diff --git a/libraries/AP_HAL_ChibiOS/AP_HAL_ChibiOS_Namespace.h b/libraries/AP_HAL_ChibiOS/AP_HAL_ChibiOS_Namespace.h
index 9d559a561c..4b62fcb928 100644
--- a/libraries/AP_HAL_ChibiOS/AP_HAL_ChibiOS_Namespace.h
+++ b/libraries/AP_HAL_ChibiOS/AP_HAL_ChibiOS_Namespace.h
@@ -17,7 +17,7 @@ namespace ChibiOS {
     class RCOutput;
     class Scheduler;
     class Semaphore;
-    class EventSource;
+    class BinarySemaphore;
     class SPIBus;
     class SPIDesc;
     class SPIDevice;
diff --git a/libraries/AP_HAL_ChibiOS/EventSource.cpp b/libraries/AP_HAL_ChibiOS/EventSource.cpp
deleted file mode 100644
index f1821bca00..0000000000
--- a/libraries/AP_HAL_ChibiOS/EventSource.cpp
+++ /dev/null
@@ -1,35 +0,0 @@
-#include "EventSource.h"
-#include <AP_Math/AP_Math.h>
-
-using namespace ChibiOS;
-
-#if CH_CFG_USE_EVENTS == TRUE
-
-bool EventSource::wait(uint16_t duration_us, AP_HAL::EventHandle *evt_handle)
-{
-    chibios_rt::EventListener evt_listener;
-    eventmask_t evt_mask = evt_handle->get_evt_mask();
-    msg_t ret = msg_t();
-    ch_evt_src_.registerMask(&evt_listener, evt_mask);
-    if (duration_us == 0) {
-        ret = chEvtWaitAnyTimeout(evt_mask, TIME_IMMEDIATE);
-    } else {
-        const sysinterval_t wait_us = MIN(TIME_MAX_INTERVAL, MAX(CH_CFG_ST_TIMEDELTA, chTimeUS2I(duration_us)));
-        ret = chEvtWaitAnyTimeout(evt_mask, wait_us);
-    }
-    ch_evt_src_.unregister(&evt_listener);
-    return ret == MSG_OK;
-}
-
-void EventSource::signal(uint32_t evt_mask)
-{
-    ch_evt_src_.broadcastFlags(evt_mask);
-}
-
-__RAMFUNC__ void EventSource::signalI(uint32_t evt_mask)
-{
-    chSysLockFromISR();
-    ch_evt_src_.broadcastFlagsI(evt_mask);
-    chSysUnlockFromISR();
-}
-#endif //#if CH_CFG_USE_EVENTS == TRUE
diff --git a/libraries/AP_HAL_ChibiOS/EventSource.h b/libraries/AP_HAL_ChibiOS/EventSource.h
deleted file mode 100644
index a1dda78b2e..0000000000
--- a/libraries/AP_HAL_ChibiOS/EventSource.h
+++ /dev/null
@@ -1,26 +0,0 @@
-#pragma once
-#include <AP_HAL/AP_HAL.h>
-
-#include <stdint.h>
-#include <AP_HAL/AP_HAL_Boards.h>
-#include <AP_HAL/AP_HAL_Macros.h>
-#include <AP_HAL/EventHandle.h>
-#include "AP_HAL_ChibiOS_Namespace.h"
-#include <ch.hpp>
-
-#if CH_CFG_USE_EVENTS == TRUE
-class ChibiOS::EventSource : public AP_HAL::EventSource {
-    // Single event source to be shared across multiple users
-    chibios_rt::EventSource ch_evt_src_;
-
-public:
-    // generate event from thread context
-    void signal(uint32_t evt_mask) override;
-
-    // generate event from interrupt context
-    void signalI(uint32_t evt_mask) override;
-
-    // Wait on an Event handle, method for internal use by EventHandle
-    bool wait(uint16_t duration_us, AP_HAL::EventHandle* evt_handle) override;
-};
-#endif //#if CH_CFG_USE_EVENTS == TRUE
diff --git a/libraries/AP_HAL_ChibiOS/Semaphores.cpp b/libraries/AP_HAL_ChibiOS/Semaphores.cpp
index 4949339977..47e24348af 100644
--- a/libraries/AP_HAL_ChibiOS/Semaphores.cpp
+++ b/libraries/AP_HAL_ChibiOS/Semaphores.cpp
@@ -18,7 +18,9 @@
 #include <AP_HAL/AP_HAL.h>
 #include "Semaphores.h"
 #include <hal.h>
+#include <chsem.h>
 #include "AP_HAL_ChibiOS.h"
+#include <AP_Math/AP_Math.h>
 
 #if CH_CFG_USE_MUTEXES == TRUE
 
@@ -78,4 +80,57 @@ void Semaphore::assert_owner(void)
     osalDbgAssert(check_owner(), "owner");
 }
 
+#if CH_CFG_USE_SEMAPHORES == TRUE
+BinarySemaphore::BinarySemaphore(bool initial_state) :
+    AP_HAL::BinarySemaphore(initial_state)
+{
+    static_assert(sizeof(_lock) >= sizeof(semaphore_t), "invalid semaphore_t size");
+    auto *sem = (binary_semaphore_t *)_lock;
+    /*
+      the initial_state in ChibiOS binary semaphores is 'taken', so we
+      need to negate it for the ArduPilot semantics
+     */
+    chBSemObjectInit(sem, !initial_state);
+}
+
+bool BinarySemaphore::wait(uint32_t timeout_us)
+{
+    auto *sem = (binary_semaphore_t *)_lock;
+    if (timeout_us == 0) {
+        return chBSemWaitTimeout(sem, TIME_IMMEDIATE) == MSG_OK;
+    }
+    // loop waiting for 60ms at a time. This ensures we can wait for
+    // any amount of time even on systems with a 16 bit timer
+    while (timeout_us > 0) {
+        const uint32_t us = MIN(timeout_us, 60000U);
+        if (chBSemWaitTimeout(sem, TIME_US2I(us)) == MSG_OK) {
+            return true;
+        }
+        timeout_us -= us;
+    }
+    return false;
+}
+
+bool BinarySemaphore::wait_blocking(void)
+{
+    auto *sem = (binary_semaphore_t *)_lock;
+    return chBSemWait(sem) == MSG_OK;
+}
+
+void BinarySemaphore::signal(void)
+{
+    auto *sem = (binary_semaphore_t *)_lock;
+    chBSemSignal(sem);
+}
+
+void BinarySemaphore::signal_ISR(void)
+{
+    auto *sem = (binary_semaphore_t *)_lock;
+    chSysLockFromISR();
+    chBSemSignalI(sem);
+    chSysUnlockFromISR();
+}
+
+#endif // CH_CFG_USE_SEMAPHORES == TRUE
+
 #endif // CH_CFG_USE_MUTEXES
diff --git a/libraries/AP_HAL_ChibiOS/Semaphores.h b/libraries/AP_HAL_ChibiOS/Semaphores.h
index 484570d086..49f258366b 100644
--- a/libraries/AP_HAL_ChibiOS/Semaphores.h
+++ b/libraries/AP_HAL_ChibiOS/Semaphores.h
@@ -37,3 +37,21 @@ protected:
     // we declare the lock as a uint32_t array, and cast inside the cpp file
     uint32_t _lock[5];
 };
+
+/*
+  BinarySemaphore implementation
+ */
+class ChibiOS::BinarySemaphore : public AP_HAL::BinarySemaphore {
+public:
+    BinarySemaphore(bool initial_state=false);
+
+    CLASS_NO_COPY(BinarySemaphore);
+
+    bool wait(uint32_t timeout_us) override;
+    bool wait_blocking(void) override;
+    void signal(void) override;
+    void signal_ISR(void) override;
+
+protected:
+    uint32_t _lock[5];
+};