CMSIS-DAP Debug Probe for Robots and Pixhawk with KiCAD

Need to debug your robot or drone? In a HSLU university research project I’m using a Pixhawk and PX4 based drone hardware. Pixhawk and PX4 is an open standard for drone hardware and firmware and runs with NuttX RTOS. It is mainly used for drones, but is very capable for any other kind of mobile robots.

With the Pixhawk 6x-RT there is a powerful flight controller, using the NXP i.MX RT1176 dual-core processor. While this and other controller hardware do offer a hardware debug probe, it is not a simple task as there are different pin-outs and connectors, making debugging a mess with different cables and adapters. To simplify this, I have now a unified debug CMSIS-DAP debug probe using the NXP LPC55S69 as processor, with all the different headers and UART adapters included: the MCU-Link-MR (Mobule Robots) debug probe.

MCU-Link-MR (v0.1)

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How to make sure no floating point code is used

Float and double data types area a bad choice for embedded applications. At least in most applications, and can or should be avoided, even with hardware FPU support present.

But how can I be sure that no floating point operations are used?

wrapping float and double runtime routines

This article describes how to configure the GNU toolchain, so that no float or double operations are used, with the example of ARM Cortex-M. What I do? ‘Poisoning’ (!!!) the source code, force the gcc compiler to use software floating point operations and then catch them with the GNU linker :-).

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Binary, do you use Hard-Float or Soft-Float?

Many cost-sensitive ARM Cortex-M devices like the M0+ do not have a hardware floating point unit, and some like the M4 only has an optional single-precision floating point unit (FPU). As outlined in “Be aware: Floating Point Operations on ARM Cortex-M4F“, using floating point operations without a hardware unit can be costly.

Looking at the disassembly for sure will tell you if the hardware is handling the float or double operation or not:

Disassembly showing runtime routines

But who wants check the all the disassembly? With the GNU tools there is an easier way: readelf.

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CNC + Laser = Personalized Cutting Board

This blog usually features Printed Circuit Boards (PCBs), but my other passion are Personalized Cutting Boards :-).

It has been a while since my last CNC or laser cutter post, so I thought I showcase just quickly one of the recent designs.

Personalized Cutting Board
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‘Experience Energy’ at the Verkehrshaus: The ‘House of Energy’ Construction Kit

The ‘Verkehrshaus der Schweiz‘, the ‘Swiss Museum of Transport’ is Switzerland’s most popular museum.

In April 2023, it opened up a new building and the ‘Experience Energy!’ exhibition. For the opening event we created a unique construction kit to explore energy: from harvesting to storing and up to distributing and using energy.

“House of Energy” at the Swiss Museum of Transport in Lucerne
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Moving Pixel Clock Project

Clock projects are cool. LED projects are cool too. And if it moves, the better. So why not building a moving pixel LED mechatronics clock? A matrix with addressable RGB LEDs, each can change color and is moved by a tiny stepper motor, to let pixels stand out?

Moving Pixel Clock
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Building with CMake Presets

I’m getting my head more and more around CMake and its features. After having so many issues with VS Code dealing with CMake Kits, I have found feature in CMake which really is a game changer for me: CMake Presets.

Working with CMake Presets in VS Code
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“No Kit Selected”: Fixing VS Code CMake Kit Assignment

One important thing in using VS Code and CMake projects is that one needs to have a CMake kit assigned to the project. But after a restart of VS Code or if I re-load a project, VS Code has lost the previously assigned CMake kit:

VS Code has forgotten about the previously assigned CMake Kit?

This is very annoying, but luckily I have found a fix for this.

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