This is the genuine article. You look on the back. You have all the markings that indicate that this is a genuine Arduino made in Italy, open source, electronics, prototyping platform. This is an dunno revision 3, but the other two are clones. Now this one looks very similar as the full size, USB type B connector and a dual inline chip, but this was about 5 pounds and this one was not much more than 3 pounds. So how much is a genuine Arduino Uno if I want to buy one today, so here we are on the map. Lynn website? Yes, I searched for you know, and here we have an you know: revision3 main board and it’s 24 pounds 99. So this genuine Arduino Uno is 25 quid now I don’t regret buying this, of course, because buying the genuine article supports the project and Arduino. If they sell enough, products will continue to thrive but there’s a huge temptation to buy clone Arduinos at 5 pounds or even a little bit above 3 pounds that’s hard to see how we could beat the 3 pound price tag on this Arduino Uno. But I wondered if I could do it by building my own Arduino Uno on breadboard now, in order for this to work I’m going to have to cheat I’m going to have to leave off everything that isn’t absolutely essential from an you know like this. When I make my breadboard version and I’m also going to have to cheat by using some pre made assemblies so, for example, the usb to serial I’m going to have to cheat by using a premade ch3 40 adapter – and I must admit I do have my doubts As to whether even the massively cut down Arduino Uno, the I’m gon na build with the essential components and the usb to serial adapter will come in under the price of this three pounds Arduino.
So this is more going to be an example of let’s see what makes up an Arduino, then actually let’s see if we can make a cheap Arduino. So where do we start well, we need the chip, of course. Now this is an atmel 80 mega 328p PU and I bought one that’s pre programmed with the arduino uno bootloader, and that does save a lot of time and hassle. So I bought this it’s. The 80 mega 328p PU microcontroller with arduino uno bootloader, and this was 1.00 97 and it came from alice. 1. 1. Oh. 1983. Now I also bought some bread boards I’m cheating again, because I bought five four dollars 86, also from Alice. So I pushed the chip into the breadboard now. The next thing we need is a crystal and the Arduinos use a 16 megahertz crystal so here’s. The 16 megahertz crystal let’s see where that came from well, once again, of course that came from Alice I cheated again. I bought 10 of them, but it was only 0.99. So now, where do we connect the crystal well? For that we need to look at the pin assignments for the 80 mega 328p, so this page is pretty essential for this project, it’s on the Arduino website and it’s the 80 mega 1, 6, 8 3 to 8 Arduino pin. Mapping and here are all the pin assignments and how they relate to the arduino z’ analog, pins and digital pins.
Now, if we zoom in here, we can see that on pins 9 and 10 we connect the crystal and also on pin 8 we’ve got ground. So there’s, the crystal on pins, 9 and 10, and there isn’t pin 8 being right next door and being ground is useful it’s because we now need to fit in these to load. Capacitors 20 Pico farad’s each and they can go between the crystal pins and ground. So this worked, one of the capacitors goes from the left hand crystal pin to ground, and the other capacitor goes from the right hand crystal pin to ground now. Another component we’re going to need is an LED, and this will go on the Arduinos d13 output so that we can run a blink program. Flash the LED on and off and that way we’ll know that the Arduino is working. So let’s have a look at where this connects: okay, so here’s digital pin, D, 13 it’s on chip pin 19 and ground is only three pins away on in 22, that’s very handy. So this is a 28 pin chip. That means that this corner pin is 14, 15, 16, 17, 18, 19. So my resistor side that’s the sort of positive side that goes to 19 20 21 22 ground is on pin 22, so the LED fits in there pretty nicely now believe it or not. That’S pretty much it there isn’t much more required other than this capacitor and our USB to serial converter I’m, going to turn this board around, because the wiring happens to work a bit better.
This way around and I’m going to put the USB to serial converter in this second breadboard and now I need some wires to start hooking up the converter to the chip. So here are a bunch of little connecting wires with pins. On the end. Now, amazingly, there are no black ones in this short length, so I’m going to have to use. I think white foreground, but I’ll try and make all the other colors relevant to the signals. So let’s have another look at the pin mapping now to connect to the USB to serial converter, which is going to provide our power we’re going to need. Vcc on7 ground is on eight but it’s, also on 22, that might be more convenient and then we’re going to need RX and TX well they’re on pins two and three and reset, which is on pin 1. So VCC is pin 7 on the chip, which is there and on the converter, it’s. The third pin in so that goes there like that now ground is where I connected my LED to here so that’s, my ground I’m using white and ground is the first pin on the USB to serial converter. Now the remaining pins on the chip, our pins, one reset to which is our X and 3, which is TX, and they go across on these orange, yellow and green wires to TX and rx. On the USB to serial converter. And this pin here the green wire, which is on pin 1 on the chip, goes to DTR, but not directly to DTR.
We have to connect it through the remaining capacitor, which is this one up here: 100 nanofarads, so there’s, the 100 nano farad capacitor that comes from DTR on the USB to serial converter and into reset on the chip. Now this is to shorten the pulse because DTR data terminal ready, isn’t the required short pulse length. So this capacitor acts as a differentiator shortens the pulse and that resets the Arduino to ensure that it’s synchronizes with us sending sketches through this converter and that’s. Actually it that is our minimalist Arduino Uno you’ve got the led so that we can see the blink program working. So all I need to do now is connect a USB cable, and this is just an extender cable into my PC and fire up the IDE. So I’m, just going to plug that cable into my PC see what happens well. Red lights come on on the converter. We did get a brief flash on the LED that’s on the chip, but nothing or is happening so let’s run up the software and open up the blink program, so here’s the arduino ide, the integrated development environment and what i’m going to do now is from file Examples when you’ve got two basics and if i can get to it blink and that simply switches the LED on and off for one. Second, at a time now, under tools board, i need to select arduino uno and under serial port, whatever the serial port number is of my USB to serial converter, its comm five on this one and now from file, i need to do an upload, let’s watch, the Compiling progress and then we’ll watch the actual uploading.
There goes uploading i’ll, do it again with the camera on the actual unit, so let’s look at the USB to serial converter. While i hit upload it’s compiling at the moment, that’s uploading, the blue light comes on and we have our one second on one second off flashing red LED now, not convinced, okay. Well then, let’s put in the signature double flash, so we have a short today high shot today low short today, high long delay low. That should give us a double blink and here’s the result on the breadboard. A double blinking LED so still not convinced that this is a genuine homemade, arduino uno. Well, let’s do something a bit more complicated let’s attach an I squared C OLED and load in some software to do some graphical on screen examples. Now, for I squared C, we need four pins VCC ground and these two up here on pins 28 and 27, which are SCL and SDA. So this should be quite easy, VCC and ground. We already know because they’re, the red and the white wires going to the chip and then SCL and SDA with these two pins here on the top corner of the chip 28 and 27 let’s hook it up. So here it is now the colors aren’t very logical. I just used whatever I happen to have in terms of wires, but essentially we’ve got VCC. I sorry ground up here, VCC over the other side, and then s o’clock, I think, was on pin 28 SDA was on pin 27, so that’s all hooked up now.
What we need to do is bring in a suitable sketch now I’m quite liking. At the moment. The graphics library u8g for OLED, so let’s go to examples down to the UHG Lib and in here there’s one graphics test, so let’s open that up now you need to make one change to this. So in this file there are a whole load of comments, or at least these specifications all commented out. You have to uncomment the one that relates to your device. So we need an SSD 1306, because that’s what’s in the OLED we don’t want software or hardware spi. We actually want this one, I squared C, so I need to take the comments out on that line. So that’s done now I’m, just gon na hit upload. Now, if somebody’s in these examples take a very long time to compile so let’s, let it compile and then wait for the upload right. That is now uploading. Cuz there’s, a blue light on the USB to serial converter, but we don’t have anything. Something must be wrong. Well, some reason I needed to press reset on the USB to serial converter, but that’s now working we’re, getting a graphics display of graphical elements, lines and triangles on the OLED. So there it is there’s a working homemade, Arduino Uno, it’s, very cut down, we’ve, not bothered with anything that’s, not essential to the operation of this thing, but we know it works. It blinks the LED – and it also runs much more complex software, as proved by the fact that we’re driving this OLED, but is this cheaper than this? This is the clone Arduino Uno.
I think it was four dollars 98. Now, if we add up the parts of this breadboard about a dollar, the chip was 2.00, the crystal and the capacitors and the LED probably about a dollar for that lot and another dollar for the USB to serial converter. Now, if you want to include wires we’re, getting very close to the five dollar cost of this, maybe you could argue that we could build this for about four dollars, but it’s not so much a price issue as an issue of understanding how these things work anyway. I’M pleased I’ve now got four Arduino.
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Originally posted 2016-07-31 02:47:24.