Hi,everyone Does the report dexcriptor support negative value.i have checked the keil usb demo of hitex board,the report descriptor is declared as unsigned char. one more question,in the get_descriptor function, case USB_CONFIGURATION_DESCRIPTOR_TYPE: pD = (BYTE *)USB_ConfigDescriptor; for (n = 0; n != SetupPacket.wValue.WB.L; n++) { if (((USB_CONFIGURATION_DESCRIPTOR *)pD)->bLength != 0) { pD += ((USB_CONFIGURATION_DESCRIPTOR *)pD)->wTotalLength; } } what is the wValue.WB.L in the configDescriptor indicate?Why here use the wTotalLength.Thanks!
No, you are wrong. The original code is correct.
USB Manual says the following: bLength - Size of descriptor wTotalLength - Total length of data returned for this configuration. Includes the combined length of all descriptors (configuration, interface, endpoint, and class- or vendor-specific) returned for this configuration.
Since we scan through complete data for one configuration the wTotalLength is correct.