2 USB Connections on Teensy 3.5 or LC

[jlvandusen]

Hello

I am trying to determine best method to add another USB adapter (type A) so I can plug in to the PC to watch debug while I use the built in USB micro with adapter to connect to a bluetooth dongle.

The goal is to use the existing USB to host a BT Class 1 EDR dongle for use with a robotics project (usb host shield) and the additional USB to debug...

Thoughts?

[KurtEck]

Hard to say.

If you are simply wanting to output some debug information from a Teensy such as a 3.5 to the PC without using the main USB connection.

I will then typically use some form of USB to serial Adapter. Sparkfun sells several of them, like: https://www.sparkfun.com/products/12731

Then you simply connect up the signals. where the TX pin goes to a serial ports RX pin and like wise the RX pin goes to probably the same Serial ports TX pin. Example pins 0, 1. You also need to hook up a ground wire as well.

The T3.5 is 5v tolerant so most any adapter should work. However I believe the LC is 3.3v only so make sure to choose an adapter whose signals output at 3.3v.

[jwatte]

Yeah, just add one of those cheap Chinese USB serial dongles, and wire it to one of the serial ports on the Teensy.
Beware that, for that setup, making sure the baud rate matches up is actually necessary!
For the SerialUSB connection, the baud rate configured doesn't matter, because USB always runs its own communication at full speed.

So, if you set the serial port on the PC to 115200 bps:

# stty 115200 < /dev/ttyUSB0
# dd if=/dev/ttyUSB0 bs=1

then you write to it on the Teensy like so:

  Serial2.begin(115200);

  Serial2.println("hello, world");

This is assuming that you wire the USB serial dongle to the RX2/TX2 pins on the Teensy.

[jlvandusen]

Is there a way to alternatively move the usb shield code to use the other serial? that way I can have the BT in the other and debug direct and upload code from the main usb?