MCUXpresso VSCode Helper Script

VAR-SOM-MX8 - MCUXpresso 2.9.0 Development with VS Code

Overview

This guide demonstrates how to develop and cross compile applications for the VAR-SOM-MX8 Cortex-m4 co-processor using Microsoft Visual Studio Code.

Please visit Variscite's MCUXpresso Guide for additional information about manually building demos, integration with Yocto, running applications from U-Boot and Linux, and JTAG debugging.

Setup Host Computer Environment

Follow the steps below to prepare a fresh Ubuntu 20.04 installation for VS Code debugging:

Install Dependencies

$ sudo apt-get -y update
$ sudo apt-get -y install build-essential gdb gdb-multiarch git cmake

Install VS Code

$ sudo snap install --classic code

Install VS Code Extensions

VS Code has a graphical interface for installing and managing extensions. To learn more, please see Using extensions in Visual Studio Code

For this guide, we will install the required extensions using the command line:

$ code --install-extension ms-vscode.cpptools
$ code --install-extension marus25.cortex-debug
$ code --install-extension dan-c-underwood.arm

Install Segger JLink

$ Download JLink_Linux_V760b_x86_64.deb from https://www.segger.com/downloads/jlink/
  Direct Download: https://www.segger.com/downloads/jlink/JLink_Linux_V760b_x86_64.deb
$ sudo dpkg -i JLink_Linux_V760b_x86_64.deb

The software will be installed in /opt/SEGGER folder

Install MCUXpresso Toolchain and SDK

Download and install GNU-ARM bare-metal toolchain:

$ mkdir ~/var-mcuxpresso
$ cd ~/var-mcuxpresso
$ wget https://developer.arm.com/-/media/Files/downloads/gnu-rm/9-2020q2/gcc-arm-none-eabi-9-2020-q2-update-x86_64-linux.tar.bz2
$ tar xvf gcc-arm-none-eabi-9-2020-q2-update-x86_64-linux.tar.bz2

Download MCUXpresso SDK for the SOM:

$ cd ~/var-mcuxpresso
$ git clone https://github.com/varigit/freertos-variscite -b mcuxpresso_sdk_2.9.x-var01
$ cd freertos-variscite

Add Visual Studio Code support to the Variscite examples

Available Demos

All of the Variscite examples are located under the following folder.

~/var-mcuxpresso/freertos-variscite/boards/som_mx8qm

Variscite provides a script to simplify the Project Configuration

Note: Using var_add_vscode_support.sh script you can specify for which Cortex-M4 core to generate vscode support: (-c <cm_c0 or cm_c1>)

If the Cortex-M4 core id is missing the default is setted as core 0

Configure a single Project

For this example, we will configure the hello_world demo. However, the process is the same for all demos.

$ ./var_add_vscode_support.sh -b  -e boards/som_mx8qm/demo_apps/hello_world -t tcm -d /opt/SEGGER/JLink  (for TCM target)
$ ./var_add_vscode_support.sh -b  -e boards/som_mx8qm/demo_apps/hello_world -t ddr -d /opt/SEGGER/JLink  (for DDR target)

Configure all Projects

$ ./var_add_vscode_support.sh -b  -e all -t tcm -d /opt/SEGGER/JLink  (for TCM target)
$ ./var_add_vscode_support.sh -b  -e all -t ddr -d /opt/SEGGER/JLink  (for DDR target)

Note: Some J-Link debuggers support connecting to your host computer via Ethernet or Wi-Fi. To enable this, add the IP Address of your J-Link to launch.json:

$ vi ~/var-mcuxpresso/freertos-variscite/boards/som_mx8qm/demo_apps/hello_world/.vscode/launch.json
{
   "configurations": [
   {
     "ipAddress": "<J-Link IP Address>"
   ...

Disable LMEM caches to debug demos mapped in DDR

Note: to debug applications mapped in DDR, is mandatory to deactivate the LMEM caches

$ cd ~/var-mcuxpresso/freertos-variscite
$ git apply patches/0002-i.MX8QM-CM40-deactivated-the-LMEM-caches-to-debug-in.patch

Please visit the SEGGER forum to additional information
https://forum.segger.com/index.php/Thread/2948-SOLVED-DEBUGGING-doesn-t-work-in-external-RAM-but-in-internal-RAM/?postID=11144&highlight=LMEM#post11144

Open a Demo in VS Code

For this example, we will use the hello_world demo mapped in TCM. However, the process is the same for all demos. From a terminal, launch VS Code and open the hello_world demo directory:

$ code ~/var-mcuxpresso/freertos-variscite/boards/som_mx8qm/demo_apps/hello_world/cm4_core0

VS Code should open and look similiar too:

Build Demo using VS Code

If the build task completes successfully, the following output files will be generated:

~/var-mcuxpresso/freertos-variscite/boards/som_mx8qm/demo_apps/hello_world/cm4_core0/armgcc/debug/hello_world_m40.bin  (for TCM target, load in U-Boot)
~/var-mcuxpresso/freertos-variscite/boards/som_mx8qm/demo_apps/hello_world/cm4_core0/armgcc/debug/hello_world_m40.elf  (for TCM target, load using debugger or remoteproc)
~/var-mcuxpresso/freertos-variscite/boards/som_mx8qm/demo_apps/hello_world/cm4_core0/armgcc/ddr_debug/hello_world_m40.bin  (for DDR target, load in U-Boot)
~/var-mcuxpresso/freertos-variscite/boards/som_mx8qm/demo_apps/hello_world/cm4_core0/armgcc/ddr_debug/hello_world_m40.elf  (for DDR target, load using debugger or remoteproc)

Please visit Variscite's MCUXpresso Guide for instructions to run the demo using U-Boot or the Linux Remote Processor Framework.

Debugging with VS Code

Test Enviroment

Hardware

JTAG Debbugger: J-Link PLUS: https://www.segger.com/products/debug-probes/j-link/models/j-link-plus/
ARM-JTAG-20-10 adapter: https://www.digikey.it/it/products/detail/olimex-ltd/ARM-JTAG-20-10/3471401
Variscite Board: Symphony

Software
You can see the Yocto release details at link:

https://variwiki.com/index.php?title=VAR-SOM-MX8_Release_Notes&release=mx8-yocto-hardknott-5.10.72_2.2.1-v1.0

Connect Hardware

Connect J-Link PLUS to JTAG connector of Variscite board
Connect J-Link PLUS to Development PC via USB cable

Load dedicated device tree

Please visit Variscite's MCUXpresso Guide for instructions to load a dedicated device tree.

For this example we will use imx8qm-var-som-symphony-lvds-m4.dtb:

From U-Boot

 => setenv fdt_file imx8qm-var-som-symphony-lvds-m4.dtb 
 => saveenv
 Saving Environment to MMC... Writing to MMC(1)... OK
 Power off / Power on the board

Or, from Linux

 $ fw_setenv fdt_file imx8qm-var-som-symphony-lvds-m4.dtb 
 $ reboot

Start Debugging

Open source code and add a breakpoint

Start Debugging

if everything worked well the program will stop at the configured breakpoint

Debug RPMSG demos

The RPMSG demos can be debugged only starting from U-Boot
You need even to change M4 Kernel Device Tree enabling rpmsg node and disabling cortex-m node

Change M4 Kernel Device Tree

Edit arch/arm64/boot/dts/freescale/imx8qm-var-m4.dtsi

imx8mm-cm4 {
    ....
    ....
    status = "disabled";
};

&rpmsg {
    ....
    ....
    status = "okay";
};

Save the changes.
Compile the device tree and update the SD-Card/eMMC.

Note: If rpmsg node is missing in the arch/arm64/boot/dts/freescale/imx8qm-var-m4.dtsi file discard the Change M4 Kernel Device Tree section above

For this example, we will debug pingpong demo mapped in DDR.

$ cd ~/var-mcuxpresso/freertos-variscite
$ git apply patches/0002-i.MX8QM-CM40-deactivated-the-LMEM-caches-to-debug-in.patch
$ ./var_add_vscode_support.sh -b  -e boards/som_mx8qm/multicore_examples/rpmsg_lite_pingpong_rtos/linux_remote -t ddr -d /opt/SEGGER/JLink
$ code ~/var-mcuxpresso/freertos-variscite/boards/som_mx8qm/multicore_examples/rpmsg_lite_pingpong_rtos/linux_remote/

Note: Debugging applications mapped in the DDR, the use of SDK_DelayAtLeastUs function is not recommended because it produces a long delay time.

You can use vTaskDelay() instead.

Build application following the guide at the Build Demo using VS Code section above:

Power on the Board and interrupt the boot in the U-Boot prompt
From Visual Studio Code start Debugging
From U-Boot prompt

=> boot

Waiting for completed boot kernel
From Userspace prompt

$ sysctl kernel.printk=7
$ modprobe imx_rpmsg_pingpong

if everything worked well the program will stop at the configured breakpoint

Note: Debugging RPMSG demos be careful to set breakpoint or debug step by step because when the M core is stopped even A core is blocked