Design flaw prevents the Raspberry Pi 4 from working with all USB-C cables

Shawn Knight

TechSpot Staff
Staff member

The Raspberry Pi Foundation a couple of weeks back announced its latest single-board computer. The Raspberry Pi 4 Model B features multiple enhancements over its predecessor including – for the first time – a USB-C connector for power delivery.

Unfortunately for the foundation and early adopters, an issue has been identified with the board that could hinder its use under certain circumstances.

As Tyler Ward explains (via Ars Technica), each of the two CC pins on the USB-C port is supposed to get its own resistor but for some reason, the Foundation designed the Pi 4 to share a single resistor. This makes the implementation a non-compliant design and tampers with compatibility.

It all boils down to the type of cable you use. Most cables should work fine although if you have an electronically marked or e-marked USB-C cable like the ones typically used to charge laptops, it may not work.

Raspberry Pi co-founder Eben Upton told TechRepublic that smart chargers with an e-marked cable will incorrectly identify the Raspberry Pi 4 as an audio adapter accessory and refuse to provide power. Upton added that he expects the issue to be fixed in a future board revision but for now, users will need to apply a workaround [use a cable that isn’t e-marked] to circumvent the problem.

“It’s surprising this didn’t show up in our (quite extensive) field testing program,” Upton said.

The Raspberry Pi Foundation isn’t the only one to have flubbed this up. Nintendo’s Switch also has a non-compliant USB-C port and thus, has compatibility issues with certain USB-C cables.

Masthead credit: Close up of Raspberry Pi 4 by mrnok

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yRaz

Nigerian Prince
As much as I love USB-C, it seems like it is having A LOT of problems on all ends. They tried to do too many things at once when, arguably, we we're better off having different standards instead of a "one size fits all" kinda deal
 

wiyosaya

TS Evangelist
As much as I love USB-C, it seems like it is having A LOT of problems on all ends. They tried to do too many things at once when, arguably, we we're better off having different standards instead of a "one size fits all" kinda deal
SMD resistors in quantity cost probably less than $0.01 each. Whoever made the decision to go with one instead of two is the one that should, IMO, take the responsibility for this action. I have to ask "what were they thinking - that they were going to get rich saving less than $0.01 per board manufactured?"

Specs are written for a reason. Not following the spec is questionable at best. If there are other problems (not addressed by this article) out there with USB-C, this makes me wonder if the manufacturer's of the devices with those problems did not follow the spec.
 

mcborge

TS Guru
I'm glad I haven't picked one up yet. You would have thought that this issue would have been noticed before production started. Manufacturers are so eager to get their products out the door these days it was only a matter of time before The Raspberry Pi Foundation did the same. It looks like I'll be waiting for the next revision.
 

EEatGDL

TS Evangelist
And here I am assuming that they go through a certification and compliance process for anything deemed "standard".
 

Stuach

TS Rookie
With ALL? Click bait.... With ALL...once again....how sad... And somehow these people think they should be taken at their word... Hey ,,,look ...the new FOX news
 
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cliffordcooley

TS Redneck
With ALL? Click bait.... With ALL...once again....how sad... And somehow these people think they should be taken at their word... Hey ,,,look ...the new FOX news
There was no click-bait in that heading. The heading was completely accurate this time.
 

cliffordcooley

TS Redneck
You are giving the word all a specific definition when it is not. The device would have to work with every cable in order to work with all cables. You are looking at this from the wrong perspective. I bet phrases like exclusive or and exclusive nor would blow your mind.
 
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Stuach

TS Rookie
It wasn't about cost. It was about not enough documentation in the wild that the engineers knew about. Lesson learned. This issue is being blown out of proportion. Use a cable/charger that isn't "E" marked, which most aren't and you're fine.
That WAS in the description
 

wiyosaya

TS Evangelist
It wasn't about cost. It was about not enough documentation in the wild that the engineers knew about. Lesson learned. This issue is being blown out of proportion. Use a cable/charger that isn't "E" marked, which most aren't and you're fine.
FYI - the USB Type-C specification was published on October 1, 2017. In fact, YOU can download it from the usb.org web site at this link https://www.usb.org/sites/default/files/documents/usb-port_controller_specification_rev2.0_v1.0_0.pdf

In fact, there is an even earlier compliance specification for Type-C connectors and cables that YOU can also download from here - https://www.usb.org/sites/default/files/USB_Type-C_Compliance_Document_rev_1_2.pdf

Not enough copies out in the wild? Uh-huh.
 
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amghwk

TS Guru
You are giving the word all a specific definition when it is not. The device would have to work with every cable in order to work with all cables. You are looking at this from the wrong perspective. I bet phrases like exclusive or and exclusive nor would blow your mind.
It may or may not have been meant to be a clickbait, but it did say "all" in the heading, which is crystal clear on it's meaning which turns out not to be true when you keep reading the article since within the gist it says "most cables should work fine..." which doesn't reflect on the heading title. This is one of the situations we describe as clickbait.
 

cliffordcooley

TS Redneck
It may or may not have been meant to be a clickbait, but it did say "all" in the heading,
OMG not another one. You people need to learn how to read. This device does not work with all cables. Why is that sentence so difficult to understand? If the device doesn't work with even one cable, it doesn't work with all of them. You two are making it sound as if the word all means 100% of the cables. That is not what it means.
 

kenc1101

TS Booster
No..."doesn't work with all" means it won't work with anything. Wholly hell...the entire race is done. ALL....are you daft
I think a better wording would have been "Doesn't work with SOME USB-C cables." I agree with you that the wording is a little confusing.
 
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kenc1101

TS Booster
It may or may not have been meant to be a clickbait, but it did say "all" in the heading,
OMG not another one. You people need to learn how to read. This device does not work with all cables. Why is that sentence so difficult to understand? If the device doesn't work with even one cable, it doesn't work with all of them. You two are making it sound as if the word all means 100% of the cables. That is not what it means.
Because the headline reads "Design flaw prevents the Raspberry Pi 4 from working with all USB-C cables". It doesn't say all cables, it says all USB-C cables. Which is very different. And misleading.
 

amghwk

TS Guru
OMG not another one. You people need to learn how to read. This device does not work with all cables. Why is that sentence so difficult to understand? If the device doesn't work with even one cable, it doesn't work with all of them. You two are making it sound as if the word all means 100% of the cables. That is not what it means.
Man...seriously? Okay think whatever you want.
 

mbrowne5061

TS Evangelist
As much as I love USB-C, it seems like it is having A LOT of problems on all ends. They tried to do too many things at once when, arguably, we we're better off having different standards instead of a "one size fits all" kinda deal
SMD resistors in quantity cost probably less than $0.01 each. Whoever made the decision to go with one instead of two is the one that should, IMO, take the responsibility for this action. I have to ask "what were they thinking - that they were going to get rich saving less than $0.01 per board manufactured?"

Specs are written for a reason. Not following the spec is questionable at best. If there are other problems (not addressed by this article) out there with USB-C, this makes me wonder if the manufacturer's of the devices with those problems did not follow the spec.
It may not have been a BOM decision. It may have been a decision based on board real estate or trace routing - they are trying to keep everything within the same footprint as the original design, and that will always get more and more tricky as time goes on and standards change.