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Blumote and SHAC on iLifestyle

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iLifestyle is a new show that started in February 2013 on SABC1; it airs on Thursdays at 18:30

The show explores how technology affects peoples everyday lives and one of the elements of ‘iLifestyle, is the profiling of South African inventors who have developed or use technology as a way of solving an existing problem or enhancing one’s life.

The team was at House4Hack today shooting a short segment which was initially intended to cover Blumote, but after they heard and saw that we are opening the door and gate using smartphones and smartwatches, SHAC was included.

I took some photos of Thuli (presenter for iLifestyle) interviewing Toby:

It was lots of fun working with the team, who seemed genuinely interested in what House4Hack is doing and are planning a follow up show, where more of our inventions can be showcased.

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Mill and Lathe

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Yesterday House4Hack got a new member of the family – a combination mill and lathe!

I was sitting at H4H minding my own business when first Guy, then Org, then Kobus arrived – ready for a road trip, so I could not help myself and tagged along.

Kobus found the machine advertised on Gumtree for R6500 and immediately knew this was excellent value for money, having been shopping around for the last couple of months.

The previous owner (Gideon) stays in Witpoortjie – this is a small residential area next to Krugersdorp.  And with the traffic, it took us about an hour to get there.

While I was taking photos, Guy, Org, Kobus and Gideon (yes it takes four people to carry), loaded it and tied it onto Org’s bakkie.

Forty five minutes later, we were back at H4H and unloaded the machine – this time with the help of Bernhardt.

Here are some photos of the machine and the moving process:

So what next?

  1. Need a table to work on – we will be buying some steel and welding
  2. Course on how to use this safely
  3. [Insert you project idea here]
  4. Profit!
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Muting DSTV using Arduino

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I have been playing around with infrared remote controls as part of the upcoming Introduction to MSP430 course – Guy and I were looking for an interesting use of PWM and timers, so the suggestion was to produce an infrared signal using an IR led.

I set out to learn a bit more about IR and prototype using the Arduino. After searching online, I found Ken Shirriff’s excellent IR library for Arduino on Github: https://github.com/shirriff/Arduino-IRremote

It supports some standard TV remote controls and a “raw” mode which looked promising for controlling other things, e.g. my DSTV remote control, air conditioner etc

In this mode you can give it an array of unsigned integers. For example:

unsigned int raw[36]={250,842,242,2374,...,250,81862};

For background on how IR remote controls works check out this article on the irq5 blog.  In short the signal is encoded in bursts of “on” and “off”.  When the LED is on, it is PWM’d at a certain frequency. To use the “raw” mode, we need to know the PWM frequency (typical values between 35-40 kHz) and then the “on” and “off” durations.  The array is then made as follows:

unsigned int raw[36]={"duration on","duration off",....};

Using an IR LED, a resistor (e.g. 10K) and an oscilloscope, one can readily discover the signal sent from the remote control:

IR Led and 10k resistor

One "ON" pulse showing PWM

The duration of seven modulation cycle for the DSTV remote control is measure as 183uS, which corresponds to ~38kHz.

To get the on-off durations, the easiest is to use an IR receiver and the InfraredReceivers sketch found on http://playground.arduino.cc/Code/InfraredReceivers

Infrared receiver

Infrared receivers removes the 38kHz and gives a digital HIGH / LOW for the received pulses.  The Arduino Playground sketch samples the duration of these pulses at 4uS and prints to the serial console.

However, to use the output I had to subtract 10uS from each measurement – I suspectthis is an additional delay in IRremote library to switch the LED.

Muting DSTV

Connecting an IR LED to pin 3 through a 220 ohm resistor

IR LED connected to pin3 and 220 ohm resistor to ground

and running the following sketch mutes DSTV PVR:

#include <IRremote.h>
IRsend irsend;

void setup(){}

unsigned int raw[36]= {250,842,242,2374,250,834,250,2790,250,1254,
250,1258,246,1258,242,1670,250,12938,254,838,250,974,250,698,
242,838,254,694,246,2370,254,698,246,694,250,81862};

void loop() {
  irsend.sendRaw(raw,36,38);
  delay(2000);
}

Next steps is to apply this to the Airconditioner at House4Hack, to be able to control that as part of the course.

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IRL:
  • Schalk 082 777 7098
    schalk dot heunis at gmail dot com
  • Guy 084 678 0045
    guy dot vandenberg at microsmart dot co dot za
  • Toby
    http://tobykurien.com

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