Teensy 4.1 solder pads for USB ...

kaspencer

Member
Good morning all.

I have been using Teensy 3.2 micro-controllers for a project very successfully. For various reasons, I have to solder the PC-USB cable to the reverse of the board (mainly, no room for a USB plug), and I have done that successfully several times with no issues, as the pads are clearly identified.

However, I have now moved the project to the Teensy 4.1, and it is working. However, I need to sort out the solder points for the four PC-USB wires. I note that D+ and D- are clearly identified on the new 4.1 board, but with the 3.2, I also connect the PC-USB-Red to the large upper pad (USB+) and PC-USB-Black to the large lower pad (GND).

Could someone kindly tell me where on the T4.1 board should I connect the PC-USB-Red and the PC-USB-Black wires from the PC-USB cable? I note that there are 4 nearby (smaller) plated through holes and wondered whether I should use any of those for the PC-USB-Red and the PC-USB-Black wires? I don't really wish to play Russian Roulette with those two connections, because it looks to me as though all of them actually connect to the micro-USB socket case - if so I'd be shorting the PC-USB+ and GND!

Any advice will be gratefully received!

KASpencer
 
I know, the sequence of 5 USB pins on the side are for 2nd USB that one typically uses for USH-Host, but can be programmed as USB device.
But if you, like me, wanted to use USB not only for Serial but also for programming, you must use the two tiny dots below the USB connector.
I wished Paul had made the two dots larger, but, I guess, they were originally thought for pogo pins.
The USB GNG (black line) goes to Teensy GND.
 
Thanks alot for that, WMXZ!

I spotted the tiny circular pads for D+ and D-, and they are fine as they are labelled.
And thanks for pointing out the GND connection for the PC-USB-Black wire.

Looking closely at the board, I think that the PC-USB-Red wire will go to the pin, unlabelled on the 4.1, but labelled on the 3.2 as VUSB, with a larger solder pad adjacent to it?

Thanks again if my assumption in my last line above is correct, than I have it - excellent.

KASpencer
 
I wished Paul had made the two dots larger

Lots of PCB routing guidelines for USB say not to have any routing stubs like these pads. For Teensy 4.0 I didn't route any stub traces. On Teensy 4.1 I risked these 2 small pads. Indeed the main idea was for pogo pins so we can verify the connectivity during the much more detailed bed-of-nails test.

Teensy 4 USB runs at 480 Mbit speed, so the routing requirements are much more important than the 12 Mbit speed on Teensy 2 & 3. How large do you believe those pads and routing stubs could be?
 
Teensy 4 USB runs at 480 Mbit speed, so the routing requirements are much more important than the 12 Mbit speed on Teensy 2 & 3. How large do you believe those pads and routing stubs could be?
I appreciate the risk and routing. But if the two pads were small ovals (or rectangles) twice the size of the actual dots, soldering would be easier, safer?
Anyhow, I succeeded to solder two short wires from T4.1 to custom base board before soldering teensy to header.
As with OP, I cannot afford space for a USB connector, but need possibility to download firmware while teensy is in small housing and speed is not as critical, but welcome.
 
Would there be any concern with using pogo pins on a production board, to link the D+ and D- pads to the circuit board it is going to be soldered to?
 
Would depend on the pin quality and selection and placement being all good.

For the T_4.0 PJRC hardware beta all the under pads were connected with POGO pins and that worked well for USBHost and the SDIO SD pins and the other pads, except the T_4.0 was socketed and that number of sprung pins over time would push the board upwards.

With only two POGO pins for Device USB that won't be such an issue, especially if as read the T_4.1 will be soldered in place? If socketed a method to secure the board would assure it can't loosen.
 
Thanks for the info and suggestions! I'll explore both. Ideally, we won't have to once Paul releases the bootloader for 4.x :)
 
usb cable soldered to pads makes teensy 4.1 disappear

Hi there,
I recently upgraded from 3.6 to 4.1 for a project..
I can't manage to see the 4.1 with an usb cable soldered to pads.
Even the normal usb connector stops working when I solder some D+ D- wires to the soldering pads.
Do you have any suggestions?
Thanks, kind regards
E
 
Hi there,
I recently upgraded from 3.6 to 4.1 for a project..
I can't manage to see the 4.1 with an usb cable soldered to pads.
Even the normal usb connector stops working when I solder some D+ D- wires to the soldering pads.
Do you have any suggestions?
Thanks, kind regards
E
Unfortunately the T4.1 has been lost to sight as it has been hidden inside the working project since 2020-ish and I have had no need to look at it again. So I can't at the moment supply and photographs or advice, but I soldered my connections as decribed in my posts, and all has worked completely normally ever since.
Best wishes
KASpencer
 
Unfortunately the T4.1 has been lost to sight as it has been hidden inside the working project since 2020-ish and I have had no need to look at it again. So I can't at the moment supply and photographs or advice, but I soldered my connections as decribed in my posts, and all has worked completely normally ever since.
Best wishes
KASpencer

Thanks for your reply,
I managed to get it work by soldering the wires perpendicularly to the teensy.
With the wires standing flat, it doesn't work...
kind regards
 
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