Does the official micro USB adapter have the 56k resistor? If so, how can it supply 2.5A of power? I though it would limit to 500ma. This is something i have been trying to understand.scorpia wrote: ↑Thu Jul 04, 2019 7:12 pmMy pi has now arrived so I have been able to do some tests. My blog post above has been updated with the info as well.
I have checked and both the CC lines are wired up as in the schematic with only one CC resistor rather than two. I then checked several power supplies with and without e-marked cables (a macbook pro charger, Pixel3 charger, Office electrics desk charger). All the chargers did not power the pi when used with the e-marked cable provided with the macbook charger. when tested with a non e-marked cable all the chargers powered the pi.
Also the 5v on the connector is connected directly to the 5v rails. If the pi is powered over the GPIO then the USB-C connector is vbus hot which means it could backfeed devices when using the type C port on the pi as a USB client.
As an aside as I was testing bits I also checked the USB-C current resistors on the official charger and micro USB adaptor and both are correct.
"A smart charger with an e-marked cable will incorrectly identify the Raspberry Pi 4 as an audio adapter accessory, and refuse to provide power," says Upton.
"I expect this will be fixed in a future board revision, but for now users will need to apply one of the suggested workarounds. It's surprising this didn't show up in our (quite extensive) field testing program."
I've been nervous about USB-C ever since I found out--some years ago--that the cables are supposed to have chips in them. Obviously, there is cost factor, but we now see that a "smart" cable can be too "smart" for its own good.Heater wrote: ↑Wed Jul 10, 2019 5:40 pmThese "e" cables are not just cables. They have some kind of micro-chip in them. No idea what it does, something to do with deciding to blast your Pi with 20v and 100amps as if it were fast charging an iPhone or not.
Grief who invents this garbage? Power leads with chips in them, ridiculous.
This is what happens when you try to make "the one port to rule them all" (it becomes VERY complicated).W. H. Heydt wrote: ↑Wed Jul 10, 2019 6:23 pmI've been nervous about USB-C ever since I found out--some years ago--that the cables are supposed to have chips in them. Obviously, there is cost factor, but we now see that a "smart" cable can be too "smart" for its own good.
Have you done that then?
Sorry, but that is incorrect. There are type-C USB 2.0 cables rated for less than 3A, so no one should make that assumption.
I am sure you could make your own usb c->a cable that is rated for 1A, but the USB spec specifically calls for 3A and 5A cables, regardless of power delivery feature. All certified usb c cables can do at least 3A with a minimal drop in VBUS.HawaiianPi wrote: ↑Wed Jul 10, 2019 7:27 pmSorry, but that is incorrect. There are type-C USB 2.0 cables rated for less than 3A, so no one should make that assumption.
That technique used to be called a "sleeper". The favored way to do it was to remove the back seat from a VW Beetle and install a large V-8 engine.
They managed to fit the engine in the front with some custom mountings, re-routing the oil filter and making a custom exhaust system.W. H. Heydt wrote: ↑Wed Jul 10, 2019 11:03 pmThat technique used to be called a "sleeper". The favored way to do it was to remove the back seat from a VW Beetle and install a large V-8 engine.
My next-door neighbour runs a repair shop, so when my 10-year-old V70 decided to not even try to start, I asked him for help, and that's what he told me.