Getting Started with the FRDM-K28F

1. Open up MCUXpresso
2. Switch to the Installed SDKs view within the MCUX 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 now 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:

   

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 .

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 TeraTerm) and connect to the debug COM port you determined earlier. Configure the terminal with these settings:

   • 15200 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 J-Link GDB Server".

4. Modify the settings as shown below. The target device selection chosen for this example is the “MK64FN1M0xxx12” 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 tool chain 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".</version>

   

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 </application_name> </example_type> </board_name> </install_dir>

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

   For this guide, the path is:

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

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". </demo_name>"

   

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.

    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 Tool
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-K64F 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