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

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 pice 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

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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McuOnEclipse Components: 06-May-2017 Release

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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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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Modifying the Teensy 3.5 and 3.6 for ARM SWD Debugging

Looking for a small, inexpensive ($25-30) ARM development board (say 120-180 MHz ARM Cortex-M4 with FPU, 512kB-1MB of FLASH and 256 KByte of RAM? Then have a look at the Teensy 3.5 and Teensy 3.6 by PJRC/Paul Stoffregen:

Teensy 3.6 with NXP K64

Teensy 3.5 with NXP K64F ARM Cortex-M4F

The only problem? it is not possible to debug it :-(. At least not in the traditional sense. This article is about how to change the board to use it with any normal SWD debugging tool e.g. Eclipse and the Segger J-Link :-).

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

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

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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MCUXpresso IDE: S-Record, Intel Hex and Binary Files

This is another article about the NXP MCUXpresso IDE (see “MCUXPresso IDE: Unified Eclipse IDE for NXPs ARM Cortex-M Microcontrollers“), this time it is about Post-build steps. Post-build steps are custom actions which can be executed after the build (or link phase), and are typically used to generate S-Record, Binary or Intel Hex files (see “S-Record, Intel Hex and Binary Files“).

Post Build Steps Details

Post Build Steps Details

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Cycle Counting on ARM Cortex-M with DWT

Some ARM Cortex-M have a DWT (Data Watchpoint and Trace) unit implemented, and it has a nice feature in that unit which counts the execution cycles. The DWT is usually implemented on most Cortex-M3, M4 and M7 devices, including e.g. the NXP Kinetis or LPC devices.

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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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Reprogramming the Mikroelektronika Hexiwear Dockingstation

The Hexiwear docking station would have a nice feature: it has embedded a debug circuit (OpenSDA). That way I would not need an external debug probe to debug the Hexiwear. However, a debug probe is required to reprogram the docking station itself:

Repgrogramming the Mikroelektronika Docking Station

Repgrogramming the Mikroelektronika Docking Station

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Debugging ARM Cortex-M0+ HardFaults

To me, one of the most frustrating things working with ARM Cortex-M cores are the hard fault exceptions. I have lost several hours this week debugging and tracking an instance of a hard fault on an ARM Cortex-M0+ device.

Next assembly step will cause a hard fault

Next assembly step will cause a hard fault

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Upgrading to Sharp 128×128 Pixel Memory Display

In “Low Power LCD: Adafruit Breakout Board with Sharp Memory Display” I used a 96×96 Sharp Display (LS013B4DN04) with the Adafruit breakout board, but because that one seems to be EOL (End Of Life), I searched for a replacement. I have found the 128×128 pixel version (Sharp LS013B7DH03), and best of all, it is pin compatible :-). With a small tweak of the driver, it works :-):

Sharp Memory Display 128x128

Sharp Memory Display 128×128

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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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Disabling EzPort on NXP Kinetis to Solve Power-On Issues

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:

NXP FRDM-K64F Board

NXP FRDM-K64F Board

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.

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McuOnEclipse Components: 12-Dec-2016 Release

Time is passing by so fast, and the year end is approache fast! I’m pleased to announce that a new release of the McuOnEclipse components is available in SourceForge:

  • Percepio Trace V3.1 for FreeRTOS which includes both Segger RTT continuous streaming and snapshot tracing in a single API
  • Generation of sources and drivers so they can be used without Processor Expert using McuLibConfig, removal of dependency to NXP Kinetis SDK: components use a generic API approach to have them working with other SDKs.
  • New contributed ExceptionsHandler component
  • Callback Setter and Getter in USB CDC stack for simpler option handling
  • GenericTimeDate with flexible RTC support and added Unix Timestamp functions
  • LongKey events in Key component
  • FreeRTOS with optimized task selection on Cortex-M4/M7
  • Many smaller bug fixes and enhancements
SourceForge

SourceForge

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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: STMicroelectronics VL6180X Time-of-Flight LIDAR Sensor

For many of my applications I need to measure a distance. I have used ultrasonic sensors, but there view angle (beam) is not able to detect smaller objects, it very much depends on the object surface and angle, it is slow and not very precise. I have used infrared sensors, but here again it depends on the infrared reflection of the object in range, it depends the amount of reflected light is not really telling much about the distance, and yet IR reflection is subject of material and object targeted.

But there is yet another sensor type to consider: ToF! ToF (or Time-of-Flight) sensors have a built-in LIDAR: The sensor is sending out light pulses and measures how much time it takes for the light to come back. Similar to ultrasonic sensors (see “Tutorial: Ultrasonic Ranging with the Freedom Board“), but instead of ultrasonic it uses an infrared laser light. Or think about a radar system using an infrared laser light.

Vl6180x Breakout Board with tinyK20 Microcontroller-board

Vl6180x Breakout Board with tinyK20 (NXP Kinetis K20) Microcontroller-board

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Making-Of Sea Shell Sand Clock

The year is coming to an end, the Holiday season is approaching. In case you are looking for a nice present: I have completed my version of a sand clock: a clock writing the time into sand:

Sandclock

Sandclock

If you are interested to build your own version, I have documented the different steps with tips and tricks…

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Tutorial: Getting ETM Instruction Trace with NXP Kinetis ARM Cortex-M4F

It seems to me that not many developers use hardware trace? ARM indicates that maybe only <5% of developers are using trace. Too bad! Why are all the ARM Cortex microcontroller vendors putting a powerful hardware (and complicated!) trace engine into their devices, if only few developers are using it? Seems like a waste of silicon and an unnecessary price adder? Well, hardware trace can be a life saver: Because only with hardware trace the most complicated bugs and problems can be solved. And maybe because only the best are using it ;-).

In this article I proudly present my research how to get instruction trace out of the ARM Cortex-M4 microcontroller on a NXP TWR-K64F120M board with a Segger J-Trace for ARM:

J-TRACE tracing NXP TWR-K64F Board

J-TRACE tracing NXP TWR-K64F Board

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