Tag Archives: Tips&Tricks

About things you might not know, or could make your life easier.

Tutorial: BLE Pairing the Raspberry Pi 3 Model B with Hexiwear

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The Hexiwear (see “Hexiwear: Teardown of the Hackable ‘Do-Anything’ Device“) is a small and portable sensor node with built-in BLE (Bluetooth Low Energy) transceiver. In a research project we try to use multiple Hexiwear in a classroom environment and to collect sensor data on a Raspberry Pi. The Raspberry Pi 3 Model B running Linux has an on-board BLE transceiver too, so why not binding them (wirelessly) together?

Raspberry Pi 3 connected with Hexiwear over BLE

Raspberry Pi 3 connected with Hexiwear over BLE

Well, things seemed easy at the beginning, and as always, there are many things to learn on a journey like this…

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Low Power LCD: Adafruit Breakout Board with Sharp Memory Display

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Many projects benefit from a small display as a user interface. For very low power applications this is usually a no-go as the display needs too much energy. I have used e-paper displays from Kent: while these e-paper displays do not need any power to keep the image, changing the display content is not for free, plus is very slow (around 1 second needed to update the display). So I was looking for something low power and fast for a long time, until Christian (thanks!) pointed me to a display from Sharp: both very low power and fast:

Font Test with Sharp Memory Display

Font Test with Sharp Memory Display

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Flashing and Restoring the Hexiwear Firmware

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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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Making-Of Sea Shell Sand Clock

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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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Failure with Solder Points and Mechanical Pressure

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The good thing with failure is: it is an opportunity to learn :-).

So here is a case: For a STEM roadshow (see “MINTomat: World’s Most Complicated Bubble Gum Automata?“), we have produced in a rush an autonomous robot with a shiny printed 3D cover:

LED effect in blue

Prototyp with LED Effects

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

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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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Accessing GNU Linker Script Symbols from C/C++

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With the GNU compiler and linker I can place variables into custom sections (see “Defining Variables at Absolute Addresses with gcc“). This article is about how to get the section start and end address so I can for example access that range in my code. Or in general ways: how to use symbols defined in the linker script accessible in the C source code.

Using Linker Script Symbols in Source Code

Using Linker Script Symbols in Source Code

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McuOnEclipse Components: 30-Oct-2016 Release

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A new McuOnEclipse components release was long overdue, so I’m pleased to announce that a new drop is available with the following major changes:

  • Segger SystemView library with kernel time reporting
  • GenericTimeDate supports different hardware RTC devices
  • Utility with little endian packet handling functions
  • Shell Standard I/O handlers for USB CDC, Segger RTT and Bluetooth
  • FreeRTOS and stack size reporting
  • printf() support in Shell component
  • Various small bug fixes and improvements
SourceForge

SourceForge

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

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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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Tutorial: Updating Embedded Linux on Toradex i.MX7 Colibri Module using SD Card

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My Toradex i.MX7Dual module comes with a preflashed Linux distribution (see “Tutorial: First Steps with NXP i.MX7 and Toradex Colibri Board“). As with any other things, Linux gets updated from time to time, and Toradex publishes new firmware. In this article I’m documenting how I can update Linux in the external FLASH on that module.

NXP i.MX7Dual Module

NXP i.MX7Dual Module

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