Category Archives: MCUXpresso

Using FreeRTOS with newlib and newlib-nano

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For reliable applications, I avoid using functions of the standard libraries. They are banned for most safety related applications anyway. I do not use or avoid malloc(), printf() and all the other variants, for many reasons including the ones listed in “Why I don’t like printf()“. Instead, I’m using smaller variants (see “XFormat“). Or I’m using only the thread-safe FreeRTOS heap memory allocation which exist for many good reasons.

Things get problematic if malloc() still is pulled in, either because it is used by a middleware (e.g. TCP/IP stack) or if using C++. Dave Nadler posted a detailed article (http://www.nadler.com/embedded/newlibAndFreeRTOS.html) about how to use newlib and newlib-nano with FreeRTOS.

FreeRTOS Newlib Memory Allocation Scheme

FreeRTOS Newlib Memory Allocation Scheme

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GNU Code Coverage on Embedded Target with Eclipse Neon and ARM gcc 5

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For a research project, we are going to send a satellite with an embedded ARM Cortex microcontroller into space early next year. Naturally, it has to work the first time. As part of all the ESA paperwork, we have to prove that we tested the hardware and software thoroughly. One piece of the that is to collect and give test coverage evidence. And there is no need for expensive tools: Free-of-charge Eclipse and GNU tools can do the job for a space mission 🙂

Eclipse with Coverage Views

Eclipse with Coverage Views

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ARM SWO Performance Counters

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In “Cycle Counting on ARM Cortex-M with DWT” I have used the ARM DWT register to count the executed cycles. With the MCUXpresso IDE comes with a very useful feature: it can capture the ARM SWO (Single Wire Output) trace data. One special kind of trace data is the ‘cycle counter’ information which is sent through SWO.

SWO Counters

SWO Counters

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MCUXpresso IDE: Terminate and Disconnect a Debug Session

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Eclipse for C/C++ (CDT) offers two different ways to get out of a debug session: Terminate and Disconnect:

Terminate and Disconnect

Terminate and Disconnect

The terminate and disconnect behaviour is not standardized, and varies between Eclipse distributions and debug connection. This article is about how things are handled in MCUXpresso IDE, and how I can influence the behaviour.

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McuOnEclipse Components: 06-May-2017 Release

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I’m pleased to announce that a new release of the McuOnEclipse components is available in SourceForge, with the following changes and updates:

  • SEGGER SystemView updated to V2.42
  • More components to work with MCUXpresso SDK: GenericSWSPI, FXO8500 and SimpleEvents
  • SSD1351 display driver supports 128×128 pixel resolution and Adafruit 1.5″ breakout module
  • Extended FreeRTOS debug helper settings
  • GenericI2C: added ReadWordAddress8() and ReadWordAddress8() functions
  • RingBuffer with new Getn() and Update() functions
  • Utility with map(), constrain(), random() and randomSetSeed()
  • XFormat: new xsnprintf(), contributed by Engin Lee
  • OneWire protocol component with Maxim DS18B20 temperature sensor
  • Many smaller bug fixes and enhancements
SourceForge

SourceForge

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Using Eclipse to Program Binary Files to an Embedded Target

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I’m using Eclipse based IDE’s to develop and debug my embedded applications. This works great, as Eclipse has all the necessary tools to edit, build and debug it. But when it comes just to download/flash a binary to the board, then things are pretty much specific to the tools used. With the advent of the new MCUXpresso IDE, here is how that Eclipse IDE can be used for this.

LinkServer GUI Flash Programmer

LinkServer GUI Flash Programmer

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Using the LPCXpresso V2/V3 Boards to Debug an external Board

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The MCUXpresso IDE (see “MCUXpresso IDE: Unified Eclipse IDE for NXPs ARM Cortex-M Microcontrollers“) has one great feature: it includes debug support for the popular LPC-Link2 debug probes. That way I have yet another powerful debug probe with extra features for ARM based boards. That LPC-Link2 circuit is present on many LPCXpresso boards from NXP. So why not using it to debug it my custom hardware?

Debugging Custom Hardware with LPCXpresso Board

Debugging Custom Hardware with LPCXpresso Board

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Tuturial: mbedTLS SSL Certificate Verification with Mosquitto, lwip and MQTT

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In “Tutorial: Secure TLS Communication with MQTT using mbedTLS on top of lwip” I already used TLS for a secure communication, but I had not enabled server certificate verification. This article is about closing that gap.

MQTT running on NXP FRDM-K64F

Secure MQTT running on NXP FRDM-K64F with lwip and mbed TLS

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Tutorial: Secure TLS Communication with MQTT using mbedTLS on top of lwip

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One of the most important aspects of the ‘IoT’ world is having a secure communication. Running MQTT on lwip (see “MQTT with lwip and NXP FRDM-K64F Board“) is no exception. Despite of the popularity of MQTT and lwip, I have not been able to find an example using a secure TLS connection over raw/native lwip TCP :-(. Could it be that such an example exists, and I have not found it? Or that someone implemented it, but has not published it? Only what I have found on the internet are many others asking for the same kind of thing “running MQTT on lwip with TLS”, but there was no answer? So I have to answer my question, which seems to be a good thing anyway: I can learn new things the hard way :-).

Blockdiagram MQTT Application with TLS using lwip

Block diagram MQTT Application with TLS using lwip

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MQTT with lwip and NXP FRDM-K64F Board

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In the area of IoT (Internet of Things), one obvious need is to have a way to send and receive data with an internet protocol. MQTT (or Message Queue Telemetry Transport) is exactly like that: a light-weight Machine-to-Machine communication protocol. With the MQTT protocol a microcontroller (or ‘client’) can send data and/or subscribe to data. For example to the Adafruit.IO:

Adafruit MQTT IO Feed

Adafruit MQTT IO Feed

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