ARM Cortex-M33 (ARMv8-M) Keil Simulator Demo
Using Keil uVision IDE
This page documents a pre-configured FreeRTOS project that targets the
Keil uVision ARM
Simulator and uses the armclang
compiler to build the FreeRTOS ARMv8-M GCC port. The project demonstrates using
the ARM Cortex-M33 TrustZone and the ARM Cortex-M33 Memory Protection Unit (MPU).
IMPORTANT! Notes on using the FreeRTOS ARM Cortex-M33 port
Please read all the following points before using this RTOS port.
Also see the FAQ My application does not run, what could be wrong?.
- Source Code Organization
- The Demo Application
- Building and Running the RTOS Demo Application
- RTOS Configuration and Usage Details
Source Code Organization
The FreeRTOS zip file download contains the source code for all the FreeRTOS ports, and
every demo application. That means it contains many more files than are required
to use the FreeRTOS ARMv8-M Cortex-M33 port. See the
Source Code Organization page for information on the zip file’s directory structure.
The project file for this demo is located in the FreeRTOS/Demo/CORTEX_MPU_M33F_Simulator_Keil_GCC
directory and is named FreeRTOSDemo.uvmpw. This Keil multi-project
workspace contains two projects – one for the secure side of the ARM Cortex-M33
core, and one for the non-secure side. The FreeRTOS ARMv8-M Cortex-M33 port files
compiled in these two projects are organized as follows:
- Port files compiled in the secure project are in the FreeRTOS/Source/portable/GCC/ARM_CM33/secure directory.
- Port files compiled in the non-secure project are in the FreeRTOS/Source/portable/GCC/ARM_CM33/non_secure directory.
The Demo Application
The project includes two demos:
- TrustZone Demo
- Memory Protection Unit (MPU) Demo
The TrustZone demo demonstrates how to export functions from the secure side
of the ARM Cortex-M33 core, and how to call them from RTOS tasks on the
- NonSecure Callable Function:
The following function is exported from the secure side and is marked
as non-secure callable:
secureportNON_SECURE_CALLABLE uint32_t NSCFunction( Callback_t pxCallback )
Note the use of secureportNON_SECURE_CALLABLE macro to mark
the function as non-secure callable. This function accepts a callback
as argument. It first invokes the callback function supplied as argument
and then increments a secure side counter. The incremented value of the
secure side counter is returned to the caller.
- NonSecure Callback:
The following function is implemented on the non-secure side and is
passed to the above mentioned non-secure callable function as argument:
void prvCallback( void )
This function increments a non-secure counter.
- Secure Calling Task:
An un-privileged non-secure task is created using the
API. This task first calls portALLOCATE_SECURE_CONTEXT to allocate
itself a secure context – any non-secure task which wants to call a
function exported from the secure side must allocate itself a secure
context by calling portALLOCATE_SECURE_CONTEXT.
The task then calls the secure side function and passes the non-secure
callback as the argument. The non-secure counter is incremented in the callback
and the secure counter is incremented in the secure function. Therefore,
both the counters must be incremented after the call to the secure function
is complete – this is ensured using configASSERT(). The task
sleeps for one second and then repeats the same.
The TrustZone Demo Call Sequence
Memory Protection Unit (MPU) Demo
The MPU demo demonstrates how to use MPU to grant a task different permissions
to various memory regions. The MPU demo consists of the following two tasks:
- RW Task:
The RW task has Read-Write access to a shared region of memory (namely
- RO Task:
The RO task has Read-Only access to the same shared region of memory
(namely ucSharedMemory). This task tries to write to the
shared memory and since it has read only permission to the shared memory,
it results in a memory fault. The fault handler checks if it is the
expected fault from the RO task and if so, it recovers gracefully by
incrementing the Program Counter to the next statement.
Building and Running the RTOS Demo Application
Double click the FreeRTOS/Demo/CORTEX_MPU_M33F_Simulator_Keil_GCC/FreeRTOSDemo.uvmpw
file to open it in the Keil uVision IDE. The Keil multi-project workspace
FreeRTOSDemo.uvmpw contains a secure project (FreeRTOSDemo_s)
and a non-secure project (FreeRTOSDemo_ns).
Set the secure project as active by right clicking on “Project: FreeRTOSDemo_s”
and selecting “Set as Active Project”.
Keil uVision IDE – Set Secure Project Active. Click to enlarge.
Build the secure project by clicking “Project –> Build ‘FreeRTOSDemo_s (FVP Simulation Model)'”.
Keil uVision IDE – Build Secure Project. Click to enlarge.
Set the non-secure project as active by right clicking on “Project: FreeRTOSDemo_ns”
and selecting “Set as Active Project”.
Keil uVision IDE – Set Non-Secure Project Active. Click to enlarge.
Build the non-secure project by clicking “Project –> Build ‘FreeRTOSDemo_ns (FVP Simulation Model)'”.
Keil uVision IDE – Build Non-Secure Project. Click to enlarge.
Start the Debug Session by clicking “Debug -> Start/Stop Debug Session”.
Keil uVision IDE – Start Debug Session. Click to enlarge.
Configuration items specific to this demo are contained in FreeRTOS/Demo/CORTEX_MPU_M33F_Simulator_Keil_GCC/Config/FreeRTOSConfig.h.
The constants defined in that file can be edited
to suit your application. The following configuration options are
specific to the ARM Cortex-M33 port:
- configENABLE_MPU – Enable/Disable Memory Protection Unit (MPU).
- configENABLE_FPU – Enable/Disable Floating Point Unit (FPU).
- configENABLE_TRUSTZONE – Enable/Disable TrustZone.
If you want to run FreeRTOS with TrustZone disabled, set configENABLE_TRUSTZONE
to 0 in your FreeRTOSConfig.h and use the FreeRTOS port files
in the FreeRTOS/Source/portable/GCC/ARM_CM33_NTZ directory.
If you want to run FreeRTOS on the secure side, set configENABLE_TRUSTZONE
to 0 and configRUN_FREERTOS_SECURE_ONLY to 1 in your FreeRTOSConfig.h
and use the FreeRTOS port files in the FreeRTOS/Source/portable/GCC/ARM_CM33_NTZ
Source/Portable/MemMang/heap_4.c is included in the project
to provide the memory allocation required by the RTOS kernel. Please
refer to the Memory Management section of
the API documentation for full information.
vPortEndScheduler() has not been implemented.
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