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geekhack Projects => Making Stuff Together! => Topic started by: Croktopus on Mon, 29 October 2018, 11:06:41

Title: Using Type C for AT90USB1286
Post by: Croktopus on Mon, 29 October 2018, 11:06:41
I was wondering if anyone's done this and would be willing to share that part of their schematic, or if someone knows of an open source schematic like this (or with a similar chip like a 32u4). I've given it my best go, but I feel like I've missed something.

My main concerns are


but if anyone notices other issues, that'd be cool. all i want out of this port is the type c physical port - so reversability, durability, and not needing so many different cables. dont need mega speed
Title: Re: Using Type C for AT90USB1286
Post by: synonzelra on Fri, 02 November 2018, 03:04:44
Simply saying, usb type c is just a combination of 2 normal usb interfaces with extra pins.

So, the resistor shall be the same as normal usb, as is, 22 ohm.

I would not recommend you to tie usb lines together, like A6 and B6. This will not work on a native type c port.
Title: Re: Using Type C for AT90USB1286
Post by: dr_derivative on Fri, 02 November 2018, 11:26:52
I often look at  this application note from ST about using USB-C connectors (https://www.st.com/content/ccc/resource/technical/document/application_note/group0/a6/91/45/9e/12/a0/4d/42/DM00235987/files/DM00235987.pdf/jcr:content/translations/en.DM00235987.pdf). You can see the schematic it uses with two 5.1k resistors on page 16.

I have also seen schematics with just one 5.1k resistor (I think this should work too), but most schematics do use two. Regardless, it should be a 5.1k resistor, not 5.6k.


Quote from: synonzelra on Fri, 02 November 2018, 03:04:44
I would not recommend you to tie usb lines together, like A6 and B6. This will not work on a native type c port.

Tying A6 and B6 together is necessary in a USB-C device. Only one set D+/D- pins is connected through a type-C cable, so the pins need to be connected together to make device work in both orientations.
Title: Re: Using Type C for AT90USB1286
Post by: Croktopus on Sat, 03 November 2018, 00:12:37
Awesome, thanks for the advice guys. I'm looking at basically copying the circuit design of JayKey1 https://github.com/josuegaleas/JayKey1 since it seems to be doing almost exactly what I want

Title: Re: Using Type C for AT90USB1286
Post by: dr_derivative on Sat, 03 November 2018, 05:21:32
Quote from: Croktopus on Sat, 03 November 2018, 00:12:37
Awesome, thanks for the advice guys. I'm looking at basically copying the circuit design of JayKey1 https://github.com/josuegaleas/JayKey1 (https://github.com/josuegaleas/JayKey1) since it seems to be doing almost exactly what I want

That schematic looks good to me. Good luck with your design!