diff --git a/src/app_console/app_console.cpp b/src/app_console/app_console.cpp
index e9bd7cdc..f6b23215 100644
--- a/src/app_console/app_console.cpp
+++ b/src/app_console/app_console.cpp
@@ -496,7 +496,7 @@ int CmdSamd(int argc, char** argv) {
 
     AppConsole::sSamd->ResetToFlashSamd();
   } else if (cmd == "charge") {
-    auto res = AppConsole::sSamd->ReadChargeStatus();
+    auto res = AppConsole::sSamd->GetChargeStatus();
     if (res) {
       switch (res.value()) {
         case drivers::Samd::ChargeStatus::kNoBattery:
diff --git a/src/drivers/gpios.cpp b/src/drivers/gpios.cpp
index f6293697..412c091f 100644
--- a/src/drivers/gpios.cpp
+++ b/src/drivers/gpios.cpp
@@ -58,7 +58,9 @@ constexpr std::pair<uint8_t, uint8_t> unpack(uint16_t ba) {
   return std::pair((uint8_t)ba, (uint8_t)(ba >> 8));
 }
 
-void interrupt_isr(void* arg) {
+SemaphoreHandle_t Gpios::sReadPending;
+
+static void interrupt_isr(void* arg) {
   SemaphoreHandle_t sem = reinterpret_cast<SemaphoreHandle_t>(arg);
   xSemaphoreGive(sem);
 }
@@ -73,10 +75,7 @@ auto Gpios::Create() -> Gpios* {
   return instance;
 }
 
-Gpios::Gpios()
-    : ports_(pack(kPortADefault, kPortBDefault)),
-      inputs_(0),
-      read_pending_(xSemaphoreCreateBinary()) {
+Gpios::Gpios() : ports_(pack(kPortADefault, kPortBDefault)), inputs_(0) {
   gpio_config_t config{
       .pin_bit_mask = static_cast<uint64_t>(1) << GPIO_NUM_34,
       .mode = GPIO_MODE_INPUT,
@@ -87,6 +86,7 @@ Gpios::Gpios()
   gpio_config(&config);
   gpio_install_isr_service(ESP_INTR_FLAG_LOWMED | ESP_INTR_FLAG_SHARED |
                            ESP_INTR_FLAG_IRAM);
+  gpio_isr_handler_add(GPIO_NUM_34, &interrupt_isr, sReadPending);
 }
 
 Gpios::~Gpios() {
@@ -141,8 +141,9 @@ auto Gpios::Read() -> bool {
   return true;
 }
 
-auto Gpios::InstallReadPendingISR() -> void {
-  gpio_isr_handler_add(GPIO_NUM_34, &interrupt_isr, read_pending_);
+auto Gpios::CreateReadPending() -> SemaphoreHandle_t {
+  sReadPending = xSemaphoreCreateBinary();
+  return sReadPending;
 }
 
 }  // namespace drivers
diff --git a/src/drivers/include/gpios.hpp b/src/drivers/include/gpios.hpp
index 5ac475bf..fe330e3b 100644
--- a/src/drivers/include/gpios.hpp
+++ b/src/drivers/include/gpios.hpp
@@ -107,8 +107,7 @@ class Gpios : public IGpios {
    */
   auto Read(void) -> bool;
 
-  auto InstallReadPendingISR() -> void;
-  auto IsReadPending() -> SemaphoreHandle_t { return read_pending_; }
+  static auto CreateReadPending() -> SemaphoreHandle_t;
 
   // Not copyable or movable. There should usually only ever be once instance
   // of this class, and that instance will likely have a static lifetime.
@@ -121,7 +120,7 @@ class Gpios : public IGpios {
   std::atomic<uint16_t> ports_;
   std::atomic<uint16_t> inputs_;
 
-  SemaphoreHandle_t read_pending_;
+  static SemaphoreHandle_t sReadPending;
 };
 
 }  // namespace drivers
diff --git a/src/drivers/include/samd.hpp b/src/drivers/include/samd.hpp
index 1560b590..4a31a577 100644
--- a/src/drivers/include/samd.hpp
+++ b/src/drivers/include/samd.hpp
@@ -8,6 +8,9 @@
 
 #include <optional>
 
+#include "freertos/FreeRTOS.h"
+#include "freertos/semphr.h"
+
 namespace drivers {
 
 class Samd {
@@ -32,7 +35,8 @@ class Samd {
     kFullCharge,
   };
 
-  auto ReadChargeStatus() -> std::optional<ChargeStatus>;
+  auto GetChargeStatus() -> std::optional<ChargeStatus>;
+  auto UpdateChargeStatus() -> void;
 
   enum class UsbStatus {
     // There is no compatible usb host attached.
@@ -44,9 +48,23 @@ class Samd {
     kAttachedMounted,
   };
 
-  auto ReadUsbStatus() -> UsbStatus;
+  auto GetUsbStatus() -> UsbStatus;
+  auto UpdateUsbStatus() -> void;
 
   auto ResetToFlashSamd() -> void;
+
+  static auto CreateReadPending() -> SemaphoreHandle_t;
+
+  // Not copyable or movable. There should usually only ever be once instance
+  // of this class, and that instance will likely have a static lifetime.
+  Samd(const Samd&) = delete;
+  Samd& operator=(const Samd&) = delete;
+
+ private:
+  std::optional<ChargeStatus> charge_status_;
+  UsbStatus usb_status_;
+
+  static SemaphoreHandle_t sReadPending;
 };
 
 }  // namespace drivers
diff --git a/src/drivers/samd.cpp b/src/drivers/samd.cpp
index e7bfbb6b..455e9ce5 100644
--- a/src/drivers/samd.cpp
+++ b/src/drivers/samd.cpp
@@ -26,7 +26,24 @@ static const char kTag[] = "SAMD";
 
 namespace drivers {
 
+SemaphoreHandle_t Samd::sReadPending;
+
+static void interrupt_isr(void* arg) {
+  SemaphoreHandle_t sem = reinterpret_cast<SemaphoreHandle_t>(arg);
+  xSemaphoreGive(sem);
+}
+
 Samd::Samd() {
+  gpio_config_t config{
+      .pin_bit_mask = static_cast<uint64_t>(1) << GPIO_NUM_35,
+      .mode = GPIO_MODE_INPUT,
+      .pull_up_en = GPIO_PULLUP_ENABLE,
+      .pull_down_en = GPIO_PULLDOWN_DISABLE,
+      .intr_type = GPIO_INTR_NEGEDGE,
+  };
+  gpio_config(&config);
+  gpio_isr_handler_add(GPIO_NUM_35, &interrupt_isr, sReadPending);
+
   // Being able to interface with the SAMD properly is critical. To ensure we
   // will be able to, we begin by checking the I2C protocol version is
   // compatible, and throw if it's not.
@@ -41,10 +58,17 @@ Samd::Samd() {
       .stop();
   ESP_ERROR_CHECK(transaction.Execute());
   ESP_LOGI(kTag, "samd firmware rev: %u", raw_res);
+
+  UpdateChargeStatus();
+  UpdateUsbStatus();
 }
 Samd::~Samd() {}
 
-auto Samd::ReadChargeStatus() -> std::optional<ChargeStatus> {
+auto Samd::GetChargeStatus() -> std::optional<ChargeStatus> {
+  return charge_status_;
+}
+
+auto Samd::UpdateChargeStatus() -> void {
   uint8_t raw_res;
   I2CTransaction transaction;
   transaction.start()
@@ -54,31 +78,39 @@ auto Samd::ReadChargeStatus() -> std::optional<ChargeStatus> {
       .write_addr(kAddress, I2C_MASTER_READ)
       .read(&raw_res, I2C_MASTER_NACK)
       .stop();
-  ESP_LOGI(kTag, "checking charge status");
   ESP_ERROR_CHECK(transaction.Execute());
-  ESP_LOGI(kTag, "raw charge status: 0x%x", raw_res);
 
   uint8_t usb_state = raw_res & 0b11;
   uint8_t charge_state = (raw_res >> 2) & 0b111;
   switch (charge_state) {
     case 0b000:
     case 0b011:
-      return ChargeStatus::kNoBattery;
+      charge_status_ = ChargeStatus::kNoBattery;
+      break;
     case 0b001:
-      return usb_state == 1 ? ChargeStatus::kChargingRegular
-                            : ChargeStatus::kChargingFast;
+      charge_status_ = usb_state == 1 ? ChargeStatus::kChargingRegular
+                                      : ChargeStatus::kChargingFast;
+      break;
     case 0b010:
-      return ChargeStatus::kFullCharge;
+      charge_status_ = ChargeStatus::kFullCharge;
+      break;
     case 0b100:
-      return ChargeStatus::kBatteryCritical;
+      charge_status_ = ChargeStatus::kBatteryCritical;
+      break;
     case 0b101:
-      return ChargeStatus::kDischarging;
+      charge_status_ = ChargeStatus::kDischarging;
+      break;
     default:
-      return {};
+      charge_status_ = {};
+      break;
   }
 }
 
-auto Samd::ReadUsbStatus() -> UsbStatus {
+auto Samd::GetUsbStatus() -> UsbStatus {
+  return usb_status_;
+}
+
+auto Samd::UpdateUsbStatus() -> void {
   uint8_t raw_res;
   I2CTransaction transaction;
   transaction.start()
@@ -88,15 +120,13 @@ auto Samd::ReadUsbStatus() -> UsbStatus {
       .write_addr(kAddress, I2C_MASTER_READ)
       .read(&raw_res, I2C_MASTER_NACK)
       .stop();
-  ESP_LOGI(kTag, "checking usb status");
   ESP_ERROR_CHECK(transaction.Execute());
-  ESP_LOGI(kTag, "raw usb status: 0x%x", raw_res);
 
   if (!(raw_res & 0b1)) {
-    return UsbStatus::kDetached;
+    usb_status_ = UsbStatus::kDetached;
   }
-  return (raw_res & 0b10) ? UsbStatus::kAttachedMounted
-                          : UsbStatus::kAttachedIdle;
+  usb_status_ =
+      (raw_res & 0b10) ? UsbStatus::kAttachedMounted : UsbStatus::kAttachedIdle;
 }
 
 auto Samd::ResetToFlashSamd() -> void {
@@ -108,4 +138,9 @@ auto Samd::ResetToFlashSamd() -> void {
   ESP_ERROR_CHECK(transaction.Execute());
 }
 
+auto Samd::CreateReadPending() -> SemaphoreHandle_t {
+  sReadPending = xSemaphoreCreateBinary();
+  return sReadPending;
+}
+
 }  // namespace drivers
diff --git a/src/main/main.cpp b/src/main/main.cpp
index 685e1fc1..f6aba812 100644
--- a/src/main/main.cpp
+++ b/src/main/main.cpp
@@ -18,7 +18,8 @@
 
 extern "C" void app_main(void) {
   ESP_ERROR_CHECK(drivers::init_i2c());
-  drivers::Gpios* gpios = system_fsm::SystemState::early_init_gpios();
+  SemaphoreHandle_t gpios_semphr = drivers::Gpios::CreateReadPending();
+  SemaphoreHandle_t samd_semphr = drivers::Samd::CreateReadPending();
 
   // Semaphores must be empty before being added to a queue set. Hence all this
   // weird early init stuff; by being explicit about initialisation order, we're
@@ -27,7 +28,8 @@ extern "C" void app_main(void) {
   QueueSetHandle_t set = xQueueCreateSet(2);
   auto* event_queue = events::queues::SystemAndAudio();
   xQueueAddToSet(event_queue->has_events(), set);
-  xQueueAddToSet(gpios->IsReadPending(), set);
+  xQueueAddToSet(gpios_semphr, set);
+  xQueueAddToSet(samd_semphr, set);
 
   tinyfsm::FsmList<system_fsm::SystemState, ui::UiState,
                    audio::AudioState>::start();
@@ -36,9 +38,12 @@ extern "C" void app_main(void) {
     QueueSetMemberHandle_t member = xQueueSelectFromSet(set, portMAX_DELAY);
     if (member == event_queue->has_events()) {
       event_queue->Service(0);
-    } else if (member == gpios->IsReadPending()) {
+    } else if (member == gpios_semphr) {
       xSemaphoreTake(member, 0);
       events::System().Dispatch(system_fsm::internal::GpioInterrupt{});
+    } else if (member == samd_semphr) {
+      xSemaphoreTake(member, 0);
+      events::System().Dispatch(system_fsm::internal::SamdInterrupt{});
     }
   }
 }
diff --git a/src/system_fsm/booting.cpp b/src/system_fsm/booting.cpp
index 2a4d5f5c..6720fb4a 100644
--- a/src/system_fsm/booting.cpp
+++ b/src/system_fsm/booting.cpp
@@ -39,7 +39,7 @@ auto Booting::entry() -> void {
   // I2C and SPI are both always needed. We can't even power down or show an
   // error without these.
   ESP_ERROR_CHECK(drivers::init_spi());
-  sGpios->InstallReadPendingISR();
+  sGpios.reset(drivers::Gpios::Create());
 
   // Start bringing up LVGL now, since we have all of its prerequisites.
   sTrackQueue.reset(new audio::TrackQueue());
@@ -97,7 +97,7 @@ auto Booting::react(const BootComplete& ev) -> void {
   // It's possible that the SAMD is currently exposing the SD card as a USB
   // device. Make sure we don't immediately try to claim it.
   if (sSamd &&
-      sSamd->ReadUsbStatus() == drivers::Samd::UsbStatus::kAttachedMounted) {
+      sSamd->GetUsbStatus() == drivers::Samd::UsbStatus::kAttachedMounted) {
     transit<Unmounted>();
   }
   transit<Running>();
diff --git a/src/system_fsm/include/system_events.hpp b/src/system_fsm/include/system_events.hpp
index 0903cb77..87461f0b 100644
--- a/src/system_fsm/include/system_events.hpp
+++ b/src/system_fsm/include/system_events.hpp
@@ -60,6 +60,8 @@ struct HasPhonesChanged : tinyfsm::Event {
   bool falling;
 };
 
+struct ChargingStatusChanged : tinyfsm::Event {};
+
 namespace internal {
 
 /*
@@ -68,11 +70,8 @@ namespace internal {
  */
 struct ReadyToUnmount : tinyfsm::Event {};
 
-/*
- * Sent when the actual unmount operation should be performed. Always dispatched
- * by SysState in response to StoragePrepareToUnmount.
- */
 struct GpioInterrupt : tinyfsm::Event {};
+struct SamdInterrupt : tinyfsm::Event {};
 
 }  // namespace internal
 
diff --git a/src/system_fsm/include/system_fsm.hpp b/src/system_fsm/include/system_fsm.hpp
index 3d513666..b31cc6b7 100644
--- a/src/system_fsm/include/system_fsm.hpp
+++ b/src/system_fsm/include/system_fsm.hpp
@@ -35,8 +35,6 @@ class SystemState : public tinyfsm::Fsm<SystemState> {
  public:
   virtual ~SystemState() {}
 
-  static auto early_init_gpios() -> drivers::Gpios*;
-
   virtual void entry() {}
   virtual void exit() {}
 
@@ -45,6 +43,7 @@ class SystemState : public tinyfsm::Fsm<SystemState> {
 
   void react(const FatalError&);
   void react(const internal::GpioInterrupt&);
+  void react(const internal::SamdInterrupt&);
 
   virtual void react(const DisplayReady&) {}
   virtual void react(const BootComplete&) {}
diff --git a/src/system_fsm/system_fsm.cpp b/src/system_fsm/system_fsm.cpp
index 96e806f4..24f65a4f 100644
--- a/src/system_fsm/system_fsm.cpp
+++ b/src/system_fsm/system_fsm.cpp
@@ -13,6 +13,8 @@
 #include "tag_parser.hpp"
 #include "track_queue.hpp"
 
+static const char kTag[] = "system";
+
 namespace system_fsm {
 
 std::shared_ptr<drivers::Gpios> SystemState::sGpios;
@@ -33,11 +35,6 @@ std::shared_ptr<audio::TrackQueue> SystemState::sTrackQueue;
 
 console::AppConsole* SystemState::sAppConsole;
 
-auto SystemState::early_init_gpios() -> drivers::Gpios* {
-  sGpios.reset(drivers::Gpios::Create());
-  return sGpios.get();
-}
-
 void SystemState::react(const FatalError& err) {
   if (!is_in_state<states::Error>()) {
     transit<states::Error>();
@@ -78,6 +75,26 @@ void SystemState::react(const internal::GpioInterrupt&) {
   }
 }
 
+void SystemState::react(const internal::SamdInterrupt&) {
+  auto prev_charge_status = sSamd->GetChargeStatus();
+  auto prev_usb_status = sSamd->GetUsbStatus();
+
+  sSamd->UpdateChargeStatus();
+  sSamd->UpdateUsbStatus();
+
+  auto charge_status = sSamd->GetChargeStatus();
+  auto usb_status = sSamd->GetUsbStatus();
+
+  if (charge_status != prev_charge_status) {
+    ChargingStatusChanged ev{};
+    events::System().Dispatch(ev);
+    events::Ui().Dispatch(ev);
+  }
+  if (usb_status != prev_usb_status) {
+    ESP_LOGI(kTag, "usb status changed");
+  }
+}
+
 }  // namespace system_fsm
 
 FSM_INITIAL_STATE(system_fsm::SystemState, system_fsm::states::Booting)