
Raspberry Pi 4 not working with some chargers - styx31
https://www.scorpia.co.uk/2019/06/28/pi4-not-working-with-some-chargers-or-why-you-need-two-cc-resistors/
======
an_d_rew
There have been a lot of comments here but I want to leave one specifically to
the person or team who designed the Pi’s circuitry:

Thank you for working on such an important project and thank you for all the
things that you got right.

I’m sure that somewhere, someone is feeling a little bit embarrassed and
possibly somewhat sheepish over this and… Please don’t let one incident
overshadow all the great things that have come from the existence of the
Raspberry Pi!

~~~
jchw
Yeah, this issue is not a big deal imo. It is an inconvenience, that may piss
people off, but it is not a showstopper. I’m sure a minor revision will be
made and most of us will not even remember this.

I hope this issue doesn’t delay preorders, because I don’t even care if my
unit has this issue.

~~~
cesarb
> Yeah, this issue is not a big deal imo.

It's not a big deal once they add to their list of "known issues" or "errata",
together with the relevant workarounds. Otherwise, they might get too many
returns from people who can't get it to power up with any of the chargers they
have (because all they have is high-end chargers with 5A cables).

------
gadgetoid
Ever since the very first model, sub-par, underrated power supplies have been
responsible for a good slice of tech support issues with the Pi. It wouldn't
be a real Pi launch without power issues.

IIRC the Pi 3B+ was butting up against (if not exceeding) the maximum rated
current for the microUSB port, so I believe the switch to USB Type-C is more
about picking a port that can handle a 3A@5V supply than a conscious effort to
support the dozens and dozens of terrible and near arbitrary USB Type-C
supplies on the market (some output 12V with zero negotiation. You know- for
giggles). I'd be surprised if they tested with more than a couple of staff
phone chargers and their own-brand chargers. I can't imagine the idea of
anyone using an expensive power-delivery enabled dock with a thick, 40cm
Thunderbolt 3 cable really entered their minds.

My advice to anyone buying a Pi 4 would be "Just buy a Pi-branded power-
supply. They're inexpensive and guaranteed to work." Granted you might want to
save a few bucks and use your phone charger... but then what are you going to
use to charge your phone?

~~~
marble-drink
Funnily enough my trusty Pi2 which has been running continuously for several
years now stopped working last night. At first I thought it must be the SD
card, as those are known to fail. Nope. So I thought it must be the Pi itself.
I suppose they weren't really designed to be left on for several years? I was
sure it couldn't be the power supply, but somehow it was. It will now power up
a Pi1, but not a 2 or 3. I've no idea why but it's gone in the bin and the Pi2
works again on a new one.

People really should consider a refurbished Dell Optiplex FX160 instead of a
Pi if it's going to be in a headless server role, though. You can get one for
about half the price of a new Pi4 on eBay and it comes with a proper power
supply unit, high quality case, and of course an Atom CPU which I'm sure
compares favourably even to the new Pi4. There was an article about them on HN
a while back. Mine has been running happily for almost two years now.

~~~
snovv_crash
Atom CPUs are core-for-core comparable to the A72 cores in the RPi4. ICP isn't
really comparable since the instruction set is different, but performance is
similar. The RPi has 4 of them, only the most modern Atoms have that.

~~~
asark
I'm not seeing USB 3 on that particular Optiplex, either. Gigabit ethernet,
yes. No HDMI. DVI, VGA. Maybe displayport? Hard to tell. Do have PS/2 keyboard
and mouse ports, which is kinda nice.

~~~
marble-drink
No USB3. I don't think it's any good as a thin client any more, it's only good
as a low power server. Before the Pi4 it was much more attractive, especially
because of GigE and because the Atom chip in it is pretty good compared to the
ARM in the Pi3. But after reading the replies here I'm thinking it's not as
good a choice as it once was.

------
michaelt

      The fact that no QA team inside of
      Raspberry Pi’s organization caught
      this bug indicates they only tested
      with one kind (the simplest) of USB-C
      cable.
    
      Raspberry Pi, you can do better.
    

I'd say at least 20% of the blame lies with whatever genius decided to have
_multiple types of USB-C cable_

I mean, cables already suffer from having A, Type A SuperSpeed, B, B
SuperSpeed, Mini-B, Micro-B, Micro-B SuperSpeed, C, and lengths from 10cm to
5m. Who'd expect adding a complete extra dimension of difference to be
trouble-free?

~~~
ProblemFactory
I believe the original plan was the opposite - one port and one cable type
that can do _everything_ \- 100W of power, 5K video, USB devices, analog
audio, Ethernet and more.

But it was naive to think that manufacturers will ship a $30 cable for a phone
charger when a cheaper hack will do.

At least there should have been mandatory color coding of the "full" and
"limited" ports and cables, just as USB 3 ports were blue to distinguish them
from older versions.

~~~
y4mi
Until cheap knockoffs heard they could charge 4x their normal price by
changing the coloring.

... You can't trust the coloring either if you're buying off of Amazon, eBay
or any Chinese site like Alibaba

~~~
Wowfunhappy
Coloring appears to have worked for distinguishing between USB 2 and USB 3, at
least in my experience.

~~~
katbyte
With USB 3 isn’t the other end of the cable usually different as well?

~~~
pdpi
USB-B for USB 3 is physically quite different, yes — looks like two stacked
connectors.

~~~
sargun
It’s a micro usb plus another kind of adapter. This gives you backwards
compatibility for devices if you want to expose usb 2 via usb-a -> micro

~~~
pdpi
I was actually thinking about B rather than micro-B, though I guess both my
description and your explanation apply either way!

------
pavlov
Before we had separate ports and cables for power, USB and Thunderbolt. There
was no way to plug the wrong cable in the wrong port.

With USB-C, we still have separate cables for these three types, but they all
look confusingly the same. Not convinced this is an improvement.

~~~
arghwhat
Just to be _entirely_ clear: While a cheap cable may be wrong, good (i.e.
fully featured) cables will always work in all combinations.

Having gone all in on Type-C, I have only ever gotten a "bad" cable as a cheap
charge cable, and have never had issues with cable incompatibilities.

~~~
gambiting
I'd love to know then why my Nintendo switch(very expensive) doesn't charge at
all when using the genuine OnePlus USB A-C cable(very expensive) and their own
OnePlus charger(also pretty expensive). It's not just cheap mislabeled crap
that sometimes doesn't work - it's proper hardware from big companies that
failed the simple "if the cable fits then it has to work" test.

~~~
TiltMeSenpai
OnePlus has had their own proprietary charger game running for quite a while
now. It's likely related to that. The Switch uses stock USB-C Power Delivery,
so Macbook and Pixel chargers would be fine.

------
cesarb
There might be yet another issue. As commented by the author of this blog post
in the RPi forums
([https://www.raspberrypi.org/forums/viewtopic.php?f=63&t=2438...](https://www.raspberrypi.org/forums/viewtopic.php?f=63&t=243875#p1492674)):
"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."

That is, when powering the RPi4 through PoE, its USB-C connector is in an
invalid configuration: it's powering VBUS when it shouldn't (that is, unlike
USB-A where VBUS is always on, IIRC with USB-C it should only be turned on
when the CC pins detect that the other side is either a power sink or an
adapter which should source power).

~~~
londons_explore
Backfeeding power is one of those things that is 'technically' a bad idea, but
practically damages pretty much nothing.

~~~
TylerWard
Another potential issue here is that if using the Pi as a client with a C-C
cable this could confuse the device at the other end meaning it wont connect
as it thinks it is being charged (will be seeing if I can get this to occur
over the weekend).

~~~
TylerWard
Have just run this test and it does appear to confuse some USB-C ports (my
phone and 3.0 usb-C port on my laptop detect the pi gadget however the 3.1
usb-C port doesn't detect the gadget if the pi is powered by gpio).

------
zimbatm
TIL; there are different types of USB-C cables with functional differences.

How do you know what type the cable is? Is is possible to detect it visually?

~~~
ProblemFactory
The USB-C ecosystem is quite a mess. Most cables are either limited
functionality, or not up to spec that they advertise. Frying your devices with
nonstandard chargers or cables is easily possible.

You can't tell them apart visually, and you can't always trust the specs
promised on Amazon either.

There are testing tools like [https://www.tindie.com/products/aroerina2/usb-
cable-checker/](https://www.tindie.com/products/aroerina2/usb-cable-checker/)

There was a Google engineer (Bensen Leung) who bought, tested and reviewed all
the cables he could find, but with the shutdown of Google+ the archive seems
to be lost.

~~~
superdaniel
Bensen Leung is also the author of this blog post

~~~
Tempest1981
Benson's medium post refers to a discovery by Tyler (aka scorpia)

Edit: original link: [https://medium.com/@leung.benson/how-to-design-a-proper-
usb-...](https://medium.com/@leung.benson/how-to-design-a-proper-usb-c-power-
sink-hint-not-the-way-raspberry-pi-4-did-it-f470d7a5910)

------
chx
How does the HN system work when I submitted the exact same URL
[https://news.ycombinator.com/item?id=20317687](https://news.ycombinator.com/item?id=20317687)
five days ago??? We have stickied this on the usbchardware subreddit as well
at the time, it's still on the top:
[https://www.reddit.com/r/UsbCHardware/](https://www.reddit.com/r/UsbCHardware/)
We have a nice wiki and if you are still confused about USB C, ask away, we
try to help (chances are, I will answer :) ). You will also find a wonderful
cornucopia of interesting USB C devices -- not just the usual chargers, power
banks and docks but also a toothbrush, a razor, headphones, speakers, video
lights, a soldering iron... we _like_ USB C :)

~~~
tracker1
Just guessing the person that submitted later has significantly more karma or
popularity. It seems to happen quite a bit. There's also time of day to
consider, it's possible this made it in when more people are browsing by
newest and upvoted pretty early.

~~~
chx
The question rather is, why would the system allow the same URL to be
submitted twice. In the past when I tried to submit something already in, I
was redirected to the existing post and my submissions was converted into an
upvote.

~~~
dang
You get redirected to an existing post if it has already had significant
attention or is less than 8 hours old. Otherwise reposts go through.

~~~
chx
Why don't you just bump the post to newest if someone attempted to resubmit
it?

~~~
dang
I don't understand what you mean exactly.

~~~
chx
Let's presume [http://example.com](http://example.com) was never submitted.
So, when it is submitted, it is on the top of
[https://news.ycombinator.com/newest](https://news.ycombinator.com/newest) but
it doesn't get much attention.

Now let's resubmit [http://example.com](http://example.com) a few days later.
It should be on top of
[https://news.ycombinator.com/newest](https://news.ycombinator.com/newest)
again. But not as a new post. No, the first submission should be moved up
here.

Obviously after some time / amount of comments this makes no sense, people
resubmit years old links etc but thresholds can be set.

~~~
dang
Thanks, I see what you mean now.

If we did that then /newest would no longer be a simple chronological log of
everything posted to HN.

------
timw4mail
The Raspberry Pi foundation has their own "official" USB-C power adapter as
well (At least, they have it for pre-order). So I doubt it's the highest
priority.

I can still see this getting fixed in a future revision, but I think it will
be a while. It is an issue, but it doesn't make the pi 4 useless.

~~~
Traster
This is going to be a really sticky issue for a consumer. Randomly not working
with some subset of USB-C cables is the sort of thing you expect the
engineering team to consider - and they missed it. How do you think the
average enthusiast is going to figure out that their Pi4 no longer works
because of the USB-C cable they're using? At best they'll decide the cable is
faulty, use a different cable and probably bin the old one, at worst they'll
just come to the conclusion the Pi is bricked and bin it.

~~~
morsch
_How do you think the average enthusiast is going to figure out that their Pi4
no longer works because of the USB-C cable they 're using?_

Presumably they're going to search for _pi 4 does not power on_ and get their
answer as the first search result[1]. You know, the same way the average
enthusiast figures out the other twenty seven roadblocks they stumble on
during their RPi project.

Not to minimize that it'll be an issue for those people who don't happen to
have a compatible charger laying around.

[1] For me, at the time of posting: [https://hackaday.com/2019/06/28/power-to-
the-pi-4-some-charg...](https://hackaday.com/2019/06/28/power-to-the-
pi-4-some-chargers-may-not-make-the-grade/)

------
MobileVet
Curious what led to this decision. Reference schematics exist for a reason...
It seems odd to not use them.

~~~
nerdponx
That's what I was thinking. I've recently gotten into hardware design myself
as part of a hobby, and this is something I learned early on.

I'm sure they had good reasons to deviate from the reference (I assume they
are experienced hardware designers over there), but I'd be very curious as to
what those reasons were.

~~~
MobileVet
Considering the heavy emphasis on budget, it could very well have been on
reduced cost. Is a single resistor expensive? No but each decision adds up and
it may just be ingrained in the team's ethos.

Many times if we push something too hard, we apply the rule without
questioning whether it truly makes sense in a particular situation.

~~~
voidwtf
In this case they directly shorted two pins together though. That would give
me pause to ask why the two pins existed in the first place. Something that
should have led to the conclusion the author reached about the configuration.

~~~
michaelt

      That would give me pause to
      ask why the two pins existed
      in the first place.
    

Bear in mind, the USB-C connector is designed to be rotationally symmetric -
so you'll start your layout by paralleling up the four ground pins, and the
four bus power pins, and the two pins for USB 2.0 negative and the two for USB
2.0 positive.

I can understand why it might get overlooked, when someone has paralleled up
12 pins in the last 5 minutes...

~~~
voidwtf
I can see now how one might end up in the position, still the spec schematic
clearly shows two separate resistors. Curious either way :|

------
consp
I would not be surprised if this is the default in the bcm2711 documentation
and they simply took that as guidance.

------
ilikepi
So the take-away for consumers is...what exactly? Don't use certain types of
cables to power a RaspberryPi 4? And how does one identify a cable that could
cause problems?

~~~
kenny_r
My personal take-away is "hold off on buying a Pi4 until this issue has been
addressed in a future revision".

~~~
tryptophan
My takeaway is "use the official $8 charger they sell".

~~~
TeMPOraL
I'd agree (and that's what I did) except here I'd suggest "maybe wait until
they solve the core overheating issue".

Mine is idling at 64°C now that I took off the official cover; with the cover
on, it was idling just below the CPU throttling point of 80°C, which meant
that almost any computation caused it to start intermittently locking up.

~~~
zamadatix
Odd, mine is idling at 49 C in a 21 C room. This is the 4G version running
fully updated Raspbian without the desktop (one of the updates fixed the USB
controller using a lot of power at idle).

~~~
TeMPOraL
Mine is 4G too; I installed heatsinks on it couple hours ago and it now sits
at 61°C idle, with an external HDD attached (but not under I/O load) to USB 3
port. Slightly better, though arguably still ridiculously high.

------
seaborn63
I read it but I have no idea what it meant. I am very interested in getting a
Pi4, so can some of you more knowledgeable folks help me understand what this
means?

~~~
wereHamster
The Pi4 does not work with all USB-C chargers. You may be lucky and it will
work, or you may be unlucky and it will not work and you will have to buy
another USB-C charger (which again may not work).

The reason is that the developers of the Pi4 made a mistake while designing
the electronic circuit. They tried to design it themselves instead of copying
it from the specification.

~~~
JshWright
The other reason for is that the developers of the USB-C specifications left
us with a terrible confusing mess where visually identical cables have
different capabilities and behaviors.

~~~
derefr
If it’s confusing, just don’t use it. They could have stuck with a micro-B
charger, or a custom charger, and no one would have questioned it. Instead,
they decided they were confident enough in their understanding of USB-C to
implement it on their device. And they were wrong.

~~~
TremendousJudge
>They could have stuck with a micro-B charger

Somebody here said they were running into the maximum rated current for the
port

>or a custom charger

Literally everyone would have complained

~~~
tracker1
I don't think anyone would complain much if they supported a popular barrel
connector with a popular power draw. As it stands, I'll only ever use a Pi
with a charger sold as working with it after all the 3B+ issues I had (7
chargers, none worked without a warning on screen).

------
crshults
Had to fire up Eagle quick and take a look at my latest design (first time
using USB-C). Looks like I got lucky this time.

------
Roritharr
Wow, this is really bad.

I have enough USB-C incompatibility in my life to make this the issue that
makes me not order the Raspberry 4 until this issue is sorted out.

~~~
toomuchequate
Can you list examples where it hasnt worked?

I support a USB system and I this was my worry since day 1.

Curious, and it would be helpful

~~~
Roritharr
The usual fare of Dongle Incompatibility, we have a Dell USB-C Dongle that
won't provide display outputs to anything that's not a specific Latitude
Model, we have quite a few HP Notebooks that won't properly charge with
standard USB-C Chargers (even Apple ones), then there's the USB-C Audio
Adaptor issue where some phones output analog audio via USB-C and others need
an active adaptor with a DAC, which look physically identical...

The Standard, if you fully embrace it, is a mess.

------
baybal2
Usb PD + type C is hard. You have to read specs for days just to get a basic
idea of the logic governing the negotiation protocol.

I'm waiting for a single chip solution that will take upon the pain of dealing
with Type-C for me.

Besides the complexity of the spec itself, another "landmine" in dealing with
Type C + PD is the divergence of different PD implementations, proprietary
extensions from big brands, and... DRMed power supplies along with devices
with DRMed PD devices... Yes, the electricity is now copyrighted too.

~~~
brandmeyer
Common misconception: USB Power Delivery is not what the RPi4 is doing. The
base Type-C spec provides the schematic for analog signaling of either a
5V/1.5A or 5V/3A state. USB-PD uses a much more complex digital signaling
method across the CC lines, and is its own separate spec.

~~~
baybal2
Yes, it is not a PD. I am talking specifically about the case of doing USB
fast charging aka USB PD, which is much, much more complex

~~~
brandmeyer
The entire USB power situation is complex. Lets see, there's pre-enumeration
classic 5V/100mA, post-enumeration 5V/500mA, a host of proprietary signaling
methods for additional power, the more or less de-facto BC 1.2 method for
extra power, Type-C analog signaling for 5V/1.5A or 5V/3A power, and USB-PD
digital signaling. Oh, and there's also Type-C VCONN power in addition to VBUS
power.

The irony in all this is that Type-C analog signaling was meant to greatly
simplify the market situation and UX well above and beyond what happened in
the micro-B charger world. And it _is_ simpler. RPi4 just goofed in their
implementation.

------
w0mbat
There's a project management lesson here.

Raspberry Pi 4 was planned for 2020, but the Broadcom SOC went final much
sooner than expected, so they shipped the Pi 4 this year.

This sounds like a great thing, but the earlier release meant that the board
as a whole spent less time being used internally before release, and they
didn't have the time to shake out bugs like this.

The lesson: when you move to a faster release cadence, you need to be more
rigorous about QA because you have less time to find problems before release.

------
Scuds
Odroid, Latte Panda, Pine, and others went with dedicated tried and true
barrel jacks.

I appreciate re-using the same microusb cables and chargers for my iPhone and
headset charger for my Pi3, and not having to handle Yet Another Wall Wart,
but barrel jacks would have sidestepped this whole issue.

Were they hoping to have users use a single cable deliver power and data over
a single cable usb just like a pi zero w? [https://desertbot.io/blog/ssh-into-
pi-zero-over-usb](https://desertbot.io/blog/ssh-into-pi-zero-over-usb)

God DAMN I hope this doesn't turn into a recall.

~~~
Narishma
Why would this turn into a recall? AFAIU, this is just an inconvenience, not a
show-stopper since it only affects high-end cables.

------
mrlambchop
The Pi people are good folk - all that is needed is to run the USB 3
conformance tests and report back the results (both as USB PD sink and
source). Better to know the knowns than have a enthusiastic fan base find them
and we get into discussions like this!

I'd also recommend they put up a compatibility table of power supplies on
their website in time - probably cables as well! Its a good opportunity to
collaborate with the Google engineer who has been spending his non-core hours
on the USB-C madness.

------
amelius
> The short summary is that bad things (no charging) happens if the CC1 and
> CC2 pins are shorted together anywhere in a USB-C system that is not an
> audio accessory.

Why should it matter what kind of accessory it is used in?

> Each CC gets its own distinct Rd (5.1 kΩ), and it is important that they are
> distinct.

Why?

I think this article was not written by an electrical engineer. The reason why
this design is inadequate still eludes me. But, RPi should have probably used
the reference design, that's clear.

~~~
InitialLastName
> Why should it matter what kind of accessory it is used in?

I suspect you're misunderstanding what they mean by "audio accessory". They
don't mean "a standard digital USB device that happens to do audio-related
things". USB-C has a special-case allowance to drive analog audio signals
through the port (to allow all-analog headphones and such) that has its own CC
configuration.

>> Each CC gets its own distinct Rd (5.1 kΩ), and it is important that they
are distinct. > Why?

Because of the above; if the CCs use the same Rd, they're shorted together by
definition, which isn't allowed to happen. Especially since the USB-C format
uses the CC's to determine plug orientation.

~~~
dTal
>USB-C has a special-case allowance to drive analog audio signals through the
port

Wat. Just when I think I've heard it all...

~~~
floatboth
You've seen the Type C - 3.5mm headphone dongles right? They're so tiny and
cheap.. did you think they could be active? :)

------
geekamongus
I just wish I could find a 4GB Pi 4 in stock/for sale so that I could even
have this problem.

~~~
sbisson
I ordered one yesterday from the Pi Hut here in the UK. It shipped today...

------
_wmd
Pretty unfortunate design flaw, and hopefully it can be corrected, but this
post is horribly finger-pointy and the tone generally stinks. Would hate to
make a mistake while working around this guy

Can the link be changed to the apparent source article? It's not as bad.
[https://www.scorpia.co.uk/2019/06/28/pi4-not-working-with-
so...](https://www.scorpia.co.uk/2019/06/28/pi4-not-working-with-some-
chargers-or-why-you-need-two-cc-resistors/)

~~~
MobileVet
Seriously. Considering what a cluster the spec is and the budgetary goals for
a project like the Pi, this feels really harsh. The focus is on the mistake
and how trivial it was without any thought of why or how.

Pointing out mistakes can be done without being such a jerk about it.

~~~
joelhaasnoot
They spend months if not years on the design and crank out millions. Getting
USB-C right seems like a no-brainer!

~~~
MobileVet
I highly doubt they spent years on the design... But regardless we all make
mistakes.

What is a no brainer to you may not be to everyone.

Besides, you are fundamentally assuming this was a mistake and not a
deliberate design decision. Maybe they prioritized X over following the spec
100%. I may not make that decision, but that doesn’t mean they didn’t.

------
moonbug
Says more about the quality of no-name usb wotsits

------
fortran77
Everything works for me except my Apple charger. I blame Apple.

~~~
jesseb
Apple followed the specification, the Pi 4 does not. How is this Apple's
fault?

