/********************************************************************FileName: usb_descriptors.cDependencies: See INCLUDES sectionProcessor: PIC18 or PIC24 USB MicrocontrollersHardware: The code is natively intended to be used on the followinghardware platforms: PICDEM FS USB Demo Board,PIC18F87J50 FS USB Plug-In Module, orExplorer 16 + PIC24 USB PIM. The firmware may bemodified for use on other USB platforms by editing theHardwareProfile.h file.Complier: Microchip C18 (for PIC18) or C30 (for PIC24)Company: Microchip Technology, Inc.Software License Agreement:The software supplied herewith by Microchip Technology Incorporated(the Company) for its PIC® Microcontroller is intended andsupplied to you, the Companys customer, for use solely andexclusively on Microchip PIC Microcontroller products. Thesoftware is owned by the Company and/or its supplier, and isprotected under applicable copyright laws. All rights are reserved.Any use in violation of the foregoing restrictions may subject theuser to criminal sanctions under applicable laws, as well as tocivil liability for the breach of the terms and conditions of thislicense.THIS SOFTWARE IS PROVIDED IN AN AS IS CONDITION. NO WARRANTIES,WHETHER EXPRESS, IMPLIED OR STATUTORY, INCLUDING, BUT NOT LIMITEDTO, IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR APARTICULAR PURPOSE APPLY TO THIS SOFTWARE. THE COMPANY SHALL NOT,IN ANY CIRCUMSTANCES, BE LIABLE FOR SPECIAL, INCIDENTAL ORCONSEQUENTIAL DAMAGES, FOR ANY REASON WHATSOEVER.*********************************************************************-usb_descriptors.c--------------------------------------------------------------------Filling in the descriptor values in the usb_descriptors.c file:-------------------------------------------------------------------[Device Descriptors]The device descriptor is defined as a USB_DEVICE_DESCRIPTOR type.This type is defined in usb_ch9.h Each entry into this structureneeds to be the correct length for the data type of the entry.[Configuration Descriptors]The configuration descriptor was changed in v2.x from a structureto a BYTE array. Given that the configuration is now a byte arrayeach byte of multi-byte fields must be listed individually. Thismeans that for fields like the total size of the configuration wherethe field is a 16-bit value "64,0," is the correct entry for aconfiguration that is only 64 bytes long and not "64," which is onetoo few bytes.The configuration attribute must always have the _DEFAULTdefinition at the minimum. Additional options can be ORedto the _DEFAULT attribute. Available options are _SELF and _RWU.These definitions are defined in the usb_device.h file. The_SELF tells the USB host that this device is self-powered. The_RWU tells the USB host that this device supports Remote Wakeup.[Endpoint Descriptors]Like the configuration descriptor, the endpoint descriptors werechanged in v2.x of the stack from a structure to a BYTE array. Asendpoint descriptors also has a field that are multi-byte entities,please be sure to specify both bytes of the field. For example, forthe endpoint size an endpoint that is 64 bytes needs to have the sizedefined as "64,0," instead of "64,"Take the following example:// Endpoint Descriptor //0x07, //the size of this descriptor //USB_DESCRIPTOR_ENDPOINT, //Endpoint Descriptor_EP02_IN, //EndpointAddress_INT, //Attributes0x08,0x00, //size (note: 2 bytes)0x02, //IntervalThe first two parameters are self-explanatory. They specify thelength of this endpoint descriptor (7) and the descriptor type.The next parameter identifies the endpoint, the definitions aredefined in usb_device.h and has the following namingconvention:_EP<##>_<dir>where ## is the endpoint number and dir is the direction oftransfer. The dir has the value of either 'OUT' or 'IN'.The next parameter identifies the type of the endpoint. Availableoptions are _BULK, _INT, _ISO, and _CTRL. The _CTRL is nottypically used because the default control transfer endpoint isnot defined in the USB descriptors. When _ISO option is used,addition options can be ORed to _ISO. Example:_ISO|_AD|_FEThis describes the endpoint as an isochronous pipe with adaptiveand feedback attributes. See usb_device.h and the USBspecification for details. The next parameter defines the size ofthe endpoint. The last parameter in the polling interval.-------------------------------------------------------------------Adding a USB String-------------------------------------------------------------------A string descriptor array should have the following format:rom struct{byte bLength;byte bDscType;word string[size];}sdxxx={sizeof(sdxxx),DSC_STR,<text>};The above structure provides a means for the C compiler tocalculate the length of string descriptor sdxxx, where xxx is theindex number. The first two bytes of the descriptor are descriptorlength and type. The rest <text> are string texts which must bein the unicode format. The unicode format is achieved by declaringeach character as a word type. The whole text string is declaredas a word array with the number of characters equals to <size>.<size> has to be manually counted and entered into the arraydeclaration. Let's study this through an example:if the string is "USB" , then the string descriptor should be:(Using index 02)rom struct{byte bLength;byte bDscType;word string[3];}sd002={sizeof(sd002),DSC_STR,'U','S','B'};A USB project may have multiple strings and the firmware supportsthe management of multiple strings through a look-up table.The look-up table is defined as:rom const unsigned char *rom USB_SD_Ptr[]={&sd000,&sd001,&sd002};The above declaration has 3 strings, sd000, sd001, and sd002.Strings can be removed or added. sd000 is a specialized stringdescriptor. It defines the language code, usually this isUS English (0x0409). The index of the string must match the indexposition of the USB_SD_Ptr array, &sd000 must be in positionUSB_SD_Ptr[0], &sd001 must be in position USB_SD_Ptr[1] and so on.The look-up table USB_SD_Ptr is used by the get string handlerfunction.-------------------------------------------------------------------The look-up table scheme also applies to the configurationdescriptor. A USB device may have multiple configurationdescriptors, i.e. CFG01, CFG02, etc. To add a configurationdescriptor, user must implement a structure similar to CFG01.The next step is to add the configuration descriptor name, i.e.cfg01, cfg02,.., to the look-up table USB_CD_Ptr. USB_CD_Ptr[0]is a dummy place holder since configuration 0 is the un-configuredstate according to the definition in the USB specification.********************************************************************//********************************************************************** Descriptor specific type definitions are defined in:* usb_device.h** Configuration options are defined in:* usb_config.h********************************************************************/#ifndef __USB_DESCRIPTORS_C#define __USB_DESCRIPTORS_C/** INCLUDES *******************************************************//*#include "GenericTypeDefs.h"#include "Compiler.h"#include "usb_config.h"#include "USB/usb_device.h"*/#include "./USB/usb.h"/** CONSTANTS ******************************************************/#if defined(__18CXX)#pragma romdata#endif/* Device Descriptor */ROM USB_DEVICE_DESCRIPTOR device_dsc={0x12, // Size of this descriptor in bytesUSB_DESCRIPTOR_DEVICE, // DEVICE descriptor type0x0200, // USB Spec Release Number in BCD format0x00, // Class Code0x00, // Subclass code0x00, // Protocol codeUSB_EP0_BUFF_SIZE, // Max packet size for EP0, see usb_config.h0x16C0, // Vendor ID VOTI AVR USB device0x05DC, // Product ID: obdev's free PID0x0000, // Device release number in BCD format0x01, // Manufacturer string index0x02, // Product string index0x03, // Device serial number string index0x01 // Number of possible configurations};/* Configuration 1 Descriptor */ROM BYTE configDescriptor1[]={/* Configuration Descriptor */0x09,//sizeof(USB_CFG_DSC), // Size of this descriptor in bytesUSB_DESCRIPTOR_CONFIGURATION, // CONFIGURATION descriptor type0x20,0x00, // Total length of data for this cfg1, // Number of interfaces in this cfg1, // Index value of this configuration0, // Configuration string index_DEFAULT | _SELF, // Attributes, see usb_device.h50, // Max power consumption (2X mA)/* Interface Descriptor */0x09,//sizeof(USB_INTF_DSC), // Size of this descriptor in bytesUSB_DESCRIPTOR_INTERFACE, // INTERFACE descriptor type0, // Interface Number0, // Alternate Setting Number2, // Number of endpoints in this intf0x00, // Class code0x00, // Subclass code0x00, // Protocol code0, // Interface string index/* Endpoint Descriptor */0x07, /*sizeof(USB_EP_DSC)*/USB_DESCRIPTOR_ENDPOINT, //Endpoint Descriptor_EP01_OUT, //EndpointAddress_BULK, //AttributesUSBGEN_EP_SIZE,0x00, //size1, //Interval0x07, /*sizeof(USB_EP_DSC)*/USB_DESCRIPTOR_ENDPOINT, //Endpoint Descriptor_EP01_IN, //EndpointAddress_BULK, //AttributesUSBGEN_EP_SIZE,0x00, //size1 //Interval};//Language code string descriptorROM struct{BYTE bLength;BYTE bDscType;WORD string[1];}sd000={sizeof(sd000),USB_DESCRIPTOR_STRING,{0x0409}};//Manufacturer string descriptorROM struct{BYTE bLength;BYTE bDscType;WORD string[12];}sd001={sizeof(sd001),USB_DESCRIPTOR_STRING,{'w','w','w','.','o','b','d','e','v','.','a','t'}};//Product string descriptorROM struct{BYTE bLength;BYTE bDscType;WORD string[10];}sd002={sizeof(sd002),USB_DESCRIPTOR_STRING,{'D','G','8','S','A','Q','-','I','2','C'}};//Serial Number string descriptorROM struct{BYTE bLength;BYTE bDscType;WORD string[9];}sd003={sizeof(sd003),USB_DESCRIPTOR_STRING,{'T','F','3','L','J','-','1','.','0'}};//Array of configuration descriptorsROM BYTE *ROM USB_CD_Ptr[]={(ROM BYTE *ROM)&configDescriptor1};//Array of string descriptorsROM BYTE *ROM USB_SD_Ptr[]={(ROM BYTE *ROM)&sd000,(ROM BYTE *ROM)&sd001,(ROM BYTE *ROM)&sd002,(ROM BYTE *ROM)&sd003};/** EOF usb_descriptors.c ***************************************************/#endif