My first efforts: I modified the Blink program that comes with it to shorten the on time to 100ms.
That worked OK so I added a few lines of code to send out a 1 microsecond pulse on another pin once a second.
Now the program compiles OK but upon upload I get a message "No Teensy boards found... Press the button...
Pressing the button does not help. Any ideas.
Code attached.Pulse_speed_test.ino