ARM Cortex-M microcontrollers can have multiple memory controllers. This is a good thing as it allows the hardware to do multiple parallel memory read/writes. However this makes the memory map more complicated for the software: it divides the memory into different regions and memory segments. This article is about how to enable FreeRTOS to use multiple memory blocks for a virtual combined memory heap:
Many of the NXP OpenSDA boot loaders are vulnerable to Windows 8.x or Windows 10: write accesses of Windows can confuse the factory bootloader and make the debug firmware and bootloader useless. In this post I show how to recover the bootloader using MCUXpresso IDE and the P&E Universal Multilink.
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?
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 :-).
The concept of Linux (Open Source, broad developer base and broad usage) is a success story. While there is a lot of diversity (and freedom) in the Linux world, Linux is Linux and again Linux :-). And the world has (mostly) standardized on Linux and its variants on the high embedded system side.
On the other side, the ‘middle and lower end’ Embedded world is fragmented and in many aspects proprietary. So it was no surprise to me when the Linux Foundation announced the ‘Zephyr’ project back in February 2016:
“The Linux Foundation Announces Project to Build Real-Time Operating System for Internet of Things Devices. Open source Zephyr™ Project aims to deliver an RTOS; opens call for developers to help advance project for the smallest footprint IoT devices.“
Ζεφυρος (Zephyros) is the Greek good of spring and the west wind. Obviously this inspired the logo for the Zephyr project:
I’m using the NXP FRDM-K64F board in several projects: it is reasonably prices, has USB, Ethernet, micro SD card socket and connectors for Bluetooth classic and Nordic Semiconductor nRF24L01+ 2.4 GHz transceiver:
But one issue I have faced several times is that the board works fine while debugging and connected and powered by a host machine, but does not startup sometimes if powered by a battery or started without a debugger attached. I have found that the EzPort on the microcontroller is causing startup issues.
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.
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:
I kind of hoped that after “Why I don’t like printf()” and all my other articles about printf and semihosting, that topic would be 200% handled and I won’t have to deal with any more. Well, I was wrong and underestimated how the Kinetis SDK is interfering with semihosting. And I underestimated how many of my readers are still using semihosting (even as there are other and better alternatives), so I keep getting questions and requests for help. That’s ok, and I hope I can help :-).
So here is yet again another post about how to turn on semihosting with Eclipse, GNU ARM Embedded and the Kinetis SDK v2.0. This time with the FRDM-K64F board:
Sometimes it is very convenient to load a new firmware to a board without the need for a hardware debugger. This is usually done with a bootloader. The NXP Freedom and Tower evaluation boards have on-board debug device/microcontroller (OpenSDA) which can load different firmware implementations like CMSIS-DAP/mbed, P&E Multilink or a Segger J-Link OpenSDA applications. Both mbed and P&E implemenations support to program the board with drag&drop: simply send a file to a virtual MSD (Mass Storage Device) to get it programmed. The latest Segger OpenSDA firmware has this ability added now too: Programming the board with a virtual MSD device:
3.5″ Diskette Drives are not widely used any more: CDs, DVDs, memory/thumb drives and downloads from the web are the usual distribution method these days for software. Back a few years ago, software was distributed on one or many 3.5″ diskettes, and even before that time on 5 1/4″ floppy disk drives. So what to do with all these not-used-anymore hardware? Play music with it 🙂
There are plenty of different software packages available for microcontroller these days from all the silicon vendors. Finding a good software package is one challenge, getting what I really need is another one. Freescale is now part of NXP since December 2015, so this is probably the first release of the former Freescale part now as NXP: The NXP Kinetis SDK Version 2.0.
It comes with an interesting distribution way: instead of downloading huge packages with all-and-everything in it, I can build it ‘on demand’ online and get what I need, on demand from a web-based front end:
I have published a Sneak Preview how GNU gprof profiling looks for an embedded target ARM Cortex-M in an earlier post:
This tutorial explains how to profile an embedded application (no RTOS needed) on ARM Cortex-M devices with GNU gprof. Additionally I explain the inner workings to generate the data necessary for gprof.
It has been a long time since I wrote my last blog. I really want to apologize to you all for the delay, but I was busy with another project about the competitive analysis of Freescale with our competitors. I hope I can provide you guys later with some important findings from my research.
Well as far as my project for neopixels using FRDM-K64F is concerned, Erich wrote the wonderful tutorial for all of us to turn on the NeoMatrix. I tried my hands on that and I was indeed able to turn on the board but not in the way I wanted it to. 😦 So, it turns out that I got few LEDs turning blue or some turning green. I asked Erich about it and I got to know that it is because I screwed up with the timing signals. I was using an oscilloscope and not a logic analyzer but Erich’s recommendation was to use the Logic Analyzer. This was the result of my experiment following Erich’s tutorials.
This is Part 5 of a Mini Series. In Part 4, I described how to set up the FTM (Kinetis Flex Timer Module) to generate the required waveforms used for DMA operations (see “Tutorial: Adafruit WS2812B NeoPixels with the Freescale FRDM-K64F Board – Part 4: Timer“). In this post I describe how to use to trigger DMA (Direct To Memory) events. The goal is to drive Adafruit’s NeoPixel (WS2812B) with the Freescale FRDM-K64F board:
This is Part 3 of a Mini Series. In Part 2, I described how to set up the development tools and to debug the first project (see “Tutorial: Adafruit WS2812B NeoPixels with the Freescale FRDM-K64F Board – Part 2: Software Tools“). Now it is time to look into the software concepts. The goal is to drive Adafruit’s NeoPixel (WS2812B) with the Freescale FRDM-K64F board:
This is Part 1 of a Mini Series. Manya has challenged herself to use the Adafruit NeoPixels (WS2812B RBG LEDs) with the Freescale FRDM-K64F board and the Kinetis SDK (see “Let’s play with Freescale FRDM-K64F“). I did a while back that with the FRDM-KL25Z board (see “NeoShield: WS2812 RGB LED Shield with DMA and nRF24L01+“). I used Processor Expert in my project (without the Kinetis SDK), and with this setup it is very easy. However, Manya wanted to do this with the Kinetis SDK and without Processor Expert. No surprise to me, she has found out that this setup with the Kinetis SDK and without the usage of Processor Expert is much more challenging (see “Not done yet!!“). I promised to Manya to give her a helping hand, so here we go! 🙂