VCP Demo

[greg_t]

Posted on May 05, 2011 at 11:13

VCP Demo

[Tesla DeLorean]

Posted on May 17, 2011 at 14:33

At a guess it is using the Unique ID of the STM32 as a USB serial number. The PC will then enumerate each uniquely. Hard code an alternate, constant, serial number.

[tsuneo]

Posted on May 17, 2011 at 14:33

Same serial number to each device is not recommended way.

Rather, no serial number is better.

When two or more devices of the same serial number of the same VID/PID are connected to single PC at the same time, Windows is confused to identify the devices. It may fail on the second device. For no serial number, Windows identify them at the USB ports to which the devices are plugged in.

On the Windows side,

IgnoreHWSerNum registry setting makes Windows ignore the difference of serial number. Instead, Windows see USB port 'location'. With this setting, all your VCP devices are assigned to the same COM port number, as long as they are plugged into the same USB port. 

Using a registry editor (regedit, etc), 

Add IgnoreHWSerNum entry under this key, 

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\UsbFlags\ 

The entry name should have VID/PID of the device.

For a device VID/PID of 0xABCD/0x1234

IgnoreHWSerNumABCD1234 

Set its value to 0x01 (REG_BINARY, length must be exactly one byte) 

IgnoreHWSerNum is helpful for production and testing of USB devices.

Tsuneo

[greg_t]

Posted on May 17, 2011 at 14:33

Thanks guys - this is very helpful information 

[greg_t]

Posted on October 16, 2011 at 09:51

How do I make my device to be without serial mumber ?

[Tesla DeLorean]

Posted on October 16, 2011 at 15:51

As I recall you put a zero in the iSerialNumber field, in the device descriptor

http://www.beyondlogic.org/usbnutshell/usb5.shtml