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An Engineer's Guide to USB Typе-С (2024)

ti.com

11–20 of 88 posts

Re: An Engineer's Guide to USB Typе-С (2024)

#11
USB-C reminds me of HTTP: one familiar interface hiding an enormous amount of complexity underneath.

That's great for experts, but difficult for everyone else because the same connector can expose wildly different capabilities depending on the implementation.

Re: An Engineer's Guide to USB Typе-С (2024)

#12

I use an Apple Silicon Mac and often use programmable keyboards like the Royal Kludge RK61 via USB C. when I press keys such as A, S, D, F, W, or nearby keys in quick succession, the keyboard stops responding completely until I unplug and reconnect it. I've even replaced the USB C cable with a new store bought cable, but the issue still persists.

Check if your keyboard has a way to enable n-key rollover (NKRO)

https://en.wikipedia.org/wiki/Key_rollover

Re: An Engineer's Guide to USB Typе-С (2024)

#13
post #9

I use an Apple Silicon Mac and often use programmable keyboards like the Royal Kludge RK61 via USB C. when I press keys such as A, S, D, F, W, or nearby keys in quick succession, the keyboard stops responding completely until I unplug and reconnect it. I've even replaced the USB C cable with a new store bought cable, but the issue still persists.

Usb isn't the issue, you bought an extremely budget mechanical keyboard.

Also avoid Epomaker, had the same issues, but needed a full reflash (every other day), losing all my layers etc. (The import function was broken lol)

Re: An Engineer's Guide to USB Typе-С (2024)

#14
post #8

Earlier quoted context omitted.

Might be for cache busting.

could be, but for pdf documents I would assume that they are not changing this much

timestamp corresponds to Oct 08 2025, so probably the last time the file was modified

Re: An Engineer's Guide to USB Typе-С (2024)

#15
Guides like this explain why there are so many broken USB-C devices. The guide mentions that you do not need a PD chip for 5Vs, but then tells you that USB C is a cold connector meaning 0V is on VBUS when nothing is connected and jumps straight into the complexities of the PD protocol running over the CC pins instead of explaining how to get the 5V without the PD chip first.

Then in the section where it tells you how to do that, it fails to properly explain how to connect a load switch (10 cent component at 100 units) to get around the 10uF limit. The vast majority of applications will require less than 15 W and a good chunk of them can't get away with 10uF between VBUS and GND so a schematic how to do it in the lowest cost way would have helped here.

Edit: After reading until the very end I got the impression that this is just an ad for Texas Instruments PD controllers.

Re: An Engineer's Guide to USB Typе-С (2024)

#16

I use an Apple Silicon Mac and often use programmable keyboards like the Royal Kludge RK61 via USB C. when I press keys such as A, S, D, F, W, or nearby keys in quick succession, the keyboard stops responding completely until I unplug and reconnect it. I've even replaced the USB C cable with a new store bought cable, but the issue still persists.

Check if your keyboard has a way to enable n-key rollover (NKRO) https://en.wikipedia.org/wiki/Key_rollover

You are genius! thanks this completely solved my issue, for those curious https://postimg.cc/75hV9tCK

I use usevia, all i had to do was find a keyboard definition file for my keyboard which claude found in 2 minutes!

Re: An Engineer's Guide to USB Typе-С (2024)

#17
The EPR safety design is the part worth highlighting for anyone not deep in USB PD. The handshake is deliberately structured so a single message error can't accidentally push a port into a 100W plus contract, the sink has to actively drive entry into EPR mode and the source verifies cable capability before sourcing anything above 20V. That's a sensible failsafe given how much heat and current you're dealing with at 48V and 5A. The eUSB2 section is also underrated context for why this matters beyond cables. As process nodes shrink below 7nm, the old 3.3V USB 2.0 signaling literally becomes a reliability risk to the silicon itself, which is why chipmakers had to invent a whole lower voltage PHY just to keep USB 2.0 alive on modern nodes.

Re: An Engineer's Guide to USB Typе-С (2024)

#18
post #9

I use an Apple Silicon Mac and often use programmable keyboards like the Royal Kludge RK61 via USB C. when I press keys such as A, S, D, F, W, or nearby keys in quick succession, the keyboard stops responding completely until I unplug and reconnect it. I've even replaced the USB C cable with a new store bought cable, but the issue still persists.

Usb isn't the issue, you bought an extremely budget mechanical keyboard.

turns out it was just me not knowing my keyboard has full qmk support and can be configured via usevia, what N-key rollover (NKRO) is.

my keyboard is actually r65 by royal kludge i got that wrong!

I was gifted this keyboard and i just love its feel.

Re: An Engineer's Guide to USB Typе-С (2024)

#19

Guides like this explain why there are so many broken USB-C devices. The guide mentions that you do not need a PD chip for 5Vs, but then tells you that USB C is a cold connector meaning 0V is on VBUS when nothing is connected and jumps straight into the complexities of the PD protocol running over the CC pins instead of explaining how to get the 5V without the PD chip first. Then in the section where it tells you how…

Basic 5V devices just need a 5.1k resistor on each CC pin to GND. It is pretty obvious when reading the actual USB-C Connector Specification.

Re: An Engineer's Guide to USB Typе-С (2024)

#20
post #8

Earlier quoted context omitted.

Might be for cache busting.

could be, but for pdf documents I would assume that they are not changing this much

TI usually links to chip datasheets, which do tend to change from time to time. Having both a reference to a specific revision and a trivial link to the latest revision is quite handy in practice.
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