System Integration

• System integration and packaging.
• Where possible, you should make rather than buy the parts of your project.

Planning

I have a rough idea how I wanted my design to look like based on the initial prototype look.

As I was experimenting around with two boards communication protocol between my input and output device, I realised that there were too many wirings. Rico dubs this “Spagetthi Electronica”

The next step was to lay out the components that I bought and measure their length. I quickly rapid prototyped the enclosure to have rough idea how I wanted the different components to attach on the enclosure and the ideal size

Objectives to look out for

• Minimal Wiring - shield mechanism with female pin headers
• Compact Design that could fit all electronics within and surviv real-world use.

Electronics Design and Production

I started with this aspect first because for system integration I want to minimise as much wiring as possible. This will also affect how the enclosure would look like and since I want to make a compact handheld device - it is important that we start from what’s within.

As I was testing out my input and output devices during those weeks, I realised that there were too many wiring, and system integration wise this was just not it.

Knowing that the TFT ILI9341 Display is designed to be used as a shield for the Arduino UNO microcontrollers, I decided to design my board with that feature in mind. I decided to mainly have female headers on my board and that the components would sit in place directly on to the headers.

This was my initial sketch for the electronic design.

Once i have laid out the components and the wiring - I made the schematic, designed the sketch in Kicad and produced it.

For my pcb production, I was using the same settings as my electronic production week - Rico and Henk suggested that I used 4 offset instead of 2 for this board. I made a mistake with the screw hole...... if you want to use a M3 screw… make sure that your screw diameter is at least 3.2mm and also I just happened to forget offseting the board when I had to drill the holes

I got to stuffing and my board worked!

However there was a problem.... Initially I wanted to use a wire to in between the rotary encoder and the female header input, but Rico told me that it wouldn’t be ideal. I had to frankenstein my board in order to make sure I can get the rotary encoder to be plugged.

The rotary encoder also had to be modified. It will be impossible for me to have original orientation plugged in with the default header that it comes with. So I desoldered the header pin and customised the rotary encoder to plug directly onto the board.

Enclosure Design

Once that my PCB Board has been finalised - it was time for me to adjust the enclosure to cater to the changes of the component position within. Because I am using minimal to no wiring..... I had to make sure that my CAD modelling were accurate to the position on the headers and components inside the PCB. I downloaded the 3D Model of the components from Grabcad. Here is how my entire system integration was meant looked like digitally - I made it as close to the measurements of the real thing.

These are some of my print-outs, testing out the sizes and the nesting of the components onto the enclosure. Had alot of print outs trying to accurately make the USB-C hole and the right offset so that the screwholes don’t snap (minimum 2mm offset is key!)

To satisfy the subtractive manufacturing requirement - I laser cut the lid. Initially I wanted to make a snap fit mechanism but I was running out of time. That also meant that I had to readjust the enclosure size to accomodate the lid.

Pre-assembling the parts. In the end I decided to forgo the LiPo battery. I will save it for next iteration. So for now the main power connection is from the USB-C connection

All set