I cannot use USB DFU bootloader

[SShir.2]

I am using STM32L082KZT6 and want to use bootloader with USB. I have read instruction and in my perspective I thought that just by connecting boot0 pint to high then usb bootloader mode would start. But it didn't. I putted the schematic picture below. Please give me any advise.

[Uwe Bonnes]

As you do not power the device from USB, beside pulling boot0 to high, you need ti reset the device with the cable connected. Otherwise the recommended 100 nf capacitor to ground is missing on NRST and may also lead to booting hickups.

[SShir.2]

Thank you for your reply. As you can see, boot pin and reset pin are designed as the pin to be shifted, so I have tried that reset pin. And also I successed this schematic for other stm32 and I am thinking of system memory on this MCU has some issues.​ Do you know the way to make sure if the bootloader has issures or not?

[TDK]

1. Power the chip
2. Short BOOT0 to 3.3V
3. Toggle NRST low then high.

The chip will enter the bootloader.

> And also I successed this schematic for other stm32 and I am thinking of system memory on this MCU has some issues.

The likelyhood of the chip being the problem here is very low.

Your schematic has DM connected to DP, which isn't what you want, but I think it's just mislabeled in your schematic.

BOOT0 is floating in your schematic which is never what you want.

I don't see any bulk capacitor on VDD, but probably not the problem either.