Electronics Desing
The assignment of this week was to design a board using any EDA software.
EDA software - KiCad
An EDA (Electronic Desinf Automation) software is a software focused on the design and production of electronics systems, going from integraded circuits to the development of printec circuit boards. To design my board, although I already have experience with Fusion 360, I used the software Kicad beacuse it was the one our instructors recommended and taught us.
Kicad is a free open-source EDA software that feautres schematic captura, integraded circuit simulation, printed circuit board (PCB) layout, 3D rendering, and plotting/data export to numerous formats. It also includes high-quality component library featuring thousands of symbols, footprints, and 3D models.
Libraries
To make the pcb design easier, our instructors gave us a library that just includes the components we have here, we jus needed to add this library on KiCad.
The first think you will see when KiCad opens is this, from this, follow the next steps to add the libraries.
Schematic
Now that I have the library with all the components I can use, it was time to create the schematic of my board. To open the schematic file go to the "File" and select "Projet". After that, you will end up with this on your screen.
To place things on the schematic we have to buttons, one to add the symbols and the other one to add the power symbols. Once you select it, you just have to search for the component you are looking for and place it.
Something I recommend is to pay attention of the components you are using, there a lot of them and it can be easy to confuse them. For example, I used the wrong attiny 45 and it gave me a lot of problems while soldering.
The components in general that I am going to use are the following.
1.- Attiny45: The microcontroller.
2.- Voltaje regulator: In case I use a battery.
3.- LEDs
4.- Buttons
5.- Resistors
6.- Capacitors
7.- Pinheaders
Once you had all the components it is time to connected, there a two tools for that, the ware to make short connections, and the label, it is the same as a connection but cleaner.
Here is the result of the schematic:
PCB Editor
Once I have all my compotents on my schematic it was time to create the PCB. First of all we have to open the PCB file. To do that just press the following button and it will open you this window.
We have the file but there are any component we have on the schematic, to add them go to preferences and click on "Update PCB from schematic" or just type F8.
We have to move the components on a convenient way and route them, but before that we have to change the clearance and width on the board setup, in my case was, clearance: 0.4mm and width: 0.5mm because is the width that I choose for the wire.
The reason I used this dimensions are because depending on the widhtness is the current that will flow on the track, a bigger the width more current will flow. The amount of power my PCB is going to use is that much ,thats why I´m using a 1mm track width.
An idea that came to my mind was to desing a little ruler on the PCB to measure little things and after spending a good amount of time I finally got it.
Once the design is ready we have to save them as SVG files, to do that go to Files 🡢 Import 🡢 SVG. Remember to set the Print Mode in "Black and white" and change the SVG page size in "Board area only".
Milling and soldering
Milling
A problem all of us was that the schedule to milling machine was full, and very tight between one use and other. So what a friend and I did was to share the same schedule and mill our pcbs at the same time.
To use the mill machine I followed the steps of the Week 4 assignment.
Soldering
First of all, I had to get the componnets that I am going to solder.
| Material | Quiantity |
|---|---|
| Attiny 45 | 1 |
| Push button | 2 |
| 2.2K Reistor | 2 |
| 1k Reisitor | 2 |
| LEDs SMD | 2 |
| Pin headers | 8 |
| Voltage regulator AMS1117-5.0 | 1 |
Although it was my second time soldering, I think I did it pretty good, expect for something...
I used the wrong footprint off the attiny 45, I had to bend the pins so they can fit, this making the solde harder. Because of this, I ended up breaking the Voltage pin, something I had to fix using a wire.
Aside from that, everything else was good.
Testing
Beacuse I had to fices the attiny pin, first I needed to test if every connection was fine, to do that I used the multimeter and used it the way we learned on our group assignment.
Fortunately, everything was in order. To test it I used and arduino uno as a ISP, our professor Huber gave us a step-by-step guide to change the Arduino into an ISP . To test the pcb I used a blink code, something simple.
void setup(){
pinMode(0, OUTPUT);
}
void loop(){
digitalWrite(0, HIGH);
delay(100);
digitalWrite(0, LOW);
delay(100);
}