I have a mystery regarding which I hope some other Teensy users may be able to supply some clues or insights. I have the following devices:

  • iMac Computer
  • 4 Teensy 3.2 modules, which I will refer to as TeensyA, TeensyB, TeensyC, and TeensyD, all programmed with the blink example app.
  • Anker powered (with AC adapter) USB hub with 8 USB ports and 4 USB charging ports, referred to as HubA. Connected to iMac with a USB3 cable (USB3 B to USB3 A connectors).


Here's the basic issue:

  1. TeensyA is connected to HubA, and is programmed with Blink example
  2. HubA is connected to iMac
  3. Power is applied to HubA and iMac
  4. TeensyA is not blinking the LED (i.e. TA is not powered)
  5. If TeensyA is disconnected from HubA, and then reconnected, the LED blinks


Other clues and observations:

  • If one substitutes any of TeensyB, TeensyC, or TeensyD in the above scenario, the LED blinks in step 4.
  • If non-powered hub is substituted for HubA, then TeensyA blinks when power is applied to iMac
  • If TeensyA is connected directly to a USB port of iMac, TA blinks when power is applied to iMac


So, the stated issue ONLY occurs with TeensyA, whereas all the Teensys are running the same Blink app, and TeensyB/C/D power up when power is applied to the hub and computer. Another possible clue is that I once mistakenly connected TeensyA to one of the hub's charging ports; but, TeensyA has shown no problems other than the power-up issue (once powered, it runs all apps without problems).

It's not ideal to have to disconnect and reconnect TeensyA every time I boot the computer, but that's presently the only way I can get it to power up.

My thanks for any thoughts or ideas.