19. Project Development

This page will showcase the process and development stages towards my final project.

Project planning

Schedule

System Integration

You can visit my system integration page to get an overview of the processes i am going to follow.

Spiral 1

To make the master module and one node module and make them communicate.

Mockup Stages

PCB Production.

I started the electronics production of the project with the node module.

ATTINY 1614
9 x Mx switches
9 x Diode
9 x Diode
Neopixel pads
2x03 Vertical Pinheader

I had some doubts regarding the placement of the neopixel pads as they had to be wrapped around the pcb and the solder part sould sit perfectly on the pads.Since the the pcb iam making is quite large , i did not want to waste an entire copperplate incase something goes wrong. So i thought of making a mockup of the PCB on cardboard see if everythng aligns well

I kept the pixels in place and found some misalignments.Thet were later corrected in the kicad editor.

pcb for the connectors

I milled out the PCB and moved on to the pick and place machine to place the parts.

CAD Model

I took some time to properly design the housing and how the elctronics would be positioned within the case.

Making Pogo connectors.

I had to think of ways to make the pogo connectors as they are quite expensive and to buy as many as i required may not be feasible within the scope of this project. I referred to some videos to make the connectors and went through some design iterations . I made a few mock pieces to test if it would work properly.

Mockup 1

The first idea was to make a PCB tht would have pin header connection from the top of the keypad PCB , on which the Pogo connectors mounted on another smaller PCB will be attached perpendicular it.

First to test the concept i tried making a small scale mockup to check the attachments. Two PCBs were made with just the pads for the connections and the slot for attaching them.

There were some issues faced while milling the PCB due to its small size and since the PCB is double sided. When the PCB had to be flipped for tracing and cutting the other side , it would fly off because it wouldn't stick properly. I spent some time trying to make the cut ,so i thought of other ways the PCB could be produced efficiently. My instructor suggested to use the milling machine to just cut the PCB and then take it to xtool to engrave it. To keep the PCB in place a cardboard jig had to be made. Even this method did not seem as effective as it looked on paper. The fit was was checked for the two PCBs and some adjustments had to be made

Also while making the CAD model for the module , it was noted that the size required for the PCB would be quite large for a double sided PCB (our lab has a limitation on the size for double sided pcbs). So we went back to the board to test another method.

Mockup 2

This was initially the plan we were supposed to go ahead with ,but after some thinking and updations we made a few alterations to it.

Basically the idea is to make the small PCBs to attach the pogo pins and the take connections from this PCB to the PCB with the connection from the keypad PCB via wires. Tecnically its the same concept as before but we can make the central PCB smaller and save space.

While making the CAD model i realised a housing had to be given for the pogo pins. The CAD model has to be altered to make space for the housing too.So that was also done parallel to this process.

For this mockup I just had to make the small PCBs and make sure it fits with it mock 3d prints made. I had made a careless mistake on the 3d model where the housing had to sit, even though I made it correctly on CAD i exported the wrong version.

After reprinting the case the PCB with housing was tested and it was fitting perfectly.