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

Re: Raspberry Pi 4 as a USB-C peripheral

#41

Post by rwha » Sun, Nov 03, 2019, 1:35 PM UTC

mmastrac wrote: post #3

Site is getting a bit slow - mirror here: http://archive.is/3bp5L

cloudflare (1.1.1.1) is resolving archive.is to 127.0.0.5 ??

Re: Raspberry Pi 4 as a USB-C peripheral

#42

Post by detaro » Sun, Nov 03, 2019, 1:40 PM UTC

rwha wrote: post #41

mmastrac wrote: post #3

Site is getting a bit slow - mirror here: http://archive.is/3bp5L

cloudflare (1.1.1.1) is resolving archive.is to 127.0.0.5 ??

Archive.is doesn't like that cloudflare doesn't give them information about the subnet the query came from, so they give a bad reply to cloudflare. (https://news.ycombinator.com/item?id=19828317)

Re: Raspberry Pi 4 as a USB-C peripheral

#43

Post by cesarb » Sun, Nov 03, 2019, 2:48 PM UTC

NicoJuicy wrote: post #38

Fyi: USB-c in the rpi 4 is not standards compliant. A new revision is underway, a fix is just using dumb cables.

Using dumb cables avoids one of the issues (configuration channel pins shorted together), but not the other one (sourcing power even when the configuration channel says it shouldn't source power).

That is, the workaround is both "use only dumb cables (which use only one of the CC pins)" and "never connect to a USB-C device which might source power while the rpi is being powered by something other than the USB-C".

Re: Raspberry Pi 4 as a USB-C peripheral

#44

Post by milkmiruku » Sun, Nov 03, 2019, 3:43 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...

Once I didn't have any USB sticks handy and didn't know about DriveDroid, so I used Servers Ultimate to host a TFTP server so I could PXE boot the netboot.xzy image from my phone to my laptop then download+install Arch Linux.

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

Re: Raspberry Pi 4 as a USB-C peripheral

#45

Post by HeyLaughingBoy » Sun, Nov 03, 2019, 4:46 PM UTC

rkagerer wrote: post #40

127 wrote: post #37

Earlier quoted context omitted.

Full ATmega32U4 board is 2.50 and doesn't need any hacks to work.

Could you provide a link to that $2.50 price?

Aliexpress. Amazon. eBay.

Re: Raspberry Pi 4 as a USB-C peripheral

#46

Post by HeyLaughingBoy » Sun, Nov 03, 2019, 4:48 PM UTC

IshKebab wrote: post #35

rkagerer wrote: post #25

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.

Why would you do that though when there are a gazillion Cortex-M chips available that support hardware USB? Fast USB and you don't have to use AVR. Hell, Atmel even sells Cortex-M chips with High Speed USB-2 support (reasonably hard to find; most are only Full Speed).

Tool Familiarity?

I've been doing embedded systems large and small for decades but before this year, never put anything with an ARM into production.

AVRs are still my go to for most things because I know them well and have all the tooling ready to go.

Re: Raspberry Pi 4 as a USB-C peripheral

#47

Post by rkagerer » Sun, Nov 03, 2019, 7:30 PM UTC

HeyLaughingBoy wrote: post #45

rkagerer wrote: post #40

Earlier quoted context omitted.

Could you provide a link to that $2.50 price?

Aliexpress. Amazon. eBay.

Hmm, quick Amazon search I'm seeing $5-6, more if you're outside USA. https://www.amazon.com/s?k=ATmega32U4

Re: Raspberry Pi 4 as a USB-C peripheral

#48

Post by xg15 » Sun, Nov 03, 2019, 10:31 PM UTC

cesarb wrote: post #43

NicoJuicy wrote: post #38

Fyi: USB-c in the rpi 4 is not standards compliant. A new revision is underway, a fix is just using dumb cables.

Using dumb cables avoids one of the issues (configuration channel pins shorted together), but not the other one (sourcing power even when the configuration channel says it shouldn't source power). That is, the workaround is both "use only dumb cables (which use only one of the CC pins)" and "never connect to a USB-C device which might source power while the rpi is being powered by something other than the USB-C".

> "never connect to a USB-C device which might source power while the rpi is being powered by something other than the USB-C"

Wouldn't this actually apply to a lot of use-cases of the project in the linked blog?

The whole point is connecting the RPi as a peripheral of a laptop, i.e. a power-sourcing host. if you do that, you'll also likely be tempted to use an external power supply for the Pi as the USB's supply is limited. It's important to note that this will lead to problems.

Re: Raspberry Pi 4 as a USB-C peripheral

#49

Post by HeyLaughingBoy » Mon, Nov 04, 2019, 12:50 PM UTC

rkagerer wrote: post #47

HeyLaughingBoy wrote: post #45

Earlier quoted context omitted.

Aliexpress. Amazon. eBay.

Hmm, quick Amazon search I'm seeing $5-6, more if you're outside USA. https://www.amazon.com/s?k=ATmega32U4

It varies and you can't always find the same price. The last price I paid for Nanos on Amazon was 5 for $17. Aliexpress is cheaper than that (that's where they're usually under $3), but I can't always wait that long.

My bad: forgot we were talking 32U4. Here's a link for $2.70: https://www.aliexpress.com/item/32846843498.html?src=google&...

Re: Raspberry Pi 4 as a USB-C peripheral

#50

Post by rkagerer » Tue, Nov 05, 2019, 11:21 AM UTC

HeyLaughingBoy wrote: post #49

rkagerer wrote: post #47

Earlier quoted context omitted.

Hmm, quick Amazon search I'm seeing $5-6, more if you're outside USA. https://www.amazon.com/s?k=ATmega32U4

It varies and you can't always find the same price. The last price I paid for Nanos on Amazon was 5 for $17. Aliexpress is cheaper than that (that's where they're usually under $3), but I can't always wait that long. My bad: forgot we were talking 32U4. Here's a link for $2.70: https://www.aliexpress.com/item/32846843498.html?src=google&...

Thanks!