Introducing Neon Flies, a live wallpaper for Android phones. Be surrounded by swarms of multicolored butterflies that flutter in and out of view. With an almost endless number of colors and flight paths you will be mesmerized. Each butterfly flaps its wings realistically as it zooms around your screen. Neon Flies is based on OpenGL for silky smooth hardware accelerated animations.

Download it now from the Market here.

It also looks great on tablets!

You can download Canopy by searching for “Canopy Live Wallpaper” in the Market or by using this QR code.

Canopy is based on the Chrome Canopy. However, there were some modifications that had to be made to allow it to be used as a background.  The biggest being that it had to be able to zoom by itself. In Chrome Canopy the user uses the mouse to control the zoom, in Canopy Live Wallpaper it automatically zooms into the place with the most action. Another change was that the number of branches on screen had to be reduced due to the fact that it has to run on a phone and not a powerful desktop. However, this is adjustable in the settings.

Canopy Live Wallpaper is fully customizable.

You have full control over

• The color of the branches
• The color of the background
• The number of branches on screen
• The number of twigs that grows off each branch
• How crooked the branches can get
• Number of vertices that compose each branch (detail vs. speed)
• Zoom speed
• Anti-Aliasing
• Max FPS

What exactly is the Fusion? Take a look at it’s features!

• XMEGA128A1
• Spartan 3A XC3S200A 5C
• 32MHz clock
• Real-time clock
• 16MB SDRAM
• 8MB DataFlash
• 3-axis accelerometer
• 2 general purpose LED connected to the XMEGA
• 1 general purpose LED connected to the FPGA
• 2Mbit FPGA PROM
• DONE LED for FPGA
• 5v-3.3V bi-directional level shifters
• 8 analog inputs (with 5V or 3.3V selectable power)
• 6 3.3V digital inputs
• 16 5V digital IOs
• 8 3.3V digital IOs
• Reset buttons
• Program button for FPGA
• Powered from 5V

The problem with FPGAs is the programmers are too expensive for most people. To combat this the FPGA will come loaded with a versatile design. It will allow for PWM on any of the pins, input capture on some, a hardware neural net, USART, and more.

The chip missing in the pictures is the DataFlash. I was not able to locate any stock right now but Atmel is sending a sample for this prototype.

So far I have identified two errors. The DONE label on the silkscreen should be next to the left LED not the right one and pins 20 and 19 on the 5v-3.3v level-shifters are flipped. I will patch that up tomorrow.

First if you have not already download the Source Code.

This code will be the base for your code. Much of the underlying code is done for you so you can just worry about implementing your patterns. Go ahead and open up main.c

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#include "hardware.h"
#include "driver.h"
#include "patterns.h"
 
extern volatile uint8_t cube[3][27];
 
int main (void)
{
    init_ports();
    USART_Init(21); //baud 115200
    init_timer1(); //set up the timer and start the main interrupt
    display_colors(3000);
    while (1)
    {
        //serial_control();
        plasma(750);
        corner_expand(35);
        rain(500);
        worm(150);
        flash_rand(100);
    }
    return 0;
}

This is the core section of the code. Everything before the while loop is setting up the cube so you should not need to mess with this. The code inside the while loop are the patterns that will be displayed. You can change the order or change their arguments (the numbers in parentheses). The number sets how long the pattern will run for.

Note that they are not a unit of time but rather how many times a pattern will execute its loop. Some patterns have fast loops and others have slow loops so the fact that plasma has 750 and corner_expand has 35 does not necessarily mean that plasma will run 21 times longer.

Now that you are familiar with the highest level open up patterns.c. This file contains the actual patterns and is where you should add yours.

Let us take a look at one of the simplest patterns, flash_rand()

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void flash_rand (uint16_t len)
{
    uint16_t ctr=0;
    for (ctr=0;ctr<len;++ctr)
    {
        fill_buffer(rand() % MAX_COLOR,rand() % MAX_COLOR,rand() % MAX_COLOR);
        display_buffer();
        delay_ms(300);
    }
}

This function simply fills the cube will a solid random color every 300ms.

There are a set of functions you can use to manipulate the cube. They are listed in driver.h. In flash_rand() we use fill_buffer() which will fill the entire cube with a single color.

The next line display_buffer() copies the cube’s frame buffer to the display buffer. This is used so your entire frame will be displayed once it has been fully rendered. MAX_COLOR is defined as the brightest value a LED can have. Anything higher than MAX_COLOR will be treated the same as if it were MAX_COLOR. This number is subject to change so it is always best to use a fraction of MAX_COLOR.

The last line is used to wait 300ms before showing the next frame. There are delay functions in driver.h which should be used instead of the normal AVR delays like _delay_ms(). This is because the cube display is interrupt driven so your delay will be interrupted many times making the delay time much longer than what you originally wanted.

Something to note is that while you can write to the cube’s frame buffer directly you should use the functions in driver.h instead. The main reason for this is that in future version of the cube the wiring of the LED matrix may change which will lead to a change in the driver and the frame buffer structure. Using the display functions guarantees that the patterns you worked hard on will be usable on future versions of the cube.

I will be adding more to this tutorial.

Inside a Transistor

Inside a transistor there are three pieces of silicon. Just like the diode each piece is ether a N-type or P-type silicon. The name of the transistor, NPN and PNP, come from how the silicon is arranged.

NPN vs. PNP

As you can see, NPN and PNP have the same structure, but differently doped silicon. Why does that matter? A NPN transistor is used to sink current, or pull it to ground, while a PNP transistor sources current, or pulls it to VDD (positive voltage). Also a NPN transistor is closed (conducting) when the base has a positive voltage, but a PNP is closed when the base is pulled to ground.

Using the Transistor

A transistor has three pins, base, collector, and emitter. The emitter of a NPN transistor is connected to ground, while in a PNP it is connected to a VDD. To make the transistor conduct electricity, you need to run current from the base pin to the emitter pin. That is why you need to connect the base of a PNP transistor to ground and a NPN to VDD to turn them on.

Biasing Resistor

A resistor should be placed between the base and whatever is driving it. This is because the base will act as a diode and short the signal when the transistor is on! The resistance of the resistor depends on the transistor as well as how much current you need. A transistor requires a certain amount of current to flow from the base to the emitter to become saturated. When a transistor is saturated is will be the best conductor it can be, allowing the most amount of current. Sometimes you do not want that, as the amount of current that flows from the collector to the emitter is related to the amount of current flowing through the base to the emitter, you can use this to amplify a signal, or to limit how much power something receives.

Forward Voltage

Just like a diode a transistor has a forward voltage of around 0.7V, as it is basically two diodes. See the diode tutorial for more on this.

How Diodes Work

Silicon is special in that it is a semiconductor, meaning it conducts electricity in some circumstances but not others. Silicon can be mixed with small amounts of impurities to give it a charge. This is called doping.To give the silicon a positive charge small amounts of boron are mixed into it, for a negative charge it is mixed with something like phosphorous. A diode consists of two pieces of silicon, a n-type(-) and a p-type(+).

When a positive voltage is applied to the p-type side the like charges repel and it creates a conductive path past the P-N junction (where P and N touch). However if a negative charge is applied to the p-type side then the opposite charges attract creating an electrical “hole” at the P-N junction, blocking the flow of electrons.

Forward Voltage

When positive voltage is applied to the P-type side of the diode it takes a specific amount of voltage before it can create the conducting bridge. The lowest voltage at which the diode starts conducting is called the forward voltage. A diode typically has a forward voltage of around 0.7V. This also means that the voltage across the diode will be 0.7V, so you will lose 0.7V. If you have a 5V connected to the P-type side then the voltage from the N-type side to ground will be the difference between 5V and the forward voltage, 4.3V. There are special diodes know as Schottky diodes that have a very low forward voltage, however they are usually more expensive and can not handle as much current.

What does an inductor do? An inductor stores electrical energy in the form of a magnetic field. An inductor can be though of as a large water wheel in a river. Where the river starts flowing and the water wheel is stopped it resists the flow of water until it starts to move and is up to speed with the river. If the river stops the momentum of the water wheel will continue to make it spin pushing the water forward for a short amount of time. An inductor does pretty much that. When electricity first pases though the inductor there is a large resistance until its magnetic field is up. Once the power stops flowing the magnetic field collapses into the inductor forcing the electricity forward until the field has completely collapsed.

Voltage Changes

When the field collapses, if there is no path for the electricity the collapsing field makes to go the voltage will build up until it dissipates somewhere, either though the inductor itself or through another circuit. This is useful in generating higher voltages. If you have a AA battery, 1.5V, and your circuit needs 5V you can use a boost converter to generate the higher voltage. Remember that when boosting voltage the current goes down, so you do not gain any power, you actually lose some as the efficiency is not 100%. To generate a higher voltage the boost circuit switches the inductor on and off very fast. When it is on the power flows through the inductor to ground, but when it is off it flows from the inductor to the 5V circuit. There are special chips that monitor the voltage so you get a nice 5V. You can get regulators for almost any voltage you will need. This property of inductors can also be used to generate high voltage, I used one to make 600V with 15V input.

Transformers

Transformers (aka “wall warts”) use two or more inductors to convert voltage. Much like the single inductor regulators the transformer turns the inductor on and off. However they turn one inductor on and off and allow the magnetic field to collapse into the other. A wall wart uses the fact that the power in your home is AC voltage, it switches directions 60 times a second. Most transformers that regulate 120AC have an inductor connected directly to the outlet and another that the field collapses into.

Chokes

Chokes are inductors that are used to smooth the current flow. When there is a larger flow then it uses is to build up the magnetic field, but when there is lower amount part of the field collapses effectively smoothing it out.

Capacitors like resistors have different ratings, voltage, farads, and ESR (Equivalent Series Resistance).

Voltage

All capacitors have a voltage rating. This is the maximum voltage you can apply to the capacitor without it going BOOM!, or simply not working anymore. Image if you left the water balloon on the hose and turned on the hose on full, once it got full it would pop. This is because inside a capacitor are two metal plates that are separated by a very thin insulator.The two plates can not touch, but the closer they are the more electrons the capacitor can store. However if you apply too high of a voltage the electrons will have enough driving force to jump across the insulator. Always stay under the rated voltage. The rule of thumb is to use a capacitor rated at twice the voltage it will ever see, so for a 5V circuit you would use a 10V capacitor.

Farads

Farads is the measure of how big of a charge a capacitor can store. Most capacitors are rated in microfarads (µF, often typed as uF), 1/1,000,000 of a farad. This is very similar to how big the water balloon is, the larger it is the more water it can store. The size of the capacitor, generally, will increase with a higher farads or a higher voltage rating.

Joules

Joules is a measure of the amount of energy stored in the capacitor. This is not used in most things, but is included for reference. 1J = 1W for 1 second. So if the capacitor stored 1J then it could supply 1V at 1A for one second before running out of power. To calculate joules you use the formula J=V^2*F*0.5, where J=joules, V=voltage, and F=farads. I almost never use that formula, instead I use J=V^2*µF*0.5*10^-6, with this you can use µF instead of farads.

ESR

ESR is used to show how fast a capacitor can be charged or discharged. This is the largest difference between a battery and a capacitor. A capacitor can dump all of it’s power almost instantly while if you shorted a battery (don’t do it) it could take hours to completely discharge. That is because a capacitor uses an electrostatic field to store the energy, that can easy dump its energy. A battery, on the other hand, uses chemicals in an electrochemical reaction to produce electricity. The amount of power the battery can discharge is relatively small compared to the amount of power stored.

Types of Capacitors

There are many types of capacitors, I will cover the four main types here. This includes ceramic, electrolyte, tantalum, and super capacitors. Each have the strengths and weaknesses that I will cover.

Ceramic Capacitors

Ceramic capacitors are the most common capacitors. They are also the cheapest and generally the smallest. They are not polarized, which means that it does not matter which way you connect them. They have a low ESR, but relatively low farads. They are commonly used for noise reduction.

Electrolyte Capacitors

Another very common capacitor, the electrolyte capacitor. These capacitors are usually larger then their ceramic counterparts, they have a higher ESR so they can not be charged/discharged as fast, and generally have a lower voltage rating. So why would anyone want them? They are fairly cheap for starters, but their main selling point is that they have a high farad rating. These capacitors are polarized and must be charged a specific way. Look at the picture below, see the silver stripe? That is used to show which pin is connected to ground. Also notice how one pin is longer then the other? The longer one is the + pin while the shorter one connects to – or ground.

Tantalum Capacitors

Tantalum capacitors look almost identical to ceramic capacitors. They are high performance capacitors. Usually they don’t have as high of farad rating as electrolyte capacitors, but they have a very low ESR. They can be charged/discharged extremely fast, because of this they are commonly used in switching regulators. This high performance comes at a price, they are usually much more expensive than ceramic capacitors, around 4-5x more. Tantalum capacitors are polarized and the + side is usually marked by a little + next to the pin.

Super Capacitors

Super capacitors are the bridge between capacitors and batteries. They have extremely high farad ratings up to a few 1000F! That is F not µF! However they have a very low voltage rating, around 2.1V. They also have a high ESR, much higher than electrolyte capacitors. They look identical to electrolyte capacitors, except they are generally bigger. They are polarized and they are marked with a stripe like the electrolyte capacitors.

Ohm

What is an ohm? Just like voltage or amperage, ohm is a unit. Ohm is used to measure how much a resistor resists the flow of electricity. The higher the rating the more it resists. Just like the hose, the more bends, or the tighter the bend, the more it resists the water. In this tutorial I use a LED as an example for the resistor. Exactly what an LED is will be covered in a later tutorial, for now all you need to know it that it is a type of light bulb. They are found in all sorts of electronics. They are commonly used to show that something is on, and are normally green or red.

Ohm’s Law

You may have heard about this before in school, the famous equation V=IR. This is very important when working with resistors. Using this formula you can find out how much current (amperage) will flow though a resistor at a set voltage. For this you want to use a variation of the formula (solve for I, I stands for current) I=V/R.

So why would I ever need this? Here is a very common example, you have a nice LED (Light Emitting Diode) and you want to use 5V to power it. If you decided to connect 5V directly to the LED then your LED might last for a second or two, it would then turn a black color and stop working, they also smell horrible, of course I have never done this .

So how can you stop this? Well the title of this tutorial gives it away, a resistor! The average LED takes around 35mA of current and a red LED has a forward voltage of around 1.7V, the voltage it takes to make it light up. That means that it uses 1.7V*0.035A=~0.06W. Now we need to know how many amps we need at 5V to equal 0.06W. First we divide 0.06W by 5V = ~0.012A. Well what this means is that if we can power the LED with 5V and 12mA then it won’t burn out. To limit the amount of current down to 12mA we need a resistor, but how many ohms? We use another variation of Ohm’s Law R=V/I, R=5V/0.012A. We need a resistor with the value of around 417ohms for this LED.

Now I commonly use 220ohm resistors with LED and most can take it. I have yet to burn one out with a 220ohm resistor at 5V. Just to be sure lets find out how much current will flow though a 220ohm resistor at 5V. In this example we know R and V so we solve for I, I=5V/220ohm. Approximately 23mA, but wait that is not through the resistor. When something (the LED) uses more power than provided (providing 23mA when 35mA are needed) the voltage will drop and the current will increase. That is why we need to calculate the wattage, W=VI. 5V*0.023A=0.115W, now how much current will flow if the voltage is 1.7V? W/V=I 0.115W/1.7V=~0.07A or 70mA.

I know what you are thinking, “OK, do you really do all this for a LED?” honestly, no, but that is because 220ohms is usually safe, but for things like high power LED or LED in series/parallel, I do.

Voltage Divider

Another fantastic use of resistors. A voltage divider does just that, it divides voltage. A common voltage divider looks like this.

The output is equal to Vo=V*[R2/(R1+R2)]. If R1=R2 and VDD=5V then:

5*[x/(x+x)]

5*[x/2x]

5*1/2

Vo=2.5V

The voltage divider is useful for reading a voltage with a microcontroller that is over the maximum voltage it can read. I have used a voltage divider to read 0-400V with a microcontroller running at 5V (meaning it can’t read anything over 5V with out damage).

The problem with voltage dividers is if you draw any current from the output then the voltage will drop. If you are using a microcontroller to read the voltage then the amount of current it draws from it is so little that the drop is not noticeable. The higher value you use for the resistors the more it is effected by current draw. For example if you used the ratio described above a 1ohm to 1ohm divider would be a lot less effected by current draw then a 1M ohm to 1M ohm (1M ohm = 1,000,000ohms). However the voltage divider draws power and that is calculated with Ohm’s Law, I=V/(R1+R2). So using 1ohm for R1 and R2 with VDD=5V you would draw 2.5A! However with 1M ohm for each you would draw only 0.0000025A! For most cases I use 10K ohm to 100K ohm for a nice balance.

What’s the value?

Resistors are measured in ohms as you probably figured out by now, but how do we know how many ohms the resistor is? As you can see in the picture below resistors have colored bands on them. Those colors tell you what the value of the resistor is and the tolerance. Here is close up of a 220ohm resistor.

Each color represents a number.

The first two bands are the 1st and 2nd digits. In this case the two red bands on the left. So that makes red red or 22. The next band is the multiplier. You add that many 0s to the end of your original number. On this one it is brown, 1. That means our resistor is 220ohm. If it were a black stripe it would be 22ohm or if it were another red strip it would be 2200ohm or 2.2K ohm.

Wait! What is that other band for? This band tells you the tolerance. Gold is +-5%, silver is +-10%, and if it is missing it is +-20%. In our case it is gold so the value of the resistor is 220ohm+-5% or 209-231ohm.

Voltage

Voltage is the measure of electrical potential between two points. Well, what does that mean?!? Voltage is the driving force that makes the electrons move through a wire. If electricity was water then voltage would be pressure. The more pressure, the more force it can move though something with.

The circuits in this tutorial require 5V to operate. That means that if you gave them a lower voltage the circuit may not operate correctly, the electrons would not be able to flow though the intended path. On the other hand if you power the circuit with too much voltage the electrons will force there where through places they should not. This is when things get toasted. You will learn from experience, as I have many times, that 5V component + 9V = bad. Remember to never power you circuits with anything above the rated voltage.

Amperage

Amperage is the measure of how many electrons are flowing past one point. Amperage is also called current or amps for short. One amp equals one coulomb of electrons per second. That equates to roughly 6,241,507,648,655,549,400 electrons per second! So if electricity was water then amperage would be the current.

We will be dealing with a small amount of current. We will be mostly using milliamp, mA. One mA is equal to 1/1000 of an amp. A LED takes only around 35mA. You can not power your circuits with too many amps. The circuit, as long as it is powered with the correct voltage, will only take what it needs. However if you do not power it will enough amps then you have problems. Remember if you have a power source that says “12V 800mA” then you can use up to 800mA. You do not need to use that much.

Wattage

Wattage is the unit used to measure power. To calculate the number of watts used you use, watts = votls * amps. That means that if your circuit is powered by one volt and draws one amp then it is said to consume one watt of power. However if you circuit is powered with 5V but draws 200mA then it also consumes 1 watt. There are methods for converting the voltage/current ratio. You can increase voltage and lose current, or increase current and lose voltage.

Now you should at least have some sort of idea of what electricity is. Be patient it will take some time to get it all. I believe the best way to learn this stuff is to use it! Just dive right in, get your hands dirty. You will learn much quicker then just reading a lot of pages that mean nothing. Now you should go back to the tutorials page and start learning about the various components you will have at your disposal.