Enabling Cortex-M4 on i.MX 8QXP MEK

The i.MX 8QuadXPlus Multisensory Enablement Kit (MEK) is a NXP development platform based on Cortex A-35 + Cortex-M4 cores. Built with high-level integration to support graphics, video, image processing, audio, and voice functions, the i.MX 8X processor family is ideal for safety-certifiable and efficient performance requirements.

This tutorial shows how to enable the Cortex-M4 using the MCUXpresso SDK package and loading the binary from the network.

NOTE: It is also possible to load the Cortex-M4 image from the SCFW using the imx-mkimage utility. Please see next blog posts for this tutorial.

Setting up the machine

NOTE: This shows the procedure for a Linux environment. For the Windows OS, please see the Getting Started documentation on the SDK package.

• Install cmake on the host machine:

$ sudo apt-get install cmake

• Download the armgcc toolchain from here and export the location as ARMGCC_DIR:

$ export ARMGCC_DIR=<your_path_to_arm_gcc>/gcc-arm-none-eabi-5_4-2016q2/

NOTE: The ARMGCC_DIR variable needs to be exported on the terminal used for compilation.

To setup the TFTP server on the host machine, follow the first two sections on this blog post (Configuring your Host PC for TFTP and Configuring your Host PC for NFS).

Downloading the SDK

Download the MCUXpresso SDK following these steps:

• Click on “Select Development Board”;

• Select MEK-MIMX8QX under “Select a Device, Board, or Kit” and click on “Build MCUXpresso SDK” on the right;

• Select “Host OS” as Linux and “Toolchain/IDE” as GCC ARM Embedded;

• Add “FreeRTOS” and all the wanted Middleware and hit “Request Build”;

• Wait for the SDK to build and download the package.

Building the image

All demos and code examples available on the SDK package are located in the directory <<SDK_dir>>/boards/mekmimx8qx/. This tutorial shows how to build and flash the hello_world demo but similar procedures can be applied for any example (demo, driver, multicore, etc) on the SDK.

• To build the demo, enter the armgcc folder under the demo directory and make sure that the ARMGCC_DIR variable is set correctly.

$ cd ~/SDK_2.3.0_MEK-MIMX8QX/boards/mekmimx8qx/demo_apps/hello_world/armgcc
$ export ARMGCC_DIR=<your_path_to_arm_gcc>/gcc-arm-none-eabi-5_4-2016q2/

• Run the build_release.sh script to build the code.

$ ./build_release.sh

NOTE: If needed, give the script execution permission by running chmod +x build_release.sh.

• This generates the M4 binary (hello_world.bin) under the release folder. Copy this image to the /tftpboot/ directory on the host PC.

NOTE: This procedure shows how to build the M4 image that runs on TCM. To run the image from DDR, use the build_ddr_release.sh script to build the binary under the ddr_release folder.

Flashing the image

• Open two serial consoles, one for /dev/ttyUSB0 for Cortex-A35 to boot Linux, and one for /dev/ttyUSB1 for Cortex-M4 to boot the SDK image.

• On the A35 console, with a SD Card with U-Boot, stop the booting process and enter the following commands to load the M4 binary to TCM:

=> dhcp
=> setenv serverip <ip_from_host_pc>
=> tftp 0x88000000 hello_world.bin
=> dcache flush
=> bootaux 0x88000000

Then the M4 core will load the image to the /dev/ttyUSB1 console.