“Learning-by-doing” is one of the core principles of my embedded systems and robotics course at the Lucerne University. For this the students apply what they learned using a robotics platform. In earlier semesters we did a Sumo battle at the end. This time the challenge was to build a remote controller plus to add the ability to explore and solve a line maze:
I’m using FreeRTOS in most of my applications. There were only a few exceptions where an RTOS has to be used in safety critical systems: there usually it is not permitted to use any dynamic memory allocation because this adds the risk that a memory allocation could fail at runtime because of memory fragmentation or memory leak. And FreeRTOS uses a dynamic memory (heap) for the task stacks and the RTOS resources including semaphore, mutex and queues.
This is now a thing of the past. This week a new FreeRTOS Version 9 was released which does not need any dynamic memory allocation anymore: it is possible now to build completely statically allocated systems with FreeRTOS :-).
Dynamic and Static Memory Allocation in FreeRTOS V9.0.0
The challenge with the selection of a microcontroller for a project is: which one has the required number of UART, I2C, SPI? Combine this with the desired package (48pins, 64pins? LQFN?), the needed FLASH and RAM size and then even the hundreds of available microcontroller shrink to a handful only. And many times I need to make compromises: such as I need two hardware I2C, but the microcontroller matching all my other needs has only one I2C hardware. So I might end up with bit-banging the slower I2C bus. Doable, but not ideal.
What is cool that some of the newer NXP Kinetis microcontroller come with an interesting hardware: FlexIO. A peripheral hardware which allows me to implement a custom protocol, including driving WS2812B (Adafruit NeoPixel) LEDs with a FRDM-KL43Z board:
I mentioned the hands-on sessions on FreeRTOS I do this week at NXP FTF Tech Forum in Austin in my previous post. What we are using in the session is an Eclipse plugin in Kinetis Design Studio showing all kinds of FreeRTOS information:
NXP FTF Tech Forum in Austin has been a blast! I’m running another FreeRTOS hands-on session (FTF-DES-N2048) this afternoon which yet again is fully booked. But we will squeeze in as many as possible from the waiting list.
One very exciting thing we are going to use is FreeRTOS thread awareness in Eclipse/Kinetis Design Studio: to see and debug the FreeRTOS threads in Eclipse using the Segger GDB and it will show the list of threads in the Debug view:
Time is passing fast, and many components have been updated to make the compatible with the NXP Kinetis SDK V2.0. As a highlight, besides of FreeRTOS the following components are now usable with the NXP Kinetis SDK:
The world is changing, and the say is “change is good” :-). In the software and API world, change very often means that a change results into something broken. So I had battled with semihosting working on the NXP Kinetis parts, only to find out that it does not work any more with using the latest version 2.0. The semihosting output e.g. with P&E debug connection remains empty:
FreeRTOS is probably the number one RTOS used, and Eclipse is likely the most popular IDE I can think of. But debugging FreeRTOS applications with Eclipse and GDB is somewhat limited? What I would like to get at the minimum is this: ability to see all the different threads in the Eclipse debug view like this:
FreeRTOS Threads in Eclipse with OpenOCD
As you might guess from that screenshot: this post is about how to make FreeRTOS tread debugging possible with Eclipse and GDB :-).
For my classes I had so far asked the students to install the Kinetis Design Studio (KDS) v3.0.0 and then apply several updates and upgrades available. NXP has now released the v3.2.0 of their KDS (Kinetis Design Studio):
Kinetis Design Studio v3.2.0
The v3.2.0 is including all the 3.x.x updates in a single installation which makes things easier to start with. And it now works for Mac OS X “El Capitan” and the latest GNU ARM Eclipse plugins :-).
I’m using the FRDM-KL25Z in my classes, and that board is very popular: low price (<$15), reasonable features (48 MHz ARM Cortex M0+, 128 KByte of FLASH, 16 KByte of RAM), and many tutorials elsewhere and on McuOnEclipse :-).
For the next (Fall) semester I’m looking for alternative boards, and one is the Freescale (now NXP) FRDM-KL27Z: