Blender Render, Panelization, and LCSC

After fixing some pins that were out of order due to routing, I started rendering the PCB in Blender based on the last file.

It looks a bit drab so I am going to add in more lights like in Trace and see if that helps out a bit.

Meanwhile, I decided to panelize the PCB because in V1, there was a lot of extra space that I could use to make more copies and not have to pay extra.

After that I also exported the BOM and went to LCSC to check out how much it cost and it was surprisingly cheap at (taking advantage of the MOQ for most).

I also had to specify the stackup (which I kinda forgot to do for Ember but I sent an email requesting to change it). This also meant that I had to change the width of the traces and also the width of the board.

Finished Routing and Antenna

I spent a bit of time finishing up the routing and also making sure that everything looks neat including the silkscreen:

I somehow did it and managed to fit an IMU and Barometer in such a tiny 1 SIDED BOARD

I had fun routing the antenna as I had a crisis and thought I had my antenna for Ember wrong but I just recalculated the impedance badly

It's a 4 layer board so SIG/GND/PWR/SIG and I had some stitching vias for 3v3:

Aside from that I just finished routing and tmrw I'll start work on the renders and also getting feedback from the KiCad Discord.

Pin Selection (BEFORE PREVIOUS JOURNAL)

I started selecting the pins on STM3CubeMX and wanted to use I2C for the BMP580 and then SPI for the IMU. Another design requirement is that I wanted it as far away from the Bluetooth antenna as possible, which is why I decided on this pinout:

I might interchange the CS and interrupt pins as to better route it later but that's a good starting point. I then finished wiring the ICM:

AND I REMEMBERED TO ADD PULL UP RESISTORS TO THE I2C LINES

then I had to organize the schematic a bit as there wasn't any space for the new sensors lol

I then edited the footprints and made sure that all of them were at least 0402 (ptsd soldering 0201).

I forgot that I had this draft saved on one laptop so when I used another I pushed a journal from there and I forgot about these changes so aja, this journal comes before PCB Layout and Routing

PCB Layout and Routing

I started the layout of the PCB and noticed a few errors in my schematic and fixed them (I2C lines strike again) and then had something like this:

I found out that I can compact the board alot and make room for the antenna as I plan to use the bottom layer mainly for the GPIO's as the top layer is kind of busy with all of the passive components.

I organized it a bit more and got this layout, but I wasn't satisfied with the way that there was a squareish hole off center so I redid it again

(before)

(after)

And after that I didn't liked how it looked so I went back to the original and planned on putting a V2 in the squareish hole.

I then started routing up the design and also making minor changes here and there to not cover some silkscreen, I also enjoyed routing this section as I find that it looks cool the stripe effect:

Fixed Schematic and Add Sensors

So after the first iteration of the Cyberboard, there were a lot of issues, mainly me being stupid and not using the right values but also in the design of the PCB (not using 4 layers) so in this version I am going to fix that and upgrade it by adding an IMU/Barometer to make it the ultimate devboard for small projects!

Ah and I also plan on hand soldering it / reflow it using my custom hotplate (lol making tools to make tools) so it will be way cheaper and make up for my past mistakes.

I will be adding on the ICM-42688 and BMP580 and also I was thinking about reducing the size of the buck-boost converter as it was one of the biggest contributors to price/complexity on the board. So like any good engineer, I went on LCSC and searched for the most used DC DC converter to implement and found TPS631000 and it's perfect looking at the application implementation:

I think with this I can rewire the board completely and add in more functionality. So I thought about what other cool functionality and I decided on adding in a current sensor for the battery

I also found a cheaper battery charging IC: BQ24072RGTR instead of the BQ24074RGT

The only thing they have differently is one pin that instead of ITERM it's TD:

AND IT'S WAY CHEAPER AND COSTS ONLY 0.8 USD INSTEAD OF 3 USD

AND IT's LITERALLY A DROP IN REPLACEMENT FOR THAT CHIP:

I just had to change the value for TD to a more standarized value but it should work the same as a pull down resistor:

Reading through the datasheet I also saw that the example application was using a custom timer and to reduce cost even more I decided to use the default timer as that will suffice.

After I got the battery fixed I went on and fixed the decoupling capacitors for the STM32:

After that I imported the new buck converter and looked at the datasheet:

I had to import this inductor DFE252012P-1R0M=P2 as it was specified in the datasheet:

After setting up the rest of the pins, I came up with this:

Now it's time to set up the sensors that I'll be using (ICM-42688-PC and BMP580):

Thankfully I have enough pins free on my devboard, and you can't say that a devboard is a devboard if you aren't using all of the pins lol.

but before deciding on which communication interface I'm going to use, I'll have to edit the pins on STM32CubeMX:

I originally had some EVENTOUT pins that labeled which pins weren't going to be used but this time, I am going to try and use all of them. In total I have 11 pins free to play around with, I plan on using LED's with the extra pins to at least have 3 status ones.