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A macOS terminal command that tells you if your USB-C cable is bad

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Re: A macOS terminal command that tells you if your USB-C cable is bad

#191

Post by _carbyau_ »

ddalex wrote: post #190
fnord77 wrote: post #182

Earlier quoted context omitted.

I was able to charge my macbook from itself using that technique.

On this site we obey the laws of thermodynamics.

The pedant in me says it's more "In this universe..." thing. :-)

I understood their statement to be that the device didn't correlate outgoing power vs incoming power.

So it would indicate that it is charging, because power is coming in - but not tell you that a similar or more power is leaving.

I do find it frustrating in a world of battery management that we have indicators for charging and quick/fast/rapid charging. But near nothing for discharge or comparisons between incoming vs outgoing.

Re: A macOS terminal command that tells you if your USB-C cable is bad

#192

Post by ddalex »

_carbyau_ wrote: post #191
ddalex wrote: post #190

Earlier quoted context omitted.

On this site we obey the laws of thermodynamics.

The pedant in me says it's more "In this universe..." thing. :-) I understood their statement to be that the device didn't correlate outgoing power vs incoming power. So it would indicate that it is charging, because power is coming in - but not tell you that a similar or more power is leaving. I do find it frustrating in a world of battery management that we have indicators for charging and quick/fast/rapid charging…

I get what you're saying, I was making a joke referencing https://www.youtube.com/watch?v=tuxbMfKO9Pg

Re: A macOS terminal command that tells you if your USB-C cable is bad

#193

Post by Tepix »

gruez wrote: post #167
Tepix wrote: post #58

Why does it mention USB 3.2 (i.e. 20 Gbps) at all if it's for Macs? I thought Macs only support 10 Gbps and 40 Gbps, but nothing inbetween? (which is inconvenient because USB 3.2 Gen 2x2 20 Gbps external SSD cases are much cheaper than USB 4 cases for now). Also, he is calling a binary a script, which i find suspicious. This task looks like it should have been a script.

>Why does it mention USB 3.2 (i.e. 20 Gbps) at all if [...] USB-IF in all their wisdom used "USB 3.2" to refer everything from 5 gbps (USB 3.2 Gen 1×1 ) to 20 gbps https://en.wikipedia.org/wiki/USB_3.0#USB_3.2

Yes but i think in this context it means 20Gpbs, doesn‘t it?

Re: A macOS terminal command that tells you if your USB-C cable is bad

#194

Post by saretup »

Izkata wrote: post #130
rcxdude wrote: post #76

Earlier quoted context omitted.

Probably 180 degrees rotation in the plug (on either end). It commonly happens if one of the contacts or conductors for USB-PD signalling is not working correctly. (because of the way the pinout is designed to work either way around, the conductors that are used for signalling swap roles depending on the orientation)

Yep, 180 degree rotation.

Yeah so probably one or more of the pins are bad in your cable, since the usb c pin design the same from left to right in either orientation: https://www.delock.com/infothek/USB-3.2_USB-Type-C/usb-3.2-u...

Re: A macOS terminal command that tells you if your USB-C cable is bad

#195

Post by hn_acc1 »

ssl-3 wrote: post #181
tom_alexander wrote: post #122

Earlier quoted context omitted.

I'm curious as to why it is so expensive? Admittedly I know very little about electronics, and naturally the validation testing that a cable manufacturer does is going to be more thorough, but for consumer-grade testing couldn't we just have an FPGA or microcontroller scream the fibonnaci sequence in one end and another listen for the fibonnaci sequence on the other end? Sort of like memtest but instead ramping up sp…

Sure. If it's easy, then it's easy. For a "regular" USB C that supports USB 2.0 speeds (and is rated for 60W and therefore lacks an internal e-marker chip), there's just 5 wires inside: Two for data, two for power, and one for CC. There's nothing particularly complex about testing those wires for end-to-end continuity (like a cheapo network cable tester does). A charging-only cable requires only 3 wires. But fancier…

>(And no, that earlier 120Gbps figure isn't a lie.)

Is that 120 Gbps or 120 GB/s as the previous poster stated? 120 GB/s is on the order of DDR5 throughput - I doubt we have any kind of cheap cable tech that can carry that kind of bandwidth right now - while 120 Gbps is more like NVME 5 SSD speed.

Re: A macOS terminal command that tells you if your USB-C cable is bad

#196

Post by ssl-3 »

hn_acc1 wrote: post #195
ssl-3 wrote: post #181

Earlier quoted context omitted.

Sure. If it's easy, then it's easy. For a "regular" USB C that supports USB 2.0 speeds (and is rated for 60W and therefore lacks an internal e-marker chip), there's just 5 wires inside: Two for data, two for power, and one for CC. There's nothing particularly complex about testing those wires for end-to-end continuity (like a cheapo network cable tester does). A charging-only cable requires only 3 wires. But fancier…

>(And no, that earlier 120Gbps figure isn't a lie.) Is that 120 Gbps or 120 GB/s as the previous poster stated? 120 GB/s is on the order of DDR5 throughput - I doubt we have any kind of cheap cable tech that can carry that kind of bandwidth right now - while 120 Gbps is more like NVME 5 SSD speed.

Good catch. I didn't notice the factorization difference.

I myself definitely meant gigabits per second. 120Gbps is about what 2x 8k 60Hz monitors use at a constant rate in the simplest sense (pixels), so that's what I assumed they were talking about.

But it's more complex than that.

Looking a bit deeper: It seems that TB5 (which uses USB C) is natively a symmetric 80Gbps: 80Gbps one way, and 80Gbps the other way. 160Gbps, total, counting both directions -- plus or minus overhead.

It can also use a "turbo" mode where things are shifted to be 120Gbps one way (host-to-device) and 40Gbps the other way (device-to-host), which is still 160Gbps in aggregate.

It isn't clear how that dual-8k-display mode provides any extra bandwidth for other things that may be downstream like storage devices, but that's as deep as I feel like going.

And that is deep enough to answer your question: It is definitely in the neighborhood of [up to] 120Gbps [in one direction], and it is definitely never in the neighborhood of 120GBps [neither in any direction, nor in aggregate].

Re: A macOS terminal command that tells you if your USB-C cable is bad

#197

Post by klausa »

hn_acc1 wrote: post #195
ssl-3 wrote: post #181

Earlier quoted context omitted.

Sure. If it's easy, then it's easy. For a "regular" USB C that supports USB 2.0 speeds (and is rated for 60W and therefore lacks an internal e-marker chip), there's just 5 wires inside: Two for data, two for power, and one for CC. There's nothing particularly complex about testing those wires for end-to-end continuity (like a cheapo network cable tester does). A charging-only cable requires only 3 wires. But fancier…

>(And no, that earlier 120Gbps figure isn't a lie.) Is that 120 Gbps or 120 GB/s as the previous poster stated? 120 GB/s is on the order of DDR5 throughput - I doubt we have any kind of cheap cable tech that can carry that kind of bandwidth right now - while 120 Gbps is more like NVME 5 SSD speed.

I mistyped in the other post!

But 120Gbps (with 40Gbps in the other direction at the same time) is still _very fast_.

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