diff --git a/cores/arduino/PendSV.cpp b/cores/arduino/PendSV.cpp
new file mode 100644
index 000000000..6eb84af90
--- /dev/null
+++ b/cores/arduino/PendSV.cpp
@@ -0,0 +1,162 @@
+#include "PendSV.h"
+
+#include <Arduino.h>
+#include <limits.h>
+
+#if defined(USE_TINYUSB)
+extern "C" void TinyUSB_Device_Task(void);
+#endif
+
+namespace {
+PendSV pendSv;
+
+#if defined(USE_TINYUSB)
+void tinyUsbDeviceTaskService(uint8_t serviceId, void *context) {
+  (void)serviceId;
+  (void)context;
+  // One invocation drains TinyUSB's queued controller events under OPT_OS_NONE.
+  TinyUSB_Device_Task();
+}
+#endif
+}
+
+PendSV &PendSV::instance() {
+  return pendSv;
+}
+
+#if defined(USE_TINYUSB)
+extern "C" void tud_event_hook_cb(uint8_t rhport, uint32_t eventId, bool inIsr) {
+  (void)rhport;
+  (void)eventId;
+  (void)inIsr;
+  // TinyUSB owns the event queue. PendSV is only its deferred wake signal, so
+  // multiple controller events before dispatch require only one service call.
+  PendSV::instance().setPendingOnce(PendSVChannels::Usb);
+}
+#endif
+
+bool PendSV::initializeCoreServices() {
+  NVIC_SetPriority(PendSV_IRQn, (1 << __NVIC_PRIO_BITS) - 1);
+#if defined(USE_TINYUSB)
+  return instance().registerService(PendSVChannels::Usb, tinyUsbDeviceTaskService, nullptr);
+#else
+  return true;
+#endif
+}
+
+uint32_t PendSV::enterCritical() {
+  const uint32_t primask = __get_PRIMASK();
+  __disable_irq();
+  return primask;
+}
+
+void PendSV::exitCritical(uint32_t primask) {
+  __set_PRIMASK(primask);
+}
+
+bool PendSV::registerService(uint8_t serviceId, ServiceFn fn, void *context) {
+  if (serviceId >= kMaxServices || fn == nullptr)
+    return false;
+
+  const uint32_t primask = enterCritical();
+  pendingCount_[serviceId] = 0;
+  pendingMask_ &= ~(1u << serviceId);
+  services_[serviceId].fn = fn;
+  services_[serviceId].context = context;
+  exitCritical(primask);
+
+  return true;
+}
+
+void PendSV::clearService(uint8_t serviceId) {
+  if (serviceId >= kMaxServices)
+    return;
+
+  const uint32_t primask = enterCritical();
+  services_[serviceId].fn = nullptr;
+  services_[serviceId].context = nullptr;
+  pendingCount_[serviceId] = 0;
+  pendingMask_ &= ~(1u << serviceId);
+  exitCritical(primask);
+}
+
+void PendSV::setPending(uint8_t serviceId) {
+  if (serviceId >= kMaxServices)
+    return;
+
+  const uint32_t primask = enterCritical();
+  uint16_t &pendingCount = pendingCount_[serviceId];
+  if (pendingCount < UINT16_MAX)
+    ++pendingCount;
+  pendingMask_ |= (1u << serviceId);
+  exitCritical(primask);
+
+  __DMB();
+  SCB->ICSR = SCB_ICSR_PENDSVSET_Msk;
+}
+
+void PendSV::setPendingOnce(uint8_t serviceId) {
+  if (serviceId >= kMaxServices)
+    return;
+
+  const uint32_t primask = enterCritical();
+  pendingCount_[serviceId] = 1;
+  pendingMask_ |= (1u << serviceId);
+  exitCritical(primask);
+
+  __DMB();
+  SCB->ICSR = SCB_ICSR_PENDSVSET_Msk;
+}
+
+void PendSV::dispatchPending() {
+  // Bound one PendSV entry so high-rate producers do not monopolize return to
+  // thread mode. Remaining work re-pends PendSV below.
+  uint8_t dispatched = 0;
+
+  while (dispatched < kDispatchBudget) {
+    uint32_t primask = enterCritical();
+    const uint32_t pending = pendingMask_;
+    if (pending == 0) {
+      exitCritical(primask);
+      return;
+    }
+
+    const uint8_t serviceId = static_cast<uint8_t>(__builtin_ctz(pending));
+    uint16_t &pendingCount = pendingCount_[serviceId];
+
+    if (pendingCount == 0) {
+      // Defensive scrub in case mask and count drift out of sync.
+      pendingMask_ &= ~(1u << serviceId);
+      exitCritical(primask);
+      continue;
+    }
+
+    --pendingCount;
+    if (pendingCount == 0)
+      pendingMask_ &= ~(1u << serviceId);
+
+    ServiceEntry entry = services_[serviceId];
+    exitCritical(primask);
+
+    // Pending work without a registered service is intentionally dropped.
+    // Producers are expected to register before calling setPending(), and
+    // clearService() cancels queued work for that service.
+    if (entry.fn != nullptr)
+      entry.fn(serviceId, entry.context);
+
+    ++dispatched;
+  }
+
+  const uint32_t primask = enterCritical();
+  const bool hasRemaining = (pendingMask_ != 0);
+  exitCritical(primask);
+
+  if (hasRemaining) {
+    __DMB();
+    SCB->ICSR = SCB_ICSR_PENDSVSET_Msk;
+  }
+}
+
+extern "C" void PendSV_Handler(void) {
+  PendSV::instance().dispatchPending();
+}
diff --git a/cores/arduino/PendSV.h b/cores/arduino/PendSV.h
new file mode 100644
index 000000000..98222b2c7
--- /dev/null
+++ b/cores/arduino/PendSV.h
@@ -0,0 +1,189 @@
+#pragma once
+
+#include <sam.h>
+
+#include <array>
+#include <stdint.h>
+
+#if defined(SERCOM0) || defined(SERCOM0_REGS)
+#define SIMIO_PENDSV_HAS_SERCOM0 true
+#else
+#define SIMIO_PENDSV_HAS_SERCOM0 false
+#endif
+#if defined(SERCOM1) || defined(SERCOM1_REGS)
+#define SIMIO_PENDSV_HAS_SERCOM1 true
+#else
+#define SIMIO_PENDSV_HAS_SERCOM1 false
+#endif
+#if defined(SERCOM2) || defined(SERCOM2_REGS)
+#define SIMIO_PENDSV_HAS_SERCOM2 true
+#else
+#define SIMIO_PENDSV_HAS_SERCOM2 false
+#endif
+#if defined(SERCOM3) || defined(SERCOM3_REGS)
+#define SIMIO_PENDSV_HAS_SERCOM3 true
+#else
+#define SIMIO_PENDSV_HAS_SERCOM3 false
+#endif
+#if defined(SERCOM4) || defined(SERCOM4_REGS)
+#define SIMIO_PENDSV_HAS_SERCOM4 true
+#else
+#define SIMIO_PENDSV_HAS_SERCOM4 false
+#endif
+#if defined(SERCOM5) || defined(SERCOM5_REGS)
+#define SIMIO_PENDSV_HAS_SERCOM5 true
+#else
+#define SIMIO_PENDSV_HAS_SERCOM5 false
+#endif
+#if defined(SERCOM6) || defined(SERCOM6_REGS)
+#define SIMIO_PENDSV_HAS_SERCOM6 true
+#else
+#define SIMIO_PENDSV_HAS_SERCOM6 false
+#endif
+#if defined(SERCOM7) || defined(SERCOM7_REGS)
+#define SIMIO_PENDSV_HAS_SERCOM7 true
+#else
+#define SIMIO_PENDSV_HAS_SERCOM7 false
+#endif
+#if defined(DMAC) || defined(DMAC_REGS)
+#define SIMIO_PENDSV_HAS_DMAC true
+#else
+#define SIMIO_PENDSV_HAS_DMAC false
+#endif
+#if defined(AES) || defined(AES_REGS)
+#define SIMIO_PENDSV_HAS_AES true
+#else
+#define SIMIO_PENDSV_HAS_AES false
+#endif
+#if defined(ICM) || defined(ICM_REGS)
+#define SIMIO_PENDSV_HAS_ICM true
+#else
+#define SIMIO_PENDSV_HAS_ICM false
+#endif
+#if defined(PUKCC) || defined(PUKCC_REGS) || defined(ID_PUKCC) || defined(PUKCC_INSTANCE_ID) || \
+    defined(PUKCC_IRQn)
+#define SIMIO_PENDSV_HAS_PUKCC true
+#else
+#define SIMIO_PENDSV_HAS_PUKCC false
+#endif
+#if defined(TRNG) || defined(TRNG_REGS)
+#define SIMIO_PENDSV_HAS_TRNG true
+#else
+#define SIMIO_PENDSV_HAS_TRNG false
+#endif
+#if defined(GMAC) || defined(GMAC_REGS)
+#define SIMIO_PENDSV_HAS_GMAC true
+#define SIMIO_PENDSV_HAS_PHY true
+#else
+#define SIMIO_PENDSV_HAS_GMAC false
+#define SIMIO_PENDSV_HAS_PHY false
+#endif
+
+template <bool HasSercom0, bool HasSercom1, bool HasSercom2, bool HasSercom3, bool HasSercom4,
+          bool HasSercom5, bool HasSercom6, bool HasSercom7, bool HasDmac, bool HasAes,
+          bool HasIcm, bool HasPukcc, bool HasTrng, bool HasGmac, bool HasPhy>
+struct PendSVChannelMap {
+  static constexpr uint8_t kUnavailable = 0xFF;
+
+private:
+  static constexpr uint8_t assign(bool present, uint8_t next) {
+    return present ? next : kUnavailable;
+  }
+  static constexpr uint8_t advance(bool present, uint8_t next) {
+    return present ? static_cast<uint8_t>(next + 1) : next;
+  }
+
+  static constexpr uint8_t kBase = 0;
+  static constexpr uint8_t kAfterSercom0 = advance(HasSercom0, kBase);
+  static constexpr uint8_t kAfterSercom1 = advance(HasSercom1, kAfterSercom0);
+  static constexpr uint8_t kAfterSercom2 = advance(HasSercom2, kAfterSercom1);
+  static constexpr uint8_t kAfterSercom3 = advance(HasSercom3, kAfterSercom2);
+  static constexpr uint8_t kAfterSercom4 = advance(HasSercom4, kAfterSercom3);
+  static constexpr uint8_t kAfterSercom5 = advance(HasSercom5, kAfterSercom4);
+  static constexpr uint8_t kAfterSercom6 = advance(HasSercom6, kAfterSercom5);
+  static constexpr uint8_t kAfterSercom7 = advance(HasSercom7, kAfterSercom6);
+  static constexpr uint8_t kAfterRtc = advance(true, kAfterSercom7);
+  static constexpr uint8_t kAfterUsb = advance(true, kAfterRtc);
+  static constexpr uint8_t kAfterAdc = advance(true, kAfterUsb);
+  static constexpr uint8_t kAfterDmac = advance(HasDmac, kAfterAdc);
+  static constexpr uint8_t kAfterAes = advance(HasAes, kAfterDmac);
+  static constexpr uint8_t kAfterIcm = advance(HasIcm, kAfterAes);
+  static constexpr uint8_t kAfterPukcc = advance(HasPukcc, kAfterIcm);
+  static constexpr uint8_t kAfterTrng = advance(HasTrng, kAfterPukcc);
+  static constexpr uint8_t kAfterGmac = advance(HasGmac, kAfterTrng);
+  static constexpr uint8_t kAfterPhy = advance(HasPhy, kAfterGmac);
+  static constexpr uint8_t kAfterUsbProtocol = advance(true, kAfterPhy);
+  static constexpr uint8_t kAfterDiscreteInput = advance(true, kAfterUsbProtocol);
+
+public:
+  static constexpr uint8_t Sercom0 = assign(HasSercom0, kBase);
+  static constexpr uint8_t Sercom1 = assign(HasSercom1, kAfterSercom0);
+  static constexpr uint8_t Sercom2 = assign(HasSercom2, kAfterSercom1);
+  static constexpr uint8_t Sercom3 = assign(HasSercom3, kAfterSercom2);
+  static constexpr uint8_t Sercom4 = assign(HasSercom4, kAfterSercom3);
+  static constexpr uint8_t Sercom5 = assign(HasSercom5, kAfterSercom4);
+  static constexpr uint8_t Sercom6 = assign(HasSercom6, kAfterSercom5);
+  static constexpr uint8_t Sercom7 = assign(HasSercom7, kAfterSercom6);
+  static constexpr uint8_t Rtc = kAfterSercom7;
+  static constexpr uint8_t Usb = kAfterRtc;
+  static constexpr uint8_t Adc = kAfterUsb;
+  static constexpr uint8_t Dmac = assign(HasDmac, kAfterAdc);
+  static constexpr uint8_t Aes = assign(HasAes, kAfterDmac);
+  static constexpr uint8_t Icm = assign(HasIcm, kAfterAes);
+  static constexpr uint8_t Pukcc = assign(HasPukcc, kAfterIcm);
+  static constexpr uint8_t Trng = assign(HasTrng, kAfterPukcc);
+  static constexpr uint8_t Gmac = assign(HasGmac, kAfterTrng);
+  static constexpr uint8_t Phy = assign(HasPhy, kAfterGmac);
+  static constexpr uint8_t UsbProtocol = kAfterPhy;
+  static constexpr uint8_t DiscreteInput = kAfterUsbProtocol;
+  static constexpr uint8_t Count = kAfterDiscreteInput;
+
+  static constexpr bool isAvailable(uint8_t channel) { return channel != kUnavailable; }
+  static constexpr uint8_t sercom(uint8_t index) {
+    return index == 0 ? Sercom0 : index == 1 ? Sercom1 : index == 2 ? Sercom2
+         : index == 3 ? Sercom3 : index == 4 ? Sercom4 : index == 5 ? Sercom5
+         : index == 6 ? Sercom6 : index == 7 ? Sercom7 : kUnavailable;
+  }
+  static constexpr uint8_t sercomIndex(uint8_t channel) {
+    return channel == Sercom0 ? 0 : channel == Sercom1 ? 1 : channel == Sercom2 ? 2
+         : channel == Sercom3 ? 3 : channel == Sercom4 ? 4 : channel == Sercom5 ? 5
+         : channel == Sercom6 ? 6 : channel == Sercom7 ? 7 : kUnavailable;
+  }
+};
+
+using PendSVChannels = PendSVChannelMap<
+    SIMIO_PENDSV_HAS_SERCOM0, SIMIO_PENDSV_HAS_SERCOM1, SIMIO_PENDSV_HAS_SERCOM2,
+    SIMIO_PENDSV_HAS_SERCOM3, SIMIO_PENDSV_HAS_SERCOM4, SIMIO_PENDSV_HAS_SERCOM5,
+    SIMIO_PENDSV_HAS_SERCOM6, SIMIO_PENDSV_HAS_SERCOM7, SIMIO_PENDSV_HAS_DMAC,
+    SIMIO_PENDSV_HAS_AES, SIMIO_PENDSV_HAS_ICM, SIMIO_PENDSV_HAS_PUKCC,
+    SIMIO_PENDSV_HAS_TRNG, SIMIO_PENDSV_HAS_GMAC, SIMIO_PENDSV_HAS_PHY>;
+
+class PendSV {
+public:
+  using ServiceFn = void (*)(uint8_t serviceId, void *context);
+  static constexpr uint8_t kMaxServices = PendSVChannels::Count;
+  static constexpr uint8_t kDispatchBudget = 16;
+  static_assert(kMaxServices <= 32, "PendSV pending mask supports at most 32 services");
+
+  static PendSV &instance();
+  static bool initializeCoreServices();
+
+  bool registerService(uint8_t serviceId, ServiceFn fn, void *context = nullptr);
+  void clearService(uint8_t serviceId);
+  void dispatchPending();
+  void setPending(uint8_t serviceId);
+  void setPendingOnce(uint8_t serviceId);
+
+private:
+  static uint32_t enterCritical();
+  static void exitCritical(uint32_t primask);
+
+  struct ServiceEntry {
+    ServiceFn fn = nullptr;
+    void *context = nullptr;
+  };
+
+  std::array<ServiceEntry, kMaxServices> services_{};
+  std::array<uint16_t, kMaxServices> pendingCount_{};
+  volatile uint32_t pendingMask_ = 0;
+};
diff --git a/cores/arduino/PendSVChannelMap.h b/cores/arduino/PendSVChannelMap.h
new file mode 100644
index 000000000..441bb92cb
--- /dev/null
+++ b/cores/arduino/PendSVChannelMap.h
@@ -0,0 +1,61 @@
+#pragma once
+
+#include <stdint.h>
+
+template <bool HasSercom0, bool HasSercom1, bool HasSercom2, bool HasSercom3,
+          bool HasSercom4, bool HasSercom5, bool HasSercom6, bool HasSercom7,
+          bool HasUsb, bool HasGmac, bool HasPhy, bool HasAdc, bool HasAes,
+          bool HasPukcc, bool HasTrng, bool HasRtc>
+struct PendSVChannelMap {
+  static constexpr uint8_t kMaxServices = 32;
+  static constexpr uint8_t kUnavailable = 0xFF;
+
+private:
+  static constexpr uint8_t assign(bool present, uint8_t next) {
+    return present ? next : kUnavailable;
+  }
+
+  static constexpr uint8_t advance(bool present, uint8_t next) {
+    return present ? static_cast<uint8_t>(next + 1) : next;
+  }
+
+  static constexpr uint8_t kBase = 0;
+  static constexpr uint8_t kAfterSercom0 = advance(HasSercom0, kBase);
+  static constexpr uint8_t kAfterSercom1 = advance(HasSercom1, kAfterSercom0);
+  static constexpr uint8_t kAfterSercom2 = advance(HasSercom2, kAfterSercom1);
+  static constexpr uint8_t kAfterSercom3 = advance(HasSercom3, kAfterSercom2);
+  static constexpr uint8_t kAfterSercom4 = advance(HasSercom4, kAfterSercom3);
+  static constexpr uint8_t kAfterSercom5 = advance(HasSercom5, kAfterSercom4);
+  static constexpr uint8_t kAfterSercom6 = advance(HasSercom6, kAfterSercom5);
+  static constexpr uint8_t kAfterSercom7 = advance(HasSercom7, kAfterSercom6);
+  static constexpr uint8_t kAfterUsb = advance(HasUsb, kAfterSercom7);
+  static constexpr uint8_t kAfterGmac = advance(HasGmac, kAfterUsb);
+  static constexpr uint8_t kAfterPhy = advance(HasPhy, kAfterGmac);
+  static constexpr uint8_t kAfterAdc = advance(HasAdc, kAfterPhy);
+  static constexpr uint8_t kAfterAes = advance(HasAes, kAfterAdc);
+  static constexpr uint8_t kAfterPukcc = advance(HasPukcc, kAfterAes);
+  static constexpr uint8_t kAfterTrng = advance(HasTrng, kAfterPukcc);
+
+public:
+  static constexpr uint8_t Sercom0 = assign(HasSercom0, kBase);
+  static constexpr uint8_t Sercom1 = assign(HasSercom1, kAfterSercom0);
+  static constexpr uint8_t Sercom2 = assign(HasSercom2, kAfterSercom1);
+  static constexpr uint8_t Sercom3 = assign(HasSercom3, kAfterSercom2);
+  static constexpr uint8_t Sercom4 = assign(HasSercom4, kAfterSercom3);
+  static constexpr uint8_t Sercom5 = assign(HasSercom5, kAfterSercom4);
+  static constexpr uint8_t Sercom6 = assign(HasSercom6, kAfterSercom5);
+  static constexpr uint8_t Sercom7 = assign(HasSercom7, kAfterSercom6);
+  static constexpr uint8_t Usb = assign(HasUsb, kAfterSercom7);
+  static constexpr uint8_t Gmac = assign(HasGmac, kAfterUsb);
+  static constexpr uint8_t Phy = assign(HasPhy, kAfterGmac);
+  static constexpr uint8_t Adc = assign(HasAdc, kAfterPhy);
+  static constexpr uint8_t Aes = assign(HasAes, kAfterAdc);
+  static constexpr uint8_t Pukcc = assign(HasPukcc, kAfterAes);
+  static constexpr uint8_t Trng = assign(HasTrng, kAfterPukcc);
+  static constexpr uint8_t Rtc = assign(HasRtc, kAfterTrng);
+  static constexpr uint8_t Count = advance(HasRtc, kAfterTrng);
+
+  static constexpr bool isAvailable(uint8_t channel) {
+    return channel != kUnavailable;
+  }
+};