2/4/2026 - Research and Schematic

For this project, I want to use the ESP32 because it's way more versatile and powerful, and once this board is made, I will have way more uses for it.

I first decided on the ESP 32 s3 WROOM. This is a multi-core processor. This allows for multiple programs to run at the same time without slowing each other down. It also has an in-built Wi-Fi antenna.

After choosing that, I found the recommended schematic. This will be a great guide for how to build my dev board. It even has the jumper pins, ordered so that the traces are the optimum width.

As you can see, this has all the circuitry to make the board. But I will be using a different chipset for the voltage regulator. There is a chip I am extremely familiar with, so I will be using that.

I will also be using bridge pads, instead of actual buttons, to improve simplicity, increase space, and it's cheaper :D.

I started by wiring the USB

The recommended schematic used Micro Usb, I wanted to use USB-C, for the piece of my mind. This means I had to use two 5.1k pull-down resistors. This tells the sender how to function.

Also, because usb c can be plugged in up or down, there are separate differential pair pins for each orientation, but as the UART bridge needs to work in both orientations, the two pairs of differential pairs are connected.

Other than this, everything else about the usb is the same.

After this, I set up the UART bridge, practically a copy of the recommended schematic.

This is identical to the recommended layout.

After that, I wired my voltage regulator, which is not the recommended one, but has a simple circuit that I understand.

After that, I wired up the ESP 32, according to the schematic.

And know the schematic is done.

2/5/2026 - Finished PCB Design

Today I finished the PCB design for my custom ESP 32 devboard.

I started by placing the components. Because I used the recommended schematic, I know that if I match the same pcb layout, routing should be easy and not have much rats nests. This is especially important for the Pins of the devboard.

After I placed everything according to the recommended layout, I started routing.

Something I changed is that I wanted the UART bridge to be a lot closer to the usb than the recommendation.

I first routed the Differential pairs, as those are extremely important, and if their skews are not identical, the USB will not work, rendering my board useless.

After the differential pair, I routed all the other components, leaving the header pins for the end.

Once I got to the headerpins I stumbled. I followed the recommended schematic, which SHOULD keep the order of the pins, identical to the ESP 32 s3's pins. This should mean that the traces should line up neatly and not overlap.

I spent many hours trying to route the misplaced headers, thinking it was placed correclty. But eventually, I would always reach a point where there isn't even enough space to add a via. I tried reducing the trace width and making my vias smaller, but I still couldn't route everything.

But then, when I was about to give up, I realized that my header pins were backwards. They were in the least optimal position. Literally every single connection was crossed. I immediately fixed that.

As you can see, they now line up really neatly, and dont need many vias.

I am pretty sure this mistake with the header pins wasted like three hours, with me just deleting all the traces and trying again.

But finally, I completed the PCB of my devboard.