strange descriptor sets for WCH-Link (v2.6) DAP mode

I just checked the descriptors of WCH-Link with UsbDeviceTreeView because i have some problems with the link.

I am using WCH-Link_APP_IAP_ARM.bin from MRS 1.82. Binary version seems to be 2.60 although it reports 2.06 in bcdDevice field.

  1. There is no usb 2.1 out there link should either report 1.1 (prefered) or 2.0 in bcdUSB field.

  2. Interfaces have to be in increasing order (for 3 interfaces. 0, 1, 2) Link has interface 0,2,3 

  3. IAD descriptor is expecting stready increasing interfaces or may fail on some OS. (Linux?)

  4. UsbStr no 5 does not exist but is reported in the CDC Data Interface 

while its not a functional problem i guess this should be changed to satisfy USB2CV from

Hello, there is no compatibility problem at present. We will evaluate your proposal,thank you!

ok maybe it would be a good idea too to set the usb serial string to the build in UUID to avoid com port confusion when more than one link is attached 

Currently all links will use the same serial no, which is not allowed by the usb spec.

I just patched the above things in the binary for test purpose. UsbDeviceTreeView does not complain any longer.

Sorry, the test found that there is a problem with the CDC under Linux, and it will be improved for compatibility in the next version,thank you

mm just learned there exists a usb 2.1 extension to the usb20 spec. So probably 0x210 for bcdUSB is a correct value.

I did not know that before, sorry for the confusion.

mm any news on this? Now its 2.7 but exept for the version no its still the same

Hello, the latest firmware version of WCH-Link is V2.9. The attachment below shows the latest firmware. You can upgrade and try it out

The usb 2.1 is used for WinUSB


the firmware you send seems not the DAP version. I supose its risc version.

Anyway it uses UIID as a serial and the interface no are in acending order.

Is there a DAP version 2.9 too? Is there a webside with the various firmware versions?

ok i suppose there now newer FW as 2.7 delivered by MRS for CMSIS-DAP mode. 

Anyway 2.6 and 2.7 are the same