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Bremenpl
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rpi 4 usb c specs

Sun Jun 30, 2019 7:08 am

Hello there,
I was wondering either:
  • Which PDO levels does rpi USB interface support? Can it be powered from 20V (highest level pdo)
  • Does the official usb c charger support only 5V output?
  • Is the actual usb connection functional this time? I mean, does the rpi appear to the host as usb device?
I would appreciate all feedback.
http://lprzenioslo.zut.edu.pl

fruitoftheloom
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Location: Delightful Dorset

Re: rpi 4 usb c specs

Sun Jun 30, 2019 7:27 am

Bremenpl wrote:
Sun Jun 30, 2019 7:08 am
Hello there,
I was wondering either:
  • Which PDO levels does rpi USB interface support? Can it be powered from 20V (highest level pdo)
  • Does the official usb c charger support only 5V output?
  • Is the actual usb connection functional this time? I mean, does the rpi appear to the host as usb device?
I would appreciate all feedback.

USB is 5V

https://www.raspberrypi.org/forums/view ... 3&t=243966
Retired disgracefully.....

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Bremenpl
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Re: rpi 4 usb c specs

Sun Jun 30, 2019 7:30 am

Thanks for answer,
This topics explains about the usb gadget interface, but not about usb c pdo capabilities.
http://lprzenioslo.zut.edu.pl

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Imperf3kt
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Re: rpi 4 usb c specs

Sun Jun 30, 2019 10:06 am

It has no pdo capabilities. It accepts 5v only.
55:55:44:44:4C
52:4C:52:42:41

drgeoff
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Re: rpi 4 usb c specs

Sun Jun 30, 2019 10:07 am

5 (+5%) volts is the highest voltage present at any place on a functional RPi board, including 4B.

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Bremenpl
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Re: rpi 4 usb c specs

Mon Jul 01, 2019 10:06 am

There is an USB C controller on board:
Untitled.jpg
Untitled.jpg (92.68 KiB) Viewed 469 times
This means it supports at least the base PDO level. The question is either it can accepts higher levels (with higher voltages). Is there a buck converter on board? I Cannot find any picture of the board with bottom side shown.

EDIT: Ok, nvm, just found this part in the schematics ( https://www.raspberrypi.org/documentati ... educed.pdf ). This is not a full USB C implementation but some weird hack... Ans what I have pointed would probably be the converter. Thanks for answers.
http://lprzenioslo.zut.edu.pl

andrum99
Posts: 778
Joined: Fri Jul 20, 2012 2:41 pm

Re: rpi 4 usb c specs

Mon Jul 01, 2019 10:49 am

Bremenpl wrote:
Mon Jul 01, 2019 10:06 am
There is an USB C controller on board:

Untitled.jpg

This means it supports at least the base PDO level. The question is either it can accepts higher levels (with higher voltages). Is there a buck converter on board? I Cannot find any picture of the board with bottom side shown.

EDIT: Ok, nvm, just found this part in the schematics ( https://www.raspberrypi.org/documentati ... educed.pdf ). This is not a full USB C implementation but some weird hack... Ans what I have pointed would probably be the converter. Thanks for answers.

The chip the red arrow points to is a custom Power Management IC (PMIC) which takes 5V in and produces the various voltages the board and SoC require - including 5V, 3.3V, 1.8V. Both the Pi 3B+ and the Pi 4 have a custom PMIC - the Pi 3B+ PMIC is different to the Pi 4 PMIC. The PMIC chip replaces a number of discrete components on previous models of Pi.

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HawaiianPi
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Re: rpi 4 usb c specs

Mon Jul 01, 2019 5:16 pm

The power port is not a true USB-C (multi-function) port.

They wanted to use a USB-C connector because it's capable of passing an extra half amp of current, compared to the old micro USB (3A vs 2.5A). There was also an unused USB 2.0 port on the SoC, so they ran the data lines out to the USB-C power port.

It's essentially a USB 2.0 port with a USB-C connector.
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scorpia
Posts: 18
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Re: rpi 4 usb c specs

Mon Jul 01, 2019 6:56 pm

The USB C port port as well as providing power has USB 2.0 client features (UFP) only allowing it to be used with Linux USB gadgets (no circuitry for host capability is on the board). There is a sense line going to the IC so it looks to be able to sense the available "Type-C current" from the power supply. Also worth noting the CC resistors on the connector are wrong so it wont work with e-marked cables often found on PD enabled chargers (There is a forum thread here about this issue https://www.raspberrypi.org/forums/view ... 5#p1487155 and also a write-up with the technical details at https://www.scorpia.co.uk/2019/06/28/pi ... resistors/)

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Bremenpl
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Re: rpi 4 usb c specs

Mon Jul 01, 2019 7:11 pm

Yes, this is all a bit dissapointing... But I gues those few components for the full usb C config would cost too much.

Thank you for feedback guys.
http://lprzenioslo.zut.edu.pl

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