The n00b mistake that I had made reared its ugly head when I plugged in my nTerm2-S v0.11 into my macbook directly, using a USB-C to USB-C cable. Up til then, I had always connected through an old USB 2.0 hub, figuring that if I made a mistake, it was better to let the USB hub go up in smoke than a USB-C port on my expensive MacBook. This is good practice that anyone should follow.

But it has a caveat...

USB 2.0 happily always provides the device with 500mA of power, regardless of anything. So if you use a USB 2.0 hub, with a USB 2.0 to USB-C cable, and plug in your USB device, it works great.

However, USB-C wants to negotiate first about how much power it will give you. And if your device doesn't negotiate, USB-C just doesn't give it power. Simple as that.

The power negotiation of USB-C (USB-C PD) is a bit involved, but at the minimum the device needs to negotiate its power role. In the case of the nTerm2-S, its role is a power sink (it needs power, doesn't deliver it), and that role is negotiated by putting two 5K1 pulldown resistors on the CC1 and CC2 connections of the USB-C connector. And guess what I forgot...?

Hacking a few resistors onto the V0.11 board confirmed that it was indeed the problem.

It's especially unfortunate because the space around the USB-C port was already quite cramped, and I just couldn't find the space for the resistors. Of course I could have actually placed them almost anywhere on the board, because they are passive. But that goes against aesthetics. So I took the time to refactor almost the whole USB and power area. And to be honest, I was quite happy with it because it now looks more neat.

Spot the differences.

And there we are. It's now 2 months later, and I have still not found any reason for any new updates to the hardware. And that means that I am done with the hardware.