Category Archives: Tips & Tricks

Replacing a cheap Chinese CO2 Laser Tube

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What is the life span of a cheap Chinese CO2 laser tube? I mean: how long can I use one these (aka K40) laser engraver/cutter tubes as used in that 50W machine I have? I have used my machine for over a year for now, and I don’t have hour meter, but I estimate it have used it for about 500 hours. I don’t have a data sheet of the tube used inside my machine. Discussions on the internet estimate the live span from DOA (Dead On Arrival) to ‘a few months with moderate usage’ up to 3000-5000h’. Well, whatever it would be: my laser cutter stopped working two weeks ago. Here is how I got it back operating again….

New Laser Tube on the Bench

New Laser Tube on the Bench

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Lasercut Plywood Board for Raspberry Pi

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Need a quick way how to attach a LED, a push button and two resistors to the Raspberry Pi header? One way is to use some ‘flying’ wires. Or to use three pieces of lasercut plywood for a nice looking Raspy extension board:

Wood Board on Raspberry Pi

Wood Circuit Board on Raspberry Pi

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Tutorial: Git with Eclipse

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There are things which are game changer in the world of software development: one such event was when I started using a VCS (Version Control System): it changed for me how I keep and store my projects and settings. It even changed the way how I deal with non-software related items like documents or other valuable things: I started storing them in to a VCS too.

EGit with Eclipse

EGit with Eclipse

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Tutorial: μCUnit, a Unit Test Framework for Microcontrollers

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Unit testing is a common practice for host development. But for embedded development this still seems mostly a ‘blank’ area. Mostly because embedded engineers are not used to unit testing, or because the usual framework for unit testing requires too many resources on an embedded target?

What I have used is the μCUnit framework which is a small and easy to use framework, targeting small microcontroller applications.

uCUnit

uCUnit

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Tutorial: Catching Rogue Memory Accesses with ARM Watchpoint Comparators and Instruction Trace

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In my “Tutorial: Catching Rogue Memory Accesses with Eclipse and GDB Watchpoints” I have used Eclipse/CDT and GDB watchpoints.  I used a conditional watchpoint, but this comes with a performance hit. In this article I show how to use the ARM Cortex trace hardware to catch specific writes to a memory location. Without severe performance degradation. But for this I need a little helper: the DEADBEEF catcher!

0xdeadbeef catcher

0xdeadbeef catcher

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Tutorial: Catching Rogue Memory Accesses with Eclipse and GDB Watchpoints

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Eclipse is great: it gives me the tools and capabilities to solve the really hard bugs to find. An example of that ‘hard’ category are ‘rogue’ memory accesses: something in the application is accessing an unwanted memory location and corrupts the data. This might be very sporadic, or takes a long while until it happens. With normal ‘stop-mode’ debugging (setting a normal breakpoint) and stepping usually won’t let me find that bug, as it might be coming from a pointer somewhere. Maybe from an interrupt routine. Or maybe an unitialized or corrupted pointer corrupts to my memory. Usually all what I know is the memory adddress of the data, maybe what is written, but not what or who is writing to that location.

In this article I’m using one of the ‘less-known’ debugging techniques available in Eclipse and CDT and how it works: watchpoints!

Watchpoint with Condition

Watchpoint with Condition

In this article I’m using one of the ‘less-known’ debugging techniques available in Eclipse and CDT and how it works: watchpoints!

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Display Library Function Help Text in Eclipse C/C++ Projects

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In this short article I show you how to enable one of the hidden gems in Eclipse: how to get a description of the library function used in the code

Library Hover

snprintf() help text

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Tutorial: Using Runtime Statistics with Amazon FreeRTOS V10

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FreeRTOS includes a nice feature to give me information about how much time every task is spending running on the system:

FreeRTOS Runtime Information

FreeRTOS Runtime Information

This tutorial explains that FreeRTOS Runtime Statistics feature and how it can be turned on and used.

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Debug the Last Launched Application with Eclipse and other Debug Tricks

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My usual workflow is: edit – build – debug and repeat. And this for the same project again and again. So here are a few tips how to make these iterations faster with Eclipse. One thing is to use the F11 shortcut to debug the last launched/debugged application:

Debug Last Launched

Debug Last Launched

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Porting Processor Expert Projects to MCUXpresso IDE

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The McuOnEclipse GitHub repository hosts many Processor Expert projects and is very popular (cloned more than 1000 times, thank you!). Processor Expert is a powerful framework which generates driver and configuration code, simplifying application development for a wide range of microcontroller and families. But Processor Expert won’t be developed further by NXP and is not part of MCUXpresso IDE. While it is possible to install Processor Expert into MCUXpresso IDE 10.2, how can these projects used ini an IDE *without* Processor Expert? This article describes how to port an existing Processor Expert project into the NXP MCUXpresso IDE.

Adafruit SSD1351 with FRDM-K64F

Ported Project with FRDM-K64F using Adafruit SSD1351 and Processor Expert

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Updating the S32K144EVB to Switch between 5V and 3.3V Logic Levels

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By default, the NXP S32K144EVB and microcontroller is using a 5V supply voltage and logic levels which is great for noisy environment or any 5V devices. Many of my displays and sensors use 3.3V logic levels, so I would have to use a level shifter from 5V to 3.3V. There is another way: to change the board for 3.3V logic levels so I can use directly things like a SSD1306 display.

S32K144EVB with OLED SSD1306 using 3.3V Logic Levels

S32K144EVB with OLED SSD1306 using 3.3V Logic Levels

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Using custom FreeRTOS with S32K SDK and OSIF for ARM

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In “Tutorial: FreeRTOS 10.0.1 with NXP S32 Design Studio 2018.R1” I showed how to use a custom FreeRTOS with the S32 Design Studio (ARM). The OSIF (OS Interface) provides an operating system and services abstraction for the application which is used by other S32K SDK components:

OSIF in S32K for ARM Eclipse Project

OSIF in S32K for ARM Eclipse Project

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Creating Disassembly Listings with GNU Tools and Eclipse

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In many cases it is very useful to see the generated assembly code produced by the compiler. One obvious way to see the assembly code is to use the Disassembly view in Eclipse:

Disassembly View

Disassembly View

But this requires a debug session. An easier way is to use command line options to generate the listing file(s).

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Eclipse Debugging with Pointers and Arrays

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In the C programming language it is good practice to pass values by reference (using a pointer), especially for large set of data. For example the following function takes a message string and pointer to integer data which then is printed to the console:

static void printData(const char *msg, const int *intBuf, size_t bufSize) {
  puts(msg); /* print message */
  for(int i=0; i<bufSize;i++) {
    printf("buf[%i] = %i\n", i, intBuf[i]);
  }
}

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Measuring ARM Cortex-M CPU Cycles Spent with the MCUXpresso Eclipse Registers View

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The ARM DWT (Data Watchpoint and Trace) is an optional feature of the ARM-Cortex-M, and many Cortex-M3, M4 and M7 devices have it implemented. With it comes a cycle counter which counts the cycles spent. In Cycle Counting on ARM Cortex-M with DWT I described an approach how the application on the target can access the cycle counter.

The MCUXpresso IDE shows that cycle counter in the Eclipse Registers view:

Cycle Counter in Register View

Cycle Counter in Register View

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Installing Darkest Theme with MCUXpresso IDE 10.2

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Is BLACK the color of the season? My students really seem to love these ‘dark’ Eclipse themes. Well, I tried ‘dark’ themes in the past, but I have not been vey excited about it. Somehow I preferred more the ‘black on white background’ thing. But: I have now managed to install the ‘Darkest Dark’ Eclipse theme into the NXP MCUXpresso 10.2 IDE for my daily work, and I feel it hurts my eyes less? Maybe I’m getting older? Or could it really be that ‘dark’ look and feel?

Darkest Dark Theme with MCUXpresso IDE

Darkest Dark Theme with MCUXpresso IDE

Find out for yourself in the following article….

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GNU Link Time Optimization finds non-matching Declarations

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By default, the GNU compiler (gcc) optimizes each compilation unit (source file) separately. This is effective, but misses the opportunity to optimize across compilation units. Here is where the Link Time Optimization (LTO,  option -flto) can help out: with a global view it can optimize one step further.

The other positive side effect is that the linker can flag possible issues like the one below which are not visible to the compiler alone:

type of '__SP_INIT' does not match original declaration [enabled by default]
Warning by LTO

Warning by LTO

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Tutorial: Understanding and Using FreeRTOS Software Timers

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Hardware Timers are essential to most embedded applications: I use them mostly for triggering actions at a given frequency, such as acquiring data from a  sensor. With using an RTOS I can do a similar thing using a task: the task will run with a given frequency and I can periodic work in it. However, using a task might be too much overhead doing this. The good news is that there is a much more efficient way to do this in FreeRTOS with Software Timers. And this is what this tutorial is about: how to use Software Timers with FreeRTOS.

FreeRTOS Software Timers

FreeRTOS Software Timers

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