May 19, 2013
Ben Martin — Some amateur electronics: hand made 8x8 LED matrix
So I made an 8x8 matrix of LEDs in a common cathode arrangement. Only one column is ever on at any time, but they cycle from left to right so quick that you and your camera can't get to see that little artefact. This does save on power though so the whole layer can be run directly from the arduino LeoStick in the top right of picture. Thanks again to Freetronics for giving those little gems away at LCA!8x8 LED matrix, two 595 shifties and a ULN2003 current sink from Ben Martin on Vimeo.
The LEDs to light on a row are selected by a 595 shift register providing power for each row. The resistors are on the far right of the grid leading to that shift register. The cathodes for each individual column are connected together leading to the top of the grid (as seen in the video). Those head over to a uln2003 current sink IC. In the future I'll use either two 2003 chips or one single 2803 (which can do all 8 columns at once) to get the first column to light up too.
The uln2003 is itself controlled by supplying power to the opposite side to select which column's cathodes will be grounded at any given moment. The control of the uln2003 is also done by a 595 shift register which is connected to the row shifty too. The joy of all this is you can pump in the new state and latch the shift registers at once to apply the new row pattern and select which column is lit.
The joy of this design is that I can add 8x8 layers on top at the cost of 8 resistors and one 595 to perform row select.
There are also some still images of the array if you're peaked.
The 595 chips can be had for around 40c a pop and the uln2003 for about 30c. LEDs in quantity 500+ go at around 5-7c a pop.
The code is fairly unimaginative, mainly to see how well the column select works and how detectable it is. In the future I should setup a "framebuffer" to run the show and have a timer refresh the array automatically...
#define DATA 6
#define LATCH 8
#define CLOCK 10 // digital 10 to pin 11 on the 74HC595
void setup()
{
pinMode(LATCH, OUTPUT);
pinMode(CLOCK, OUTPUT);
pinMode(DATA, OUTPUT);
}
void loop()
{
int i;
for ( i = 0; i < 256; i++ )
{
int col = 1;
for( col = 1; col < 256; col <<= 1 )
{
digitalWrite(LATCH, LOW);
shiftOut(DATA, CLOCK, MSBFIRST, col );
shiftOut(DATA, CLOCK, MSBFIRST, i );
digitalWrite(LATCH, HIGH);
}
delay(20);
}
}
May 15, 2013
Blue Hackers — Autism/Aspergers and Online Learning
A resource link you may find useful:
http://www.onlineeducation.net/2013/04/05/autism-and-online-learning-a-guide-for-teachers
Online learning environments present an opportunity to better serve autistic students that teachers can learn to use effectively.
May 14, 2013
Blue Hackers — New evidence on body clock and depression
Researchers found something relevant to people with depression while working on something else (original article at Independent.co.uk, tnx Andrew for the link). In a nutshell, what they found was that people with severe depression had their body clock out of whack: they were essentially living in a different timezone. I don’t think it’s actually news to us, I wrote about this and it being the equivalent of jetlag in the BlueHackers HowTo. But, I do think it’s interesting in the sense that at least in the cases the researchers encountered, for people with severe depression there was a genetic cause. We like to know why things are the way they are, so this new info can help in that respect. Modern life, in particular with the type of work many of us do, makes it really easy to stuff up your day and night rhythm, and also your eating pattern which is actually related to this as well. Getting your day/night, daylight and food intake patterns right is generally a very important base. Not for everybody, but I think definitely for most of us. And while some of these things might still be hard for some, they’re relatively easy steps compared to others. It’s worth a try and they’re also specifically things you can get external help with – you can get a friend to come by for a walk at a specific time of day, or go get a meal. Once the new pattern is trained (can take up to three months but often it’s much sooner) you’ll find it much easier to stick to, and also that other tasks become easier. Mind you, I’m very aware that this is still easier said than done – I have my own company arranged in such a way that it doesn’t create nasty work hours, but I also have a family and thus in the mayhem (or even just because of the weather) I sometimes lose (some of) the pattern for a while. But, I’m now aware of it and that does make a difference already – it’s easier to fix. Typically my food pattern stays ok, but the morning walk loses out (by the way, it may be an afternoon walk that works best for you). Do you know what’s messed with my morning walk lately? The city council has closed off a footbridge crossing a creek (storm damage), and that was the only way through in that particular direction. I can create other walking loops but they’re less convenient for several reasons – I’ve walked some but it feels less comfortable. I’m generally ok with change but it’s funny how this is just very disruptive! How do day/night, exercise and food patterns work for you, and how have you tweaked them to work better for you? Please tell, it will help others.May 13, 2013
Daniel Devine — New Site New Server
DDEVnet.net is now running on a new server, in Australia. I also took the opportunity to replace my personal website, HTTP server and change my mail setup. Rather than coming out scarred, I've come through enlightened and more enthusiastic than ever.