12/27/2025 - Chose Components

I will be using an rp2040, because I have experience with this microcontroller.

For the gyro and barometer, I chose the MPU5060 and mpl3115a2, because I have used both of these, and because the gyro has a gyroscope and accelerometer.

For the battery charger, I want to use a MCP73871, because it can charge the battery while powering the system at the same time.

1/1/2026 3 PM - Finished PCB Schematic

I finished the schematic for the PCB.

Most of it was copied from datasheets & online tutorials, and I am hoping it works. The pin layout is just going to be the same as the rpi Pico, but hopefully my extra sensors will fit too.

1/1/2026 9 PM - Routed the PCB

I routed the PCB today.

After putting into JPCPCB, they cannot put on the barometer, and because it is not as important, I will just remove it. I also need to replace all the 0402 caps with 0201 ones.

1/1/2026 11 PM - Finished PCB

I was able to finish the pcb.

After finding out that my components would need to be advanced pcba, I just decided to use 0201 smd components because they fit better.

1/2/2026 - PCB Overview

Custom RP2040 board

This is a quick summary of the whole process it took me to make this board.

I knew I wanted to learn pcb design, so I chose to make a custom board. At the beginning, I did not know what features I wanted to add. However, I thought back to my summer, when I made a drone flight controller out of a Seeed XIAO RP2040, and separate gyro and barometer components.

I noticed that the separate components took a lot more space than they needed to, and that this could be easily resolved with a board that had the rp2040, barometer and gyro all together. This lead me to thinking that all small moving robots, like cars, would also need these components, so it could be nice to have a board with everything already put together. It could also be nice to have a battery charger, since many of these devices operate without wall power.

My finalized criteria was this:

• Some sort of MCU
• A gyroscope & accelerometer
• A battery charger (preferably load sharing)

Selecting Components

When it came to the MCU, I knew I wanted to use the RP2040. This was mainly because there was a nice guide on how to make a dev board with this chip,

The barometer was the MPL3115A2, mainly because it seemed cost effective and simple to use.

I chose a MPU5060 for its gyro & accelerometer so I would not need two separate ICs, and because this is the one I have used before.

The battery charger was the MCP73871, because it had load sharing capabilities, and it was suggested by other people.

With my components selected, it was time to start designing.

PCB Schematic

For the first while, I followed the guide on a RP2040 microcontroller. Once I got to my custom parts, I had to search up the datasheets, and copy the circuits from there.

Once I was finished putting those circuits together, I had to chose the pinout. To keep it simple, I copied the pinout from the tutorial. I also connected the I2C pins & status pins to some on the MCU, trying to prioritize unused pins when possible.

PCB Routing

I have no clue how to route PCBs, so it does not look too great.

Since everything is so crowded, I chose to use a 4-layer board. Components are on top, middle is for traces & ground plane, and bottom is for traces. It looks very scuffed but I'm hoping it turns out fine.

Since I'm not doing any wireless/RF, my scuffed routing should suffice.

1/10/2026 - Remade PCB

To make costs less, I chose to make all the resistors and capacitors 0603 since it is larger.

This made me need to reorder a lot of components, but hopefully it is good now. This also lets me hand solder it if absolutely necessary.