Highway to Undercity

20 Hours total

06-18-25: Research and Initation

A post in the r/simracing discord led me to this link: https://www.printables.com/model/1276952-diy-simagic-p-hpr-neo-clone

The motors only 1.5$? Easy steal for something like this. Obviously I wouldn't use the commerical controller they are supposed to work with, so designing my own was the next move.

I decided on 8 channels because while overkill, it keeps the PCB small but still maximizes performance for cost.

I looked into some MCUs and FETs on JLCPCB and came up with ATSAMD11D14A and AO3400A, economical and perfect for this use case

1 Hour

06-19-25: Schematic Creation

Now to pick parts: USB header, screw terminals, USB protector.

Downloaded the docs for all of them and spent a flight connecting them in schematic, as well as the other components

8 Hours

06-21-25: PCB Creation

Routing everything on one layer to preserve the high current ground plane. Each motor is like 2A max max max so this enourmous plane is just fine for 8.

This took another flight and some addtional pre and post time.

7 Hours

06-22-25: Part Selection

Finding appropriate JLCPCB parts for PCBA, and uploading the Gerbers to test the prices.

I didn't account for the extended component library or whatever when choosing parts, and those are a 3$ each cost, so I need to find alternatives for those. It was about 56$ with those, and about half of that price was because of the extended.

With replacements for those, the PCB should be about 25$ and that means about 7-8 motors.

2 Hours

06-23-25: Swapping extended parts for basic

Changing the pieces did indeed have a great effect on the price