19 - project development

final project development

The work done so far

This is the week I started to make everything for my final project, however, I did already do a lot of research during the weekly assignments. This is where I stood during the week of project development:
I have tried to use most of the weekly assignments for my final project, and have already built quite a few prototypes and early versions. Below are some pictures of experiments made during the weekly assignments.

These were the first laser cut bricks I made, that didn't hold any electronics, but were just there to prove you could make LEGO compatible bricks in the Fab Lab.


The first PCB integrated in a LEGO compatible case

This brick has LEDs inside which I made during the output devices week.



These were the first real prototypes of the prototype which hold a WiFi chip and the blue brick holds a temperature sensor

In week 17 I managed to make the WiFi brick(orange) considerably smaller compared to the clear one I made earlier, even though it holds the same components!

In order to make the bricks connect to each other when you stack them, the new PCBs have rivets on the bottom which will touch on pogo pins from the top of the connecting brick

I'm reviewing various sizes and types of pogo pins.


The new PCBs look something like this, the black wires connect from the PCB to the pogo pins that will be in the top layer.



In order to plan my final project, I need to take the following into account:

deadline
My presentation is exactly one week after this week's lecture, I want everything to be done AT LEAST on Sunday the 11th of June, as my presentation is on Wednesday the 14th. So my personal deadline is the 11th. This leaves me less then a week, which at this point doesn't worry me as I don't expect any major setbacks.
To make this I already did a lot of work, which you can see above.

tasks completed and remaining
At this point, I already have the PCBs, I tried the casings, those fit, although I do need to laser cut a few more. And all the code works right now.
The only thing that I still have to do is a final assembly of three bricks and test if the stacking works well enough. My goal is to have two sets of bricks ready, but I'm still waiting for an extra WeMos board, so I will probably have one fully working set, two extra sensor and LED bricks and prepare everything for the second WiFi brick.
I might also make an extra button brick which I'm not sure I will be able to write code for, but hopefully I can finish the hardware as an extra.


complete remaining tasks
I will assemble and glue the three bricks I have ready first, today or tomorrow. That way I will know if the system works or if it needs adjustments.
If this works, I will proceed with making the second set.
I have a week to assemble, test and adjust if neccesary which should be enought as I already checked all the electronics and code, at this point it's just a matter of the casings to see wether they fit or not, but as they are laser cut, adjustments are made quickly.

what has worked
So far I know the code works, and all the bricks communicate with each other over the audio cables via I2C. So I know all the electronics work and all the code works.
I have also assembled the casings without glue, and that also seems to fit.

what hasn't
I am at this point still unsure if the pogo pins will make a good enough connection when three bricks are stacked. I did perform some tests with the bricks unglued, but that obviously doesn't hold as the tolerances are quite tight and you pull them apart without glue.

questions to resolve
I am unsure how many bricks I can stack while keeping a clean digital connection, also I am unsure how resistant the 3D printed top is when connecting and disconnecting frequently.

what have I learned
So far I've learned that spiral development is the way to go, if I had made all the different bricks, and had never completed one at this point I might have been in big trouble.
Also I've learned to keep it simple, I know I want to make the extra button bricks, but each addition also comes with more trouble. So I know that the requirements for the final project are to make an input, output and a microcontroller board, so those are the first three bricks that I make, assemble, test and finish before anything else.
This spiral development method has been a great learning experience for me!