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Spansion (was Fujitsu) FM3 Demo
Using the Keil and IAR development tools
[RTOS Ports]

Fujitsu SK-FM3-100PMC MB9BF506 development and evaluation board
Spansion SK-FM3-100PMC MB9BF506 starter kit board,
a project is also provided for the SK-FM3-64PMC1 starter kit

This page documents a FreeRTOS ARM Cortex-M3 demo application that targets a Spansion FM3 microcontroller. IAR and Keil projects are provided that are already pre-configured to run on both the SK-FM3-100PMC and SK-FM3-64PMC1 starter kit evaluation boards. The evaluation boards are fitted with a MB9BF506N and a MB9AF314 microcontroller respectively.

Note: If this project fails to build then it is likely the version of IAR Embedded Workbench being used is too old. If this is the case, then it is also likely that the project file has been (silently) corrupted and will need to be restored to its original state before it can be built even with an updated IAR version.

IMPORTANT! Notes on using the FreeRTOS Keil and IAR FM3 example projects

Please read all the following points before using this RTOS port.

  1. Source Code Organisation
  2. The Demo Application
  3. RTOS Configuration and Usage Details
See also the FAQ My application does not run, what could be wrong?

Source Code Organisation

The FreeRTOS zip file download contains source code for all the FreeRTOS ports, and every demo application project. It therefore contains many more files than are required to build and run the FM3 MB9BF500 demo. See the Source Code Organization section for a description of the downloaded files, and information on creating a new project.

The table below provides information on locating the relevant FM3 projects within the official FreeRTOS download:

Compiler Target Project name Project file location in the FreeRTOS source tree
IAR MB9B500 RTOSDemo_IAR.eww FreeRTOS/Demo/CORTEX_MB9B500_IAR_Keil
IAR MB9A300 RTOSDemo_IAR.eww FreeRTOS/Demo/CORTEX_MB9A310_IAR_Keil
ARM/Keil MB9B500 RTOSDemo_Keil.uvproj FreeRTOS/Demo/CORTEX_MB9B500_IAR_Keil
ARM/Keil MB9A300 RTOSDemo_Keil.uvproj FreeRTOS/Demo/CORTEX_MB9A310_IAR_Keil

The Spansion FM3 MB9BF500/MB9AF300 Demo Applications


The IAR and Keil projects each contain three build configurations:

Build configuration Description
Blinky This is a very simple configuration. It creates two tasks, one software timer, and also uses a button interrupt.

The two tasks communicate via a queue, with the receiving task toggling one of the seven segment display LEDs each time a value is received. The "Blinky demo functionality" section of this documentation page highlights the LED used.

Pressing user button SW2 generates an interrupt, the service routine for which resets a software timer before turning an LED on. The software timer has a five second period, and when the five seconds expire, the timer callback function turns the LED off again. Therefore, pressing SW2 will turn the LED on, and the LED will remain on until a full five seconds pass without the button being pressed again.

The Blinky build configuration uses the main-blinky.c source file. The other two build configurations use the main-full.c source file.

Full This is a comprehensive configuration that creates lots of tasks, queues, semaphores (of various types) and software timers.

The Full configuration creates the same tasks and timers that are created by the Blinky build configuration. In addition to these, the Full configuration also creates a lot of tasks from the set of standard demo tasks.

The standard demo tasks don't perform any particular function. Their purpose is firstly to test the FreeRTOS port, and secondly to provide examples of how to use the FreeRTOS API functions.

The Full build configuration creates yet more timers that are neither part of the Blinky configuration, or the set of standard demo tasks. These additional tasks are described briefly below this table.

In total, the full configuration creates approximately 45 tasks! Use the blinky build configuration if a simpler demo is required.

Full_with_optimisation The functionality of the Full_with_optimisation configuration is identical to that of the Full configuration. The compiler optimisation setting is the only difference between the two. Full uses no optimisation, while Full_with_optimisation uses high optimisation.

Software timers that are created by both Full build configurations, that are not part of either the Blinky demo, or the standard demo tasks, include:

  • A "Check" software timer and callback

    Each time the check timer expires, its associated callback function queries the status of all the running standard demo tasks. If a status is returned as 'failed', then the period of the Check timer is shortened to 500ms, from its original setting of 3 seconds.

    The check timer callback toggles an LED within the seven segment display each time it executes. The "Blinky demo functionality" and Full demo functionality sections of this documentation page highlight the LEDs used. If the LED toggles every three seconds, then no errors have been reported. If the LED toggles every 500ms, then at least one standard demo task has reported an error. The name of the standard demo task that reported the error is logged in the pcStatusMessage variable, which is defined in main-full.c.

  • A "Digit Counter" software timer and callback

    This controls the display of an incrementing number on one of the two seven segment displays.

Hardware set up

The demo application includes tasks that send and receive characters over UART0. The characters sent by one task are received by another - with an error condition being flagged if any character is missed or received out of order. A loopback connector is required on the 9way D socket marked X4 on the SK-FM3-100PMC development board for this test to function (pins 2 and 3 the socket should be connected together - a paper-clip is normally adequate for the purpose). Further, the jumpers marked JP4 and JP5 must be set to route the UART0 signals to the X4 connector. This requires them to be turned 90 degrees from their default position. JP4 and JP5 are adjacent to the X4 connector, and their required position is visible in the image at the top of this file (the jumpers should point to, and not be parallel with, the connector).

Note that the UART driver in this demo uses queues to send each character into an interrupt service routine, and out of an interrupt service routine, individually. This is done to demonstrate queues being used in an interrupt, and to deliberately load the system to test the FreeRTOS port. It is not meant to be an example of an efficient driver implementation. An efficient implementation should use FIFOs or DMA if available, and only use FreeRTOS API functions when enough data has been received to warrant a task being unblocked to process the data.

Building and executing the demo application, using the IAR tools

  1. Open the RTOSDemo_IAR.eww Embedded Workbench workspace from within the Embedded Workbench IDE.

  2. Select the required build configuration.

  3. Select "Build All" from the Embedded Workbench "Project" menu - the demo application should build without errors.

  4. When the build completes, select "Download and Debug" from the Embedded Workbench "Project" menu (or just press CTRL+D) to program the microcontroller flash memory, and start a debug session. The application will start to run, and then break on entry to the main() function.

Building and executing the demo application using Keil tools

  1. Open the RTOSDemo_Keil.uvproj project from within the Keil IDE.

  2. Select the required build configuration. Build configurations are called 'targets' in the uVision IDE.

  3. Select "Build Target" from the IDE's "Project" menu - the demo application should build without errors.

  4. When the build complete, select "Start/Stop Debug Session" from the IDE's "Debug" menu (or just press CTRL+F5) to program the microcontroller flash memory, and start a debug session.

Visible blinky demo functionality

Spansion FM3 FreeRTOS blinky demo led assignment
The LED assignment used by the "blinky" build configuration

When the "blinky" build configuration is executing correctly:

  • The LED marked 'A' in the image above is used by the LED timer. This is the LED that will turn on when user button SW2 is pressed, and then turn off when SW2 has not been pressed for a full five seconds.

  • The LED marked 'B' in the image above is used by the queue receive task. This is the LED that will toggle each time an item is received on the queue (and therefore toggle every 200ms).

Visible full demo functionality

Spansion FM3 FreeRTOS full demo led assignment
The LED assignment used by the "full" build configurations

Only a few of the many tasks and timers that are created by the full demo have externally observable behaviour. When the "full" build configurations are executing correctly, the following behaviour will be observed:

  • The LEDs marked A in the image above are under the control of the 'digit counter' timer. These are the LEDs that will show a digit that repeatedly increments from 0 to 9.

  • The LED marked B in the image above is under the control of the 'check' software timer. This is the LED that will toggle every 3 seconds if no errors have been reported, or every 500ms if a standard demo task has ever reported an error. This mechanism can be tested by removing the loopback connector, and in so doing deliberately generating an error in the standard demo 'comtest' tasks.

  • The LEDs marked C in the image above are under the control of the standard demo 'comtest' tasks. One will toggle each time a character is transmitted, and the other each time the same character is received. The toggle rate is very rapid, and only just visible to the naked eye.

  • The LED marked D in the image above is used by the LED timer. This is the LED that will turn on when user button SW2 is pressed, and then turn off when SW2 has not been pressed for a full five seconds.

  • The LEDs marked E in the image above are under the control of the standard demo 'flash' tasks. Each will toggle at a fixed frequency, with each of the three LEDs using a different frequency.

  • The LED marked F in the image above is under the control of queue receive task. This is the LED that will toggle each time an item is received on the queue (and therefore toggle every 200ms).

RTOS Configuration and Usage Details

Cortex-M3 FreeRTOS port specific configuration

Configuration items specific to this demo are contained in FreeRTOS/Demo/CORTEX_MB9B500_IAR_Keil/FreeRTOSConfig.h (or FreeRTOS/Demo/CORTEX_MB9A310_IAR_Keil/FreeRTOSConfig.h) The constants defined in this file can be edited to suit your application. In particular -
  • configTICK_RATE_HZ

    This sets the frequency of the RTOS tick interrupt. The supplied value of 1000Hz is useful for testing the RTOS kernel functionality but is faster than most applications require. Lowering this value will improve efficiency.


    See the RTOS kernel configuration documentation for full information on these configuration constants.

Attention please!: Remember that ARM Cortex-M3 cores use numerically low priority numbers to represent HIGH priority interrupts. This can seem counter-intuitive and is easy to forget! If you wish to assign an interrupt a low priority do NOT assign it a priority of 0 (or other low numeric value) as this will result in the interrupt actually having the highest priority in the system - and therefore potentially make your system crash if this priority is above configMAX_SYSCALL_INTERRUPT_PRIORITY. Also, do not leave interrupt priorities unassigned, as by default they will have a priority of 0 and therefore the highest priority possible.

The lowest priority on a ARM Cortex-M3 core is in fact 255 - however different Cortex-M3 vendors implement a different number of priority bits and supply library functions that expect priorities to be specified in different ways. For example, on FM3 microcontrollers the lowest priority you can specify is in fact 15 - this is defined by the constant configLIBRARY_LOWEST_INTERRUPT_PRIORITY in FreeRTOSConfig.h. The highest priority that can be assigned is always zero.

It is also recommended to ensure that all four priority bits are assigned as being premption priority bits, and none as sub priority bits.

Each port #defines 'BaseType_t' to equal the most efficient data type for that processor. This port defines BaseType_t to be of type long.

Interrupt service routines

Unlike most ports, interrupt service routines that cause a context switch have no special requirements, and can be written as per the compiler documentation. The macro portEND_SWITCHING_ISR() can be used to request a context switch from within an interrupt service routine.

Note that portEND_SWITCHING_ISR() will leave interrupts enabled.

This demo project provides examples of FreeRTOS interrupt service routines - namely INT0_7_Handler() defined in main-full.c and main-blinky.c, and the two UART interrupt handlers MFS0RX_IRQHandler() and MFS0TX_IRQHandler() defined in serial.c.

Only FreeRTOS API functions that end in "FromISR" can be called from an interrupt service routine - and then only if the priority of the interrupt is less than or equal to that set by the configMAX_SYSCALL_INTERRUPT_PRIORITY configuration constant.

Resources used by FreeRTOS

FreeRTOS requires exclusive use of the SysTick and PendSV interrupts. SVC number #0 is also used.

Switching between the pre-emptive and co-operative RTOS kernels

Set the definition configUSE_PREEMPTION within RTOSDemo/FreeRTOSConfig.h to 1 to use pre-emption or 0 to use co-operative. The full demo application may not execute correctly when the co-operative RTOS scheduler is selected.

Compiler options

As with all the ports, it is essential that the correct compiler options are used. The best way to ensure this is to base your application on the provided demo application files.

Memory allocation

Source/Portable/MemMang/heap_2.c is included in the FM3 demo application 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.


Note that vPortEndScheduler() has not been implemented.

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