Control Anything with one AVR pin

This instructable shows how to control a group of led's with one microprocessor output.

The micro I will be using is an Atmel Attiny2313.

Step 1 Parts and Tools

Parts:
Attiny2313 (got 5 free samples from Atmel)
20 pin socket
Resistors (any size will work, depending on your setup. I will explain later)
5v regulator (any will work, I'm using an LM340)
Transistors or Mosfets (easiest to find and cheapest ones are usually 2n3904's. Just make sure it's an NPN transistor, or an N-Channel Mosfet)
2 small Capacitors (look up data sheet for regulator, .1uf and .22uf with LM340)
Lots of LED's
Some protoboard or a breadboard
Any programmer for the AVR
Wire


Tools:
Soldering Iron

Comments

[budabob07]

its more like 7 pins than one pin, but good guide. isnt charlieplexing better than multiplexing though?

[KayvonX]

You probably want those LEDs facing the other way. In this diagram, they're reverse biased and won't light up.

[jufreese]

Whoops....it's fixed now.

[Photo-Worx]

I'm not trying to be negative or anything, but the title is kind of misleading. You are not actually controlling the LED's with one output pin of the attiny2313. You are controlling each row of led's with it's own output pin, so you are actually using 7 output pins. To do it properly you would use a serial led driver chip like the A6279 from Allegro and use one output pin on the attiny2313 to send the serial data to the led controller. I am working with these chips and they are great. each chip controls 16 outputs and they are chainable to control even more led's.

[jufreese]

You are right, I am only controlling 10 leds per output pin, but as I say later in this, you can have hundreds of leds or whatever you want, as long as your transistor or mosfet can handle it. It can be stepper motors, dc motors, 1000 leds, high power leds, whatever you want.

[syrax]

You can use simple shifting algorithm for moving

// code left shift
byte = 0x01; //0b00000001
for(x=0; x<7; x++){
PORT = byte;
byte << 1;
_delay_ms(200);
}

// code right shift
byte = 0x40; //0b01000000
for(x=0; x<7; x++){
PORT = byte;
byte >> 1;
_delay_ms(200);
}

// code fill right
byte = 0x40; //0b01000000
for(x=0; x<7; x++){
PORT = byte;
byte >> 1;
byte |= 0x40;
_delay_ms(200);
}

REGARDS FROM BULGARIA

[jufreese]

I am still new to C programming. All I really know is asm from school and that was on a Motorola micro. I have heard that if you know asm, C is much easier to learn though.

[syrax]

it is high level of programming :))) easy, fast ... only one is not so good when you write C the compiller transform this in asm /not so good like human / :) the programs are little bigger

[AndyGadget]

I see you're using each bank the same colour, but beware of mixing colours within a bank as the perceived brightness of the various colours varies even though the current is the same. I found this in my recent Instructable and used different resistor values to compensate. Green was the brightest, then blue, red, yellow (didn't use white). Experiment to get them matched up.
^{(BTW, your LEDs are drawn reversed in the schematic.)}

[jufreese]

Yes, as I state later in the instructable, Blue LEDs usually drop around 3-3.3v, green is around 3-3.2v, and red is around 2.2v. I dont remember for the rest of the colors.

[AndyGadget]

Agreed, but I'm saying something a bit different :

If you put (say) 15mA through a green, a blue, a red and a yellow LED (taking the Vf into consideration), the green will appear brighter than the blue, the blue brighter than the red etc. because of different efficiencies of the LEDs and the eye's sensitivity to the different colours.
For my project, I initially did the calculations for the same current through each colour LED and found it no good at all, so I chose the resistor values by 'eyeballing' it.

[jufreese]

ok, yes, I know what you mean. For a school project we used a light meter to figure out exactly how to make them all look the same, but eyeballing it works the best because of the different wavelengths and how the human eye sees 555 nm the best.