Running a Swan, my Win10 computer does not see a serial port when I plug into the Swan’s built-in USB micro. I have confirmed that the option bytes are set properly using STM32CubeProgrammer and the STM32 CLI. When I run Zadig, I do see a port “STM32 Bootloader”, I’m not an ace at using Zadig but the installed driver seems to be WinUSB 1.1.0.0 and Zadig offers to upgrade it to WinUSB 6.1.7600.16385.
I’ve also tried different ports and USB cables.
Hi @occamman,
I always recommend using an STLINK debugger when working with any STM32-based host. It’s just far and away the best experience.
If that isn’t an option, did you upgrade the WinUSB driver with Zadig (wasn’t quite clear in your text if you followed through or not). And of course reboot 
. More context is available in this blog post.
Rob
Thanks Rob.
Agree on STLink! I use it during development, but need a USB/Serial port for shipping product.
I tried upgrading the driver. Even rebooting . Still no USB port.
In Windows Device Manager, I do see “STM32 BOOLOADER”.
Hi @occamman,
Under which category in the device manager do you see “STM32 BOOTLOADER”? For example, on Windows 11 with just a Swan (no STLINK) in its bootloader, I see this:
Under my Win10 computer with STLINK disconnected, it shows up under Universal Serial Bus Devices as STM32 BOOTLOADER. I just tried this out on my Win11 computer and I don’t see anything in Device Manager.
Working off of a hunch here. I would try installing STM32CubeCLT and see if that helps. Gotta love the STM32 tool chain!
Rob
I apologize if I’m being obtuse – what should I do with the STM32CubeCLT once installed?
Nothing actually - it installs some proprietary software from ST that, in many cases, resolves these types of issues on Windows.
OK. I installed, re-booted, no improvement.
Hi @occamman,
A colleague pointing out something to me that I may have missed early on. If you do see “STM32 BOOTLOADER” in device manager, then your Swan is already in its bootloader and ready to receive updated firmware. If you want to reset the board you can press the white RST button.
OK, I’ve had a chance to follow up on this…
I’m still unable to see the Swan USB as a serial port from my PC.
The STM32 BOOTLOADER device only shows up when I do the Boot/Reset combo.
I’ve now tried this on two different computers, one with Win10 and one with Win11, and using two Swan units. AFAICT, in no case does device manager see any device until I go into bootloader mode.
Hi @occamman,
I’m trying to replicate this problem, but I’m unable to. I just pulled a fresh Swan out, plugged it into my Windows 11 PC, and under “Ports (COM & LPT)” in Device Manager it shows up as “USB Serial Device (COM3)”.
I just want to confirm you don’t see any additional device appear in Device Manager when you plug the Swan in?
Rob
I don’t see anything else, until I go into the bootloader. Also I do not get the “USB attached” sound when plugging in.
Just verifying - you’ve tried this on multiple Swans with different Windows computers as well? While one faulty Swan would be surprising, multiple faulty Swans is extremely unlikely. And you’ve tried different cables? And you’re not using a USB dock or anything - connecting directly to the computers?
The answers to all of those questions is “true”. Which I admit, seems pretty odd.
I was just reminded of this thread, where installing STM32 Cube IDE along with Cube Programmer resolved the issue on Windows. Worth a shot!