Adding a more robust connector & USB Hub to the REV Expansion Hub
[Come back later for the write-up.]
It's no secret that most USB hubs have 4-layer PCBs. However, making 4-layer PCBs would have easily quadrupled the cost per PCB and increased development time over a 2-layer design. So what would happen if someone tried to make a 2-layer hub?
This is a little journey back into the prototyping for this project.
It all started with a dream...
The original idea:
And thus, the mini V1 prototype was born:
However, after I did some polling of interested customers, about 2/3 of teams responded that they would also like to use a webcam on their robot. That would mean introducing a USB hub into the wiring of the robot, which can lead to disconnects from the sheer number of connections.
So what's the solution? Slapping a USB hub controller on the board, obviously.
The IC used was a USB2422 from SMSC (Microchip). This is the absolute smallest 2-port USB hub chip available. The LDO was an NCP170 LDO. Unfortunately, I learned the hard way that you can't just willy-nilly route the USB lines on a 2-layer board, because no matter what I tried, I was always greeted with USB errors.
It was time for some research...