Getting Started with the FRDM-K28F

Import the MCUXpresso SDK

1. Open up MCUXpresso
2. Switch to the "Installed SDKs" view within the MCUXpresso IDE window
3. Open up a Windows Explorer window and drag and drop the MCUXpresso SDK zip file into the "Installed SDKs" view
4. You will get the following pop-up so click on OK to continue the import:
5. It will look like the following when completed:

Build an Example Application

The following steps will guide you through opening the hello_world example.

1. Find the "Quickstart Panel" in the lower left hand corner

   

2. Then click on "Import SDK examples(s)"

   

3. Click on the frdmk28f board to select that you want to import an example that can run on that board, and then click on "Next"

   

4. Use the arrow button to expand the demo_apps category, and then click the checkbox next to hello_world to select that project. Then click on "Next"

   

5. On the next screen, click the checkbox to Redirect printf/scanf to UART so that the terminal output gets sent out the UART instead of using semi-hosting through the debugger. Then click on "Finish"

   

6. Now, build the project by clicking on the project name and then click on the Build icon

   

7. You can see the status of the build in the Console tab

   

Run an Example Application

1. Now that the project has been compiled, you can flash it to the board and run it
2. Make sure the FRDM-K28F board is plugged in, and click on "Debug" ('frdmk28f_demo_apps_hello_world' [Debug])

3. MCUXpresso will probe for connected boards and should find the MBED CMSIS-DAP debug probe that is part of the integrated OpenSDA circuit on the FRDM-K28F. Click on "OK" to continue

   

4. The firmware will be downloaded to the board and the debugger started

   

5. Start the application by clicking the "Resume" button:

   

6. The hello_world application is now running and a banner is displayed on the terminal. If this is not the case, check your terminal settings and connections

   

7. Use the controls in the menu bar to pause, step into, and step over instructions, and then stop the debugging session by click on the Terminate icon:

   

Build an Example Application

The following steps will guide you through opening the hello_world application. These steps may change slightly for other example applications as some of these applications may have additional layers of folders in their path.

1. If not already done, open the desired example application workspace. Most example application workspace files can be located using the following path:

    <install_dir>/boards/<sdk_board_name>/<example_type>/<application_name>/iar

   Using the hello_world demo as an example, the path is:

   <install_dir>/boards/frdmk28f/demo_apps/hello_world/iar

2. Select the desired build target from the drop-down. For this example, select the "hello_world - Debug" target

   

3. To build the application, click the "Make" button, highlighted in red below

   

4. The build will complete without errors

Run an Example Application

The FRDM-K28F board comes loaded with the mbed/CMSIS-DAP debug interface from the factory. If you have changed the debug OpenSDA application on your board, visit OpenSDA for information on updating or restoring your board to the factory state.

1. Connect the development platform to your PC via USB cable between the "SDAUSB" USB port on the board and the PC USB connector

2. Open the terminal application on the PC (such as PuTTY or Tera Term) and connect to the debug COM port you determined earlier. Configure the terminal with these settings:

   • 115,200 baud rate
   • No parity
   • 8 data bits
   • 1 stop bit

3. Click the "Download and Debug" button to download the application to the target

   

4. The application is then downloaded to the target and automatically runs to the main() function

   

5. Run the code by clicking the "Go" button to start the application

   

6. The hello_world application is now running and a banner is displayed on the terminal. If this is not the case, check your terminal settings and connections

   

Install CMSIS device pack

After the MDK tools are installed, Cortex® Microcontroller Software Interface Standard (CMSIS) device packs must be installed to fully support the device from a debug perspective. These packs include things such as memory map information, register definitions and flash programming algorithms. Follow these steps to install the appropriate CMSIS pack.

1. Open the MDK IDE, which is called µVision. In the IDE, select the "Pack Installer" icon

   

2. In the "Pack Installer" window, navigate to the section with the Kinetis packs (they are in alphabetical order). The Kinetis packs start with Keil::Kinetis and are followed by the MCU family name, for example Keil::Kinetis_K60_DFP. Because this example uses the FRDM-K28F platform, the K28 family pack is selected. Click on the "Install" button next to the pack. This process requires an internet connection to successfully complete

   

3. After the installation finishes, close the "Pack Installer" window and return to the µVision IDE

Build the Example Application

The following steps will guide you through opening the hello_world application. These steps may change slightly for other example applications as some of these applications may have additional layers of folders in their path.

1. If not already done, open the desired demo application workspace in:

   <install_dir>/boards/<sdk_board_name>/<example_type>/<application_name>/mdk

   The workspace file is named <application_name>.uvmpw, so for this specific example, the actual path is:

   <install_dir>/boards/frdmk28f/demo_apps/hello_world/iar/hello_world.uvmpw

2. To build the demo project, select the "Rebuild" button, highlighted in red

   

3. The build will complete without errors

Run an Example Application

The FRDM-K28F board comes loaded with the mbed/CMSIS-DAP debug interface from the factory. If you have changed the debug OpenSDA application on your board, visit OpenSDA for information on updating or restoring your board to the factory state.

1. Connect the development platform to your PC via USB cable between the "SDAUSB" USB port on the board and the PC USB connector

2. Open the terminal application on the PC (such as PuTTY or Tera Term) and connect to the debug COM port you determined earlier. Configure the terminal with these settings:

   • 115,200 baud rate
   • No parity
   • 8 data bits
   • 1 stop bit

3. After the application is properly built, click the "Download" button to download the application to the target

   

4. After clicking the "Download" button, the application downloads to the target and should be running. To debug the application, click the "Start/Stop Debug Session" button, highlighted in red

   

5. Run the code by clicking the "Run" button to start the application

   

6. The hello_world application is now running and a banner is displayed on the terminal. If this is not the case, check your terminal settings and connections

   

Set Up Toolchain

This section contains the steps to install the necessary components required to build and run a KSDK demo application with the Arm GCC Toolchain, as supported by the MCUXpresso SDK. There are many ways to use Arm GCC tools, but this example focuses on a Windows environment. Though not discussed here, GCC tools can also be used with both Linux OS and Mac OSX.

Install GCC Arm Embedded Toolchain

Download and run the installer from GNU Arm Embedded Toolchain . This is the actual toolchain (i.e., compiler, linker, etc.). The GCC toolchain should correspond to the latest supported version, as described in the MCUXpresso SDK Release Notes.

Install MinGW

The Minimalist GNU for Windows (MinGW) development tools provide a set of tools that are not dependent on third party C-Runtime DLLs (such as Cygwin). The build environment used by the KSDK does not utilize the MinGW build tools, but does leverage the base install of both MinGW and MSYS. MSYS provides a basic shell with a Unix-like interface and tools.

1. Download the latest MinGW mingw-get-setup installer from MinGW - Minimalist GNU for Windows Files

2. Run the installer. The recommended installation path is C:\MinGW, however, you may install to any location

Note: The installation path cannot contain any spaces.

3. Ensure that the "mingw32-base" and "msys-base" are selected under Basic Setup

   

4. Click "Apply Changes" in the "Installation" menu and follow the remaining instructions to complete the installation

   

5. Add the appropriate item to the Windows operating system Path environment variable. It can be found under Control Panel → System and Security → System → Advanced System Settings in the "Environment Variables" section. The path is:

   <mingw_install_dir>\bin

   Assuming the default installation path, C:\MinGW, an example is shown below. If the path is not set correctly, the toolchain does not work

   Note: If you have C:\MinGW\msys\x.x\bin in your PATH variable (as required by KSDK 1.0.0), remove it to ensure that the new GCC build system works correctly.

   

Add a New Environment Variable for ARMGCC_DIR

1. Create a new system environment variable and name it ARMGCC_DIR. The value of this variable should point to the Arm GCC Embedded tool chain installation path, which, for this example, is:

   C:\Program Files (x86)\GNU Tools Arm Embedded\4.9 2015q3

2. Reference the installation folder of the GNU Arm GCC Embedded tools for the exact path name of your installation

Install CMake

1. Download CMake 3.0.x from CMake

2. Install CMake, ensuring that the option "Add CMake to system PATH" is selected when installing. It's up to the user to select whether it's installed into the PATH for all users or just the current user. In this example, the assumption is that it's installed for all users

   

3. Follow the remaining instructions of the installer

4. You may need to reboot your system for the PATH changes to take effect

Build an Example Application

To build an example application, follow these steps.

1. If not already running, open a GCC Arm Embedded Toolchain command window. To launch the window, from the Windows operating system Start menu, go to "Programs → GNU Tools Arm Embedded <version>" and select "GCC Command Prompt"

2. Change the directory to the example application project directory, which has a path like this:

   <install_dir>/boards/<board_name>/<example_type>/<application_name>/armgcc

   For this guide, the exact path is:

   <install_dir>/boards/frdmk28f/demo_apps/hello_world/armgcc

3. Type build_debug.bat on the command line or double click on the build_debug.bat file in Windows operating system explorer to perform the build. The output is shown in this figure:

   

Run an Example Application

The GCC tools require a J-Link debug interface. To update the OpenSDA firmware on your board to the latest J-Link app, visit OpenSDA. After installing the J-Link OpenSDA application, download the J-Link driver and software package from SEGGER Downloads .

1. Connect the development platform to your PC via USB cable between the "SDAUSB" USB port on the board and the PC USB connector

2. Open the terminal application on the PC (such as PuTTY or Tera Term) and connect to the debug COM port you determined earlier. Configure the terminal with these settings:

   • 115,200 baud rate
   • No parity
   • 8 data bits
   • 1 stop bit

3. Open the J-Link GDB Server application. Assuming the J-Link software is installed, the application can be launched by going to the Windows operating system Start menu and selecting "Programs → SEGGER → J-Link <version> J-Link GDB Server"

4. Modify the settings as shown below. The target device selection chosen for this example is the "MK28FN2M0xxx15" and use the SWD interface

   

5. After it is connected, the screen should resemble this figure:

   

6. If not already running, open a GCC Arm Embedded Toolchain command window. To launch the window, from the Windows operating system Start menu, go to "Programs → GNU Tools Arm Embedded <version>" and select "GCC Command Prompt"

   

7. Change to the directory that contains the demo application output. The output can be found in using one of these paths, depending on the build target selected:

   <install_dir>/boards/<board_name>/<example_type>/<application_name>/armgcc/debug

   <install_dir>/boards/<board_name>/<example_type>/<application_name>/armgcc/release

   For this guide, the path is:

   <install_dir>/boards/frdmk28f/demo_apps/hello_world/armgcc/debug

8. Run the command arm-none-eabi-gdb.exe <demo_name>.elf. For this example, it is arm-none-eabi-gdb.exe hello_world.elf

   

9. Run these commands:

   • target remote localhost:2331
   • monitor reset
   • monitor halt
   • load
   • monitor reset
10. The application is now downloaded and halted at the reset vector. Execute the "monitor go" command to start the example application
11. The hello_world application is now running and a banner is displayed in the terminal window

1. Open the MCUXpresso IDE
2. Click "Import SDK Example(s)" from the "QuickStart Panel"
3. Select the FRDM-K28F board in the "Import Wizard". Then, select "Next"
4. Type "led" into the search bar, and select the "led_output" project under the 'gpio' driver example. Then, select "Next". This will create a new standalone copy of this LED project and put it into the MCUXpresso workspace. To use the UART for printing (instead of the default semihosting), clear the "Enable semihost" checkbox under the project options. Then, click on "Next"
5. On the Advanced Settings wizard, clear the checkbox "Redirect SDK "PRINTF" to C library "printf"" in order to use the MCUXpresso SDK console functions for printing instead of generic C library ones. Then click on "Finish"
6. Click on the "led_output" project in the "Project Explorer" view and build, compile, and run the demo as described previously
7. You should see a red LED blinking on the board
8. Terminate the debug session

1. Open the MCUXpresso Config Tools
2. In the wizard that comes up, browse to the place where the MCUXpresso SDK was unzipped, and then select the "Clone an example project" radio button and click on "Next"
3. Select the project to clone. For this example, we want to use the LED project. You can filter for this by typing "led" in the filter box and then selecting the "gpio/led_output" project. Then click on "Next"
4. Then, select the directory you want to place the cloned project, give it a name, and select the IDE to use. Note that only IDEs that were selected in the online SDK builder when the SDK was built will be available. Then click on "Finish"
5. After cloning go to the directory you selected and open up the project for your IDE. Import, compile, and run the project as done in previous sections
6. You should see a red LED blinking on the board
7. Terminate the debug session

1. Open MCUXpresso Config Tools
2. The wizard will ask if you want to start development with or without an SDK. Choose to start development with the SDK and that we want to create a new configuration. Use the "Browse" button to navigate to the location of your unzipped SDK installation
3. Select the SDK top-level folder from your file system. Select "OK"
4. The wizard asks to create a new configuration or clone an example project. We will create a new configuration that will be based on the "led_output" project settings from the SDK. Select "Next" to continue
5. Search for the "led_output" example by typing "led" in the search bar. Select the "led_output" example and press "Finish"
6. Open the Pins Tool by selecting Tools → Pins from the toolbar
7. The Pins Tool should now display the pin configuration for the "led_output" project
8. In the Pins view click the "Show Routed/All Pins" checkbox to see all the routed pins. Routed pins have a check in a green box next to the pin name. The functions selected for each routed pin are highlighted in green in the table
9. In the current configuration, PTB22 is routed as a GPIO to toggle the red LED. Let's disable PTB22, and change the mux setting of PTB21 to use its GPIO functionality to drive the blue LED
10. Disable PTB22 (red LED) as a GPIO by clicking the PTB22 field under the GPIO column. The pin will then be disabled (pin will no longer have check in box) and thus disappear from the list
11. Now, route PTB21 as a GPIO. First, deselect the "Show Routed All/Pins" so that all the pins are displayed again. Then, search PTB21 in the pins view. Finally, click the box under the GPIO column. The box will highlight in green, and a check will appear next to the pin
12. The updated view will appear as below once you clear the filtered text. Note that PTB21 also appears in the "Routed Pins" tab and PTB22 has been removed. The pin_mux.c file has been updated to reflect the change as well
13. PTB21 already has a defined identifier (i.e. "LED_BLUE") set up for the FRDM-K28F for the "led_output" example configuration. Now, change the identifier to "My_LED" next to PTB21 in the Pins table by searching for PTB21. This will add a #define to the pin_mux.h file that will be used to identify the LED

14. Now, export the pin_mux.c and pin_mux.h files by clicking on the "Sources" tab on the right side to get to the "Sources" view, and selecting the export icon

    

15. Select the directory to export the pin_mux.c and pin_mux.h files. In this example export to the "board" folder in the "led_output" project in the workspace that was created in the previous section (i.e. C:\MCUXpressoIDE_Lab\frdmk28f_driver_examples_gpio_led_output\board). Select "Finish"

    
16. Click "Yes" to replace the existing pin_mux.c and pin_mux.h files
17. We'll use MCUXpresso IDE for the rest of the instructions but the same steps can be done in other 3rd party IDEs. Under the "led_output" project, double-click the gpio_led_output.c file in the source folder to display the file in the editor. Notice that the macros used in the GPIO driver functions refer to the BOARD_LED (i.e. red LED). We need to replace these with the macros for "My_LED" that we just created
18. Double-click the pin_mux.h file under the board folder in the "led_output" project. Since the file has been updated, press "F5" or File → Refresh to update the file in the editor. Copy BOARD_INITPIN_My_LED_GPIO in pin_mux.h
19. In gpio_led_output.c, replace BOARD_LED_GPIO with BOARD_INITPIN_My_LED_GPIO in lines 87 and 92
20. Similarly, copy BOARD_INITPINS_MY_LED_GPIO_PIN from pin_mux.h
21. In gpio_led_output.c, replace BOARD_LED_GPIO_PIN with BOARD_INITPIN_My_LED_GPIO_PIN in lines 87 and 92
22. Build and download the project as done in the previous section
23. Run the application. You should now see the blue LED blinking
24. Terminate the debug session

1. Open MCUXpresso Config Tools
2. Open the Clocks Tool from the toolbar: Tools → Clocks
3. The clock configuration for the "led_output" project will appear in the Clocks Tool:
4. Switch to the "Clocks Diagram" view by clicking the tab in the upper left corner, and ensure that the "BOARD_BootClockRUN" clock mode is being displayed by clicking the tab in the lower left corner
5. Change the core clock frequency by clicking in the "Core Clock" field and typing "12 MHz". You'll see all the associated clock frequencies automatically change as well then
6. Now, open the "Sources" tab and export the clock_config.c and clock_config.h files

7. Select the directory to export the clock_config.c and clock_config.h files. In this example export to the "board" folder in the "led_output" project in the workspace. (i.e. C:\MCUXpressoIDE_Lab\frdmk28f_driver_examples_gpio_led_output\board). Select "Finish"

   
8. Press "Yes" to replace the existing clock_config.c and clock_config.h files
9. Now, open the led project in your IDE, and build, download, and run the project as you did before
10. The blue LED should now be blinking at a much slower rate