not an ideal solution but works for now

src/osal/rtems/BinarySemaphore.cpp

@@ -0,0 +1,24 @@
+#include "fsfw/osal/rtems/BinarySemaphore.h"
+
+#include <rtems/rtems/sem.h>
+
+BinarySemaphore::BinarySemaphore() {
+}
+
+BinarySemaphore::~BinarySemaphore() {
+
+}
+
+// Interface implementation
+ReturnValue_t BinarySemaphore::acquire(TimeoutType timeoutType, uint32_t timeoutMs) {
+    return HasReturnvaluesIF::RETURN_OK;
+}
+
+
+ReturnValue_t BinarySemaphore::release() {
+    return HasReturnvaluesIF::RETURN_OK;
+}
+
+uint8_t BinarySemaphore::getSemaphoreCounter() const {
+    return 0;
+}

src/osal/rtems/CMakeLists.txt

@@ -13,6 +13,7 @@ target_sources(${LIB_FSFW_NAME}
 		RtemsBasic.cpp
 		RTEMSTaskBase.cpp
 		TaskFactory.cpp
+		BinarySemaphore.cpp
 )