ARCHANA R
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USB Type C of Pi 4 model B

Wed Jul 03, 2019 1:25 pm

I need the exact specifications of the Type C USB (Power Supply USB) used in the Pi 4 model B because , there are different number of contacts types (i.e Type C with 12 contacts , 22 contacts , 24 contacts ) available in the market. If somebody could provide a solution it would be helpful for me. Without knowing that how could I select the Male USB Type C connector for it?

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Paeryn
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Re: USB Type C of Pi 4 model B

Wed Jul 03, 2019 4:04 pm

As the USB-C connector is for power and the SoC's USB 2.0 port only then I'd say only the 2x GND, 2x Vbus, CC, D+ & D- on each side are connected for a total of 7x2 = 14 pins, though a plug should only have D+ & D- connected on one side which would make 12. As long as you have those connections you should be fine, and if you only need it for power then you don't need to connect D+ & D- (or the CCs unless your end needs them).
Note, I'm not an electrical engineer, I assume the D+/- and CCs can be left unconnected if not needed.
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davidcoton
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Re: USB Type C of Pi 4 model B

Wed Jul 03, 2019 7:52 pm

The schematic diagram lists 12 connections.
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ARCHANA R
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Re: USB Type C of Pi 4 model B

Thu Jul 04, 2019 4:31 am

davidcoton wrote:
Wed Jul 03, 2019 7:52 pm
The schematic diagram lists 12 connections.
But what about the Shell pins in the schematic..?

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davidcoton
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Re: USB Type C of Pi 4 model B

Thu Jul 04, 2019 9:01 am

ARCHANA R wrote:
Thu Jul 04, 2019 4:31 am
davidcoton wrote:
Wed Jul 03, 2019 7:52 pm
The schematic diagram lists 12 connections.
But what about the Shell pins in the schematic..?
AIUI shell connections go to the outer case of the connector (hence "shell"), they are not pins on the connector.
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scorpia
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Re: USB Type C of Pi 4 model B

Fri Jul 05, 2019 12:25 am

The USB-C port on the Pi4 is in a USB 2.0 client configuration hence many of the connections aren't used. All of the type C connectors should be incompatible as long as the connector you are using has the pins you need for your application (for example the pi uses one without the superspeed pins as it doesn't need them).

I wrote a guide a couple of years ago that covers the various ways that type C can be implemented https://www.scorpia.co.uk/2016/03/17/us ... -projects/ the section labelled "Type-C as a 2.0 device with a type-C receptacle" is equivalent to what is used on the pi (ignoring the cc resistor issue on the pi4).

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Re: USB Type C of Pi 4 model B

Fri Jul 05, 2019 1:04 am

scorpia wrote:
Fri Jul 05, 2019 12:25 am
The USB-C port on the Pi4 is in a USB 2.0 client configuration hence many of the connections aren't used. All of the type C connectors should be incompatible as long as the connector you are using has the pins you need for your application (for example the pi uses one without the superspeed pins as it doesn't need them).
Minor correction... The USB 2.0 port the USB-C is connected to can be either client or host. In the more usual parlance, it can be a OTG port. This has the rather interesting implication that a Pi4B can be both a USB host through it's USB-A port and a client through the USB-C port at the same time.

aBUGSworstnightmare
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Re: USB Type C of Pi 4 model B

Fri Jul 05, 2019 9:08 am

davidcoton wrote:
Wed Jul 03, 2019 7:52 pm
The schematic diagram lists 12 connections.
There is A12 and B12 when you look at the pinout --> USB-C has 24pins.
https://en.wikipedia.org/wiki/USB-C

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davidcoton
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Re: USB Type C of Pi 4 model B

Fri Jul 05, 2019 9:14 am

aBUGSworstnightmare wrote:
Fri Jul 05, 2019 9:08 am
davidcoton wrote:
Wed Jul 03, 2019 7:52 pm
The schematic diagram lists 12 connections.
There is A12 and B12 when you look at the pinout --> USB-C has 24pins.
https://en.wikipedia.org/wiki/USB-C
Good point, but look at how the A/B pairs are wired. It is, almost certainly, a 24 pin socket, but a 12 pin plug will connect properly.
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pwinwood
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Re: USB Type C of Pi 4 model B

Fri Jul 05, 2019 1:09 pm

The two cc pins on the USB-C power are connected together to a single pull-down rather than a separate pull-down on each so that some USB-C power supplies do not output anything to power the Pi 4 however the Raspberry Pi USB-C power supply does not have this problem?

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Re: USB Type C of Pi 4 model B

Fri Jul 05, 2019 3:11 pm

W. H. Heydt wrote:
Fri Jul 05, 2019 1:04 am
scorpia wrote:
Fri Jul 05, 2019 12:25 am
The USB-C port on the Pi4 is in a USB 2.0 client configuration hence many of the connections aren't used. All of the type C connectors should be incompatible as long as the connector you are using has the pins you need for your application (for example the pi uses one without the superspeed pins as it doesn't need them).
Minor correction... The USB 2.0 port the USB-C is connected to can be either client or host. In the more usual parlance, it can be a OTG port. This has the rather interesting implication that a Pi4B can be both a USB host through it's USB-A port and a client through the USB-C port at the same time.
My phone comes with an OTG adapter. Device mode: connect phone to PC. Host mode: connect mouse, flash drive, etc to phone.
The difference is that while my phone has internal battery power during this time while the Pi does not. How can the Pi work as an OTG port since it relies on the port for power?

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rpdom
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Re: USB Type C of Pi 4 model B

Fri Jul 05, 2019 3:17 pm

MisterEd wrote:
Fri Jul 05, 2019 3:11 pm
How can the Pi work as an OTG port since it relies on the port for power?
1. It could use some sort of USB-C power splitter.

2. It can be powered by the PoE HAT.

3. It can be powered via anything the provides a suitable stable voltage and current to the 5V and GND GPIO pins.

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Re: USB Type C of Pi 4 model B

Fri Jul 05, 2019 4:00 pm

rpdom wrote:
Fri Jul 05, 2019 3:17 pm
MisterEd wrote:
Fri Jul 05, 2019 3:11 pm
How can the Pi work as an OTG port since it relies on the port for power?
1. It could use some sort of USB-C power splitter.

2. It can be powered by the PoE HAT.

3. It can be powered via anything the provides a suitable stable voltage and current to the 5V and GND GPIO pins.
4. If it is in client mode, the host can provide 3A at 5v.

scorpia
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Re: USB Type C of Pi 4 model B

Fri Jul 05, 2019 9:04 pm

W. H. Heydt wrote:
Fri Jul 05, 2019 1:04 am
scorpia wrote:
Fri Jul 05, 2019 12:25 am
The USB-C port on the Pi4 is in a USB 2.0 client configuration hence many of the connections aren't used. All of the type C connectors should be incompatible as long as the connector you are using has the pins you need for your application (for example the pi uses one without the superspeed pins as it doesn't need them).
Minor correction... The USB 2.0 port the USB-C is connected to can be either client or host. In the more usual parlance, it can be a OTG port. This has the rather interesting implication that a Pi4B can be both a USB host through it's USB-A port and a client through the USB-C port at the same time.
While the SOC has dual role support (OTG) support the connector circuitry on the pi doesn't have the required circuitry for doing host mode (DFP) negotiation on the type C port and is wired up for client mode only.

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rpdom
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Re: USB Type C of Pi 4 model B

Sat Jul 06, 2019 8:06 am

scorpia wrote:
Fri Jul 05, 2019 9:04 pm
W. H. Heydt wrote:
Fri Jul 05, 2019 1:04 am
scorpia wrote:
Fri Jul 05, 2019 12:25 am
The USB-C port on the Pi4 is in a USB 2.0 client configuration hence many of the connections aren't used. All of the type C connectors should be incompatible as long as the connector you are using has the pins you need for your application (for example the pi uses one without the superspeed pins as it doesn't need them).
Minor correction... The USB 2.0 port the USB-C is connected to can be either client or host. In the more usual parlance, it can be a OTG port. This has the rather interesting implication that a Pi4B can be both a USB host through it's USB-A port and a client through the USB-C port at the same time.
While the SOC has dual role support (OTG) support the connector circuitry on the pi doesn't have the required circuitry for doing host mode (DFP) negotiation on the type C port and is wired up for client mode only.
Even if it is, this can be controlled by software.

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HawaiianPi
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Re: USB Type C of Pi 4 model B

Sat Jul 06, 2019 8:12 am

scorpia wrote:
Fri Jul 05, 2019 9:04 pm
While the SOC has dual role support (OTG) support the connector circuitry on the pi doesn't have the required circuitry for doing host mode (DFP) negotiation on the type C port and is wired up for client mode only.
Curious where you got this information, because I've heard differently.
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Re: USB Type C of Pi 4 model B

Sat Jul 06, 2019 9:34 am

HawaiianPi wrote:
Sat Jul 06, 2019 8:12 am
scorpia wrote:
Fri Jul 05, 2019 9:04 pm
While the SOC has dual role support (OTG) support the connector circuitry on the pi doesn't have the required circuitry for doing host mode (DFP) negotiation on the type C port and is wired up for client mode only.
Curious where you got this information, because I've heard differently.
It is based on my analysis of the reduced schematics published for the pi 4 https://www.raspberrypi.org/documentati ... educed.pdf whic are an attempted implementation of figure 4-9 in the USB-C spec which is for UFP sink (client only ports) (this was what i was trying to find info on when i discovered the CC resistor problem with the Pi4). It is also confirmed in the USB documentation https://www.raspberrypi.org/documentati ... erview_pi4.

drgeoff
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Re: USB Type C of Pi 4 model B

Sat Jul 06, 2019 11:19 am

The USB C socket on a RPi4 is not a USB C port. It has 5 volt power input pins and it has the D+ and D- pins electrically compatible with USB 2.

The socket was chosen for its small size and ability to carry higher current for the RPi4 and USB peripherals. Having an otherwise redundant USB port with host/client capability appearing on it is a bonus.

johnjones
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Re: USB Type C of Pi 4 model B

Mon Jul 08, 2019 1:18 am

it would have been really nice if they had just used a USB C port for the video output (since you have to buy a dongle anyway) and the USB ports !
maybe the C revision will have USB C interfaces replacing HDMI mini and the USB 3.1 PHY's leaving a USB-A and RJ45 and all others USB C

would simplify the parts list and the layout... maybe a fun exercise for the layout...

fruitoftheloom
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Re: USB Type C of Pi 4 model B

Mon Jul 08, 2019 4:54 am

johnjones wrote:
Mon Jul 08, 2019 1:18 am
it would have been really nice if they had just used a USB C port for the video output (since you have to buy a dongle anyway) and the USB ports !
maybe the C revision will have USB C interfaces replacing HDMI mini and the USB 3.1 PHY's leaving a USB-A and RJ45 and all others USB C

would simplify the parts list and the layout... maybe a fun exercise for the layout...

Actually there is a Q&A with Eben where he stated using USB-C would of complicated the board design due to requiring more parts and cost.

Though if you know better, prove your point.
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drgeoff
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Re: USB Type C of Pi 4 model B

Mon Jul 08, 2019 8:43 am

johnjones wrote:
Mon Jul 08, 2019 1:18 am
it would have been really nice if they had just used a USB C port for the video output (since you have to buy a dongle anyway) and the USB ports !
maybe the C revision will have USB C interfaces replacing HDMI mini and the USB 3.1 PHY's leaving a USB-A and RJ45 and all others USB C

would simplify the parts list and the layout... maybe a fun exercise for the layout...
https://www.raspberrypi.org/forums/view ... 5#p1492354

johnjones
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Re: USB Type C of Pi 4 model B

Mon Jul 08, 2019 9:38 am

regarding the link above as it has been proved they had some issues
https://medium.com/@leung.benson/how-to ... 470d7a5910

to my point If you reduce the number of ports i.e. no micro HDMI ports (thats at least 2 Physical interfaces) and no USB 3.1 Interfaces (thats more expensive than regular USB 2 Interface so saving both parts bin and BOM) then replace them with 1 USB C port (which is the same physical interface as your power ) edit: hey I would even get rid of the RCA connector and maybe bring back the old HDMI, anyway I would say your parts bin is reduced by removing the micro HDMI and USB 3.1 (both are new to the 4) even if you have to add an IC for USB C display and like I said the routing may get easier since you have more layout room on the board and potentially you could reduce the size of the board, I hope for a rev C :-)
its up to the clever layout people to prove it one way or another...

jamesh
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Re: USB Type C of Pi 4 model B

Mon Jul 08, 2019 10:18 am

If we wanted to do this, we would have done.

But it would be very expensive for end users, many of whom have not got any sort of USB-C devices (ie monitors, hubs etc). My laptop has USB-C out - to make use of it I have an extra dongle with USB and ethemet, plus a docking station to convert the display side to HDMI and DVI....both expensive options. You need to take in to account the total code - on the Pi and at the other end, given our target market.

Once USB-C devices become commonplace and cheap, it might be an option.
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johnjones
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Re: USB Type C of Pi 4 model B

Mon Jul 08, 2019 12:25 pm

I certainly hope its something you and others will consider in the future !

https://www.reuters.com/brandfeatures/v ... ?id=110005

Well done on the 4 release and I hope all your future releases are smooth !

bunklung
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Re: USB Type C of Pi 4 model B

Mon Jul 08, 2019 12:29 pm

drgeoff wrote:
Sat Jul 06, 2019 11:19 am
The USB C socket on a RPi4 is not a USB C port. It has 5 volt power input pins and it has the D+ and D- pins electrically compatible with USB 2.

The socket was chosen for its small size and ability to carry higher current for the RPi4 and USB peripherals. Having an otherwise redundant USB port with host/client capability appearing on it is a bonus.
To claim this makes a bit of sense why it's not fully compliant with the USB C spec.

However, it seems like only one resistor is in place wrong which seems more like a design snafu instead of a straight up technology imposibility.

Do you think they will revise the board design? Will they supply/sell a dongle that adds the resistor in place?

https://www.scorpia.co.uk/2019/06/28/pi ... resistors/

What percentage of failure to power are in the wild?

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