SAMD21E18 bootloader programming - Unknown USB Device

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#1
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New to SAMD21.

Made a minimal schematic (please see below) based on Trinket M0, the chip it self and couple caps (C3,C2) with Micro-USB.

Was able to programm trinket bootloader (via SEGGER and also via Atmel Studio) the Trinket M0 bootloader (bootloader-trinket_m0-v3.14.0.bin)

but when attaching USB to Windows 10 I see "Unknown usb device" error, please see below:

 

 

Any help is appreciated!

 

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Trinket M0 fuses:

 

 

my fuses:

 

 

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Could it be because my device is self-powered (VBUS is not used)? Should I put some load on VBUS or pull up some pins?

Thank you.

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I just tested that bootloader in an old board that has the SAME21E, works fine. There is nothing on VBUS. You might have a connection problem (could be the USB cable/connector, not necessarily a problem on your board).

/Lars

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Lajon wrote:

I just tested that bootloader in an old board that has the SAME21E, works fine. There is nothing on VBUS. You might have a connection problem (could be the USB cable/connector, not necessarily a problem on your board).

/Lars

Thank you for doing that.

It's a very strange issue.

I was able to make one board (similar to Trinket M0) which was detected via USB and have been able to upload sketches to it for a week, until yesterday. It starts showing the same USB error right after I upload the sketch.

Tried to resolder all components on the board again - nothing. PC restart - nothing. I'm clueless.