Getting Started with i.MX RT600 Evaluation Kit

LPCScrypt is a command-line based, fast flash, EEPROM, OTP and security programming tool for LPC microcontrollers. It is the recommended tool to program the latest CMSIS-DAP and J-Link firmware.

1. Download the LPCScrypt tool using the button below, choose your platform (Windows, MAC OC X, Linux). After the download, run the installer. During the installation the DFU and VCOM drivers will be automatically installed for all platforms.

Download

2. Configure To update the LPC-Link2 debug circuit firmware, unplug the USB cable on J5 and then put on the DFULink jumper
   • In the MIMXRT685-EVK, JP1 is the LPCXpresso DFU jumper. Connect JP1 using the jumper

GS-MIMXRT685-EVK-CONFIGURE-DFU



GS-MIMXRT685-EVK-CONFIGURE-DFU


3. Reconnect the board to your host computer over the debug link USB connector J5
4. Launch LPCScrypt by double-clicking on the “Boot LPCScrypt” file in the LPCScrypt install C:\ProgramData\Microsoft\Windows\Start Menu\Programs\LPCScrypt

5. In that command shell, run the program JLINK script to install the JLink debug firmware:

   Note: File paths in this document use Windows directory separator, on Linux or Mac OSX these must be replaced with '/.'

   Note: For Windows users, shortcuts to these scripts are available from the LPCScrypt entry on the Start menu.


6. Verify once you select on firmware (in this case J-Link), LPCScrypt will show something like below in the console

7. Ready once programming is complete, disconnect the board from the host. Remove the DFULink jumper, then reconnect the board to the host computer. You should see that the probe enumerates on the host's USB system

1. Download J-Link software

Enter the SEGGER download page.

2. Expand “J-Link Software and Documentation Pack” section

3. Select the software that matches your OS and download the newest version


Accept terms and download the software

4. Execute the .exe file you just downloaded by doing double-click. Follow the setup instructions until the J-Link installation is complete

5. You're ready to go

Cadence® Tensilica® Xplorer is a complete development environment that helps users create application code for high-performance Tensilica® processors. Xplorer is the interface to powerful software development tools such as the XCC compiler, assembler, linker, debugger, code profiler and full set of GUI tools.

Xplorer (including both GUI and command line environment). Is the only available development IDE for the DSP core of MIMXRT600.

1. Create a profile: This is needed to download the Tensilica Tools. Go to the download page and login. If this is the first time to access, please register first


You will receive an email confirmation with the activation link from “Tensilica tools”. Click the activation link to complete the registration.

2. Install Xtensa Xplorer IDE once registered, please login and you will see available materials. Note that there may be multiple version numbers available and it is recommended to use the latest version currently available. The steps are the exact same for all versions except for slight name differences
   • Download and install “Xtensa Xplorer IDE” for your operating system
   • Download the “DSP Configuration” for your operating system. Make sure to select the NEWLIB version. This file will be used later

3. Download a License Key to generate the correct license file, you should first identify the appropriate MAC for the computer you plan to run Xtensa tools on. Open a Command Prompt and type:
   Windows:
Linux:

Reload and return to the Tensilica download page and click on “Get a License Key for RT600 SDK”



Type your MAC address without '-' or ':' symbols.


4. Install License Key once the license has been generated and downloaded, open Xplorer IDE and select on menu Help → Xplorer License Keys → License Options → Install Software Keys. Select the license key file and click 'Finish'


NOTE:

The generated license file only supports debug/run on the RT600 device target. It does not support software simulation/Xplorer ISS. Please contact Cadence directly if you have special needs to run software simulations.

5. Install RT600 DSP Build Configuration: The build configuration can be installed into the IDE using the 'System Overview' panel, which is located on the lower left corner by default. If this panel is not visible, it can be toggled using menu item Window → Show View → System Overview


Search the configuration you downloaded at Step 2.


6. Install Xtensa On Chip Debugger Deamon: The Xtensa On Chip Debugger Deamon (xt-ocd), is a powerful gdb-based debugging tool. It is not installed by default with the Xplorer IDE. A self-extracting executable installer is included with the IDE. It is located at:

Windows:

C:\usr\xtensa\XtDevTools\downloads\RI2019.1\tools\xt-ocd-14.0.1-windows64-installer.exe

Linux:

~/xtensa/XtDevTools/downloads/RI2019.1/tools/xt-ocd-14.0.1-linux64-installer

At this moment xt-ocd supports J-Link and Arm RVI/DSTREAM probes over Serial Wire Debug (SWD) for RT600. Xt-ocd installs support for J-Link probes but does not install the required J-Link drivers, which must be installed separately. The RT600 requires J-Link software version 6.46 or newer.

Note: When installing xt-ocd on Linux, you must manually add a symlink to the installed J-Link driver:

“ln -s <jlink-install-dir>libjlinkarm.so.6 <xocd-install-dir>/modules/libjlinkarm.so.6”

7. Identify the Jlink serial number of your LPC-Link2. Run JLINK commander to check the serial number. It is located at:

   "C:\Program Files (x86)\SEGGER\JLink"


Every EVK/LPC-Link2 will have different Jlink S/N.



Note: Please note that J-Link firmware needs to be installed to identify this serial number. If you haven't update the firmware, please refer to the step “2.4 LPCScrypt” on this guide.

8. Edit topology file: xt-ocd is configured with an XML input file named "topology.xml". This file is located in the Xtensa OCD installation directory at: C:\Program Files (x86)\Tensilica\Xtensa OCD Daemon 14.01
9. You will need to modify this file for your debugger hardware. Using J-link as example, please use this topology.xml file to replace the original file. Or copy one of the examples below

Please note that you need to replace 'usbser' section with your own Jlink serial number (9-digit number obtained on the previous step).



Below is another topology.xml example if using Arm RealView ICE (RVI) and DSTREAM debug probes:”

The RT600 SDK provides a collection of DSP example applications. Each DSP example has two source directories, one for the Arm CM33 and one for the DSP HiFi4.

In order to debug a DSP demo, you will need to follow two processes. The first one is to build and flash the CM33 application to your MIMXRT685-EVK. The second is to build and debug the DSP application using Xtensa Xplorer IDE.

Build and Flash Cortex-M33 Application

The following steps will guide you through the mu_polling application using MCUXpresso IDE for the Cortex-M33 application. The MCUXpresso IDE installation can be found at the section “2. Get Software” of this Getting Started guide.

1. Open the MCUXpresso IDE
2. Switch to the Installed SDKs view within the MCUXpresso IDE window

3. Drag and drop the MIMXRT685-EVK SDK (zipped) file into the Installed SDKs view
4. You will get the following pop-up. Click on OK to continue the import:

5. The installed SDK will appear in the Installed SDKs view as shown below:

6. Find the Quickstart Panel in the lower left-hand corner

7. Then click on Import SDK example(s)

8. Click on the evkmimxrt685 board to select that you want to import an example that can run on that board, and then click on Next

9. Use the arrow button to expand the dsp_examples category, and then click the checkbox next to dsp_mu_polling_cm33 to select that project. To use the UART for printing (instead of the default semihosting), Select UART as the SDK Debug Console checkbox under the project options. Then, click on Finish

10. Verify the DSP_IMAGE_COPY_TO_RAM macro value. To do this, go to project properties doing right click on the project

11. Open C/C++ Build option and select Settings

12. Once in there, into the Tool Settings, select the Preprocessor folder and change the value of DSP_COPY_IMAGE_TO_RAM to 0

13. Apply and Close

14. Open incbin.S file and edit the same macro

15. Select the project and build it

16. The project will build without problems

17. Connect the board to your computer with the micro USB to J5 'LINK USB' port

18. Download the application to your MIMXRT685-EVK

19. Select the J-Link debug probe

20. Run the application

Build the DSP Application

The following steps will guide you through the mu_polling application using Xtensa Xplorer IDE for the DSP. The Xtensa Xplorer IDE installation can be found at the section “2. Get Software” of this Getting Started guide.

1. Open Xtensa Xplorer IDE
2. Import the “mu_polling” demo on your workspace. File → Import

3. Select Existing Projects into Workspace

4. Use the Browse button and select the mu_polling dsp demo on the SDK. Make sure the path name to the SDK does not contain any spaces.
   The path is:
<SDK install dir> \boards\evkmimxrt685\dsp_examples\mu_polling\dsp
5. Once imported, you will see 'dsp_mu_polling_hifi4' in the Project Explorer. This project includes the code for the DSP. You can see the main function at source → main_dsp.c

6. To build the DSP application, you must set the following configuration (use the drop down buttons on the menu bar):

7. Build the application by doing click on the “Build Active” button
8. The build should complete without errors. If there are errors, verify that the SDK directory path does not contain any spaces

9. Open a command prompt on the following location: “C:\Program Files (x86)\Tensilica\Xtensa OCD Daemon 14.01” and execute the following command: “xt-ocd.exe -c→topology.xml”. You should see the following:

10. 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:
    • 115200 baud rate
    • No parity
    • 8 data bits
    • 1 stop bit
11. Go to Xtensa Xplorer IDE and use the Debug action button to open the Debug Configuration

12. Please select the dsp_mu_polling Xtensa On Chip Debug. And Click on Debug

13. A new window will be opened asking to download the application to the core 0. Click Yes

14. Xtensa Xplorer will transition to the Debug perspective

15. Click on 'Resume' button to start the program

16. You should see the LED D9 blinking and the following on the terminal:

17. Click on 'Terminate' button to stop the debugging session on Xtensa Xplorer IDE

18. Stop the debugger on the IDE running the CM33 application

Build an Example Application

The following steps will guide you through opening the mu_polling application. This application consists of code for both the Cortex M33 core and the DSP core. The instructions for compiling and debugging for the Cortex M33 core are covered in the instructions below. Instructions for compiling and debugging for the DSP code can be found in Section 2 of the “Use MCUXpresso IDE” tutorial. These steps may change slightly for other example applications as some of these applications may have additional layers of folders in their path.

1. First, install the IAR patch for IAR EWARM 8.50.1 found on the IAR site which will add NXP i.MXRT600 flashloader support. The patch can be found by clicking on “Find Updates” after logging into the IAR website.
2. Next, unzip the previously downloaded SDK package

3. 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/evkmimxrt685/dsp_examples /mu_polling/cm33/iar
4. Select the desired build target from the drop-down. For this example, select the “dsp_mu_polling_cm33 - debug” target
5. Change DSP_IMAGE_COPY_TO_RAM macro value to 0. Open the project properties by doing right click on the project and selecting Options
6. Click on C/C++ Compiler and select Preprocessor. Change the DSP_IMAGE_COPY_TO_RAM to 0
7. Now go to Assembler, select Preprocessor option and change the same macro
8. Now go to Debugger section and change the debugger driver to Jlink. Press OK button
9. To build the application, click the “Make” button, highlighted in red below

10. The build will complete without errors

    

    NOTE:

    In case of building errors, make sure that the correct Board is selected, right click in the project → Options → General Options → Target → Device, Select the NXP MIMXRT685S_M33, this board is support in IAR Embedded Workbench for Arm version 8.40.1 or Higher.

    

Run an Example Application

The LPC-Link2 circuit on the board should have been updated to use the J-Link interface during Step 2.4 “LPCScrypt” of the Getting Started website. See that section of the Getting Started website for more details on using LPCScrypt to update the debug circuit firmware on the board to use the J-Link interface if this has not already been done.

1. Connect the development platform to your PC via USB cable to J5 “Link USB”. Ensure the DFULink jumper (JP1) is removed when powering the board
2. Click the "Download and Debug" button to download the application to the target.
3. The application is then downloaded to the target and automatically runs to the main() function
4. Run the code by clicking the "Go" button to start the application
5. The mu_polling_cm33 application is now running

Build the DSP Application

To build and debug the code for the DSP part of this application, open the “Use MCUXpresso IDE” tutorial and follow the instructions starting at “2. Build the DSP Application.

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, search for “imxrt685” to bring up the LPC55S28 family. Click on the MIMXRT685S name, and then in the right-hand side you'll see the NXP::MIMXRT685S_DFP pack. 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 mu_polling application. This application consists of code for both the Cortex M33 core and the DSP core. The instructions for compiling and debugging for the Cortex M33 core are covered in the instructions below. Instructions for compiling and debugging for the DSP code can be found in Section 2 of the “Use MCUXpresso IDE” tutorial. 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/evkmimxrt685/dsp_examples/mu_polling/cm33/mdk/dsp_mu_polling_cm33.uvmpw
2. Select debug configuration
3. Do right click on the project and select the project options:
4. Select the C/C++ option and change the DSP_IMAGE_COPY_TO_RAM to 0
5. Open Asm option and change the same macro to 0
6. Now, go to the Debug option and select J-LINK. Click on Ok button
7. To build the demo project, select the "Rebuild" button, highlighted in red
8. The build will complete without errors

Run an Example Application

The LPC-Link2 circuit on the board should have been updated to use the J-Link interface during Step 2.4 “LPCScrypt” of the Getting Started website. See that section of the Getting Started website for more details on using LPCScrypt to update the debug circuit firmware on the board to use the J-Link interface if this has not already been done.

1. Connect the development platform to your PC via USB cable to J5 “Link USB”. Ensure the DFULink jumper (JP1) is removed when powering the board to boot the debug probe from internal flash
2. After the application is properly built, click the "Download" button to download the application to the target
3. Click on “Start/Stop Debug Session” to open the debug view
4. Run the code by clicking the "Run" button to start the application
5. The mu_polling_cm33 application is now running

Build the DSP Application

To build and debug the code for the DSP part of this application, open the “Use MCUXpresso IDE” tutorial and follow the instructions starting at “2. Build the DSP Application.

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. This is the actual toolchain (i.e., compiler, linker, etc.). The GCC toolchain should correspond to the latest supported version, as described in the Kinetis 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

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\<version>

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

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. Open the next directory on the file explorer <SDK Install dir>\boards\evkmimxrt685\dsp_examples\mu_polling\cm33\armgcc

   and open CMakeList.txt file


2. Edit the next lines changing the value to 0:

    SET(CMAKE_ASM_FLAGS_DEBUG "${CMAKE_ASM_FLAGS_DEBUG} -DDSP_IMAGE_COPY_TO_RAM=0") SET(CMAKE_C_FLAGS_DEBUG "${CMAKE_C_FLAGS_DEBUG} -DDSP_IMAGE_COPY_TO_RAM=0") 

3. 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”

4. 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/evkmimxrt685/dsp_examples/mu_polling/cm33/armgcc
5. 5. 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. The LPC-Link2 circuit on the board should have been updated to use the J-Link interface during Step 2.4 “LPCScrypt” of the Getting Started website. See that section of the Getting Started website for more details on using LPCScrypt to update the debug circuit firmware on the board to use the J-Link interface if this has not already been done.

1. Connect the development platform to your PC via USB cable to J5 “Link USB”. Ensure the DFULink jumper (JP1) is removed when powering the board

2. 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"
3. Modify the settings as shown below. The target device selection chosen for this example is the “MIMXRT685S_M33” and use the SWD interface

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

5. 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"

6. 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/debug 

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

   For this guide, the path is:

    <install_dir>/boards/frdmk64f/demo_apps/hello_world/armgcc/debug 

7. Run the command "arm-none-eabi-gdb.exe <demo_name>.elf". For this example, it is "arm-none-eabi-gdb.exe dsp_mu_polling_cm33.elf"
8. Run these commands:
   • "target remote localhost:2331"
   • "load"

9. Execute the "monitor go" command to start the example application.

   The mu_polling cm33 application is now running.

Build the DSP Application

To build and debug the DSP application follow the instructions of chapter “2. Build the DSP Application” at MCUXpresso tutorial on this same section.

Build an Example Application

The following steps will guide you through the manipulation of the general-purpose outputs. The example sets up a switch button and an LED. The LED blinks if the button SW2 is pressed.

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

2. Then click on Import SDK examples(s)

3. Click on the evkmimxrt685 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 driver_examples category, then expand the sctimer examples, click on the checkbox next to sctimer_pwm_with_dutycycle_change to select it. To use the UART for printing (instead of the default semihosting), Select UART as the SDK Debug Console checkbox under the project options. Then, click on Finish

5. Click on the “evkmimxrt685_sctimer_pwm_with_duty_cycle_change” project in the Project Explorer View and build, compile and run the demo as described previously

6. You should see the GREEN LED changing the brightness

Note: On “Use Pin Tool” tutorial, you will learn how to change the LED output pin of the board.

7. Terminate the debug session

The following steps will guide you through the manipulation of the general-purpose outputs. The example sets up a switch button and an LED. The LED blinks if the button SW2 is pressed.

1. Open the MCUXpresso Config Tool
2. In the wizard that comes up, select the “Create a new configuration based on an SDK example or hello word project” radio button and click on Next

3. On the next screen, select the location of the MCUXpresso SDK that you had unzipped earlier. Then select the IDE that is being used. Note that only IDEs that were selected in the online SDK builder when the SDK was built will be available and click on clone select example


Then select the project to clone. For this example, we want to use the GPIO LED output project. You can filter for this by typing “sctimer” in the filter box and then selecting the “sctimer_pwm_with_dutycycle_change” example project. You can then also specify where to clone the project and the name. Then click on Finish.

4. After cloning go to the directory you selected and open the project for your IDE. Import, compile and run the project as done in previous sections
5. You should see the GREEN LED changing the brightness

Note: On “Use Pin Tool” tutorial, you will learn how to change the LED output pin of the board.

6. Terminate the debug session

Note: Previously, you had to clone an SDK project like in the previous step.

To Open Pin Tools in MCUXpresso IDE

Open the pins tool by right clicking on the “evkmimxrt685_sctimer_pwm_with_dutycycle_change” project, and selecting “MCUXpresso Config Tools” and then “Open Pins”.

The pins tool should now display the pin configuration for the sct project.

To Open Pin Tools in MCUXpresso Config Tools

1. Open the MCUXpresso Config Tool
2. In the wizard that comes up, select the “Open existing configuration” radio button, then select the project that you had clone and click on Next

3. Open the pins tool by selecting Tools → Pins from the toolbar

4. The pins tool should now display the pin configuration for the sctimer project

Use the Pins Tools to Modify the LED Routed Pin

1. We'll use MCUXpresso IDE for the rest of the instructions, but the same steps can be done in MCUXpresso Config tools for third party IDEs. In the Pins view deselect the “Show not routed pins” checkbox to see only the routed pins, you also going to see the pins that are routed by default. 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

2. In the current configuration, PIO0_14 is routed as a SCT0_OUT0. Let's disable, PIO0_14 and change the MUX setting of PIO0_26 to use its SCT0_OUT6 functionality
3. Disable PIO0_14 by clicking the “SCT0_OUT0” field under the SCT column. The pin will then be disabled (pin will no longer have check in box) and thus disappear from the list

4. Now, route PIO0_26 as a SCT_OUT6. First, select the “Show not routed pins” so that all the pins are displayed again. Then, search PIO0_26 in the pins view. Finally, click the box under the SCT column “PIO0_26”. The box will highlight in green, and a check will appear next to the pin

5. Now it's time to implement these changes into the project by exporting the new updated pin_mux.c and pin_mux.h files that are generated by the Pins tool. Click on Update Project in the menu bar

6. The screen that pops up will show the files that are changing and you can click on “diff” to see the difference between the current file and the new file generated by the Pins tool. Click on “OK” to overwrite the new files into your project

Note: The clocks files may also be tagged as being updated since the header has been changed.


7. Now inside the IDE, open the pin_mux.c file under board folder

8. Note that when we change the sct routed pin in the tool the PIO0_14 was selected and configured as SCT_OUT (green LED). Now, we have the declaration of PIO0_26 and configured as SCT_OUT (blue LED)

9. Open sctimer_update_dutycycle.c file and change macro DEMO_SCTIMER_OUT to kSCTIMER_Out_6

10. Build and download the project as done in the previous section
11. Run the application. You should now see the BLUE LED changing the brightness
12. Terminate the debug session

Note: Previously, you had to clone an SDK project like in the past step.

To Open Clock Tools in MCUXpresso IDE

1. Open the Clock tool by right clicking on the “evkmimxrt685_sctimer_pwm_with_dutycycle_change” project and selecting “MCUXpresso Config Tools” and then “Open Clocks”

2. In the wizard that comes up, select the “Open existing configuration” radio button, then select the project that you had clone and click on Next

To Open Clock Tools in MCUXpresso Config Tools

1. Open the MCUXpresso Config Tool

2. Open the clocks tool by selecting Tools → Clocks from the toolbar
3. The pins tool should now display the clock configuration for the project

Use the Clock Tools to Modify the System Clock

1. We'll use MCUXpresso IDE for the rest of the instructions, but the same steps can be done in MCUXpresso Config tools for third party IDEs. Switch to the Clocks Diagram view by clicking the tab in the upper left corner

2. Make sure that you are in the functional group called “BOARD_BootClockRUN”

3. By default, the MIMXRT685 is running at 250MHz. Change the core clock frequency to 125 MHz by clicking in the SYSCPUAHBCLKDIV field and select “/4” option. You'll see all the other clock values automatically change as well to adjust to this slower speed. It will look like this when done:

4. Now it's time to implement these changes into the project by exporting the new updated clock_mux.c and clock_mux.h files that are generated by the Pins tool. Click on Update Project in the menu bar

5. The screen that pops up will show the files that are changing and you can click on “diff” to see the difference between the current file and the new file generated by the Clock tool. Click on “OK” to overwrite the new files into your project

Note: The Pins files may also be tagged as being updated since the header has been changed.


6. Build and download the project as done in the previous section. You can confirm the changes at clock_config.c on the following lines:

7. Run the application. You should see that the LED changes the brightness slowly
8. Terminate the debug session