP_LOGI(kTag, "exiting connected state");
   esp_a2d_source_disconnect(connected_to_.data());
+
+  std::invoke(sEventHandler_, SimpleEvent::kConnectionStateChanged);
 }
 
 void Connected::react(const events::Disable& ev) {
   transit<Disabled>();
 }
 
-void Connected::react(const events::PreferredDeviceChanged& ev) {
-  sConnectingDevice_ = sPreferredDevice_;
-  transit<Connecting>();
+void Connected::react(const events::PairedDeviceChanged& ev) {
+  transit<Idle>();
+  if (sPairedWith_) {
+    connect(*sPairedWith_);
+  }
 }
 
 void Connected::react(const events::SourcesChanged& ev) {
diff --git a/src/drivers/display.cpp b/src/drivers/display.cpp
index efc9df93..7321f20b 100644
--- a/src/drivers/display.cpp
+++ b/src/drivers/display.cpp
@@ -242,6 +242,7 @@ void Display::SendInitialisationSequence(const uint8_t* data) {
   spi_device_release_bus(handle_);
 }
 
+IRAM_ATTR
 void Display::SendCommandWithData(uint8_t command,
                                   const uint8_t* data,
                                   size_t length) {
@@ -249,17 +250,20 @@ void Display::SendCommandWithData(uint8_t command,
   SendData(data, length);
 }
 
+IRAM_ATTR
 void Display::SendCmd(const uint8_t* data, size_t length) {
   SendTransaction(COMMAND, data, length);
 }
 
+IRAM_ATTR
 void Display::SendData(const uint8_t* data, size_t length) {
   SendTransaction(DATA, data, length);
 }
 
+IRAM_ATTR
 void Display::SendTransaction(TransactionType type,
-                              const uint8_t* data,
-                              size_t length) {
+                                        const uint8_t* data,
+                                        size_t length) {
   // TODO(jacqueline): What's sending this?
   if (length == 0) {
     return;
@@ -290,6 +294,7 @@ void Display::SendTransaction(TransactionType type,
   ESP_ERROR_CHECK(spi_device_transmit(handle_, &sTransaction));
 }
 
+IRAM_ATTR
 void Display::OnLvglFlush(const lv_area_t* area, uint8_t* color_map) {
   // Swap the pixel byte order first, since we don't want to do this whilst
   // holding the SPI bus lock.
diff --git a/src/drivers/i2s_dac.cpp b/src/drivers/i2s_dac.cpp
index 4e2e171a..46bf8e80 100644
--- a/src/drivers/i2s_dac.cpp
+++ b/src/drivers/i2s_dac.cpp
@@ -46,12 +46,12 @@ extern "C" IRAM_ATTR auto callback(i2s_chan_handle_t handle,
   if (event == nullptr || user_ctx == nullptr) {
     return false;
   }
-  if (event->data == nullptr || event->size == 0) {
+  if (event->dma_buf == nullptr || event->size == 0) {
     return false;
   }
   assert(event->size % 4 == 0);
 
-  uint8_t* buf = *reinterpret_cast<uint8_t**>(event->data);
+  uint8_t* buf = reinterpret_cast<uint8_t*>(event->dma_buf);
   auto* src = reinterpret_cast<OutputBuffers*>(user_ctx);
 
   BaseType_t ret1 = src->first.receive(
diff --git a/src/drivers/include/drivers/bluetooth.hpp b/src/drivers/include/drivers/bluetooth.hpp
index eaecfb2b..99c71e52 100644
--- a/src/drivers/include/drivers/bluetooth.hpp
+++ b/src/drivers/include/drivers/bluetooth.hpp
@@ -3,6 +3,7 @@
 
 #include <array>
 #include <atomic>
+#include <functional>
 #include <map>
 #include <mutex>
 #include <optional>
@@ -25,28 +26,68 @@
 namespace drivers {
 
 /*
- * A handle used to interact with the bluetooth state machine.
+ * A handle used to interact with the bluetooth state machine. This is the main
+ * API that the rest of the system should use to interact with Bluetooth.
  */
 class Bluetooth {
  public:
-  Bluetooth(NvsStorage& storage, tasks::WorkerPool&);
+  /*
+   * Callback invoked when an event is generated by the Bluetooth stack. This
+   * callback is invoked synchronously from a Bluetooth task context, so
+   * implementations should immediately hop to a different task to process the
+   * event.
+   */
+  using EventHandler = std::function<void(bluetooth::Event)>;
+
+  Bluetooth(NvsStorage&, tasks::WorkerPool&, EventHandler);
+
+  /* Enables or disables the entire Bluetooth stack. */
+  auto enable(bool en) -> void;
+  auto enabled() -> bool;
+
+  auto sources(OutputBuffers*) -> void;
+  auto softVolume(float) -> void;
+
+  enum class ConnectionState {
+    kConnected,
+    kConnecting,
+    kDisconnected,
+  };
+
+  auto connectionState() -> ConnectionState;
+
+  /*
+   * The 'paired' device is a device that will be preferred for connections.
+   * When Bluetooth is first enabled, we immediately try to connect to the
+   * paired device. If the paired device is seen during a scan, then we will
+   * also automatically connect to it.
+   */
+  auto pairedDevice() -> std::optional<bluetooth::MacAndName>;
+
+  /*
+   * Sets the preferred device. If a device is provided, a connection will be
+   * attempted immediately, even if the device has not been detected in a
+   * previous scan.
+   */
+  auto pairedDevice(std::optional<bluetooth::MacAndName> dev) -> void;
+
+  /* A list of devices that have previously been the paired device. */
+  auto knownDevices() -> std::vector<bluetooth::MacAndName>;
+  auto forgetKnownDevice(const bluetooth::mac_addr_t&) -> void;
+
+  /* Enables or disables scanning for nearby Bluetooth devices. */
+  auto discoveryEnabled(bool) -> void;
+  auto discoveryEnabled() -> bool;
+
+  /*
+   * A list of nearby devices that have been discovered since discovery was
+   * last enabled. This list may include the paired device, as well as devices
+   * that are also present in the known devices list.
+   */
+  auto discoveredDevices() -> std::vector<bluetooth::MacAndName>;
 
-  auto Enable() -> bool;
-  auto Disable() -> void;
-  auto IsEnabled() -> bool;
-
-  auto IsConnected() -> bool;
-  auto ConnectedDevice() -> std::optional<bluetooth::MacAndName>;
-
-  auto KnownDevices() -> std::vector<bluetooth::Device>;
-
-  auto SetPreferredDevice(std::optional<bluetooth::MacAndName> dev) -> void;
-  auto PreferredDevice() -> std::optional<bluetooth::MacAndName>;
-
-  auto SetSources(OutputBuffers*) -> void;
-  auto SetVolumeFactor(float) -> void;
-
-  auto SetEventHandler(std::function<void(bluetooth::Event)> cb) -> void;
+ private:
+  NvsStorage& nvs_;
 };
 
 namespace bluetooth {
@@ -56,7 +97,7 @@ struct Enable : public tinyfsm::Event {};
 struct Disable : public tinyfsm::Event {};
 
 struct ConnectTimedOut : public tinyfsm::Event {};
-struct PreferredDeviceChanged : public tinyfsm::Event {};
+struct PairedDeviceChanged : public tinyfsm::Event {};
 struct SourcesChanged : public tinyfsm::Event {};
 struct DeviceDiscovered : public tinyfsm::Event {
   const Device& device;
@@ -94,6 +135,8 @@ class Scanner {
   auto StopScanning() -> void;
   auto StopScanningNow() -> void;
 
+  auto enabled() -> bool;
+
   auto HandleGapEvent(const events::internal::Gap&) -> void;
 
  private:
@@ -103,25 +146,22 @@ class Scanner {
   auto HandleDeviceDiscovery(const esp_bt_gap_cb_param_t& param) -> void;
 };
 
+/*
+ * The main state machine for managing the state of the Bluetooth stack, and
+ * the current (if any) Bluetooth connection.
+ */
 class BluetoothState : public tinyfsm::Fsm<BluetoothState> {
  public:
-  static auto Init(NvsStorage& storage) -> void;
+  static auto Init(NvsStorage& storage, Bluetooth::EventHandler) -> void;
 
   static auto lock() -> std::lock_guard<std::mutex>;
 
-  static auto devices() -> std::vector<Device>;
-
-  static auto preferred_device() -> std::optional<bluetooth::MacAndName>;
-  static auto preferred_device(std::optional<bluetooth::MacAndName>) -> void;
+  static auto pairedDevice() -> std::optional<bluetooth::MacAndName>;
+  static auto pairedDevice(std::optional<bluetooth::MacAndName>) -> void;
 
-  static auto scanning() -> bool;
   static auto discovery() -> bool;
   static auto discovery(bool) -> void;
-
-  static auto sources() -> OutputBuffers*;
-  static auto sources(OutputBuffers*) -> void;
-
-  static auto event_handler(std::function<void(Event)>) -> void;
+  static auto discoveredDevices() -> std::vector<Device>;
 
   virtual ~BluetoothState(){};
 
@@ -131,7 +171,7 @@ class BluetoothState : public tinyfsm::Fsm<BluetoothState> {
   virtual void react(const events::Enable& ev){};
   virtual void react(const events::Disable& ev) = 0;
   virtual void react(const events::ConnectTimedOut& ev){};
-  virtual void react(const events::PreferredDeviceChanged& ev){};
+  virtual void react(const events::PairedDeviceChanged& ev){};
   virtual void react(const events::SourcesChanged& ev){};
 
   virtual void react(const events::DeviceDiscovered&);
@@ -146,10 +186,9 @@ class BluetoothState : public tinyfsm::Fsm<BluetoothState> {
   static Scanner* sScanner_;
 
   static std::mutex sFsmMutex;
-  static std::map<mac_addr_t, Device> sDevices_;
-  static std::optional<bluetooth::MacAndName> sPreferredDevice_;
-
-  static std::optional<bluetooth::MacAndName> sConnectingDevice_;
+  static std::map<mac_addr_t, Device> sDiscoveredDevices_;
+  static std::optional<bluetooth::MacAndName> sPairedWith_;
+  static std::optional<bluetooth::MacAndName> sConnectingTo_;
   static int sConnectAttemptsRemaining_;
 
   static std::function<void(Event)> sEventHandler_;
@@ -176,7 +215,7 @@ class Idle : public BluetoothState {
   void exit() override;
 
   void react(const events::Disable& ev) override;
-  void react(const events::PreferredDeviceChanged& ev) override;
+  void react(const events::PairedDeviceChanged& ev) override;
 
   void react(events::internal::Gap ev) override;
 
@@ -188,7 +227,7 @@ class Connecting : public BluetoothState {
   void entry() override;
   void exit() override;
 
-  void react(const events::PreferredDeviceChanged& ev) override;
+  void react(const events::PairedDeviceChanged& ev) override;
 
   void react(const events::ConnectTimedOut& ev) override;
   void react(const events::Disable& ev) override;
@@ -203,7 +242,7 @@ class Connected : public BluetoothState {
   void entry() override;
   void exit() override;
 
-  void react(const events::PreferredDeviceChanged& ev) override;
+  void react(const events::PairedDeviceChanged& ev) override;
   void react(const events::SourcesChanged& ev) override;
 
   void react(const events::Disable& ev) override;
diff --git a/src/drivers/include/drivers/bluetooth_types.hpp b/src/drivers/include/drivers/bluetooth_types.hpp
index d2e55ee5..05caee47 100644
--- a/src/drivers/include/drivers/bluetooth_types.hpp
+++ b/src/drivers/include/drivers/bluetooth_types.hpp
@@ -27,9 +27,12 @@ struct Device {
 };
 
 enum class SimpleEvent {
-  kKnownDevicesChanged,
   kConnectionStateChanged,
-  kPreferredDeviceChanged,
+  kPairedDeviceChanged,
+  kKnownDevicesChanged,
+  kDiscoveryChanged,
+  kDeviceDiscovered,
+
   // Passthrough events
   kPlayPause,
   kStop,
diff --git a/src/drivers/include/drivers/nvs.hpp b/src/drivers/include/drivers/nvs.hpp
index 88dd5ae0..e147c8c7 100644
--- a/src/drivers/include/drivers/nvs.hpp
+++ b/src/drivers/include/drivers/nvs.hpp
@@ -34,7 +34,7 @@ class Setting {
       dirty_ = true;
     }
   }
-  auto get() -> std::optional<T>& { return val_; }
+  auto get() -> std::optional<T> { return val_; }
 
   /* Reads the stored value from NVS and parses it into the correct type. */
   auto load(nvs_handle_t) -> std::optional<T>;
@@ -90,12 +90,19 @@ class NvsStorage {
   auto LraCalibration() -> std::optional<LraData>;
   auto LraCalibration(const LraData&) -> void;
 
+  auto FastCharge() -> bool;
+  auto FastCharge(bool) -> void;
+
   auto PreferredBluetoothDevice() -> std::optional<bluetooth::MacAndName>;
   auto PreferredBluetoothDevice(std::optional<bluetooth::MacAndName>) -> void;
 
   auto BluetoothVolume(const bluetooth::mac_addr_t&) -> uint8_t;
   auto BluetoothVolume(const bluetooth::mac_addr_t&, uint8_t) -> void;
 
+  auto BluetoothNames() -> std::vector<bluetooth::MacAndName>;
+  auto BluetoothName(const bluetooth::mac_addr_t&, std::optional<std::string>)
+      -> void;
+
   enum class Output : uint8_t {
     kHeadphones = 0,
     kBluetooth = 1,
@@ -106,6 +113,9 @@ class NvsStorage {
   auto ScreenBrightness() -> uint_fast8_t;
   auto ScreenBrightness(uint_fast8_t) -> void;
 
+  auto InterfaceTheme() -> std::optional<std::string>;
+  auto InterfaceTheme(std::string) -> void;
+
   auto ScrollSensitivity() -> uint_fast8_t;
   auto ScrollSensitivity(uint_fast8_t) -> void;
 
@@ -146,6 +156,7 @@ class NvsStorage {
   Setting<uint16_t> display_rows_;
   Setting<uint8_t> haptic_motor_type_;
   Setting<LraData> lra_calibration_;
+  Setting<uint8_t> fast_charge_;
 
   Setting<uint8_t> brightness_;
   Setting<uint8_t> sensitivity_;
@@ -154,7 +165,12 @@ class NvsStorage {
   Setting<int8_t> amp_left_bias_;
   Setting<uint8_t> input_mode_;
   Setting<uint8_t> output_mode_;
+
+  Setting<std::string> theme_;
+
   Setting<bluetooth::MacAndName> bt_preferred_;
+  Setting<std::vector<bluetooth::MacAndName>> bt_names_;
+
   Setting<uint8_t> db_auto_index_;
 
   util::LruCache<10, bluetooth::mac_addr_t, uint8_t> bt_volumes_;
diff --git a/src/drivers/include/drivers/pcm_buffer.hpp b/src/drivers/include/drivers/pcm_buffer.hpp
index 968c3398..4e5fa041 100644
--- a/src/drivers/include/drivers/pcm_buffer.hpp
+++ b/src/drivers/include/drivers/pcm_buffer.hpp
@@ -28,8 +28,12 @@ class PcmBuffer {
   PcmBuffer(size_t size_in_samples);
   ~PcmBuffer();
 
-  /* Adds samples to the buffer. */
-  auto send(std::span<const int16_t>) -> void;
+  /*
+   * Adds samples to the buffer. Returns the number of samples that were added,
+   * which may be less than the number of samples given if this PcmBuffer is
+   * close to full.
+   */
+  auto send(std::span<const int16_t>) -> size_t;
 
   /*
    * Fills the given span with samples. If enough samples are available in
diff --git a/src/drivers/include/drivers/samd.hpp b/src/drivers/include/drivers/samd.hpp
index 897e78d6..ff479225 100644
--- a/src/drivers/include/drivers/samd.hpp
+++ b/src/drivers/include/drivers/samd.hpp
@@ -10,6 +10,7 @@
 #include <optional>
 #include <string>
 
+#include "drivers/nvs.hpp"
 #include "freertos/FreeRTOS.h"
 #include "freertos/semphr.h"
 
@@ -17,9 +18,7 @@ namespace drivers {
 
 class Samd {
  public:
-  static auto Create() -> Samd* { return new Samd(); }
-
-  Samd();
+  Samd(NvsStorage& nvs);
   ~Samd();
 
   auto Version() -> std::string;
@@ -37,8 +36,14 @@ class Samd {
     kChargingFast,
     // The battery is full charged, and we are still plugged in.
     kFullCharge,
+    // Charging failed.
+    kFault,
+    // The battery status returned isn't a known enum value.
+    kUnknown,
   };
 
+  static auto chargeStatusToString(ChargeStatus) -> std::string;
+
   auto GetChargeStatus() -> std::optional<ChargeStatus>;
   auto UpdateChargeStatus() -> void;
 
@@ -68,6 +73,8 @@ class Samd {
   Samd& operator=(const Samd&) = delete;
 
  private:
+  NvsStorage& nvs_;
+
   uint8_t version_;
   std::optional<ChargeStatus> charge_status_;
   UsbStatus usb_status_;
diff --git a/src/drivers/include/drivers/touchwheel.hpp b/src/drivers/include/drivers/touchwheel.hpp
index 60902087..9cd925a6 100644
--- a/src/drivers/include/drivers/touchwheel.hpp
+++ b/src/drivers/include/drivers/touchwheel.hpp
@@ -39,7 +39,8 @@ class TouchWheel {
   auto Update() -> void;
   auto GetTouchWheelData() const -> TouchWheelData;
 
-  auto PowerDown() -> void;
+  auto Recalibrate() -> void;
+  auto LowPowerMode(bool en) -> void;
 
  private:
   TouchWheelData data_;
diff --git a/src/drivers/nvs.cpp b/src/drivers/nvs.cpp
index 5c7d2218..d004201b 100644
--- a/src/drivers/nvs.cpp
+++ b/src/drivers/nvs.cpp
@@ -26,8 +26,10 @@ static constexpr uint8_t kSchemaVersion = 1;
 static constexpr char kKeyVersion[] = "ver";
 static constexpr char kKeyBluetoothPreferred[] = "bt_dev";
 static constexpr char kKeyBluetoothVolumes[] = "bt_vols";
+static constexpr char kKeyBluetoothNames[] = "bt_names";
 static constexpr char kKeyOutput[] = "out";
 static constexpr char kKeyBrightness[] = "bright";
+static constexpr char kKeyInterfaceTheme[] = "ui_theme";
 static constexpr char kKeyAmpMaxVolume[] = "hp_vol_max";
 static constexpr char kKeyAmpCurrentVolume[] = "hp_vol";
 static constexpr char kKeyAmpLeftBias[] = "hp_bias";
@@ -39,6 +41,7 @@ static constexpr char kKeyDisplayRows[] = "disprows";
 static constexpr char kKeyHapticMotorType[] = "hapticmtype";
 static constexpr char kKeyLraCalibration[] = "lra_cali";
 static constexpr char kKeyDbAutoIndex[] = "dbautoindex";
+static constexpr char kKeyFastCharge[] = "fastchg";
 
 static auto nvs_get_string(nvs_handle_t nvs, const char* key)
     -> std::optional<std::string> {
@@ -130,6 +133,69 @@ auto Setting<bluetooth::MacAndName>::store(nvs_handle_t nvs,
 }
 
 template <>
+auto Setting<std::vector<bluetooth::MacAndName>>::load(nvs_handle_t nvs)
+    -> std::optional<std::vector<bluetooth::MacAndName>> {
+  auto raw = nvs_get_string(nvs, name_);
+  if (!raw) {
+    return {};
+  }
+  auto [parsed, unused, err] = cppbor::parseWithViews(
+      reinterpret_cast<const uint8_t*>(raw->data()), raw->size());
+  if (parsed->type() != cppbor::MAP) {
+    return {};
+  }
+  std::vector<bluetooth::MacAndName> res;
+  for (const auto& i : *parsed->asMap()) {
+    auto mac = i.first->asViewBstr()->view();
+    auto name = i.second->asViewTstr()->view();
+    bluetooth::MacAndName entry{
+        .mac = {},
+        .name = {name.begin(), name.end()},
+    };
+    std::copy(mac.begin(), mac.end(), entry.mac.begin());
+    res.push_back(entry);
+  }
+  return res;
+}
+
+template <>
+auto Setting<std::vector<bluetooth::MacAndName>>::store(
+    nvs_handle_t nvs,
+    std::vector<bluetooth::MacAndName> v) -> void {
+  cppbor::Map cbor{};
+  for (const auto& i : v) {
+    cbor.add(cppbor::Bstr{{i.mac.data(), i.mac.size()}}, cppbor::Tstr{i.name});
+  }
+  auto encoded = cbor.encode();
+  nvs_set_blob(nvs, name_, encoded.data(), encoded.size());
+}
+
+template <>
+auto Setting<std::string>::store(
+    nvs_handle_t nvs,
+    std::string v) -> void {
+  cppbor::Tstr cbor{v};
+  auto encoded = cbor.encode();
+  nvs_set_blob(nvs, name_, encoded.data(), encoded.size());
+}
+
+template <>
+auto Setting<std::string>::load(nvs_handle_t nvs)
+    -> std::optional<std::string> {
+  auto raw = nvs_get_string(nvs, name_);
+  if (!raw) {
+    return {};
+  }
+  auto [parsed, unused, err] = cppbor::parseWithViews(
+      reinterpret_cast<const uint8_t*>(raw->data()), raw->size());
+  if (parsed->type() != cppbor::TSTR) {
+    return {};
+  }
+  auto v = parsed->asViewTstr()->view();
+  return std::string{v.begin(), v.end()};
+}
+
+template <>
 auto Setting<NvsStorage::LraData>::load(nvs_handle_t nvs)
     -> std::optional<NvsStorage::LraData> {
   auto raw = nvs_get_string(nvs, name_);
@@ -200,6 +266,7 @@ NvsStorage::NvsStorage(nvs_handle_t handle)
       display_rows_(kKeyDisplayRows),
       haptic_motor_type_(kKeyHapticMotorType),
       lra_calibration_(kKeyLraCalibration),
+      fast_charge_(kKeyFastCharge),
       brightness_(kKeyBrightness),
       sensitivity_(kKeyScrollSensitivity),
       amp_max_vol_(kKeyAmpMaxVolume),
@@ -207,7 +274,9 @@ NvsStorage::NvsStorage(nvs_handle_t handle)
       amp_left_bias_(kKeyAmpLeftBias),
       input_mode_(kKeyPrimaryInput),
       output_mode_(kKeyOutput),
+      theme_{kKeyInterfaceTheme},
       bt_preferred_(kKeyBluetoothPreferred),
+      bt_names_(kKeyBluetoothNames),
       db_auto_index_(kKeyDbAutoIndex),
       bt_volumes_(),
       bt_volumes_dirty_(false) {}
@@ -231,7 +300,9 @@ auto NvsStorage::Read() -> void {
   amp_left_bias_.read(handle_);
   input_mode_.read(handle_);
   output_mode_.read(handle_);
+  theme_.read(handle_);
   bt_preferred_.read(handle_);
+  bt_names_.read(handle_);
   db_auto_index_.read(handle_);
   readBtVolumes();
 }
@@ -250,7 +321,9 @@ auto NvsStorage::Write() -> bool {
   amp_left_bias_.write(handle_);
   input_mode_.write(handle_);
   output_mode_.write(handle_);
+  theme_.write(handle_);
   bt_preferred_.write(handle_);
+  bt_names_.write(handle_);
   db_auto_index_.write(handle_);
   writeBtVolumes();
   return nvs_commit(handle_) == ESP_OK;
@@ -341,6 +414,47 @@ auto NvsStorage::BluetoothVolume(const bluetooth::mac_addr_t& mac, uint8_t vol)
   bt_volumes_.Put(mac, vol);
 }
 
+auto NvsStorage::BluetoothNames() -> std::vector<bluetooth::MacAndName> {
+  std::lock_guard<std::mutex> lock{mutex_};
+  return bt_names_.get().value_or(std::vector<bluetooth::MacAndName>{});
+}
+
+auto NvsStorage::BluetoothName(const bluetooth::mac_addr_t& mac,
+                               std::optional<std::string> name) -> void {
+  std::lock_guard<std::mutex> lock{mutex_};
+  auto val = bt_names_.get();
+  if (!val) {
+    val.emplace();
+  }
+
+  bool mut = false;
+  bool found = false;
+  for (auto it = val->begin(); it != val->end(); it++) {
+    if (it->mac == mac) {
+      if (name) {
+        it->name = *name;
+      } else {
+        val->erase(it);
+      }
+      found = true;
+      mut = true;
+      break;
+    }
+  }
+
+  if (!found && name) {
+    val->push_back(bluetooth::MacAndName{
+        .mac = mac,
+        .name = *name,
+    });
+    mut = true;
+  }
+
+  if (mut) {
+    bt_names_.set(*val);
+  }
+}
+
 auto NvsStorage::OutputMode() -> Output {
   std::lock_guard<std::mutex> lock{mutex_};
   switch (output_mode_.get().value_or(0xFF)) {
@@ -361,6 +475,16 @@ auto NvsStorage::OutputMode(Output out) -> void {
   nvs_commit(handle_);
 }
 
+auto NvsStorage::FastCharge() -> bool {
+  std::lock_guard<std::mutex> lock{mutex_};
+  return fast_charge_.get().value_or(true);
+}
+
+auto NvsStorage::FastCharge(bool en) -> void {
+  std::lock_guard<std::mutex> lock{mutex_};
+  fast_charge_.set(en);
+}
+
 auto NvsStorage::ScreenBrightness() -> uint_fast8_t {
   std::lock_guard<std::mutex> lock{mutex_};
   return std::clamp<uint8_t>(brightness_.get().value_or(50), 0, 100);
@@ -371,6 +495,16 @@ auto NvsStorage::ScreenBrightness(uint_fast8_t val) -> void {
   brightness_.set(val);
 }
 
+auto NvsStorage::InterfaceTheme() -> std::optional<std::string> {
+  std::lock_guard<std::mutex> lock{mutex_};
+  return theme_.get();
+}
+
+auto NvsStorage::InterfaceTheme(std::string themeFile) -> void {
+  std::lock_guard<std::mutex> lock{mutex_};
+  theme_.set(themeFile);
+}
+
 auto NvsStorage::ScrollSensitivity() -> uint_fast8_t {
   std::lock_guard<std::mutex> lock{mutex_};
   return std::clamp<uint8_t>(sensitivity_.get().value_or(128), 0, 255);
diff --git a/src/drivers/pcm_buffer.cpp b/src/drivers/pcm_buffer.cpp
index 1d2bab1e..1e416301 100644
--- a/src/drivers/pcm_buffer.cpp
+++ b/src/drivers/pcm_buffer.cpp
@@ -17,6 +17,7 @@
 #include "freertos/FreeRTOS.h"
 
 #include "esp_heap_caps.h"
+#include "freertos/projdefs.h"
 #include "freertos/ringbuf.h"
 #include "portmacro.h"
 
@@ -39,9 +40,13 @@ PcmBuffer::~PcmBuffer() {
   heap_caps_free(buf_);
 }
 
-auto PcmBuffer::send(std::span<const int16_t> data) -> void {
-  xRingbufferSend(ringbuf_, data.data(), data.size_bytes(), portMAX_DELAY);
+auto PcmBuffer::send(std::span<const int16_t> data) -> size_t {
+  if (!xRingbufferSend(ringbuf_, data.data(), data.size_bytes(),
+                       pdMS_TO_TICKS(100))) {
+    return 0;
+  }
   sent_ += data.size();
+  return data.size();
 }
 
 IRAM_ATTR auto PcmBuffer::receive(std::span<int16_t> dest, bool mix, bool isr)
@@ -67,10 +72,12 @@ IRAM_ATTR auto PcmBuffer::receive(std::span<int16_t> dest, bool mix, bool isr)
 
 auto PcmBuffer::clear() -> void {
   while (!isEmpty()) {
-    size_t bytes_cleared;
+    size_t bytes_cleared = 0;
     void* data = xRingbufferReceive(ringbuf_, &bytes_cleared, 0);
-    vRingbufferReturnItem(ringbuf_, data);
-    received_ += bytes_cleared / sizeof(int16_t);
+    if (data) {
+      vRingbufferReturnItem(ringbuf_, data);
+      received_ += bytes_cleared / sizeof(int16_t);
+    }
   }
 }
 
diff --git a/src/drivers/samd.cpp b/src/drivers/samd.cpp
index e4aa73ad..c2308760 100644
--- a/src/drivers/samd.cpp
+++ b/src/drivers/samd.cpp
@@ -5,11 +5,13 @@
  */
 
 #include "drivers/samd.hpp"
+#include <stdint.h>
 
 #include <cstdint>
 #include <optional>
 #include <string>
 
+#include "drivers/nvs.hpp"
 #include "esp_err.h"
 #include "esp_log.h"
 #include "hal/gpio_types.h"
@@ -32,7 +34,29 @@ namespace drivers {
 
 static constexpr gpio_num_t kIntPin = GPIO_NUM_35;
 
-Samd::Samd() {
+auto Samd::chargeStatusToString(ChargeStatus status) -> std::string {
+  switch (status) {
+    case ChargeStatus::kNoBattery:
+      return "no_battery";
+    case ChargeStatus::kBatteryCritical:
+      return "critical";
+    case ChargeStatus::kDischarging:
+      return "discharging";
+    case ChargeStatus::kChargingRegular:
+      return "charge_regular";
+    case ChargeStatus::kChargingFast:
+      return "charge_fast";
+    case ChargeStatus::kFullCharge:
+      return "full_charge";
+    case ChargeStatus::kFault:
+      return "fault";
+    case ChargeStatus::kUnknown:
+    default:
+      return "unknown";
+  }
+}
+
+Samd::Samd(NvsStorage& nvs) : nvs_(nvs) {
   gpio_set_direction(kIntPin, GPIO_MODE_INPUT);
 
   // Being able to interface with the SAMD properly is critical. To ensure we
@@ -51,7 +75,7 @@ Samd::Samd() {
 
   UpdateChargeStatus();
   UpdateUsbStatus();
-  SetFastChargeEnabled(true);
+  SetFastChargeEnabled(nvs.FastCharge());
 }
 Samd::~Samd() {}
 
@@ -78,16 +102,38 @@ auto Samd::UpdateChargeStatus() -> void {
     return;
   }
 
-  // FIXME: Ideally we should be using the three 'charge status' bits to work
-  // out whether we're actually charging, or if we've got a full charge,
-  // critically low charge, etc.
+  // Lower two bits are the usb power status, next three are the BMS status.
+  // See 'gpio.c' in the SAMD21 firmware for how these bits get packed.
+  uint8_t charge_state = (raw_res & 0b11100) >> 2;
   uint8_t usb_state = raw_res & 0b11;
-  if (usb_state == 0) {
-    charge_status_ = ChargeStatus::kDischarging;
-  } else if (usb_state == 1) {
-    charge_status_ = ChargeStatus::kChargingRegular;
-  } else {
-    charge_status_ = ChargeStatus::kChargingFast;
+  switch (charge_state) {
+    case 0b000:
+      charge_status_ = ChargeStatus::kNoBattery;
+      break;
+    case 0b001:
+      // BMS says we're charging; work out how fast we're charging.
+      if (usb_state >= 0b10 && nvs_.FastCharge()) {
+        charge_status_ = ChargeStatus::kChargingFast;
+      } else {
+        charge_status_ = ChargeStatus::kChargingRegular;
+      }
+      break;
+    case 0b010:
+      charge_status_ = ChargeStatus::kFullCharge;
+      break;
+    case 0b011:
+      charge_status_ = ChargeStatus::kFault;
+      break;
+    case 0b100:
+      charge_status_ = ChargeStatus::kBatteryCritical;
+      break;
+    case 0b101:
+      charge_status_ = ChargeStatus::kDischarging;
+      break;
+    case 0b110:
+    case 0b111:
+      charge_status_ = ChargeStatus::kUnknown;
+      break;
   }
 }
 
@@ -127,9 +173,15 @@ auto Samd::ResetToFlashSamd() -> void {
 }
 
 auto Samd::SetFastChargeEnabled(bool en) -> void {
+  // Always update NVS, so that the setting is right after the SAMD firmware is
+  // updated.
+  nvs_.FastCharge(en);
+
   if (version_ < 4) {
     return;
   }
+  ESP_LOGI(kTag, "set fast charge %u", en);
+
   I2CTransaction transaction;
   transaction.start()
       .write_addr(kAddress, I2C_MASTER_WRITE)
diff --git a/src/drivers/spi.cpp b/src/drivers/spi.cpp
index 632fe89f..40487197 100644
--- a/src/drivers/spi.cpp
+++ b/src/drivers/spi.cpp
@@ -41,7 +41,7 @@ esp_err_t init_spi(void) {
       // manages its own use of DMA-capable memory.
       .max_transfer_sz = 4096,
       .flags = SPICOMMON_BUSFLAG_MASTER | SPICOMMON_BUSFLAG_IOMUX_PINS,
-      .isr_cpu_id = ESP_INTR_CPU_AFFINITY_0,
+      .isr_cpu_id = ESP_INTR_CPU_AFFINITY_1,
       .intr_flags = ESP_INTR_FLAG_LOWMED | ESP_INTR_FLAG_IRAM,
   };
 
diff --git a/src/drivers/test/test_samd.cpp b/src/drivers/test/test_samd.cpp
index c466d88e..96248377 100644
--- a/src/drivers/test/test_samd.cpp
+++ b/src/drivers/test/test_samd.cpp
@@ -4,6 +4,7 @@
  * SPDX-License-Identifier: GPL-3.0-only
  */
 
+#include "drivers/nvs.hpp"
 #include "drivers/samd.hpp"
 
 #include <cstdint>
@@ -16,7 +17,8 @@ namespace drivers {
 
 TEST_CASE("samd21 interface", "[integration]") {
   I2CFixture i2c;
-  auto samd = std::make_unique<Samd>();
+  std::unique_ptr<drivers::NvsStorage> nvs{drivers::NvsStorage::OpenSync()};
+  auto samd = std::make_unique<Samd>(*nvs);
 
   REQUIRE(samd);
 
diff --git a/src/drivers/touchwheel.cpp b/src/drivers/touchwheel.cpp
index 5d55c6f2..402b839d 100644
--- a/src/drivers/touchwheel.cpp
+++ b/src/drivers/touchwheel.cpp
@@ -137,8 +137,12 @@ TouchWheelData TouchWheel::GetTouchWheelData() const {
   return data_;
 }
 
-auto TouchWheel::PowerDown() -> void {
-  WriteRegister(LOW_POWER, 0);
+auto TouchWheel::Recalibrate() -> void {
+  WriteRegister(CALIBRATE, 1);
+}
+
+auto TouchWheel::LowPowerMode(bool en) -> void {
+  WriteRegister(LOW_POWER, en ? 0 : 1);
 }
 
 }  // namespace drivers