diff --git a/hal/src/main/native/include/MockData/I2CData.h b/hal/src/main/native/include/MockData/I2CData.h
index 524361ea82..b46cf4c198 100644
--- a/hal/src/main/native/include/MockData/I2CData.h
+++ b/hal/src/main/native/include/MockData/I2CData.h
@@ -30,7 +30,7 @@ int32_t HALSIM_RegisterI2CReadCallback(int32_t index,
 void HALSIM_CancelI2CReadCallback(int32_t index, int32_t uid);
 
 int32_t HALSIM_RegisterI2CWriteCallback(int32_t index,
-                                        HAL_BufferCallback callback,
+                                        HAL_ConstBufferCallback callback,
                                         void* param);
 void HALSIM_CancelI2CWriteCallback(int32_t index, int32_t uid);
 
diff --git a/hal/src/main/native/include/MockData/NotifyListener.h b/hal/src/main/native/include/MockData/NotifyListener.h
index 42c6aed8cf..1982eabc00 100644
--- a/hal/src/main/native/include/MockData/NotifyListener.h
+++ b/hal/src/main/native/include/MockData/NotifyListener.h
@@ -15,6 +15,10 @@ typedef void (*HAL_NotifyCallback)(const char* name, void* param,
 typedef void (*HAL_BufferCallback)(const char* name, void* param,
                                    unsigned char* buffer, unsigned int count);
 
+typedef void (*HAL_ConstBufferCallback)(const char* name, void* param,
+                                        const unsigned char* buffer,
+                                        unsigned int count);
+
 namespace hal {
 
 template <typename CallbackFunction>
diff --git a/hal/src/main/native/include/MockData/NotifyListenerVector.h b/hal/src/main/native/include/MockData/NotifyListenerVector.h
index 5547d83766..a6f5a8bbe1 100644
--- a/hal/src/main/native/include/MockData/NotifyListenerVector.h
+++ b/hal/src/main/native/include/MockData/NotifyListenerVector.h
@@ -132,5 +132,7 @@ void HalCallbackListenerVectorImpl<ListenerType>::erase_impl(unsigned int uid) {
 
 typedef HalCallbackListenerVectorImpl<HAL_NotifyCallback> NotifyListenerVector;
 typedef HalCallbackListenerVectorImpl<HAL_BufferCallback> BufferListenerVector;
+typedef HalCallbackListenerVectorImpl<HAL_ConstBufferCallback>
+    ConstBufferListenerVector;
 
 }  // namespace hal
diff --git a/hal/src/main/native/include/MockData/SPIData.h b/hal/src/main/native/include/MockData/SPIData.h
index ffbe376da5..170a6cdd00 100644
--- a/hal/src/main/native/include/MockData/SPIData.h
+++ b/hal/src/main/native/include/MockData/SPIData.h
@@ -30,7 +30,7 @@ int32_t HALSIM_RegisterSPIReadCallback(int32_t index,
 void HALSIM_CancelSPIReadCallback(int32_t index, int32_t uid);
 
 int32_t HALSIM_RegisterSPIWriteCallback(int32_t index,
-                                        HAL_BufferCallback callback,
+                                        HAL_ConstBufferCallback callback,
                                         void* param);
 void HALSIM_CancelSPIWriteCallback(int32_t index, int32_t uid);
 
diff --git a/hal/src/main/native/sim/MockData/I2CData.cpp b/hal/src/main/native/sim/MockData/I2CData.cpp
index dee130c174..dc21866aef 100644
--- a/hal/src/main/native/sim/MockData/I2CData.cpp
+++ b/hal/src/main/native/sim/MockData/I2CData.cpp
@@ -80,7 +80,7 @@ void I2CData::CancelReadCallback(int32_t uid) {
   m_readCallbacks = CancelCallback(m_readCallbacks, uid);
 }
 
-int32_t I2CData::RegisterWriteCallback(HAL_BufferCallback callback,
+int32_t I2CData::RegisterWriteCallback(HAL_ConstBufferCallback callback,
                                        void* param) {
   // Must return -1 on a null callback for error handling
   if (callback == nullptr) return -1;
@@ -141,7 +141,7 @@ void HALSIM_CancelI2CReadCallback(int32_t index, int32_t uid) {
 }
 
 int32_t HALSIM_RegisterI2CWriteCallback(int32_t index,
-                                        HAL_BufferCallback callback,
+                                        HAL_ConstBufferCallback callback,
                                         void* param) {
   return SimI2CData[index].RegisterWriteCallback(callback, param);
 }
diff --git a/hal/src/main/native/sim/MockData/I2CDataInternal.h b/hal/src/main/native/sim/MockData/I2CDataInternal.h
index 59cb28983a..ed172c7a81 100644
--- a/hal/src/main/native/sim/MockData/I2CDataInternal.h
+++ b/hal/src/main/native/sim/MockData/I2CDataInternal.h
@@ -32,7 +32,7 @@ class I2CData {
   int32_t RegisterReadCallback(HAL_BufferCallback callback, void* param);
   void CancelReadCallback(int32_t uid);
 
-  int32_t RegisterWriteCallback(HAL_BufferCallback callback, void* param);
+  int32_t RegisterWriteCallback(HAL_ConstBufferCallback callback, void* param);
   void CancelWriteCallback(int32_t uid);
 
   void Write(int32_t deviceAddress, const uint8_t* dataToSend,
@@ -47,7 +47,7 @@ class I2CData {
   std::atomic<HAL_Bool> m_initialized{false};
   std::shared_ptr<NotifyListenerVector> m_initializedCallbacks = nullptr;
   std::shared_ptr<BufferListenerVector> m_readCallbacks = nullptr;
-  std::shared_ptr<BufferListenerVector> m_writeCallbacks = nullptr;
+  std::shared_ptr<ConstBufferListenerVector> m_writeCallbacks = nullptr;
 };
 extern I2CData SimI2CData[];
 }  // namespace hal
diff --git a/hal/src/main/native/sim/MockData/NotifyCallbackHelpers.cpp b/hal/src/main/native/sim/MockData/NotifyCallbackHelpers.cpp
index 567d3f8f76..4edf646460 100644
--- a/hal/src/main/native/sim/MockData/NotifyCallbackHelpers.cpp
+++ b/hal/src/main/native/sim/MockData/NotifyCallbackHelpers.cpp
@@ -83,3 +83,30 @@ void InvokeCallback(std::shared_ptr<BufferListenerVector> currentVector,
     listener.callback(name, listener.param, buffer, count);
   }
 }
+
+std::shared_ptr<ConstBufferListenerVector> RegisterCallback(
+    std::shared_ptr<ConstBufferListenerVector> currentVector, const char* name,
+    HAL_ConstBufferCallback callback, void* param, int32_t* newUid) {
+  return RegisterCallbackImpl<ConstBufferListenerVector,
+                              HAL_ConstBufferCallback>(currentVector, name,
+                                                       callback, param, newUid);
+}
+
+std::shared_ptr<ConstBufferListenerVector> CancelCallback(
+    std::shared_ptr<ConstBufferListenerVector> currentVector, int32_t uid) {
+  return CancelCallbackImpl<ConstBufferListenerVector, HAL_ConstBufferCallback>(
+      currentVector, uid);
+}
+
+void InvokeCallback(std::shared_ptr<ConstBufferListenerVector> currentVector,
+                    const char* name, const uint8_t* buffer, int32_t count) {
+  // Return if no callbacks are assigned
+  if (currentVector == nullptr) return;
+  // Get a copy of the shared_ptr, then iterate and callback listeners
+  auto newCallbacks = currentVector;
+  for (size_t i = 0; i < newCallbacks->size(); ++i) {
+    if (!(*newCallbacks)[i]) continue;  // removed
+    auto listener = (*newCallbacks)[i];
+    listener.callback(name, listener.param, buffer, count);
+  }
+}
diff --git a/hal/src/main/native/sim/MockData/NotifyCallbackHelpers.h b/hal/src/main/native/sim/MockData/NotifyCallbackHelpers.h
index 7e598a481f..95c6ed9a48 100644
--- a/hal/src/main/native/sim/MockData/NotifyCallbackHelpers.h
+++ b/hal/src/main/native/sim/MockData/NotifyCallbackHelpers.h
@@ -30,3 +30,15 @@ std::shared_ptr<hal::BufferListenerVector> CancelCallback(
 
 void InvokeCallback(std::shared_ptr<hal::BufferListenerVector> currentVector,
                     const char* name, uint8_t* buffer, int32_t count);
+
+std::shared_ptr<hal::ConstBufferListenerVector> RegisterCallback(
+    std::shared_ptr<hal::ConstBufferListenerVector> currentVector,
+    const char* name, HAL_ConstBufferCallback callback, void* param,
+    int32_t* newUid);
+
+std::shared_ptr<hal::ConstBufferListenerVector> CancelCallback(
+    std::shared_ptr<hal::ConstBufferListenerVector> currentVector, int32_t uid);
+
+void InvokeCallback(
+    std::shared_ptr<hal::ConstBufferListenerVector> currentVector,
+    const char* name, const uint8_t* buffer, int32_t count);
diff --git a/hal/src/main/native/sim/MockData/SPIData.cpp b/hal/src/main/native/sim/MockData/SPIData.cpp
index 5ad1d08319..13150a548e 100644
--- a/hal/src/main/native/sim/MockData/SPIData.cpp
+++ b/hal/src/main/native/sim/MockData/SPIData.cpp
@@ -82,7 +82,7 @@ void SPIData::CancelReadCallback(int32_t uid) {
   m_readCallbacks = CancelCallback(m_readCallbacks, uid);
 }
 
-int32_t SPIData::RegisterWriteCallback(HAL_BufferCallback callback,
+int32_t SPIData::RegisterWriteCallback(HAL_ConstBufferCallback callback,
                                        void* param) {
   // Must return -1 on a null callback for error handling
   if (callback == nullptr) return -1;
@@ -219,7 +219,7 @@ void HALSIM_CancelSPIReadCallback(int32_t index, int32_t uid) {
 }
 
 int32_t HALSIM_RegisterSPIWriteCallback(int32_t index,
-                                        HAL_BufferCallback callback,
+                                        HAL_ConstBufferCallback callback,
                                         void* param) {
   return SimSPIData[index].RegisterWriteCallback(callback, param);
 }
diff --git a/hal/src/main/native/sim/MockData/SPIDataInternal.h b/hal/src/main/native/sim/MockData/SPIDataInternal.h
index 242cc31783..e8f88ac6b2 100644
--- a/hal/src/main/native/sim/MockData/SPIDataInternal.h
+++ b/hal/src/main/native/sim/MockData/SPIDataInternal.h
@@ -32,7 +32,7 @@ class SPIData {
   int32_t RegisterReadCallback(HAL_BufferCallback callback, void* param);
   void CancelReadCallback(int32_t uid);
 
-  int32_t RegisterWriteCallback(HAL_BufferCallback callback, void* param);
+  int32_t RegisterWriteCallback(HAL_ConstBufferCallback callback, void* param);
   void CancelWriteCallback(int32_t uid);
 
   int32_t RegisterResetAccumulatorCallback(HAL_NotifyCallback callback,
@@ -61,7 +61,7 @@ class SPIData {
   std::atomic<int64_t> m_accumulatorValue{false};
   std::shared_ptr<NotifyListenerVector> m_initializedCallbacks = nullptr;
   std::shared_ptr<BufferListenerVector> m_readCallbacks = nullptr;
-  std::shared_ptr<BufferListenerVector> m_writeCallbacks = nullptr;
+  std::shared_ptr<ConstBufferListenerVector> m_writeCallbacks = nullptr;
   std::shared_ptr<NotifyListenerVector> m_resetAccumulatorCallback = nullptr;
   std::shared_ptr<NotifyListenerVector> m_setAccumulatorCallback = nullptr;
 };