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My knowledge with USB type C is very limited. For my new project I am planning to use USB type C port. I want my device to work as a power sink e.g. it will be powered by the source or host device. As well as it will have that capabilities of data data swapping (it can transfer data in both direction). What protocol do I need to use to achieve this? Do I have to use any IC? Or, is there any simple connection diagram for the CC using pull down resistors would do the work. I went through a lot of docs. But I am still confuse. I don't have the proper understanding yet.

JYelton
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Z0iS
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  • If you just want 5V from the other end you can use a couple of resistors. Higher voltages need negotiation through USB-PD. – Finbarr May 19 '22 at 16:27
  • Yup 3.3 or 5V would be perfect. Can you show me an example? – Z0iS May 19 '22 at 16:45
  • No 3.3V is available from USB ports. To get 5V see [this question](https://electronics.stackexchange.com/questions/574317/usb-c-and-5v-power-supply/574324#574324) – Finbarr May 19 '22 at 18:10
  • So, if I use two pull-down resistors in CC1 and CC2 pin, it will do the job for me. That means my device will power up with 5V and be able to transfer data in both directions. Thank you so much for your replies. – Z0iS May 19 '22 at 18:22
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    What do you mean by "transfer data in both directions"? Any USB device can do that. USB is inherently a bidirectional interface. Or do you have anything special in mind? – Codo May 19 '22 at 20:17
  • No. Now it's clear – Z0iS May 20 '22 at 17:30

2 Answers2

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If you want to have a device that takes power while being a USB host, then you have to master the entire PowerDelivery protocol to implement Power_swap function (and all the Discover_ID etc. functions). There are ICs from Texas Instruments, Cypress, Renesas etc, all are based on a serious embedded microcontroller that requires properly loaded firmware. But to engage them (to configure the PD IC to the set of modes supported by your device) you will need a really proper understanding.

Ale..chenski
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USB-C can support being a power source or sink, and can support 'dual role' operation (upstream or downstream).

Sounds like what you want is to make a downstream device that accepts power. Easy-peasy, don't need much more than USB3.2 and a bit of stuff to support flip-over. If you only need USB2 speed then it’s strictly wiring, no ICs needed.

Here's a quick intro to USB-C here: https://www.reclaimerlabs.com/blog/2016/12/31/usb-c-for-engineers-part-1

And here: https://www.reclaimerlabs.com/blog/2017/1/12/usb-c-for-engineers-part-2

Here's a related answer about 'dual role' support in USB-C: Connecting two "USB C" hosts, what happens?

hacktastical
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