Hacker News Reader

Comment by the__alchemist | Hacker News Reader

Related: When designing small electronics devices, my go to for plug-in power and simple data transmission (including serial-over-USB) is USB-C. It's small, reversible, and common due to phone chargers... and you can still wire it up and use it easily by just using the D+/- lines, power, and ground. (With appropriate CC resistors etc)

View on HN

And the best part is that you don't even need a connector, you can just build it right into your PCB! USB-A also lets you do a PCB-only connector, but if you're doing anything that requires a cable instead of just plugging directly into a port, it's a lot more annoying to require a USB-A extension cable than any USB-C cable.

What PCB thickness? Got a footprint?

0.8mm, https://github.com/jmgao/PCB-USB-C

The Eagle one yours is based on says it needs 0.6 mm PCB to work. Is it just close enough not to matter?

Annoyingly, the USB-C midplate is specified at 0.7mm. In my experience, 0.6mm boards are too thin to make a reliable connection. Going thicker has worked perfectly with all of the cables I've tried. I suppose there might be some risk of damaging your cables, but it doesn't seem too likely to me (the spec is 0.7 +/- 0.05), and I haven't had any problems.

Thank you!

Do you have an example for such a "USB-C edge connector"? Intuitively I would have said that common PCB thickness is too large, or do I misunderstand what you mean?

Yeah, you need a 0.8mm thick PCB, but everyone can do that now (JLCPCB and oshpark both do it for the same price as a regular 1.6mm board). Here's a footprint: https://github.com/jmgao/PCB-USB-C

Sweet, I will consider that next time I need something USB-like, thanks!

I need photos to understand this, including one where a cable is connected to it

Sure: https://photos.app.goo.gl/CerrZNcQiQE254pTA

Wow that’s crazy

Awesome

Very cool!

Oh my god this is incredible! And it has the full pinout so you can use debug accessory mode!

Game changing!

You can also do this with thicker PCBs (2.4 or 2mm, nominal 2.235mm, 1.6mm works with a good USB cable or a shim) to form a USB-A male connector, eg:

https://eleccelerator.com/usb-business-card/

http://goodfet.sourceforge.net/hardware/goodfet31/

https://www.digikey.com/en/products/filter/usb-dvi-hdmi-conn...

That seems to be opposite of what jmgao means, which was forming a USB-C edge connector out of the PCB itself.

Oh wow, I misinterpreted. That's awesome!

> my go to for plug-in power and simple data transmission (including serial-over-USB) is USB-C

Can you push for USB-O, the round USB connector? /s

> common due to phone chargers

Thanks to Apple keeping iPhones on lightning connectors the only things with USB-C I have in my house is a Nintendo Switch and a Soldering Iron.

I don’t understand, my new iPhone 13 came with a usb-c to lightning cable. My new iPad is usb-c too as well as my new kindle and new Sony camera. Even my vape has usb-c!

Edit: and my soldering iron!

Ok, so the iPhone 13 does come with a usb-c to lightning, but that cable is completely useless to me as it didn't come with a charger. All my previous iPhones and iPads came with a usb-a chargers.

Other than that Switch Charger I've got no other USB-c chargers.

Older devices! And some new ones that still have USB-micro.

It's quite difficult to buy a USB-C cable that is not USB-C or Lightning on the other end. While USB-A on the charger's side with USB-C on device side is quite common and comes with a lot of devices that don't include a charger.

I couldn't find USB-C to USB-micro device cables at any retail store near me.

Ended up getting them off Amazon.

My transition to all USB-C is also much slower than it could be, since you can't get 6- or 10-port chargers that are all USB-C. iirc best I've seen is 2x USB-C and then 4 USB-A.

Use cases:

- my embedded dev boards are all USB-micro (sometimes 2x of) and worse, USB-mini or USB-B. setup for dev on the go from my MBP now is a foot-long USB-C to USB-micro.

- charging older Kindles, bike lights, etc

I got a device in the past 2 years that uses mini USB

There are super cheap usb-a to usb-c-female adapters, tiny little cable-less adapters. I heartily recommend buying in quantity, so your existing charging gear can all expose usb-c.

Then I buy usb-c to usb-c cables. And a usbc-to-usb-micro adapter, which comes with a little chain that clips on to the cable. I use less and less micro (the majority of my recent dev boards have been usbc for example) but having a cable good for both is super convenient & easy.

I'd be careful with these: USB-A male to USB-C female adapters are illegal in the specification because they let you connect two power sources together, which can lead to explosions.

I'm pretty sure you can easily do that with a presumably legal USB-A male to USB-C male cable.

Plug one end into a charger with a USB-A port (very common among phone chargers) and the other end into a charger with a USB-C port (Apple's chargers seem to be like this?).

> Plug one end into a charger with a USB-A port (very common among phone chargers) and the other end into a charger with a USB-C port (Apple's chargers seem to be like this?).

It's forbidden to make a charger like that unless it has a chip that actually speaks the protocol and does power negotiation properly. Same for anything that has a female USB-C port.

The trick is that USB-C has a pair of pins that identify what type of cable is connected. Different value resistors on the pins identify different types of cables, so the USB-C charger will know that the cable plugged into it is a legacy A to C cable, and not actually connect its VBUS.

Can you recommend an IC and development tools?

I've been using STM32 and nRF-52. For development tools, I've been using Probe-Run to flash, and Defmt to debug.

Reply on news.ycombinator.com