murratw
Posts: 24
Joined: Wed Mar 26, 2014 12:24 pm

Pi 4 with USB A to C cable

Sun Jun 30, 2019 9:10 pm

Is anybody using a Pi 4 and powering it with an A to C cable. It is my understanding that if they are in spec they will have a 56k resistor and will force the device to negotiate for higher current over 500ma. I don't think the previous versions of the Pi ever negotiated for power as there were no data lines. I was wondering what would happen with this one.

I used the 2.5A official micro B power supply with a USB C adapter with the 56k resistor and the pi4 just pulled whatever it wanted.

W. H. Heydt
Posts: 10899
Joined: Fri Mar 09, 2012 7:36 pm
Location: Vallejo, CA (US)

Re: Pi 4 with USB A to C cable

Mon Jul 01, 2019 1:17 am

From comments I've seen, the Pi has a 10K resistor at the USB-C connector and that is the "negotiation" to get 3A.

Aardappeltaart
Posts: 47
Joined: Wed Mar 02, 2016 11:32 am

Re: Pi 4 with USB A to C cable

Mon Jul 01, 2019 9:33 am

murratw wrote:
Sun Jun 30, 2019 9:10 pm
Is anybody using a Pi 4 and powering it with an A to C cable. It is my understanding that if they are in spec they will have a 56k resistor and will force the device to negotiate for higher current over 500ma. I don't think the previous versions of the Pi ever negotiated for power as there were no data lines. I was wondering what would happen with this one.

I used the 2.5A official micro B power supply with a USB C adapter with the 56k resistor and the pi4 just pulled whatever it wanted.

Yes, I tried to power and connect the RPI4 with just an USB cable, and a USB-micro <-> USB-C adapter from my laptop. It's working with Raspbian Lite. Haven't tried Kodi.

Like described here:
https://dev.webonomic.nl/4-ways-to-conn ... e-internet

emilfr
Posts: 22
Joined: Thu May 14, 2015 5:25 am
Location: Dublin, IE

Re: Pi 4 with USB A to C cable

Mon Jul 01, 2019 11:46 am

I run RPIs as home server, so wiill there be any problem in the long run to powered RPI4 with usb C converter?
I just don't like to have more unused micro USB, so if the converter would do the job especially for the long run, I'll get that instead.
RPI Zero W || RPI 2B || 2x RPI 3B || 2x RPI 4B4G

murratw
Posts: 24
Joined: Wed Mar 26, 2014 12:24 pm

Re: Pi 4 with USB A to C cable

Mon Jul 01, 2019 12:55 pm

W. H. Heydt wrote:
Mon Jul 01, 2019 1:17 am
From comments I've seen, the Pi has a 10K resistor at the USB-C connector and that is the "negotiation" to get 3A.
A legacy adapter to USB A has a 56k resistor which in theory tells the device to only draw 500ma. Wondering if that will limit what current the Pi4 will draw.

User avatar
Imperf3kt
Posts: 2781
Joined: Tue Jun 20, 2017 12:16 am
Location: Australia

Re: Pi 4 with USB A to C cable

Mon Jul 01, 2019 9:23 pm

murratw wrote:
Mon Jul 01, 2019 12:55 pm
W. H. Heydt wrote:
Mon Jul 01, 2019 1:17 am
From comments I've seen, the Pi has a 10K resistor at the USB-C connector and that is the "negotiation" to get 3A.
A legacy adapter to USB A has a 56k resistor which in theory tells the device to only draw 500ma. Wondering if that will limit what current the Pi4 will draw.
It shouldn't.
55:55:44:44:4C
52:4C:52:42:41

Return to “General discussion”