I am having issues power the Teensy 4.0 from an external source to the USB ie VUSB.
I have cut the pads to separate Vin from VUSB.
I have then applied 5v to Vin and I get nothing from the Teensy.
Probe the 3.3v pin and there is 3.3v there.
If I remove 5v from Vin, and then apply 3.3v to the 3.3v pin, again the Teensy does not spark up.
Reconnect VUSB to Vin and it all works as expected.
I have read the thread "Teensy 4.0 Can't program when using external power supply"
but there does not seem to be a definitive outcome to that thread; plus it is suggesting that is powering up ok, just not programming.
I have two Teensy 4.0 and they both behave the same.
I have reviewed the schematic, and it should be a simple, cut the pads, and apply 5v to Vin.
However, when you disconnect the USB, then the Teensy starts to work.
My only thought is the GND from the USB is dragging something down, and maybe there needs to be 2 pads one for VUSB to Vin and one for the USB Gnd to Gnd.
I have cut the pads to separate Vin from VUSB.
I have then applied 5v to Vin and I get nothing from the Teensy.
Probe the 3.3v pin and there is 3.3v there.
If I remove 5v from Vin, and then apply 3.3v to the 3.3v pin, again the Teensy does not spark up.
Reconnect VUSB to Vin and it all works as expected.
I have read the thread "Teensy 4.0 Can't program when using external power supply"
but there does not seem to be a definitive outcome to that thread; plus it is suggesting that is powering up ok, just not programming.
I have two Teensy 4.0 and they both behave the same.
I have reviewed the schematic, and it should be a simple, cut the pads, and apply 5v to Vin.
However, when you disconnect the USB, then the Teensy starts to work.
My only thought is the GND from the USB is dragging something down, and maybe there needs to be 2 pads one for VUSB to Vin and one for the USB Gnd to Gnd.