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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McuOnEclipse Components: 12-Dec-2016 Release

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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

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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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Prototype of tiny Hexiwear Docking Station

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For a research project we are using Hexiwear to measure the effectiveness of teaching and learning. The Hexiwear is used as a networking sensor device in that project. For that project we needed a docking station with wireless capabilities:

Mini Docking Station for Hexiwear

Mini Docking Station for Hexiwear

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