As we learn more about programming the Arduino, we become more and more excited about connecting and controlling simple circuits. In order to do this, we need to begin to understand how to design and analyze the circuits we are building. In this lesson we introduce you to Ohm’s Law and some techniques that will allow you to design and analyze simple series circuits. If you want to follow along at home, you can order the Arduino Kit we are using HERE. The nice digital voltmeter used in the lesson is available HERE.
In Lesson 7, we learned how we can get in-between voltages from the Arduino pins using the analogWrite command. Actually, this command only approximates analog voltages, and does not produce actual analog signals. It works by quickly turning the voltage to the pin on and off. For example, if you ask for 2.5 volts, it will quickly switch the pin on, with it on 50% of the time and off 50% of the time. Similarly, if you asked for 1 volt, it is really switching 5 volts on and off quickly. For this case, it would be on 20% of the time and off 80% of the time. This technique is called Pulse Width Modulation. In this video we show you the actual waveforms coming from the analogWrite command on an oscilloscope. If you want to follow this lesson at home, you can get the Arduino kit we are using HERE.
In earlier lessons we learned how to turn pins on and off with the Arduino digitalWrite command. This is great if you only want 0 or 5 volts. In this lesson we show how you can get the in between values by using the analogWrite command. In later lessons we will show more specifically how analogWrite works, but this present lesson gets you started, and shows you how to control brightness of an LED. In all these lessons we are using the Arduino Super Starter Kit, which you can pick up HERE.
In this series of Tutorials, I really want you to understand the magic that is happening under the hood of your digital devices. Whether you are talking about in Iphone, a laptop or a digital camera, they all work on the same, very simple principle. That principle is as follows. Any thing around you in the physical world can be represented as a number. You can create a different number for each letter, so letters can be represented by numbers. By stringing those numbers together we can create words, paragraphs and even entire books. Similarly, music and colors can be represented by numbers. At their core, digital devices only understand numbers, so everything around you must be converted to a number for the computer to understand it. The thing is, though, that computers only understand special numbers, known as binary numbers. Binary numbers contain only two characters . . . “0” and “1”. Hence all numbers must be converted to sequences of zeros and ones strung together. With this, any number you can come up with can be represented equally well by a long sequence of zeros and ones. This video shows how Binary numbers work.
Digital devices are simply made up of very large numbers of tiny switches. A modern digital computer might have over 10 billion switches cleverly connected together. Each switch can be thought of as a zero or a one. Hence, even though a switch is a very simple device, when you have lots of them, very complicated things can be done.
In our earlier lessons we would program using “constants” when we needed numbers. For example, if we wanted to set pin 13 to an output, we would use the command:
The problem with using constants like the number 13, if you decided later to use pin 8 instead, you would have to edit every line of code that used that number. It is much better practice to use variables when coding. In this video we show you have to program using variables. We start by doing things the wrong way, using constants, then show you the advantages of using variables.
Hopefully you can see from this video how much better it is, and more efficient to use variables instead of constants. In all the future lessons, we expect you to use variables.
Making The World a Better Place One High Tech Project at a Time. Enjoy!