With the GNU compiler and linker I can place variables into custom sections (see “Defining Variables at Absolute Addresses with gcc“). This article is about how to get the section start and end address so I can for example access that range in my code. Or in general ways: how to use symbols defined in the linker script accessible in the C source code.
Using Linker Script Symbols in Source Code
My Toradex i.MX7Dual module comes with a preflashed Linux distribution (see “Tutorial: First Steps with NXP i.MX7 and Toradex Colibri Board“). As with any other things, Linux gets updated from time to time, and Toradex publishes new firmware. In this article I’m documenting how I can update Linux in the external FLASH on that module.
NXP i.MX7Dual Module
In my previous article (see “Tutorial: First Steps with NXP i.MX7 and Toradex Colibri Board“) I have booted the i.MX7 on a Toradex CPU module. In this post I’m showing how to run a FreeRTOS application on that board.
UART-A and UART-B Connections
Recently I have been running into the following error message in Eclipse when I started the GDB debugger:
Error in Final Launch Sequence
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
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
I’m experimenting with different 3D printed LED frames printed with ABS (see “Avoid Warping ABS on Ultimaker 2“). I frame multiple Adadfruit 8×8 NeoPixel WS2812B LED modules with 3D printed diffuser and frames to create color effects:
Diffuser with Frame Effect
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
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 :-(.
Pile of bad ABS Parts
MCU on Eclipse 