External USB to program Teensy 4.1

J

jayd99

Member
Hi,
We're currently developping a PCB to connect different peripherals to the Teensy 4.1. We tried adding external USB connectors to program the teensy without success. We've connected D+, D- and 0V but not VUSB since our teensy is already powered externally. Does anyone happen to have a schematic of a PCB that has working external USB port to program a Teensy 4.1


Best regards,
Jeremy
 
Maybe you've read this already / looking for something more discrete, but Mark's explanation here involves splitting a panel mount cable to program an externally powered Teensy without needing to sever the trace on the board itself:

kd5rxt-mark said:
@Robot:

If I understand your request correctly, I did that exact same thing for my TeensyMIDIPolySynth project using the Adafruit PowerBoost 1000 (2465) & the Adafruit Panel Mount Extension USB Cable Micro-B Male to Micro-B Female (3258). I opened up the middle of the cable & split the 5VDC & GND wires, leaving the D+ & D- signals intact. The power wires from the panel-mount socket were connected to the input of the PowerBoost, & the power wires to the Micro-B Male connector were connected to the output of the PowerBoost. The Micro-B Male was plugged into the T4.1 (no cutting of the power trace). Cabling from the PC to the panel-mount socket allowed programming/serial monitoring of the T4.1 (& low-current battery recharging, although that was just a by-product of the connectivity). Cabling from an external USB supply to the panel-mount socket allowed full-current battery recharging and/or powered operation. With nothing connected to the USB, portable operation on battery power was accomplished.

I believe that, with your intent & hardware (if I understand everything correctly), you should definitely be able to do the same thing.

Mark J Culross
KD5RXT
Click to expand...

Although this^ does employ the use of another board - Adafruit Powerboost 1000C

...cable split example as seen in option #2:

Using External Power and USB with the Teensy USB development board

www.pjrc.com www.pjrc.com

Best,
Colby
 
My issue isn't actually powering my Teensy while programming it. I'm fine with cutting the trace. I want to be able to use an external USB which I've added on my PCB. I thought it'd be pretty straight forward but we haven't been able to make it work yet...
 
We're actually unable to program the teensy with any other USB port than the one already on the Teensy. Are there special requirements for the traces or any pin that needs to be connected for us to be able to achieve our goal?
 
We're actually unable to program the teensy with any other USB port than the one already on the Teensy. Are there special requirements for the traces or any pin that needs to be connected for us to be able to achieve our goal?
Click to expand...
Can you show us what other USB ports you have tried? What cables did you use?
There can be many causes for failure, like noise, polarity, impedance, etc.
After all, we are talking about high-speed USB at 480Mbps.

Paul
 
We're using this Micro-USB port bought on Digikey.
The PCB schematic is confidential, but we've literally connected D+ and D- to D+ and D- of the Teensy.
We're using the same cables used while programming the Teensy from its own USB port.
 
OK. Can you show us that part of the PCB layout? I would like to have a look at how the D+ and D- traces are run on your PCB.
How does your PCB make contact with the Teensy D+ and D- pins?

Paul
 
jayd99 said:
The PCB schematic is confidential, but we've literally connected D+ and D- to D+ and D- of the Teensy.
We're using the same cables used while programming the Teensy from its own USB port.
Click to expand...

This really should work. Similar connections have worked for other people, so I'm pretty sure the problems you're facing are a mistake or misunderstanding in the connection, even though it seems so simple.

Obviously we can't do much to help troubleshoot something we can't see. But hopefully knowing it should work, and connecting a USB cable to those pads has worked for others, helps at least somewhat?
 
What you could do is connect 2 USB-A to micro-USB cables, one to the Teensy and the other to your PCB. Then measure conductivity between the corresponding pins of both USB-A connectors. And check for shorts as well.
All while both boards are not powered ofcourse.

Paul
 
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