Category Archives: Tutorial

FreeRTOS: how to End and Restart the Scheduler

Posted on by
4

Most host or desktop systems (say Linux, Mac or Windows) have a normal use case where you start the operating system say in the morning and shut it down in the evening, and then you leave the machine. Embedded Systems are different: they are not attended, and they are supposed to run ‘forever’. Not every embedded system needs to run an OS (or in that world: Real-Time Operating System or RTOS), but the same applies here: after the RTOS is started, it is not intended that it will shutdown and restart. To the extend that you won’t they support the ‘shutdown’ and ‘restart’ functionality at all. In case of gathering coverage information this would be really useful:

coverage information from freertos application

coverage information from FreeRTOS application

In the case of FreeRTOS: what if I really need to shutdown the RTOS and restart it again, as by default this is not supported. This is what this article is about …

Continue reading →

GDB All-Stop and Non-Stop Mode with LinkServer

Posted on by
3

GDB supports a mode which allows the GDB debug client to read memory while the target is running. This allows features like ‘live variables’: that way I can see the variables refreshed and changing over time without halting the target. Another functionality which comes with that feature is to check stopped threads or to see all threads in the system.

multiple freertos threads in debug view

multiple FreeRTOS threads in debug view

Continue reading →

Regaining Debug Access to NXP i.MX RT1064-EVK executing WFI

Posted on by
23

Working with low power modes can be challenging. It can severely affect debugging capabilities of a microprocessor or microcontroller. I ported a FreeRTOS application using the Tickless Idle Mode to the NXP i.MX RT1064 board, and all of a sudden, the board was unresponsive to any debugger connection. Luckily the board was not really bricked, but it took me while to find a way to recover it. So for when you end up in a situation with a ‘bricked’ i.MX RT1064 board, this article might be helpful for you to recover it.

i.MX RT1064-EVK Board

i.MX RT1064-EVK Board

Continue reading →

Freelink LPC4322JET100 based Debug Circuit on NXP i.MX RT1064-EVK Board

Posted on by
11

As noticed in “First Steps with the NXP i.MX RT1064-EVK Board” there is a new LPC4322 based debug interface on the RT1064-EVK board.

LPC4322JET100 based Debug Interface

LPC4322JET100 based Debug Interface

Continue reading →

Playing Zork with FreeRTOS on ARM in three different Ways

Posted on by
3

You might wonder what ‘Zork‘ is? Zork is one of the first and earlist fictive computer games, written around 1977 and 1979, written in MDL on a DEC PDP-10 by members of the MIT Dynamic Modelling group (see https://en.wikipedia.org/wiki/Zork). I believe the first time I have played Zork was around 1984 on a Commodore 64.

Zork

Zork

Continue reading →

Tutorial: Git with Eclipse

Posted on by
30

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
Continue reading →

Tutorial: μCUnit, a Unit Test Framework for Microcontrollers

Posted on by
30

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

Continue reading →

Tutorial: First Steps with Embedded Artists NXP i.MX RT1052 OEM Module

Posted on by
14

Not ready for the complexity of a full blown Embedded Linux, but need that extra compute performance? Need an ARM Cortex-M7 running at 600 MHz module on a half-sized business card, ready to be integrated? Here we go: the Embedded Artists i.MX RT1052 OEM module:

Embedded Artists NXP i.MX RT1052 OEM Module

Embedded Artists NXP i.MX RT1052 OEM Module

Compute modules are very common in the Embedded Linux space, for example see this Toradex module. The reason is simple: these high-performance boards simplify the design, as I don’t have to care about the BGA packages and the external SDRAM and FLASH devices: everything is on a module I can easily integrate into my base board.

Continue reading →

Tutorial: Open-Source Embedded GUI Library LittlevGL with i.MX RT1050-EVK

Posted on by
13

Most embedded projects need an user input device. For the NXP i.MX RT1050-EVK board I have recently added a 480×272 full color touch LCD (see “Adding a Rocktech Capacitive Touch LCD to the NXP i.MX RT1052 EVK“). I have looked at different commercially available GUI libraries, but none of them really were matching my expectations: either very expensive or closed source, or an overkill for small LCDs and projects. But then I have found LittlevGL: free-of-charge, open source, easy to use, well documented and has everything I need. And it really looks gorgeous 🙂

Hello from LittlevGL

Hello from LittlevGL

Continue reading →

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

Posted on by
16

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

Continue reading →