Issues Connecting Teensy 4.0 to Newer Macs with USB-C

T

Thundercat

Well-known member
Hi, for some time now I've been using internal USB-micro-B to USB-C adapters with my units that I sell with Teensy 4.0s. That way, externally on the units, users have a nice USB-C connector. It's been working fine.

Lately, however, I've noticed that newer Macs don't work AT ALL when directly plugging these units in. If I plug a USB-C to USB-C cable into the units, directly into the Mac, NOTHING happens. No power, nada. The units are dead to the world.

The workaround is goofy.

I must either connect the USB-C cable to a powered hub that is then connected to the Mac via USB-C, or it also works by connecting the unit with a USB-C to USB-A adapter, then re-adapting back to USB-C with a dongle adapter into the computer.

This, obviously, is a bit crazy, and I'm getting customer complaints at having to use a dongle adapter or a powered hub. When previously I didn't have this issue.

Is this a known problem of some kind? Teensy's simply not powering up when plugged directly into a USB-C connector and then directly into the Mac (when properly adapted internally from USB Micro-B to USB-C)?

Any thoughts?

Thanks,

Mike
 
Hi blackketter, that is super helpful.

It sounds like an ongoing issue for these kinds of units.

Can this be solved with a special cable with the 5.1k resistors on CC lines on both sides? Or is it a lot more involved? I am currently using a USB A-C adapter and this works, but it's kludgy for the product to tell people they can't plug the units directly into their computers.

Thank you again,

Mike
 
Thank you Paul. I'm looking into it with the cable manufacturer. I had custom cables made; perhaps they didn't follow spec. I'll post back what I find out from them.

Thanks again!
 
Hi, I'm still struggling with this. I had some custom internal short connectors made, USB-C to USB-uB, and still no joy. These are the second round from the manufacturer, and they are supposed to transfer data and power, and supposedly have whatever internal resistors are necessary. But they don't work. (I only had 5 samples made!).

After a lot of reading, I can see that the USB-C spec is all over the map. It's such a minefield. I don't even know what I don't know at this point.

So I thought I'd try this again, posting exactly what I'm doing, and what I'd like to do.

Here is the short internal connector that goes inside the product, from USB-C to USB-uB into the Teensy, that I had made to the 3.1 speed spec. It's supposed to transfer data and power, the one I mentioned above:

IMG_0525.jpeg

Here is what I'd like to do, that doesn't work:

IMG_0527.jpeg
Here is what does work:

IMG_0526.jpeg

As you can see, the working solution is goofy. Currently, pun intended, the Teensys do not power on if they are not connected to an USB-A to C adapter as shown, or plugged into a USB-A to USB-C external hub.

I'd like to be able to plug the units directly into a PC or Mac and have them powered.

Can anyone suggest what I'm missing here? Do I need to look for a certain USB-C to USB-C cable? What could be going wrong here?

Customers are complaining they can only use the units with external hubs or adapters. And after a lot of research, I'm more confused than when I started.

Thanks for any insights.

By the way I tried putting a Makerfire USB tester in between on the non-working example that gets no power, and the Makerfire USB tester showed nothing - it did not even turn on.

Thanks again,

Mike
 
@luni made a USB C adaptor for teensy complete with the required resistors, here it is.
Alternatively you could use something like this, though you will have to supply your own resistors.

Both the above solutions would then just need a bog standard USB C - USB C cable (OR USB C to USB A).
 
BriComp said:
@luni made a USB C adaptor for teensy complete with the required resistors, here it is.
Alternatively you could use something like this, though you will have to supply your own resistors.

Both the above solutions would then just need a bog standard USB C - USB C cable (OR USB C to USB A).
Click to expand...
Thank you so much!

I will check out this solution and post back.

If anyone has any other ideas I’m all ears.

Thank you again!

Mike

EDIT: OK checked it out; just wondering if there's any commercially available cables for this? While I can "roll my own," isn't this a common need? Also, mounting that solution would be tricky in current designs...

In any case, again, thank you BriComp
 
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Have you tried the cable in each possible orientation, at both ends? I'm wondering if they've messed up and only put one resistor inside that USB-C socket.

(The only other possibility is they didn't put in any resistors at all... or they've tied the CC pins together with one resistor, instead of pulling down both separately.)
The Pololu breakout board that BriComp linked does have them, you can see both of them going from CC1 and CC2 to GND.
 
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EDIT: OK checked it out; just wondering if there's any commercially available cables for this? While I can "roll my own," isn't this a common need? Also, mounting that solution would be tricky in current designs...
Click to expand...
I think it's unlikely, see below:
Ziginox
•4mo ago


If that cable truly has a 56k pullup, it will cause issues with PD negotiation. It could very well be that the written specifications are just wrong, because everybody was looking for A-to-C cables with a 56k pullup years ago.
Specifically, you'll end up with 30.55k pulldown when used with a device that has 5.1k pulldown built-in. A USB-C power supply wouldn't enable output with that weird value.
Really, you only time you should see pullup/down in a type C to C cable is ~1k pulldown on VCONN to signal that an emarker is present.
EDIT: I think the page is just wrong. If you look at their type-A to C cables, the wording in the description is verbatim.
https://www.juicebitz.co.uk/product...er-cable-data-lead-limited-edition-steel-grey
"WARNING: Non-certified cables can harm your device.
These have a 56kΩ Pull Up Resistor and abide to the correct power and data transfer speeds as follows:"

mpossibleDesk6419
OP•4mo ago

That's a good point. I hadn't even thought of the effect it would also have on the pulldown at the other end.
https://www.reddit.com/user/ImpossibleDesk6419/
ImpossibleDesk6419
OP•4mo ago

That's a good point. I hadn't even thought of the effect it would also have on the pulldown at the other end.

CaptainSegFault

It is incredibly unlikely the cable actually has such a resistor because nothing would work.

It is a tossup whether it is an error or a lie -- that is, something along the lines of:

  1. The seller copied over some text from an A to C cable and this is pure oversight.
  2. The seller is under the impression that the resistor is supposed to be there and is claiming it is there because everything works properly.
  3. The seller is lying in order to sell to end users confused about the old A to C cable issue.
None of these are a good look.
Click to expand...
 
jmarsh said:
Have you tried the cable in each possible orientation, at both ends? I'm wondering if they've messed up and only put one resistor inside that USB-C socket.

(The only other possibility is they didn't put in any resistors at all... or they've tied the CC pins together with one resistor, instead of pulling down both separately.)
The Pololu breakout board that BriComp linked does have them, you can see both of them going from CC1 and CC2 to GND.
Click to expand...
Thank you for the reminder - I tried the cables I have both ways, but they didn't work.

If I buy new cables, what do I specifically look for? It's not like they advertise "we install the 5.1k resistors on both sides."

Thanks,

Mike
 
BriComp said:
I think it's unlikely, see below:
Click to expand...
Thank you...my brain is melting...I can't figure out something so simple...it's all so incredibly complicated.

I'm also worried if I roll my own connector with the link you shared, would it be safe for consumers? I'm not an EE...hence my desire to find something already correctly implemented...

Thank you again BriComp.

Mike
 
These (the Color: 6Pin black CC1 2 variety) have the resistors already mounted, you would just have to wire/solder leads to D-. D+, Vusb and GND on the Teensy 4.0.
 
BriComp said:
These (the Color: 6Pin black CC1 2 variety) have the resistors already mounted, you would just have to wire/solder leads to D-. D+, Vusb and GND on the Teensy 4.0.
Click to expand...
I really appreciate that BriComp, thank you.

Would I have issues of the Teensy not being the main USB host? I would need to solder to the underside of the Teensy, right?

I’d reaaally like not to have to solder onto the bottom of the Teensys if possible, as I'd have to do these for dozens, and this contacts are tiny! Reliability (due to my soldering skills) might be a n issue.

Thank you so much, and I appreciate the wonderful support and options you and everyone has shared.

Mike
 
Can we re-cap what you are trying to do.
Are you trying to have a panel mount USB socket which connects to the Micro USB on the Teensy?

If so the panel mount does NOT need to be USB C, just more robust than the Teensy micro connector.

Here is a USB A panel mount to USB Micro connector/cable. Would something like that not suit?
z.png
 
BriComp said:
Can we re-cap what you are trying to do.
Are you trying to have a panel mount USB socket which connects to the Micro USB on the Teensy?

If so the panel mount does NOT need to be USB C, just more robust than the Teensy micro connector.

Here is a USB A panel mount to USB Micro connector/cable. Would something like that not suit?
View attachment 34414
Click to expand...
yes - clients have clamored for USB-C connectors. So I used to do what you are showing above, but then people feel it is not "future proof" etc for a product, and they are turned off...

So while the above connector is great for prototyping and DIY stuff, in a product people want USB-C connectors, which is why I'm using the USB-uB to USB-C internal connector.

I appreciate the legit question!

Mike
 
If these cables were custom made, guaranteed to have the resistors, and they don't work - I'd be taking it up with the manufacturer. It's really not complicated - if there's a USB-C socket on a device meant to consume power (as opposed to supply power), it needs the pulldown resistors on both CC pins.

I would bet that they've simply copied Adafruit's cable: https://www.adafruit.com/product/4056
Which, as the description states, "don't have PD resistors in them, so they are not going to be happy with Apple chargers or laptops that require PD resistors".
 
I would suggest using these (the Color: 6Pin black CC1 2 variety) and taking a bog standard USB mini cable and cutting off the end with the USB mini plug on it, expose the cables inside and solder to the above USB C breakout board.

That way you don't have to solder to the underside of the Teensy and you can test your "new cable system" before before connecting it to the Teensy.

Be aware that it is possible that different cable manufacturers may change the colour/arrangement of the internal cables so it is important to ensure polarity of the mini plug.

Easy way get a USB mini breakout and measure polarity of pins.
Red and green LEDs wired back to back with a limiting resistor would do the job very well. Make the GREEN led light for the good polarity and the RED led light for the wrong polarity.
 
BriComp said:
I would suggest using these (the Color: 6Pin black CC1 2 variety) and taking a bog standard USB mini cable and cutting off the end with the USB mini plug on it, expose the cables inside and solder to the above USB C breakout board.

That way you don't have to solder to the underside of the Teensy and you can test your "new cable system" before before connecting it to the Teensy.

Be aware that it is possible that different cable manufacturers may change the colour/arrangement of the internal cables so it is important to ensure polarity of the mini plug.

Easy way get a USB mini breakout and measure polarity of pins.
Red and green LEDs wired back to back with a limiting resistor would do the job very well. Make the GREEN led light for the good polarity and the RED led light for the wrong polarity.
Click to expand...
Thank you so much for the ideas and the links. I really appreciate it.

The issue isn't even so much "can I get this to work" - yes already with an adapter I can - but if I have to add some complicated additional soldering and cable cutting and shrink wrapping, this adds considerably to assembly time for the units I make. They already take a lot of time to make.

I am reaching out to the manufacturer in hopes of resolution to make the right cable with the 5.1K cables installed. It's a very slow process as they are in China and take days and days sometimes just to respond.

Alternately I can look for another cable manufacturer.

Thank you again so much BriComp. I really appreciate your time and ideas.

Mike
 
Thundercat said:
I am reaching out to the manufacturer in hopes of resolution to make the right cable with the 5.1K cables installed. It's a very slow process as they are in China and take days and days sometimes just to respond.

Alternately I can look for another cable manufacturer.
Click to expand...
Make sure it is clear that they need to be pull down resistors.
From the looks of things there are many sellers offering these cables online but they're all labelled as OTG cables, meaning they're designed for connecting USB-C peripherals to older phones that only have micro-b sockets. In that case they would have pull up resistors to let the USB-C device know that power is available.
 
jmarsh said:
Make sure it is clear that they need to be pull down resistors.
From the looks of things there are many sellers offering these cables online but they're all labelled as OTG cables, meaning they're designed for connecting USB-C peripherals to older phones that only have micro-b sockets. In that case they would have pull up resistors to let the USB-C device know that power is available.
Click to expand...
Hi jmarsh, thank you so much.

I didn't fully understand your reply. The cable will be attaching to the Teensy, with the micro-b socket. Wouldn't that fall under your second case, needing a pull UP?

Thank you,

Mike
 
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