Hello everyone,
I am posting this for anyone who might have the same problem regarding USB communication with the teensy 4.1 when using external power on the VIN pin.
For a project that involves a teensy 4.1 on a custom PCB I used the minimum voltage requirement of 3.6V for the VIN pin to conserve as much power as possible.
This gave me inconsistent serial detection and programming on my computer. After raising the VIN voltage to 3.9V by replacing a resistor on the PCB these problems dissapeared completely.
Serial detection and programming did work with 3.6V on VIN, but it could take up to a minute for it to start working. Once it was working however it was perfectly stable afterwards which was the weirdest part.
I was worried it might be a signal integrity issue at first, as the bottom d- and d+ pads are connected to a PCB underneath and routed to a USB mini port.
But it was the actual voltage on the VIN pin of 3.6V that was too low for consistent detection of USB. I dont know if this is reproducable on a different setup but if you come accross issues like very slow serial detection or slow programming it might be worth it to try this.
I am posting this for anyone who might have the same problem regarding USB communication with the teensy 4.1 when using external power on the VIN pin.
For a project that involves a teensy 4.1 on a custom PCB I used the minimum voltage requirement of 3.6V for the VIN pin to conserve as much power as possible.
This gave me inconsistent serial detection and programming on my computer. After raising the VIN voltage to 3.9V by replacing a resistor on the PCB these problems dissapeared completely.
Serial detection and programming did work with 3.6V on VIN, but it could take up to a minute for it to start working. Once it was working however it was perfectly stable afterwards which was the weirdest part.
I was worried it might be a signal integrity issue at first, as the bottom d- and d+ pads are connected to a PCB underneath and routed to a USB mini port.
But it was the actual voltage on the VIN pin of 3.6V that was too low for consistent detection of USB. I dont know if this is reproducable on a different setup but if you come accross issues like very slow serial detection or slow programming it might be worth it to try this.