Unable to get B-L072Z-LRWAN1 into DFU mode

[SBurs.1]

I'm wondering if i'm missing something here.

I've hooked up BOOT0 to the 5V pin on CN2. I have nBOOT1 set to 1, and i'm connected to the device via the ST-LINK as the other usb port doesn't seem to be active. I've also installed the udev rules, and just to be sure i tried removing all of the non stm related udev rules. no luck.

When i start up this way the normal application doesn't start up, so i appear to be effecting the bootloader somehow, but my computer doesn't recognize the device as a DFU device.

Any ideas?

[SBurs.1]

dmesg:

[75737.717267] usb 3-1: new full-speed USB device number 49 using xhci_hcd

[75737.867965] usb 3-1: New USB device found, idVendor=0483, idProduct=3752, bcdDevice= 1.00

[75737.867974] usb 3-1: New USB device strings: Mfr=1, Product=2, SerialNumber=3

[75737.867977] usb 3-1: Product: STM32 STLink

[75737.867980] usb 3-1: Manufacturer: STMicroelectronics

[75737.867982] usb 3-1: SerialNumber: 066CFF343635484257215550

Finds the device fine. I'm guessing i must be doing something wrong trying to set the BOOT0 pin?

[Tesla DeLorean]

You're using the wrong USB connection.

The ST-LINK doesn't communicate with the L0 part via USB on the board.

The Target's USB connector needs to have DP/DM pins connected, seem to recall you need to add 27R resistors, look at the schematic.

[SBurs.1]

thanks. so can i simultaniously power the board via ST Link and the microusb?

i note from the manual:

If the board is supplied by CN13, by battery or by CN11, SB37 must be removed to release the RESET pin managed by ST-LINK. In that case the ST-LINK is no more powered.

i'd rather not do that if i don't have to.

[Tesla DeLorean]

The board is complex, and allows for multiple powering options.

Depending on the ST-LINK firmware, and it not being powered, can lead to issues with it holding the NRST line.

You can use the ST-LINK via it's USB to program the L0 via it's SWD interface.

If you want to use the USER USB to connect to the L0 in System Loader mode, with USB/DFU, you're going to have to modify the board. Suggest you print the schematic and use a high-lighter pen.

I'd expect you'd need to add connectivity of the DP/DM lines, probably jumper power back to the ST-LINK via JP5 so that you can get an HSE clock from it that the STM32L0 can use for USB operation, and SB13 that gets that clock into the L0.

[Tesla DeLorean]

Ok, AN2606 suggests it uses HSI48 for USB operation, so doesn't need HSE source.

https://www.st.com/resource/en/application_note/cd00167594-stm32-microcontroller-system-memory-boot-mode-stmicroelectronics.pdf

[SBurs.1]

awesome, detailed answer. thanks