In this semester course, students (and myself too, of course :-)) are building a Mini Sumo Robot. That robot is using the Freescale FRDM-KL25Z board with an ARM Cortex-M0+ on it. Today I’ll give an introduction to the ARM core to the class, and timing is right: this morning I have found an excellent overview about ARM microcontroller and tools written by Jay Carlson.: Getting Started with ARM Microcontrollers.
In my tutorial “Bits and Pins with Kinetis” I showed how to use the BitIO_LDD approach for Bit I/O access. I do not like this LDD (logical device driver) approach for several reasons:
Luckily, there is a way to hack around this 🙂
The ARM Cortex specification includes the ‘SysTick’ (System Tick Timer): a dedicated system timer which is intended to be used as time base for an RTOS. While technically it would be possible to use any periodic interrupt timer, I’m using as well the SysTick for my FreeRTOS ARM ports. And because Processor Expert includes a nice timer interface, I’m using the TimerUnit_LDD:
TimerUnit LDD for SysTick
While this is great for flexibility, it has its price in efficiency. That TimerUnit_LDD adds overhead. So I want to get rid of the TimerUnit_LDD and use a more efficient way.
For everyone who wants to build a Do-It-Yourself toolchain for Kinetis on Linux, I recommend to read the following excellent post by Karibe:
Setting up Linux opensource build and debug tools for freescale freedom board FRDM-KL25Z
He describes how to get OpenOCD with CMSIS-DAP working with Eclipse on Ubuntu to debug the FRDM-KL25Z board.
Happy Linuxing 🙂
A week ago, the updated FreeRTOS V7.5.0 has been released on FreeRTOS.org. So time to have my Processor Expert FreeRTOS component updated as well :-).
FreeRTOS V7.5.0
This is the second part of a multi-part tutorial about how to set up an open source tool chain with GNU ARM gcc + Eclipse to build and debug an application for Kinetis ARM devices.
Eclipse Kepler
This is the first part of a multi-part tutorial on setting up a free and functional GNU gcc + Eclipse + debugger environment for use with the Freescale FRDM-KL25Z board.
In this first part, I’m showing how to install the GNU ARM tool chain to build a ‘blinking LED’ application for the FRDM-KL25Z. With 100% free tools 😉
Blinking Red RGB LED made with free tools
While working on a project for the FRDM-K20D50M, I faced a problem: I was running out of SRAM for my application. The GNU linker reports: “section `.bss’ will not fit in region `m_data'”: 😦
bss will not fit in region m_data
But my device has 16 KByte of SRAM, and I knew I use much less than 10 KByte. So what is the problem? Continue reading
❗ This article has been written for the version 4 of µVision. There is an update for version 5 of µVision here: “Using Keil μVision 5 with Processor Expert“
The good thing with using ARM microcontroller is: there are plenty of tool choices. Even myself, I’m using multiple different tool chains. And while I’m heavily using Eclipse, there are non-Eclipse tool chains which have their advantages too.
The cool thing with CodeWarrior is that beside of Eclipse based, it comes with Processor Expert integrated. And I’m using Processor Expert a lot in my projects. But using Processor Expert does not mean I’m limited to CodeWarrior or Eclipse. So I can use CodeRed or IAR as tool chain with it. And this post is about using Processor Expert with the µVision tool chain from Keil/ARM.
Keil uVision Splash Screen
Having many projects open the same time, and working on them in parallel is a challenge. Ok, the human brain is not built for multitasking, but I still try ;-). What I typically I end up in my Eclipse Problems View to have entries from multiple projects mixed up:
Problems View with Entries for multiple Projects
How to show it that I can fix the problems for ony project only, and not showing all problems from all projects?
MCU on Eclipse 