Tobias – Page 10 – www.haegi.org

16. February 2015

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SmartSwitch with Spark Core

During the wintersemester 2014/2015 Phil and I developed a SmartSwitch with a Spark.Core in “Embedded Systems”.

The goal was to develop an input device which can control local network components without the need to pull your smartphone out of your pocket by pressing a button. We implemented the neccessary software to process the button clicks and trigger HTTP requests in the local network. Additionally we produced a custom PCB. The project is open source and open hardware.

We published the project on hackster.io: www.hackster.io/hdm/smartswitch where it was on the Top Projects on February: http://www.hackster.io/blog/top-projects-feb-7

To increase the inputs we use a MCP23017 Port-Expander which is connected to the Spark in the following way:

When pressing a button connected to the MCP23017 an interrup on the Spark Core is triggered.

While developing we had some problems with the interrupts on the MCP23017 and figured out that the MCP Interrupt Register must be read to recognize interrupts correct. That means after the initialization of the MCP and after the interrupt occurred it must be cleared with mcp.readGPIOAB(). (see our post: https://community.particle.io/t/mcp23017-library-port/6770/39)

16. September 2014

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Projects » Sortify

Sortify: Harmonize your playlist

Sortify was developed during the summer term 2014 in “Programming Intelligent Applications”. The goal is to rearrange your playlist and make it more harmonic.

The progress is described in the following gallery:

We used plot.ly to visualize the result and the guys wrote a blog post about out “German Robo-DJ”: http://blog.plot.ly/post/92062112527/the-data-of-music-the-anatomy-of-pain

1. August 2014

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Projects » Papers

Performance Aussichten von Webseiten durch den Einsatz von WebP und JPEG XR (german, 01.08.2014)

Abstract Im nachfolgenden Paper soll es um die Performance Aussichten der neuen Dateiformate WebP und JPEG XR gehen. Die Geschwindigkeitseigenschaften werden durch einen Vergleich der Ladezeit und der Dateigröße mit JPEG betrachtet. Auf die technische Funktionsweise der beiden Dateiformate wird dabei nicht weiter eingegangen.

5. March 2014

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Projects » Papers

Simulate M/M/1 queues with RabbitMQ and compare results to Queuing Theory (english, 05.03.2014)

Abstract Queuing Theory deals with the mathematical consideration of waiting queues. This paper simulates a M/M/1 queue, which is the simplest model in Queuing Theory, with the help of the server software Rabbit MQ. Thereby the average number of users in the queuing system and in the queue is measured. Furthermore the average time in the queuing system per user and the waiting time in the queue per user is calculated. The resulting values of 25 runs are compared to the expected values of the equations by the Queuing Theory. The results show that the expected value is nearby the mean of the simulation and most likely in the 95% confidence interval around the mean value. Moreover the FIFO property of M/M/1 queues is confirmed.

11. February 2014

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Projects » OSMC / Ambilight

Raspberry Pi Ambilight

My second Raspberry Pi is connected to my TV running Raspbmc to play video files. I liked the idea of a custom ambilight installation described by _nadnerb so I bought some WS2801 LEDs and installed Boblight. The LEDs are connected by SPI to the raspberry. Boblight is then able to control the LEDs based on the output.

You can see the mounted LEDs and the Boblight config in the following images: