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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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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DIY IKEA Wireless Qi Charging for the Hexiwear

The Achilles Heel of the Mikroelektronika Hexiwear is its charging: the charging and USB connector are only designed for a limited number of plug-unplug cycles, and it does not have a wireless charging capability like the Apple iWatch. Until now! I have built a DIY wireless charging system for the Hexiwear 🙂 :

Wireless Qi Charging the Hexiwear

Wireless Qi Charging the Hexiwear

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Tutorial: Hexiwear Bluetooth Low Energy Packet Sniffing with Wireshark

For a university reasearch project I try to pair the Raspberry Pi 3 with a Mikroelektronika Hexiwear using BLE (Bluetooth Low Energy). Most of things worked after a lot of trial and error, but at a certain point I was stuck trying to write to send data from the Raspy to the BLE device.The Hexiwear BLE protocol description is very thin, so I ended up using a BLE sniffer to reverse engineer the protocol with Wireshark.

Sniffing BLE Packets between Raspy and Hexiwear

Hardware setup between Raspy and Hexiwear

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Low Power LCD: Adafruit Breakout Board with Sharp Memory Display

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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FatFS with Adafruit MicroSD Breakout Board and NXP FRDM-KL25Z

Breakout boards are great: they allow me to explore functions quickly, without to build my custom board: all what I need is some wires and ideally a bread board.

Adadfruit MicroSD Card Breakout Board

Adadfruit MicroSD Card Breakout Board

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Kinetis Lava LED Light Cube

In “openHAB RGB LED Light Cube with WS2812B and NXP Kinetis” I started experimenting Kinetis boards, a LED cube diffuser and Adafruit WS2812B NeoPixel LEDs. That worked well, but I was not to very happy about the visual effect. So here is my next version: I wanted to have control over each side of the cube. For this I have built a cube inside the cube with a 3D printed structure:

Bare LED Cube

Bare LED Cube

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How to Add Bluetooth Low Energy (BLE) Connection to ARM Cortex-M

In many of my embedded projects I’m using successfully the Nordic Semiconductor nRF24L01+ (see “Tutorial: Nordic Semiconductor nRF24L01+ with the Freescale FRDM-K64F Board“) and the HC-06 Bluetooth transceivers (see “Getting Bluetooth Working with JY-MCU BT_BOARD V1.06“) for wireless communication. However, the nRF24L01+ is using a proprietary protocol, and the HC-06 does not work with Apple products (it does very well with Android devices). To close that gap I decided to add Bluetooth Low Energy (BLE, or Bluetooth 4.x). So this post is about how to add Bluetooth Low Energy (BLE) to NXP (formerly Freescale) Kinetis devices:

BLE Enabled Kinetis

BLE Enabled Kinetis

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Tutorial: Adafruit WS2812B NeoPixels with the Freescale FRDM-K64F Board – Part 5: DMA

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:

FRDM-K64F with Adafruit NeoPixel

FRDM-K64F with Adafruit NeoPixel

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Tutorial: Adafruit WS2812B NeoPixels with the Freescale FRDM-K64F Board – Part 4: Timer

This is Part 4 of a Mini Series. In Part 3, I described the software concepts (see “Tutorial: Adafruit WS2812B NeoPixels with the Freescale FRDM-K64F Board – Part 3: Concepts“). In this post I describe how to set-up the timer to trigger later DMA operations. The goal is to drive Adafruit’s NeoPixel (WS2812B) with the Freescale FRDM-K64F board:

NeoPixels with FRDM-K64F

NeoPixels with FRDM-K64F

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Tutorial: Adafruit WS2812B NeoPixels with the Freescale FRDM-K64F Board – Part 3: Concepts

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:

Adafruit 8x8 NeoPixel Shield with Freescale FRDM-K64F Board

Adafruit 8×8 NeoPixel Shield with Freescale FRDM-K64F Board

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Tutorial: Adafruit WS2812B NeoPixels with the Freescale FRDM-K64F Board – Part 1: Hardware

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! 🙂

Adafruit 8x8 NeoPixel Shield with Freescale FRDM-K64F Board

Adafruit 8×8 NeoPixel Shield with Freescale FRDM-K64F Board

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LED Clock with Kitchen Hot Pan Protector

When I showed my 60 NeoPixel LED clock prototype to my daughter and her girlfriend, and they both wanted to have one right away :-). Well, that clock was just a proof of concept, with lots of temporary wiring. So I decided this week-end to beautify it and to make it look nice and clean(er). There is nothing like a week-end project with adding a few more LEDs and features :-).

Adafruit Neopixel Clock with 60+24+12 LEDs

Adafruit Neopixel Clock with 60+24+12 LEDs

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