Raspberry Pi 4 as a USB-C peripheral • Hacker News Board

Re: Raspberry Pi 4 as a USB-C peripheral

#21

Post by fanf2 » Sat, Nov 02, 2019, 11:24 PM UTC

kees99 wrote: post #19

[R]ecent update to the Raspberry Pi 4 bootloader (...) enables data over the USB-C port Am I reading this right that RPi4 has five usable USB ports, i.e. unlike earlier models, port on bottom left of the board can carry data along with power? This is awesome!

USB-C includes a USB-2 management channel in addition to the high-bandwidth lanes. It is used for things like advanced power delivery negotiation. On the Raspberry Pi 4, the USB-C port has no high-bandwidth lanes, and it only uses passive power negotiation.

Re: Raspberry Pi 4 as a USB-C peripheral

#22

Post by ngcc_hk » Sat, Nov 02, 2019, 11:49 PM UTC

jagger27 wrote: post #6

lhoff wrote: post #2

I fail to imagine a usw case for that. Could someone enlighten me?

So you can add GPIO to your computer with lots of preprocessing power.

Wow. What a good summary. Should be the heading. :-)

Re: Raspberry Pi 4 as a USB-C peripheral

#23

Post by ce4 » Sat, Nov 02, 2019, 11:54 PM UTC

nougatbyte wrote: post #14

mmastrac wrote: post #12

Earlier quoted context omitted.

That's awesome. Do you recall the name?

https://play.google.com/store/apps/details?id=com.softwareba...

The last time i checked it needed gadget kernel driver support and root, a showstopper for me...

Apart from that, great concept: load your 5+ cd images onto your 64+ gb android and be done (win10, ubuntu, debian, grml, kali, bios update cd image, etc) and forget about your usb drive collection...

Re: Raspberry Pi 4 as a USB-C peripheral

#24

Post by p1mrx » Sun, Nov 03, 2019, 12:06 AM UTC

Yay, that feature was previously only available on the Pi Zero. Does anyone know if this will work on older computers, using a USB A-to-C cable?

Re: Raspberry Pi 4 as a USB-C peripheral

#25

Post by rkagerer » Sun, Nov 03, 2019, 12:15 AM UTC

You can also do a USB client on a $1.50 AVR chip: https://www.obdev.at/products/vusb/index.html

Source: Compiled and connected a mouse/keyboard firmware running on an ATtiny861a using internal RC oscillator.

Re: Raspberry Pi 4 as a USB-C peripheral

#26

Post by mmastrac » Sun, Nov 03, 2019, 12:55 AM UTC

fanf2 wrote: post #21

kees99 wrote: post #19

[R]ecent update to the Raspberry Pi 4 bootloader (...) enables data over the USB-C port Am I reading this right that RPi4 has five usable USB ports, i.e. unlike earlier models, port on bottom left of the board can carry data along with power? This is awesome!

USB-C includes a USB-2 management channel in addition to the high-bandwidth lanes. It is used for things like advanced power delivery negotiation. On the Raspberry Pi 4, the USB-C port has no high-bandwidth lanes, and it only uses passive power negotiation.

This seems to be in opposition to the blog post. In addition, according to the schematic there's USB-2 over that USB-C port:

https://www.raspberrypi.org/documentation/hardware/raspberry...

Re: Raspberry Pi 4 as a USB-C peripheral

#27

Post by cesarb » Sun, Nov 03, 2019, 2:14 AM UTC

fanf2 wrote: post #21

kees99 wrote: post #19

[R]ecent update to the Raspberry Pi 4 bootloader (...) enables data over the USB-C port Am I reading this right that RPi4 has five usable USB ports, i.e. unlike earlier models, port on bottom left of the board can carry data along with power? This is awesome!

USB-C includes a USB-2 management channel in addition to the high-bandwidth lanes. It is used for things like advanced power delivery negotiation. On the Raspberry Pi 4, the USB-C port has no high-bandwidth lanes, and it only uses passive power negotiation.

> USB-C includes a USB-2 management channel in addition to the high-bandwidth lanes. It is used for things like advanced power delivery negotiation.

No, all the power delivery negotiation in USB-C, both the basic one using only passive resistor values and the advanced one using the USB-PD protocol, is through the configuration channel pins, which is a separate pair of pins completely independent from the USB 2.0 pins in the middle. (The configuration channel is implemented incorrectly on the Raspberry Pi 4, however; it shorts together the pins, while they should be separate, so it fails with advanced cables which use both pins; and when powered through a source other than the USB-C connector, it incorrectly sources 5V to the USB-C port even when it shouldn't.)

Re: Raspberry Pi 4 as a USB-C peripheral

#28

Post by jpablo » Sun, Nov 03, 2019, 3:44 AM UTC

p1mrx wrote: post #24

Yay, that feature was previously only available on the Pi Zero. Does anyone know if this will work on older computers, using a USB A-to-C cable?

Also in the PI 3A, but needs a weird cable.

Re: Raspberry Pi 4 as a USB-C peripheral

#29

Post by johnchristopher » Sun, Nov 03, 2019, 3:58 AM UTC

mmastrac wrote: post #4

lhoff wrote: post #2

I fail to imagine a usw case for that. Could someone enlighten me?

... build a smart boot device that provides a bunch of different CD images for BIOSes that don't do USB boot well ... build a safe password keeper that looks like a HID device ... do something interesting with USB-based gamepads to map those to keyboard keys for playing old DOS games ... make a connected USB storage device that offers some sort of additional sync services for the data stored on it (maybe over wifi?)…

> ... make a connected USB storage device that offers some sort of additional sync services for the data stored on it (maybe over wifi?)

There used to be a KS funded case built around a Pi and an HDD that would act as an external storage when plugged to a USB port and would work as Kodi based media player once booted and connected to an HDMI port.

If anybody knows if this can be done DIY style with minimal cable mess I am all ear :).

edit: ah ! https://geekworm.com/blogs/raspberry-pi/how-to-add-extra-sto...

Re: Raspberry Pi 4 as a USB-C peripheral

#30

Post by lawik » Sun, Nov 03, 2019, 7:16 AM UTC

lhoff wrote: post #2

I fail to imagine a usw case for that. Could someone enlighten me?

In the Nerves project (Elixir thing for embedded linux) it is used to be able to power, SSH to the device and push new firmware changes without needing to reimage the SD card. Already used that a lot with the zero and 3A.