Cannot open the com port

3DPiper · 22 Apr 2021

I am using the program STM32Flasher from this link:
FLASHER-STM32 - STM32 Flash loader demonstrator (UM0462) (replaced by STM32CubeProgrammer) - STMicroelectronics
When I run it, it correctly finds the only used com port. But when I click Next, I always get the error "cannot open the com port, the port may be used by another application'
THis is from a clean boot, how do I see what else is using the port?
In the device manager it is the only listed com port

Paul Black · 25 Apr 2021

Hello @3DPiper,

3DPiper said:

. . . when I click Next, I always get the error "cannot open the com port, the port may be used by another application'
This is from a clean boot, how do I see what else is using the port?
In the device manager it is the only listed com port

View Port Use Along with Process Names => netstat -an
View Port Use Along with Process Identifiers => netstat -aon

I did a bit of investigating for you and found this => How to Check Open TCP/IP Ports in Windows

I hope this helps.

Samuria · 25 Apr 2021

Look in device manager check the IRQ and DMA often its shared with other resource

Compumind · 25 Apr 2021

Hmm....

Perform the steps mentioned below and see if it helps.

a: Press the Windows key and the X key
b: Select device manager
c: Go to the view menu and select "Show hidden devices"
d: Select the grayed out COM ports (if any), right click and choose "Uninstall" from the popup menu.

Please revert back if you face any issues with clearing the com ports.

HTH

Gurn Blanston · 25 Apr 2021

Is the STM32Flasher a USB type COM port? Is the device plugged into the port while you are trying to connect? Try unplugging it and replugging it during the connect operation when it fails.

Also, is the driver for the STM32Flasher installed properly?

EOF · 25 Apr 2021

Is your STM32Flasher original one or some sort of clone china derivation?
Can you post a picture about your pcb maybe?

I think it is an USB type of programmer, if so, go to Device Manager and find the list of COM ports.
When you expand the com port section, disconnect the stm and check if some of the COM por is disapeared
If you identified which COM port is you stm installing, then select the same COM port in the stm too.

Should work.

Some time, clone stm's hav problems with high number of COM ports like if you COM port is designated as a COM22...

In this case, put you stm COM number lower, something to COM3 or COM4 .