1-Day Project: Build Your Own Arduino Uno for $5

good morning all now here I have three arduino uno x' 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 gonna 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 gonna 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 who knows the genuine thing couple of clones and my homemade one cheerio

Channel: Julian Ilett

Views: 1,541,471

Keywords: USB serial, CH340, Quartz Crystal, capacitor, resistor, LED, ATmega328P

Id: sNIMCdVOHOM

Length: 14min 22sec (862 seconds)

Published: Sun Dec 14 2014

Reddit Comments

[u/Proto_G]

I did that on one of my pcb business cards.

[u/[deleted]]

How does he initially flash the chip so that it has the Arduino boot loader to do serial programming?

[u/TheSpeedy]

If you want to build a slightly more robust one you can pick up Make's Mintduino kit. It's a pretty fun little kit, though I think scratch building your arduino is more of a novelty than a practical replacement for buying a clone or original uno.

[u/Pynath]

Could someone explain to me why there needs to be capacitors on the oscillator pins?

Also, exactly how do the capacitor shorten the length of the pulse from the DTR on the USB-to-serial adapter?

[u/invenio78]

Ah,.. you know that you can buy Uno's for under $3 a piece (with free shipping) from aliexpress, right?

[u/llburg]

Yeah, it's a valuable project, but you can buy and ship a Chinese one for less.