18. SYSTEM INTEGRATION - fixed. To be marked¶

This weeks task was to document my system ingtegration. This is essentially, how everything is connected together.

My parts¶

My project is made up of two major component sets of components:
The maze panels (walls and flooring) and connector pieces.
The microcontroller board, rechargable battery, and ultrosonic sensor.
The design files and completed maze panels are documented on my final page in Maze wall and base pieces. This also documents how they all fit together.
My electronic components are the same as I used for my input devices week.
However they needed a housing to be complete and to be able to mount them onto the maze

I needed a housing for my electronics that:
Would still allow it to be accessable and removable for easier reprogramming or changing out the sensor if a different type was to be used instead.
Let the housing be easily mountable and removed from the maze wall.
Had a mechanism for mounting the ultrasonic sensor in the chosen “maze exit” where it could identify when the robot exitted the maze.
Allowed the OLED screen to be visible.
Allowed the onboard button to be pressed.
Could hold a battery and have it be wired to the board.
Could allow a UPDI or FTDI cable to be connected to the board even while mounted.

I want my housing to be open.
I decided that my housing will be 3D printed from PLA.
I decided to use an 18650 battery as my power source. Because:
They provide 3.7 volts which can power my ATtiny boards (needs 1.8V to 5V) and HC-SR04 ultrasonice sensor (needs 3.0 - 5.0V).
They are rechargable so more environmentally friendly than disposable batteries.
They are an appropriate size and weight for a project my size.
They are used in allot of devices (like larger battery packs, poweful flashlights, and vape pens), so they are reasily available.
I decided to mount my box horizontally, so that the screen is more easily readable when the maze is on the floor.
I decided to make a holder for the battery attached to the main housing.
The ultrasonic sensor mount would clip to a side wall and hold the sensor so that it points at a 90 degree angle.

I Really want my housing to be open, so that users and spectators can see all the components and board inside:
This whole project is to support kids and teens in doing robotics.
This gives us a great oportunity to get them exited about electronics and circuit design as well and teach them that it’s not that intimidating and it’s something that they can do themselves.
It also gives us a great opportunity to show off what we made and to talk about all the components and how they work. And that can hopefully end up inspiring allot of future engineers, designers and programmers when they are at the perfect age to be encouraged.
Hiding away most of the electronics means that everyone will only see a plastic box with a screen and a few wires sticking out. This means we would lose allot of the awe factor and the impact would be less.

The main body of the housing is an open top box with ports on the side positioned in line with the circuit board’s connector pins.
The port on the left side can accomodate the FTDI cable or wires leading to the battery pack.
The port on the right could accomodate the UPDI connector or the ultrasonic sensor’s wires.
The circuit board would be mounted onto the housing’s “floor” using snap-in clips designed into the housings body.
I decided to make my board housing with my components on one side and the battery holder on the other, with a channel between them that will allow it to snuggly fit ontop of the maze walls. This was to help with weight balance and to put less strain on the housing.
The different colours are just for easier identification of parts.
Horizontal view so that you can see the channel.
main housing design TinkCAD link
main housing download (STL file)

The ultasonic sensor holder will also have snap-in clips built in to hold the sensor in place.
The sensor holder also has a clip to clamp on to the side walls of the maze.
The sensor holder positions the sensor at 90 degtrees so it is pointing away from the top of the clip.
I also designed a second holder that just protects and holds the sensor but doesn’t have a clip mechanism for the wall. This was as a backup in case a user wanted to mount the sensor on something other than the walls.
The different colours are just for easier identification of parts.
Horizontal view so that you can see the channel.
sensor holders TinkCAD link
sensor holders download (STL file)

Here’s what everything looks like together
use the previous models for actually 3d printing the housing. These are useful mainly to see how all the components are combined.

I should have designed the end caps of the battery holder with an inward slant so that they could hold the battery more firmly.
I would put groves and channels for better wire management.
I would make a removable lid and place clasps to attach it, so that the circuit board could be protected when not in use.
I deigned the snap in clips a little too tall to get a snug grip. I would fix this.
If I was to redo my project I would have a different board design that would be more adaptable to different uses. That would necessitate a redesign of the housing as well.

Last update: May 31, 2025