Freescale FRDM-K64F

Interrupts

Interrupt numbers are virtual and numbered from 0 through N, regardless of how the interrupt controllers are set up. However, with the Cortex-M3 which has only one NVIC, interrupts map directly to physical interrupts 0 through N, and to exceptions 16 through (N + 16).

The Cortex-M4 has an 8-bit priority register. However, some of the lowest-significant bits are often not implemented. When citing priorities, a priority of 1 means the first priority lower than 0, not necessarily the priority whose numerical value is 1. For example, when only the top three bits are implemented, priority 1 has a priority numerical value of 0x20h.

When specifying an interrupt priority either to connect an ISR or to set the priority of an interrupt, use low numbers. For example, if 3 bits are implemented, use 1, 2, and 3, not 0x20h, 0x40h, and 0x60h.

Interrupt priority is set using the prio parameter of IRQ_CONNECT() or irq_connect_dynamic().

The range of available priorities is different if using Zero Latency Interrupts (ZLI) or not.

When not using ZLI:

• 2 to 2ⁿ-2, where n is the number of implemented bits (e.g. 2 to 14 for 4 implemented bits)
• Interrupt locking is done by setting BASEPRI to 2, setting exceptions 4, 5, 6, and 11 to priority 1, and setting all other exceptions, including interrupts, to a lower priority (2+).

When using ZLI:

• 3 to 2ⁿ-2, where n is the number of implemented bits (e.g. 3 to 6 for 3 implemented bits)
• Interrupt locking is done by setting BASEPRI to 3, setting exceptions 4, 5, 6, and 11 to priority 1, setting ZLI interupts to priority 2 and setting all other exceptions, including interrupts, to a lower priority (3+).

Interrupt Tables

There are a number of ways of setting up the interrupt table depending on the range of flexibility and performance needed. The two following kconfig options drive the interrupt table options:

SW_ISR_TABLE and SW_ISR_TABLE_DYNAMIC

Depending on whether static tables are provided by the platform configuration or by the application, two other kconfig options are available:

SW_ISR_TABLE_STATIC_CUSTOM and IRQ_VECTOR_TABLE_CUSTOM

The following interrupt table scenarios exist:

SW_ISR_TABLE=y, SW_ISR_TABLE_DYNAMIC=y

For maximum ease of use, maximum flexibility, a larger footprint, and weaker performance.

This is the default setup. The vector table is static and uses the same handler for all entries. The handler finds out at runtime what interrupt is running and invokes the correct ISR. An argument is passed to the ISR when the ISR is connected.

The table, in the data section and therefore in SRAM, has one entry per interrupt request (IRQ) in the vector table. An entry in that table consists of two words, one for the ISR and one for the argument. The table size, calculated by multiplying the number of interrupts by 8 bytes, can add significant overhead.

In this scenario, some demuxing must take place which causes a delay before the ISR runs. On the plus side, the vector table can be automatically generated by the Zephyr kernel. Also, an argument can be passed to the ISR, allowing multiple devices of the same type to share the same ISR. Sharing an ISR can potentially save as much, or even more, memory than a software table implementation might save.

Another plus is that the vector table is able to take care of the exception handling epilogue because the handler is installed directly in the vector table.

SW_ISR_TABLE=y, SW_ISR_TABLE_DYNAMIC=n

For advanced use, medium flexibility, a medium footprint, and medium performance.

In this setup, the software table exists, but it is static and pre-populated. ISRs can have arguments with an automatic exception handling epilogue. Table pre-population provides better boot performance because there is no call to irq_connect() during boot up; however, the user must provide a file to override the platform’s default ISR table defined in sw_isr_table.S. This file must contain the _sw_isr_table[] variable initialized with each interrupt’s ISR. The variable is an array of type struct _IsrTableEntry. When a user provides their own sw_isr_table.c, the type can be found by including sw_isr_table.h.

SW_ISR_TABLE=n

For advanced use, no flexibility, the best footprint, and the best performance.

In this setup, there is no software table. ISRs are installed directly in the vector table using the _irq_vector_table symbol in the .irq_vector_table section. The symbol resolves to an array of words containing the addresses of ISRs. The linker script puts that section directly after the section containing the first 16 exception vectors (.exc_vector_table) to form the full vector table in ROM. An example of this can be found in the platform’s irq_vector_table.c. Because ISRs hook directly into the vector table, this setup gives the best possible performance regarding latency when handling interrupts.

When the ISR is hooked directly to the vector, the ISR must manually invoke the _IntExit() function as its very last action.

SW_ISR_TABLE=y, SW_ISR_TABLE_STATIC_CUSTOM=y

For overriding the static ISR tables defined by the platform:

In this setup, the platform provides the _irq_vector_table symbol and data in sw_isr_table.s.

SW_ISR_TABLE=n, IRQ_VECTOR_TABLE_CUSTOM=y

In this setup, the platform provides the _irq_vector_table symbol and data in irq_vector_table.c.

Prerequisite

Although FRDM K64F firmware may be pre-installed on the FRDM_K64F, you must replace it with the latest version.

Steps

1. Go to the FRDM K64F firmware instructions.

2. Download the lastest version of the FRDM K64F firmware from the mbed project.

3. Update the FRDM K64F firmware using the following online instructions:

   1. Enter Bootloader mode.
   2. Update Using Windows and Linux.
   3. Power Down, Power Up.

3. Follow the online instructions to Connect the microcontroller to a PC.

   1. Connect your microcontroller to a PC.
   2. Click the MBED.HTM link to log in.

4. Follow the online instructions to Configure a terminal application.

   1. Install a Terminal Application.
   2. Setup the Connection Use COMx at 8-N-1 with 115200 baud.

   The Status light on the FRDM K64F Microcontroller flickers when you type in the terminal application.

5. Configure the host to run a progam binary using the online instructions Downloading a Program.

   1. Save a program binary (.bin) to the FRDM Platform.
   2. Press the Reset button.
   3. Download a program binary.

6. Disconnect and re-connect the terminal serial port connection after copying each .bin file.

Prerequisites

• You understand that Segger does not warranty or support OpenSDA V2 firmware.

• You comply with all OpenSDA V2 firmware conditions of use, but particularly:

  • Use with Freescale target devices only. Use with other devices

    is prohibited and illegal.

  • Use with evaluation boards only; not with custom hardware.

  • Use for development and/or evaluation purposes only.

• You have licensed J-Link firmware.

• You have USB drivers for J-Links with VCOM support.

Steps

1. Go to the J-Link site.

2. Locate the section, J-Link software & documentation pack for Linux ARM systems and click the Download button for Software and documentation pack for Linux ARM systems V5.00b.

3. Go to Segger OpenSDA.

4. Download JLink_OpenSDA_V2_2015-04-23.zip.

5. Install the USB Driver for J-Link with Virtual COM Port on the PC.

6. Extract the OpenSDA image from the download.

7. Press and hold the board Reset button while connecting the board to the PC with a USB cable.

   The OpenSDA platform starts in MSD mode.

8. From the PC, drag & drop the .sda/.bin file to the board to load the firmware.

9. Disconnect and reconnect the board.

   The OpenSDA platform is now available on the PC as a J-Link appearance.

10. Run the J-Link Commander (JLinkExe on Linux) program on the PC to test if the J-Link connects to the target.

Prerequisites

• You already have the GDB Server and J-Link Commander utility you downloaded with the Software and documentation pack for Linux ARM systems V5.
• Review the GNU Tools for ARM Embedded Processors documentation.

Steps

1. Download and install a Linux version of Eclipse IDE for C/C++ Developers if you do not have Eclipse installed already.
2. Download and install the GNU ARM Eclipse Plug-ins, and follow the online instructions.
3. Follow the online instructions to install the GDB Server.
4. Download and install the GCC, the GNU Compiler Collection. [This step does not apply to Wind River customers.]
5. Download and install GDB: The GNU Project Debugger. [This step does not apply to Wind River customers.]
6. Download and install the J-Link hardware debugging Eclipse plug-in.

Prerequisites

• The J-Link hardware debugging Eclipse plug-in page is open.

Steps

1. Follow the online configuration instructions that should be open already from the previous procedure, then optimize the configuration using the remaining steps in this procedure.
2. Create an empty C project.
3. Create a reference to the project.
   1. In the Eclipse menu, select Run -> Debug Configurations -> C/C++Application -> Main.
   2. Click the Project: Browse button and select the project you created a reference to.
   3. Click the C/C++Application: Browse button and select an existing ELF or binary file.
   4. Deselect Enable auto build and click Apply.
4. Select the Common tab.
5. In the Save as: field, type Local file and click Apply.
6. Select the Debugger tab.
7. In the Executable: field, type the path to the GDB installation.
8. In the Device name: field, type MK64FN1M0xxx12 and click Apply.
9. Select the Startup tab.
10. Deselect SWO Enable.
11. Deselect Enable semihosting.
12. Select Load symbols.
13. Click Use File and type the name of a Zephyr .elf file.
14. Click Apply.

Prerequisites

• Have the Zephyr application image file saved as a binary file. (The build should have created this binary file automatically.)

Steps

1. In a console, change directory to the J-Link installation directory.

2. At the J-Link> prompt, enter:

   exec device = MK64FN1M0xxx12
   

3. Enter:

   loadbin [filename], [addr]
   

   Example: loadbin zephyr.bin, 0x0

4. Enter:

   verifybin [filename],[addr]
   

   Example: verifybin zephyr.bin, 0x0

5. To reset the target, enter:

   r
   

6. To start the image running directly from the shell, enter:

   g
   

7. To stop the image from running, enter:

   h