As a standard procedure, I add some console functionality to my embedded applications. That way I have a command line interface and can inspect and influence the target system. One interesting hardware feature of ARM Cortex-M is Single Wire Output (SWO): it allows to send out data (e.g. strings) over up to 32 different stimulus ports, over a single wire.
swo-pin-on-arm-debug-header
In my first post about Segger Ozone (see “First Steps with Ozone and the Segger J-Link Trace Pro“) I missed the fact that it includes support for kernels like FreeRTOS. So here is how to show the FreeRTOS (or any other RTOS) threads with Ozone:
freertos-threads-in-ozone
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! 🙂
tracing-cortex-m4-with-j-trace
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 🙂
NXP NFC PN7120S with a FRDM-K64F Board
This tutorial goes through the steps how to create a blinking LED application, using Kinetis SDK and Processor Expert, using the TWR-KL43Z48M board from Freescale (now NXP):
twr-kl43z48m
The first enclosure for the INTRO robot remote controller board (see “INTRO Robot Remote – First Production PCB“) is ready, and it is looking good:
Enclosure for the Remote Controller Board
After the first prototype (see “Prototype of Wireless Remote Controller with NXP Kinetis K20“), we have received the boards and populated a first PCB to verify everything is working properly.
INTRO Robot Remote
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.
NXP KV58F ARM Cortex-M7
The ARM Cortex-M microcontroller are very popular. And it has a very flexible and powerful nested vectored interrupt controller (NVIC) on it. But for many, including myself, the Cortex-M interrupt system can be 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….
MCU on Eclipse 