July 16-18 - I had to replace the one thing that my design truly relies on :(((( (the IMU for the actual posture tracking part of my posture tracking device)

What Went Wrong

After finishing the pcb and schematic I wanted to put it in to jlcpb to get a quote, and it came out to almost one hundred dollars (see the image below)

that was actualy crazy to me and so I did some investigating and it was because I chose to use a LSM6DSV16X IMU, which made my pcb switch from economic to standard, wildly inflating prices.

A little background on why I chose the LSM6DSV16X: it had smart power features to make the device last a long time, and a machine learning core for more advanced tracking making it a perfect fit.

My solution

I could either suck it up and go forward with a 100+ device, or fix it which would require to restructure everything. Fix it i did.
I wanted to find a comprable IMU that was supported in the economic manufacturing, similar footprint to the LSM6DSV16X, and had power regulating features that would not degrade my original plan.

I originaly looked into other candidates like the MPU-6500(which a website I looked at for footprints literaly told me was too old to use). I also looked at the ICM-45686, ICM-42670-P, and LSM6DSOX, which where all standard-only.

I then came across the LSM6DSVQTR, one of the only IMUs comprable to the LSM6DSV16X, on the economic tier. It retained the Machine learning core, low power mode, and had an almost identical footrpint to the original.

So, with that change, and a few components that where replaced with a basic instead of extended variant, I had to rebuild the schematic. That was not as bad as I thought and took about an hour.

Next up: CAD

July 14/15 - PCB Routing, probably the most important part in hardware design

A brief overview of what I did

so basicaly today I had to route the pcb, which would determine the layout of all of my parts in the real assembled design. It was very important for me to make this compact and accessible.
to accomplish this I would place the xiao port, switch, and battery and motor connectors on the edge of the board for ease of use.

the process

when starting out I used the default 0.2mm traces for my routing. I wanted to double check this and as it turns out there are different sized traces for different use cases, rendering my original traces useless. Nonetheless I perservered.

When I thought I was done, I ran the DRC, and a whopping 39 errors (if you go to 1:13 in the video you can see all of the errors). Luckily, a lot of these errors where the same thingd multiple times. For instance, In some of the narrower spaces, the increased traces I drew interfered with other pads and traces, so I had to change and alter portions. this was especialy true for the imu, which was microscopic.
I also had issues with some of the ground pins being stranded away from the copper pour I placed, so I just routed them to the back of the board. there where a bunch more issues but that should sufice to cover my process for these days

All in all pretty successful portion of the design process.

July 10th - Schematics!!

Goal

Today, I wanted to finalize the BOM and get everything on to the KiCad Schematic, (making sure nothing gets fried :)

My Circuitry

Throughout this whole learning experience of creating the BOM, researching electronics, and so much more, I found it helpful to explain things so a 5 year old can understand it, so hopefully my explanation of this circuit does it justice :)

My design works by taking power from a battery, not shown on the schematic, and controlling it with a sliding switch. For a microcontroller, I used an ESP32S3. To track posture, I used an IMU, with a super long name that if you care for, you can find it as the big square at the bottom of the schematic
I also used a simple coin motor.

Ultimately, this monstrosity was formed, with those key components and a whole bunch of researching in regards to capacitors, resistors, and so much more. (Any “pause” in the timelapse was me researching what to do because I didnt want to screw it up)

Some stuff I found along the way

I had to learn how to import footprints, and what to do when there arent any to be found.
I ended up having to use the command prompt and a tool called easyeda2kicad to find footprints for the slide switch.

Issues and Problems i encountered, because of course there are.

Although I found out that I had to use easyeda2kicad, I ran into problems with it. Most notably was that it didnt work lol. This had a simple fix of just adding a python -m command to the beginning of the command. Worked like a charm after that.

When doing the electrical check, I ran into a whopping 18 ERC Errors!!!
15 of these where solved simply with a cool feature that most people already know but I didnt, called the No Connect flag, which marked that I didnt use some of the pins on the XIAO and IMU. I guess they want me to use all of them :/
The last 3 occured because I did not include the battery in the schematic, so there was no power. (the battery would be connected through a cable, not soldering, so it didnt matter). I used another flag tool called the Power Flag to fix this.

Of course, there where so many more problems, but I dont want to bore anyone reading this, so just enjoy the timelapse (I hope it looks cool)

Next Time

Next up is the PCB itself, how exciting!