From time to time I face some problems which are really hard to find. Mostly these kind of bugs are very timing sensitive and depend on interrupt execution order. Maybe a dangling pointer is overwriting memory, code is running wild, or some functions are not reentrant as they should be. For these kind of bugs, good tools are worth their weight in gold. The Percepio FreeRTOS+Trace and the Segger SystemView have helped me many times to narrow down such kind problems in my applications. Another ultimate tools is hardware trace: Now I have a Segger J-Trace Pro for ARM Cortex-M in my arsenal of bug extinguishing weapons on my desk:
Dear bugs, look what I have on my desk. Your hiding time is over! 🙂
Playing with RFID and NFC is definitely fun :-), and they are everywhere! For a research project I’m exploring different RFID tags and solutions. I several types around for a long time, but never found the time to actually work on it, so last nightI thought I give it a try, and I have it working with GNU ARM and Eclipse, powered by the NXP FRDM-K64F board 🙂
The past weeks have been extremely busy with the new semester started. As a result, no time for new posts on this blog for nearly three weeks :-(.
Until my projects-in-progress about MQTT, Time-of-Flight sensors, LoRa (long range) wireless networking and a cool robotics project are ready, here is something to share with you all: a cool time-lapse video of my home and work area, created by Pirmin Henseler: 2 years, 30’000 pictures, 2 broken cameras, and the result is amazing:
This is the third part about ARM Cortex-M and how the interrupts are used. In Part 1 I discussed the Cortex-M interrupt system and in Part 2 I showed nested interrupt examples. This part is about FreeRTOS and how it uses the Cortex-M interrupt system.
In “ARM Cortex-M, Interrupts and FreeRTOS: Part 1” I started with the ARM Cortex-M interrupt system. Because the ARM implementation cann be very confusing, I confused myself and had to fix and extend the description in Part 1 :-). Thank for all the feedback and comments!
Originally I wanted to cover FreeRTOS in Part 2. Based on the questions and discussions in Part 1 I thought it might be a good idea to provide visual examples.
When I have hit ‘publish’ for this post, the McuOnEclipse blog exists for exactly 0x888888 seconds. Or almost. I admit there might be a latency of a few seconds. But hey, that’s still a good (hexadecimal) number! :-).
I would like to reach out about what you would like to see on McuOnEclipse in a not too distant future:
What do you like the most?
About what should I write more?
Any other subject or topic you would like to see?
Add a comment if you have anything else on your mind.
The ARM Cortex-M microcontroller are insanely popular. And it features a flexible and powerful nested vectored interrupt controller (NVIC). But for many, including myself, the Cortex-M interrupt system can be counter-intuitive, complex, inconsistent and confusing, leading to many bugs and lots of frustration :-(.
ARM Cortex-M7: NXP KV58
Understanding the NVIC and the ARM Cortex-M interrupt system is essential for every embedded application, but even for if using an realtime operating system: if you mess up with interrupts, very bad things will happen….
3D printing is like cooking or like BBQ: It is more about barometric pressure, humidity and temperature than you might think of. To me, printing (and cooking) is a combination of art and science. And as with cooking, sometimes the result is not usable.
I’m very happy with the Ultimaker 2 printing PLA material. For a LED matrix project I have to use ABS as this material is suitable for higher temperature: PLA simply will not stand the heat produced by the LEDs I’m going to use. And here the joy ended: printing using ABS was definitely no fun. While the first small test print came out OK, I produced afterwards a pile of unusable parts because of warping :-(.
After brining fish (see “Cedar Planked Smoked Sesame Salmon and Tuna“) and thanks to Greg I’m now exploring brining pork shoulder for pulled pork. Pulled pork is amazingly simple, but requires preparation work. Brining adds to this, but is well worthy.
It seems that my pulled pork BBQ (see “Tutorial: BBQ Pulled Pork“) gets more and more fans :-). We will have a BBQ party for 10 person tomorrow evening :-). In preparation for that, the two pork shoulders started brining in the refrigerator from yesterday night on. Today we prepared the BBQ sauce for tomorrow, in four different styles: North Carolina, South Carolina, Alabama and Kansas: