Hi, this is Wayne again with a topic “Arduino Neural Network Robot Part 2: Soldering and Assembly”.
Hey everyone: my name is sean hodgins and welcome back to the multi-part series on building your own arduino-based neural network robot. So last week we explored early development stages, so we prototyped some components using an arduino. Some motors made sure everything worked, then wrote a program to make sure that everything worked together. We also created a schematic and a custom circuit board and sent that off to be made well they’re here now and we’ve got all the parts to assemble it.
So i’m going to go through the steps of putting the surface mount components on this, the through hole components, finally, putting a boot loader on it and putting some firmware on it and testing it out. So, let’s get to it. So i mentioned that. I already have the components for the board ordered you’re, more than likely going to order the components from digikey which will have everything that you need. So within keycad.
There are a number of uh exporters, custom ones that will extract the parts and put them into a csv file. If this is your first project, i suggest putting each part manually just from the bomb in digi-key so going through and searching for each part. So you search for the microcontroller the same d21. When you add the part to your cart – and you add you want to put in the customer reference, the name that you used on the circuit board.
So, in this case it’s u2 and it will say this in the keycad bomb and when this component arrives from digikey, it’s going to say u2 here so it’ll make everything a lot easier when you’re assembling the board. A lot of people forget to do this. The first time around, and it will cause a lot of headache. So the next thing that i like to do, as you saw me doing in the intro, is separate the components from the discrete components to the more complex, the ics, the microcontroller leds.
Anything in these silver anti-static bags – i will separate them out and then also the surface. Mount components will separate out because what you’re going to be doing is you’re going to be installing all the resistors and the capacitors first, all the surface mount ones. The second set of surface mount things will be the ics like the microcontroller and the motor driver, and then once you reflowed these, if you’re doing it in an oven afterwards, you can put all the through-hole components on, and this is just the way i do it. Uh – and it makes sense to have the capacitors on the board before just to eliminate any possible chances of esd, but it’s never personally happened to me.
I’Ve never fried an arduino with esd, so i’m not even sure it’s possible again. This is where you have a few options: the solder paste. So for most cases i like to order a stencil for the board, because they’re actually really cheap, there’s a lot of stencil services that you can get them done. But if i’m only doing a couple of boards in this case one or two, then i’m just gon na, do it by hand by using a very fine tip on the solder syringe.
What i’m going to do is on each pad. Where there’s a surface mount component. I’M going to apply a little bit of solder, and this is going to take a lot of trial and error you’re, going to end up putting too much solder. Almost all the time, especially when you have really small pins you’ll, find that less is often more but again trial and error and you’re going to see how to fix it afterwards, because you’re definitely going to have bridges no matter. What, if you don’t use a stencil, even when you use a stencil, you often have a couple so trial and error. Let’S get going so i’ve got all of the solder paste on the board now for the components that i’m going to be doing.
This will be a good example of when you have too much solder paste, especially notice on the microcontroller, so we’re gon na have to clean that up for sure um, after with the soldering iron but generally have to anyway. So that’s another technique. You’Re gon na have to learn and with the really small pads on the motor driver, i actually used a little piece of solid core wire and just took some solder paste on the tip of it and spread it out and you notice you don’t need to go On each individual pins you can go along them because when the solder paste heats up, it actually spreads out anyways it spreads out on its own, so you can go between them. As long as there’s solder paste touching the pin and the solder paste touching the pad. You should be good.
The next thing you’re really going to want to have is a really good pair of tweezers, though these will make your life so much better when dealing with really small, resistors and components because they’ll, let you grab onto them so much easier. Okay, we’ve got all the components on so we’re ready to reflow it. It’S really simple. Let’S just pick it up carefully kind of near the front, so this is honestly the cheapest toaster oven. I could find it was like 20.
You don’t need anything fancy, though it is nice to have one that has a fan in it. This one doesn’t anyways close it up. It’S set to as hot as it can go and we’ll just turn it on and watch it. So just wait for it to reflow, you visually watch it reflow, and then i like to leave it in there for like another five or ten seconds after everything is flowed.
Also, i like to have a little fan going for when i open it and also something that you can put the hot surface on. Normally i put it on like a heat sink or something and some needle nose pliers looks like everything is done and then once i’m sure everything is solid, pick it up and there it is. Some components have obviously shifted around because we’ve used too much solder paste, which is normally the case. It’S rare that you get a perfect board, though it does happen, so we’re gon na use the soldering iron to fix all these.
The idea here is you’re gon na take your flux and wherever you need to move a component you’re going to apply some flux to that solder pad. So if you’ve got a resistor, that’s slightly off and it’s only on one of the pads, you don’t need to fix the ones that are like crooked but they’re still connected. But if it’s only connected to one pad, then you’re going to apply the solder paste to the side that is connected and then you’ll heat that side, while grabbing onto whatever you’re moving this case a resistor and it’s going to come free and then you can move It over so that it’s touching both pads like so and now it’s only connected on the one side. You add a little bit more flux on the other side and just touch it like that and it’s connected so that one has moved and it’s fixed. Now, since we use a lot of solder paste on the board, there’s a lot of bridge pins on the microcontroller, the way to fix it is to take a dry soldering iron, which means there’s no solder on the end, apply a bit of flux to where the Bridges and then it will naturally wick the extra solder up and leave just two pins with a little bit of solder remaining, but now they’re separated it works really well, and it’s really simple once you understand that the soldering iron wants to wick the solder away from The pins so every time it gets too full you have to then clean it off again with the brass sponge, or else it won’t be able to pull any more solder away. So that’s the easiest way to get the pins from stop being bridged together.
Now that we’ve fixed all the surface mount component problems, we can move on and install all the through-hole components. So now that all the components are soldered on, i actually realized that the mounts that hold these are fuse holders, but they weren’t ordered for some reason. So that happens. So i’m going to make some ones that you can 3d print and those files will be available in the github as well. So i’m going to 3d print the motor mounts we’ll get those mounted on we’ll get the boot loader put on and we’re rocking. Oh okay.
We just have one last step to do before we can load some firmware on it and that’s to load a bootloader on the chip. So what the bootloader allows you to do is program it using the arduino ide. It enables the usb so that you can plug it into your computer and use the samd driver to be detected as a com port. So, since we use the sparkfun samd board to test it, we might as well use that bootloader to put it on.
So what i’m using to program it? The first time is called an atmel ice, but you can also use an arduino itself to do it so just plug this into usb, and then we connect this cable and also the device does not power the chip itself. You have to give it a power supply, so we’ll attach the battery green light means we’re good. So now we’re going to open up atmel studio, i’m using ammo studio, seven, it’s free to download, of course, and we’re gon na go tools, device programming and see we’re using the admiral ice. So you hit apply which enables that programmer then read to make sure you can see.
Now you don’t really know this is okay, but if anything shows up it’s probably fine. Next, you go to memories. We have to locate the sparkfun bootloader. So what you’re going to do is present at data which brings you here, but you actually want to go one back and go to local arduino and packages.
Sparkfun hardware samd: whatever version is there bootloaders zero? And here it is sparkphonesamd.dev, not hex, so that is our bootloader and you find that simple as hitting program and if everything works you get that, and that is it it’s now programmed so we’re going to connect it to usb we’re going to write some firmware. We’Re going to test out the robot okay, so everything assembled. We got the battery hooked up with the oled screen on there got it connected and we’re going to run a test program that we made originally.
So all we have to do is hit upload on this. Hopefully the motors do something and then we’re good programming, all right. That’S what it’s supposed to do so programs, that’s all we need, and that is it for this segment, which is assembling the neural network robot, so stay tuned for part.
Three. Where we’ll be discussing neural networks, we’ll be talking about running neural networks on arduinos, it’s totally possible. I’Ve done it before we’ll be installing a neural network on this robot. So we can navigate using one and the whole project will be open source, so anyone can download it and make their own circuit board and do the whole thing and assemble it.
That is the whole point, so be sure to subscribe. Hit that like button and also check out my channel where i do a whole bunch of projects that are like this as well anyways everyone, you know the deal, be good and have a good night. You .