Is Developing for ARM more difficult than for other Architectures?

I believe in ‘life-long-learning’. With this I continue to learn and discover new things every day. I’m writing tutorials to give something back to the community from which I have learned so much.

On top of this, I receive emails on a nearly daily basis, asking for help. Many articles have the origin in such requests or questions. I prefer questions or comments in a public forum, because that way I feel all others can benefit from it. Last week Alessandro contacted me with this:

“Hi Erich,

I hope this find you well! I’m starting to using ARM processors, but I find them quite complicated on the configuration side. I started in the past with PIC micro (PIC16) with asm, and I found them quite straightforward to be configured (clock, IO, peripherals, …). Then I moved myself on C language, and on PIC18 without any big issues.

Now I would really like join the ARM community, I see that these processors are what I’ve always looking for, on energy, calc power, peripherals, and FINALLY on IDE (editor, toolchain and utilities)… AMAZING!!!”

The topic is about how to start learning developing for ARM. Alessandro agreed to make this public, so I thought this might be a good topic for an article?

Firmware

Firmware

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MQTT with lwip and NXP FRDM-K64F Board

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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MCUXpresso IDE: Installing Processor Expert into Eclipse Neon

In “MCUXpresso IDE: Importing Kinetis Design Studio Projects” I explained how Kinetis Design Studio projects can be imported and used inside the MCUXpresso IDE. Processor Expert projects can be used, but no new components added, modified or new Processor Expert projects created. To fully use Processor Expert, two plugins need to installed, and this is what this article is about.

Processor Expert in MCUXpresso IDE

Processor Expert in MCUXpresso IDE

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MCUXpresso IDE: Importing Kinetis Design Studio Projects

Many of my currently active projects are using Kinetis Design Studio (KDS) V3.2.0 from NXP (I have published many of my projects on GitHub). Now with the advent of the MCUXpresso IDE (see “MCUXpresso IDE: Unified Eclipse IDE for NXPs ARM Cortex-M Microcontrollers“), I have migrated several projects from KDS to MCUXpresso. This post is about how to easily get KDS projects ported and running in MCUXpresso IDE.

Debugging KDS Project in MCUXpresso IDE

Debugging KDS Project in MCUXpresso IDE

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Embedded World Nürnberg 2017 Impressions: MCUXpresso, Hexiwear, NTAG, LPC800-DIP and Alan Hawse

This year I managed to attend the Embedded World in Nürnberg/Germany after missing the 2016 show. And 2017 has been a blast! With more than 1000 exhibitors and >30’000 visitors it was huge! There were too many exciting things, so I just pick a few: NXP demonstrated the new MCUXpresso Software and Tools with a new Eclipse Neon based IDE, lots of IoT and Hexiwear, the tiny LPC800-DIP board, and I have met Alan Hawse in person!

Impresson from the Show (embeddedworld 2017)

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Zephyr: Thoughts and First Steps on the ARM Cortex-M4F with gcc, gdb and Eclipse

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:

Zephyr logo

Zephyr logo (Source: https://www.zephyrproject.org/)

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Building the NXP BLE Stack with Open Source GNU and Eclipse Tools

One of the biggest road blocks (beside of closed source) using the BLE (Bluetooth Low Energy) stack from NXP is that it requires expensive tools to compile and build the stack. The good news is that I have now the NXP BLE stack for the Mikroelektronika Hexiwear ported to Eclipse and GNU gcc build tools for ARM 🙂

NXP BLE Stack in Eclipse

NXP BLE Stack in Eclipse

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Flashing and Restoring the Hexiwear Firmware

The Hexiwear device is a great and versatile device with two microcontrollers on it. Developing firmware on a Hexiwear means changing what was originally on it. And sometimes it happens that I’m not sure if the changes are for good. Or that I accidentally destroyed the firmware on the NXP Kinetis KW40 BLE microcontroller :-(. So I had to find a way to restore the original firmware, and this is what this post is about.

Restoring the Hexiwear Firmware with a Segger J-Link

Restoring the Hexiwear Firmware with a Segger J-Link

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Tutorial: Building FreeRTOS Applications for ARM Cortex-M4 on i.MX7 with Eclipse

Command line tools to build applications are great. But productivity goes up if I can use the standard Eclipse environment with GNU tools. This tutorial is about how to use standard and free GNU and Eclipse tools to build my FreeRTOS application for the ARM Cortex-M4 on i.MX7 🙂 :

Eclipse used to build FreeRTOS applications for M4 on i.MX7

Eclipse used to build FreeRTOS applications for M4 on i.MX7

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First Steps with Ozone and the Segger J-Link Trace Pro

From time to time I face some problems which are really hard to find. Mostly these kind of bugs are very timing sensitive and depend on interrupt execution order. Maybe a dangling pointer is overwriting memory, code is running wild, or some functions are not reentrant as they should be. For these kind of bugs, good tools are worth their weight in gold. The Percepio FreeRTOS+Trace and the Segger SystemView have helped me many times to narrow down such kind problems in my applications. Another ultimate tools is hardware trace: Now I have a Segger J-Trace Pro for ARM Cortex-M in my arsenal of bug extinguishing weapons on my desk:
Dear bugs, look what I have on my desk. Your hiding time is over! 🙂

tracing-cortex-m4-with-j-trace

tracing-cortex-m4-with-j-trace

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Hexiwear: Teardown of the Hackable ‘Do-Anything’ Device

Smartwatches are around for a while now. To me it is still questionable how useful the ‘big’ ones for iOS and Android are. But there are definitely the crowd funded smartwatch projects which caught my attention. Maybe it is about the ‘do-anything’ with connectivity?  One of these gadgets is Hexiwear: a hackable open source device

Hexiwear Device

Hexiwear Device

While it *could* be a kind of smartwatch, the value of this thing is more that it includes a plethora of sensors with two microcontroller, and I can use Eclipse with GNU tools to build my firmware :-).

Alert: Hackster.io is giving away 100 Hexiwears, but you need to hurry up (submission until July 15th 2016)!

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Assembly Files in Eclipse CDT Projects

My embedded applications are implemented mostly in C, a few in C/C++. But all of them have one or few assembly files included too: Assembly programming is the needed to do low-level things so it is a natural part of a true embedded application. For example I use often an assembly file for the application startup code.

I have run into a nasty Eclipse CDT issue which deals with assembly files projects. Here is a quizz for you: can you spot the problem in my project below?

Startup Assembly Code

Startup Assembly Code

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Changing Heap and Stack Size for NXP Kinetis SDK V2.0 gcc Projects

With Processor Expert projects it is very easy to change the heap and stack size: There is a setting for this in the Cpu component settings, under the ‘Build options’ tab:

Heap and Stack Size with Processor Expert

Heap and Stack Size with Processor Expert

As there is no Processor Expert in the NXP Kinetis SDK V2.0 (see “First NXP Kinetis SDK Release: SDK V2.0 with Online On-Demand Package Builder“), how to do the same in a SDK V2.0 project?

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NXP Kinetis Design Studio v3.2.0

For my classes I had so far asked the students to install the Kinetis Design Studio (KDS) v3.0.0 and then apply several updates and upgrades available. NXP has now released the v3.2.0 of their KDS (Kinetis Design Studio):

Kinetis Design Studio v3.2.0

Kinetis Design Studio v3.2.0

The v3.2.0 is including all the 3.x.x updates in a single installation which makes things easier to start with. And it now works for Mac OS X “El Capitan” and the latest GNU ARM Eclipse plugins :-).

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Merging S19 Files

If using a bootloader with an application, one thing is to to merge the bootloader with the application into a single file. I do this with the ‘SRecord’ tool like this:

srec_cat bootloader.s19 application.s19 -o merged.s19
Combining S19 Files

Combining S19 Files

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Renaming Eclipse CDT Projects

When I create a project in Eclipse (e.g. in Kinetis Design Studio with the GNU ARM Eclipse plugins), I have to specify the name of the project during creation time:

Project Name in Eclipse

Project Name in Eclipse

But what if I change my mind later on and want to use a different name? How to rename the project?

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Linting with Eclipse and the GNU ARM Embedded Launchpad Compiler

For a space project we have to make sure that things are not failing while our hardware orbits around the Mother Earth. Therefore we are using different static and dynamic analysis tools, and one of it is using PC-lint from Gimpel to catch as many errors and bugs as possible. For that project, we are using Eclipse with the GNU ARM Embedded (launchpad) ARM compiler and Eclipse as IDE with the GNU ARM Eclipse plugins. There are commercial plugins available for linting with Eclipse (e.g. Linticator), but with a few tweaks it is possible to lint with Eclipse free-of-charge. So this article is about how to lint an Eclipse (Freescale/NXP Kinetis Design Studio) project with PC-Lint.

Lint messages in Eclipse

Lint messages in Eclipse

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GNU gcc printf() and BuiltIn Optimizations

Readers of my blog know: I’m not a fan of printf(), and I think for many good reasons. Still printf() is widely used, and the GNU gcc tries to optimize things. This is observed with a simple example: If I’m writing

printf("a");

Then the code produced (ARM Cortex-M0+ with GNU ARM Embedded 4.9 2015q2 gives:

movs r0, #97    ; 0x61
bl 0xa98

Instead of calling printf(), it is calling putchar()! Why is that?

PutChar instead of Printf

PutChar instead of Printf

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