/* * The MIT License (MIT) * * Copyright (c) 2023 HiFiPhile * * Permission is hereby granted, free of charge, to any person obtaining a copy * of this software and associated documentation files (the "Software"), to deal * in the Software without restriction, including without limitation the rights * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell * copies of the Software, and to permit persons to whom the Software is * furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN * THE SOFTWARE. * */ #include "bsp/board_api.h" #include "tusb.h" //--------------------------------------------------------------------+ // Device Descriptors //--------------------------------------------------------------------+ static tusb_desc_device_t const desc_device = { .bLength = sizeof(tusb_desc_device_t), .bDescriptorType = TUSB_DESC_DEVICE, .bcdUSB = 0x0200, // Use Interface Association Descriptor (IAD) for Audio // As required by USB Specs IAD's subclass must be common class (2) and protocol must be IAD (1) /*.bDeviceClass = TUSB_CLASS_MISC, .bDeviceSubClass = MISC_SUBCLASS_COMMON, .bDeviceProtocol = MISC_PROTOCOL_IAD,*/ .bDeviceClass = 0x00, .bDeviceSubClass = 0x00, .bDeviceProtocol = 0x00, .bMaxPacketSize0 = CFG_TUD_ENDPOINT0_SIZE, .idVendor = 0x054C, .idProduct = 0x0CE6, .bcdDevice = 0x0100, .iManufacturer = 0x01, .iProduct = 0x02, .iSerialNumber = 0x03, .bNumConfigurations = 0x01 }; // Invoked when received GET DEVICE DESCRIPTOR // Application return pointer to descriptor uint8_t const *tud_descriptor_device_cb(void) { return (uint8_t const *) &desc_device; } //--------------------------------------------------------------------+ // Configuration Descriptor //--------------------------------------------------------------------+ #define EPNUM_AUDIO 0x01 #define CONFIG_UAC1_TOTAL_LEN (TUD_CONFIG_DESC_LEN + TUD_AUDIO10_SPEAKER_STEREO_FB_DESC_LEN(2)) uint8_t const descriptor_configuration[] = { // --- CONFIGURATION DESCRIPTOR --- 0x09, // bLength 0x02, // bDescriptorType (CONFIGURATION) 0xE3, 0x00, // wTotalLength: 227 0x04, // bNumInterfaces: 4 0x01, // bConfigurationValue: 1 0x00, // iConfiguration: 0 0xC0, // bmAttributes: SELF-POWERED, NO REMOTE-WAKEUP 0xFA, // bMaxPower: 500mA (250 * 2mA) // --- INTERFACE DESCRIPTOR (0.0): Audio Control --- 0x09, // bLength 0x04, // bDescriptorType (INTERFACE) 0x00, // bInterfaceNumber: 0 0x00, // bAlternateSetting: 0 0x00, // bNumEndpoints: 0 0x01, // bInterfaceClass: Audio (0x01) 0x01, // bInterfaceSubClass: Audio Control (0x01) 0x00, // bInterfaceProtocol: 0x00 0x00, // iInterface: 0 // Class-specific AC Interface Header Descriptor 0x0A, // bLength: 10 0x24, // bDescriptorType: CS_INTERFACE (0x24) 0x01, // bDescriptorSubtype: Header (0x01) 0x00, 0x01, // bcdADC: 1.00 0x49, 0x00, // wTotalLength: 73 (0x0049) 0x02, // bInCollection: 2 streaming interfaces 0x01, // baInterfaceNr(1): Interface 1 0x02, // baInterfaceNr(2): Interface 2 // Input Terminal Descriptor (Terminal ID 1: USB Streaming → Output to Speaker) 0x0C, // bLength: 12 0x24, // bDescriptorType: CS_INTERFACE 0x02, // bDescriptorSubtype: Input Terminal 0x01, // bTerminalID: 1 0x01, 0x01, // wTerminalType: USB Streaming (0x0101) 0x06, // bAssocTerminal: 6 (paired with USB OUT terminal) 0x04, // bNrChannels: 4 0x33, 0x00, // wChannelConfig: L/R Front + L/R Surround (0x0033) 0x00, // iChannelNames: 0 0x00, // iTerminal: 0 // Feature Unit Descriptor (Unit ID 2 ← from Terminal 1) 0x0C, // bLength: 12 0x24, // bDescriptorType: CS_INTERFACE 0x06, // bDescriptorSubtype: Feature Unit 0x02, // bUnitID: 2 0x01, // bSourceID: 1 0x01, // bControlSize: 1 byte per control 0x03, // bmaControls[0]: Master – Mute, Volume 0x00, 0x00, 0x00, 0x00, 0x00, // bmaControls[1..4]: No per-channel controls // Output Terminal Descriptor (Terminal ID 3: Speaker ← from Unit 2) 0x09, // bLength: 9 0x24, // bDescriptorType: CS_INTERFACE 0x03, // bDescriptorSubtype: Output Terminal 0x03, // bTerminalID: 3 0x01, 0x03, // wTerminalType: Speaker (0x0301) 0x04, // bAssocTerminal: 4 (paired with mic input) 0x02, // bSourceID: 2 (Feature Unit) 0x00, // iTerminal: 0 // Input Terminal Descriptor (Terminal ID 4: Headset Mic) 0x0C, // bLength: 12 0x24, // bDescriptorType: CS_INTERFACE 0x02, // bDescriptorSubtype: Input Terminal 0x04, // bTerminalID: 4 0x02, 0x04, // wTerminalType: Headset (0x0402) 0x03, // bAssocTerminal: 3 (paired with speaker) 0x02, // bNrChannels: 2 0x03, 0x00, // wChannelConfig: L/R Front (0x0003) 0x00, // iChannelNames: 0 0x00, // iTerminal: 0 // Feature Unit Descriptor (Unit ID 5 ← from Terminal 4) 0x09, // bLength: 9 0x24, // bDescriptorType: CS_INTERFACE 0x06, // bDescriptorSubtype: Feature Unit 0x05, // bUnitID: 5 0x04, // bSourceID: 4 0x01, // bControlSize: 1 0x03, // bmaControls[0]: Master – Mute, Volume 0x00, // bmaControls[1]: Ch1 – no controls 0x00, // iFeature: 0 // Output Terminal Descriptor (Terminal ID 6: USB Streaming ← from Unit 5) 0x09, // bLength: 9 0x24, // bDescriptorType: CS_INTERFACE 0x03, // bDescriptorSubtype: Output Terminal 0x06, // bTerminalID: 6 0x01, 0x01, // wTerminalType: USB Streaming (0x0101) 0x01, // bAssocTerminal: 1 0x05, // bSourceID: 5 0x00, // iTerminal: 0 // --- INTERFACE DESCRIPTOR (1.0): Audio Streaming (OUT - Alternate 0) --- 0x09, // bLength 0x04, // bDescriptorType (INTERFACE) 0x01, // bInterfaceNumber: 1 0x00, // bAlternateSetting: 0 0x00, // bNumEndpoints: 0 0x01, // bInterfaceClass: Audio 0x02, // bInterfaceSubClass: Audio Streaming 0x00, // bInterfaceProtocol 0x00, // iInterface // --- INTERFACE DESCRIPTOR (1.1): Audio Streaming (OUT - Alternate 1) --- 0x09, // bLength 0x04, // bDescriptorType (INTERFACE) 0x01, // bInterfaceNumber: 1 0x01, // bAlternateSetting: 1 0x01, // bNumEndpoints: 1 0x01, // bInterfaceClass: Audio 0x02, // bInterfaceSubClass: Audio Streaming 0x00, // bInterfaceProtocol 0x00, // iInterface // AS General Descriptor (for Interface 1.1) 0x07, // bLength: 7 0x24, // bDescriptorType: CS_INTERFACE 0x01, // bDescriptorSubtype: AS_GENERAL 0x01, // bTerminalLink: connected to Terminal ID 1 0x01, // bDelay: 1 frame 0x01, 0x00, // wFormatTag: PCM (0x0001) // Format Type Descriptor (4-channel, 16-bit, 48kHz) 0x0B, // bLength: 11 0x24, // bDescriptorType: CS_INTERFACE 0x02, // bDescriptorSubtype: FORMAT_TYPE 0x01, // bFormatType: TYPE_I 0x04, // bNrChannels: 4 0x02, // bSubframeSize: 2 bytes/sample 0x10, // bBitResolution: 16 bits 0x01, // bSamFreqType: 1 discrete frequency 0x80, 0xBB, 0x00, // tSamFreq: 48000 Hz (0x00BB80) // Endpoint Descriptor (Audio OUT: EP1) 0x09, // bLength 0x05, // bDescriptorType (ENDPOINT) 0x01, // bEndpointAddress: OUT EP1 0x09, // bmAttributes: Isochronous, Adaptive 0x88, 0x01, // wMaxPacketSize: 392 bytes 0x04, // bInterval: 4 (1/(2^(4-1)) ms ≈ 125 µs/frame) 0x00, // bRefresh 0x00, // bSynchAddress // Class-specific Audio Streaming Endpoint Descriptor (EP1) 0x07, // bLength 0x25, // bDescriptorType: CS_ENDPOINT 0x01, // bDescriptorSubtype: GENERAL 0x00, // Attributes: No pitch/sampling freq control 0x00, // Lock Delay Units: Undefined 0x00, 0x00, // Lock Delay: 0 // --- INTERFACE DESCRIPTOR (2.0): Audio Streaming IN (Alternate 0) --- 0x09, // bLength 0x04, // bDescriptorType (INTERFACE) 0x02, // bInterfaceNumber: 2 0x00, // bAlternateSetting: 0 0x00, // bNumEndpoints: 0 0x01, // bInterfaceClass: Audio 0x02, // bInterfaceSubClass: Audio Streaming 0x00, // bInterfaceProtocol 0x00, // iInterface // --- INTERFACE DESCRIPTOR (2.1): Audio Streaming IN (Alternate 1) --- 0x09, // bLength 0x04, // bDescriptorType (INTERFACE) 0x02, // bInterfaceNumber: 2 0x01, // bAlternateSetting: 1 0x01, // bNumEndpoints: 1 0x01, // bInterfaceClass: Audio 0x02, // bInterfaceSubClass: Audio Streaming 0x00, // bInterfaceProtocol 0x00, // iInterface // AS General Descriptor (for Interface 2.1) 0x07, // bLength: 7 0x24, // bDescriptorType: CS_INTERFACE 0x01, // bDescriptorSubtype: AS_GENERAL 0x06, // bTerminalLink: connected to Terminal ID 6 0x01, // bDelay: 1 frame 0x01, 0x00, // wFormatTag: PCM (0x0001) // Format Type Descriptor (2-channel, 16-bit, 48kHz) 0x0B, // bLength: 11 0x24, // bDescriptorType: CS_INTERFACE 0x02, // bDescriptorSubtype: FORMAT_TYPE 0x01, // bFormatType: TYPE_I 0x02, // bNrChannels: 2 0x02, // bSubframeSize: 2 0x10, // bBitResolution: 16 0x01, // bSamFreqType: 1 0x80, 0xBB, 0x00, // tSamFreq: 48000 Hz // Endpoint Descriptor (Audio IN: EP2) 0x09, // bLength 0x05, // bDescriptorType (ENDPOINT) 0x82, // bEndpointAddress: IN EP2 0x05, // bmAttributes: Isochronous, Asynchronous 0xC4, 0x00, // wMaxPacketSize: 196 bytes 0x04, // bInterval: 4 0x00, // bRefresh 0x00, // bSynchAddress // Class-specific Audio Streaming Endpoint Descriptor (EP2) 0x07, // bLength 0x25, // bDescriptorType: CS_ENDPOINT 0x01, // bDescriptorSubtype: GENERAL 0x00, // Attributes: No controls 0x00, // Lock Delay Units 0x00, 0x00, // Lock Delay // --- INTERFACE DESCRIPTOR (3.0): HID (DualSense 5 Gamepad + Touchpad) --- 0x09, // bLength 0x04, // bDescriptorType (INTERFACE) 0x03, // bInterfaceNumber: 3 0x00, // bAlternateSetting: 0 0x02, // bNumEndpoints: 2 (IN + OUT) 0x03, // bInterfaceClass: HID 0x00, // bInterfaceSubClass: None 0x00, // bInterfaceProtocol: None 0x00, // iInterface // HID Descriptor 0x09, // bLength: 9 0x21, // bDescriptorType (HID) 0x11, 0x01, // bcdHID: 1.11 0x00, // bCountryCode: Not localized 0x01, // bNumDescriptors: 1 report descriptor 0x22, // bDescriptorType: Report 0x21, 0x01, // wDescriptorLength: 289 (0x0121) // Endpoint Descriptor (HID IN: EP4) 0x07, // bLength 0x05, // bDescriptorType (ENDPOINT) 0x84, // bEndpointAddress: IN EP4 0x03, // bmAttributes: Interrupt 0x40, 0x00, // wMaxPacketSize: 64 0x06, // bInterval: 6 (polling every 8ms) // Endpoint Descriptor (HID OUT: EP3) 0x07, // bLength 0x05, // bDescriptorType (ENDPOINT) 0x03, // bEndpointAddress: OUT EP3 0x03, // bmAttributes: Interrupt 0x40, 0x00, // wMaxPacketSize: 64 0x06, // bInterval: 6 }; // Invoked when received GET CONFIGURATION DESCRIPTOR // Application return pointer to descriptor // Descriptor contents must exist long enough for transfer to complete uint8_t const *tud_descriptor_configuration_cb(uint8_t index) { (void) index; // for multiple configurations return descriptor_configuration; } //--------------------------------------------------------------------+ // HID Report Descriptor //--------------------------------------------------------------------+ uint8_t const desc_hid_report[] = { 0x05, 0x01, // Usage Page (Generic Desktop Ctrls) 0x09, 0x05, // Usage (Game Pad) 0xA1, 0x01, // Collection (Application) 0x85, 0x01, // Report ID (1) 0x09, 0x30, // Usage (X) 0x09, 0x31, // Usage (Y) 0x09, 0x32, // Usage (Z) 0x09, 0x35, // Usage (Rz) 0x09, 0x33, // Usage (Rx) 0x09, 0x34, // Usage (Ry) 0x15, 0x00, // Logical Minimum (0) 0x26, 0xFF, 0x00, // Logical Maximum (255) 0x75, 0x08, // Report Size (8) 0x95, 0x06, // Report Count (6) 0x81, 0x02, // Input (Data,Var,Abs,No Wrap,Linear,Preferred State,No Null Position) 0x06, 0x00, 0xFF, // Usage Page (Vendor Defined 0xFF00) 0x09, 0x20, // Usage (0x20) 0x95, 0x01, // Report Count (1) 0x81, 0x02, // Input (Data,Var,Abs,No Wrap,Linear,Preferred State,No Null Position) 0x05, 0x01, // Usage Page (Generic Desktop Ctrls) 0x09, 0x39, // Usage (Hat switch) 0x15, 0x00, // Logical Minimum (0) 0x25, 0x07, // Logical Maximum (7) 0x35, 0x00, // Physical Minimum (0) 0x46, 0x3B, 0x01, // Physical Maximum (315) 0x65, 0x14, // Unit (System: English Rotation, Length: Centimeter) 0x75, 0x04, // Report Size (4) 0x95, 0x01, // Report Count (1) 0x81, 0x42, // Input (Data,Var,Abs,No Wrap,Linear,Preferred State,Null State) 0x65, 0x00, // Unit (None) 0x05, 0x09, // Usage Page (Button) 0x19, 0x01, // Usage Minimum (0x01) 0x29, 0x0F, // Usage Maximum (0x0F) 0x15, 0x00, // Logical Minimum (0) 0x25, 0x01, // Logical Maximum (1) 0x75, 0x01, // Report Size (1) 0x95, 0x0F, // Report Count (15) 0x81, 0x02, // Input (Data,Var,Abs,No Wrap,Linear,Preferred State,No Null Position) 0x06, 0x00, 0xFF, // Usage Page (Vendor Defined 0xFF00) 0x09, 0x21, // Usage (0x21) 0x95, 0x0D, // Report Count (13) 0x81, 0x02, // Input (Data,Var,Abs,No Wrap,Linear,Preferred State,No Null Position) 0x06, 0x00, 0xFF, // Usage Page (Vendor Defined 0xFF00) 0x09, 0x22, // Usage (0x22) 0x15, 0x00, // Logical Minimum (0) 0x26, 0xFF, 0x00, // Logical Maximum (255) 0x75, 0x08, // Report Size (8) 0x95, 0x34, // Report Count (52) 0x81, 0x02, // Input (Data,Var,Abs,No Wrap,Linear,Preferred State,No Null Position) 0x85, 0x02, // Report ID (2) 0x09, 0x23, // Usage (0x23) 0x95, 0x2F, // Report Count (47) 0x91, 0x02, // Output (Data,Var,Abs,No Wrap,Linear,Preferred State,No Null Position,Non-volatile) 0x85, 0x05, // Report ID (5) 0x09, 0x33, // Usage (0x33) 0x95, 0x28, // Report Count (40) 0xB1, 0x02, // Feature (Data,Var,Abs,No Wrap,Linear,Preferred State,No Null Position,Non-volatile) 0x85, 0x08, // Report ID (8) 0x09, 0x34, // Usage (0x34) 0x95, 0x2F, // Report Count (47) 0xB1, 0x02, // Feature (Data,Var,Abs,No Wrap,Linear,Preferred State,No Null Position,Non-volatile) 0x85, 0x09, // Report ID (9) 0x09, 0x24, // Usage (0x24) 0x95, 0x13, // Report Count (19) 0xB1, 0x02, // Feature (Data,Var,Abs,No Wrap,Linear,Preferred State,No Null Position,Non-volatile) 0x85, 0x0A, // Report ID (10) 0x09, 0x25, // Usage (0x25) 0x95, 0x1A, // Report Count (26) 0xB1, 0x02, // Feature (Data,Var,Abs,No Wrap,Linear,Preferred State,No Null Position,Non-volatile) 0x85, 0x0B, 0x09, 0x41, 0x95, 0x29, 0xB1, 0x02, // ID 0B (新增项) 0x85, 0x0C, 0x09, 0x42, 0x95, 0x29, 0xB1, 0x02, // ID 0C (新增项) 0x85, 0x20, // Report ID (32) 0x09, 0x26, // Usage (0x26) 0x95, 0x3F, // Report Count (63) 0xB1, 0x02, // Feature (Data,Var,Abs,No Wrap,Linear,Preferred State,No Null Position,Non-volatile) 0x85, 0x21, // Report ID (33) 0x09, 0x27, // Usage (0x27) 0x95, 0x04, // Report Count (4) 0xB1, 0x02, // Feature (Data,Var,Abs,No Wrap,Linear,Preferred State,No Null Position,Non-volatile) 0x85, 0x22, // Report ID (34) 0x09, 0x40, // Usage (0x40) 0x95, 0x3F, // Report Count (63) 0xB1, 0x02, // Feature (Data,Var,Abs,No Wrap,Linear,Preferred State,No Null Position,Non-volatile) 0x85, 0x80, // Report ID (128) 0x09, 0x28, // Usage (0x28) 0x95, 0x3F, // Report Count (63) 0xB1, 0x02, // Feature (Data,Var,Abs,No Wrap,Linear,Preferred State,No Null Position,Non-volatile) 0x85, 0x81, // Report ID (129) 0x09, 0x29, // Usage (0x29) 0x95, 0x3F, // Report Count (63) 0xB1, 0x02, // Feature (Data,Var,Abs,No Wrap,Linear,Preferred State,No Null Position,Non-volatile) 0x85, 0x82, // Report ID (130) 0x09, 0x2A, // Usage (0x2A) 0x95, 0x09, // Report Count (9) 0xB1, 0x02, // Feature (Data,Var,Abs,No Wrap,Linear,Preferred State,No Null Position,Non-volatile) 0x85, 0x83, // Report ID (131) 0x09, 0x2B, // Usage (0x2B) 0x95, 0x3F, // Report Count (63) 0xB1, 0x02, // Feature (Data,Var,Abs,No Wrap,Linear,Preferred State,No Null Position,Non-volatile) 0x85, 0x84, // Report ID (132) 0x09, 0x2C, // Usage (0x2C) 0x95, 0x3F, // Report Count (63) 0xB1, 0x02, // Feature (Data,Var,Abs,No Wrap,Linear,Preferred State,No Null Position,Non-volatile) 0x85, 0x85, // Report ID (133) 0x09, 0x2D, // Usage (0x2D) 0x95, 0x02, // Report Count (2) 0xB1, 0x02, // Feature (Data,Var,Abs,No Wrap,Linear,Preferred State,No Null Position,Non-volatile) 0x85, 0xA0, // Report ID (160) 0x09, 0x2E, // Usage (0x2E) 0x95, 0x01, // Report Count (1) 0xB1, 0x02, // Feature (Data,Var,Abs,No Wrap,Linear,Preferred State,No Null Position,Non-volatile) 0x85, 0xE0, // Report ID (224) 0x09, 0x2F, // Usage (0x2F) 0x95, 0x3F, // Report Count (63) 0xB1, 0x02, // Feature (Data,Var,Abs,No Wrap,Linear,Preferred State,No Null Position,Non-volatile) 0x85, 0xF0, // Report ID (240) 0x09, 0x30, // Usage (0x30) 0x95, 0x3F, // Report Count (63) 0xB1, 0x02, // Feature (Data,Var,Abs,No Wrap,Linear,Preferred State,No Null Position,Non-volatile) 0x85, 0xF1, // Report ID (241) 0x09, 0x31, // Usage (0x31) 0x95, 0x3F, // Report Count (63) 0xB1, 0x02, // Feature (Data,Var,Abs,No Wrap,Linear,Preferred State,No Null Position,Non-volatile) 0x85, 0xF2, // Report ID (242) 0x09, 0x32, // Usage (0x32) 0x95, 0x0F, // Report Count (15) 0xB1, 0x02, // Feature (Data,Var,Abs,No Wrap,Linear,Preferred State,No Null Position,Non-volatile) 0x85, 0xF4, // Report ID (244) 0x09, 0x35, // Usage (0x35) 0x95, 0x3F, // Report Count (63) 0xB1, 0x02, // Feature (Data,Var,Abs,No Wrap,Linear,Preferred State,No Null Position,Non-volatile) 0x85, 0xF5, // Report ID (245) 0x09, 0x36, // Usage (0x36) 0x95, 0x03, // Report Count (3) 0xB1, 0x02, // Feature (Data,Var,Abs,No Wrap,Linear,Preferred State,No Null Position,Non-volatile) 0xC0, // End Collection }; // Invoked when received GET HID REPORT DESCRIPTOR // Application return pointer to descriptor // Descriptor contents must exist long enough for transfer to complete uint8_t const *tud_hid_descriptor_report_cb(uint8_t itf) { (void) itf; return desc_hid_report; } //--------------------------------------------------------------------+ // String Descriptors //--------------------------------------------------------------------+ // String Descriptor Index enum { STRID_LANGID = 0, STRID_MANUFACTURER, STRID_PRODUCT, STRID_SERIAL, }; // array of pointer to string descriptors static char const *string_desc_arr[] = { (const char[]){0x09, 0x04}, // 0: is supported language is English (0x0409) "TinyUSB", // 1: Manufacturer "Wireless Controller", // 2: Product NULL, // 3: Serials will use unique ID if possible "UAC2 Speaker", // 4: Audio Interface "UAC1 Speaker", // 5: UAC1 Audio Interface }; static uint16_t _desc_str[60 + 1]; // Invoked when received GET STRING DESCRIPTOR request // Application return pointer to descriptor, whose contents must exist long enough for transfer to complete uint16_t const *tud_descriptor_string_cb(uint8_t index, uint16_t langid) { (void) langid; size_t chr_count; switch (index) { case STRID_LANGID: memcpy(&_desc_str[1], string_desc_arr[0], 2); chr_count = 1; break; case STRID_SERIAL: chr_count = board_usb_get_serial(_desc_str + 1, 32); break; default: // Note: the 0xEE index string is a Microsoft OS 1.0 Descriptors. // https://docs.microsoft.com/en-us/windows-hardware/drivers/usbcon/microsoft-defined-usb-descriptors if (!(index < sizeof(string_desc_arr) / sizeof(string_desc_arr[0]))) return NULL; const char *str = string_desc_arr[index]; // Cap at max char chr_count = strlen(str); size_t const max_count = sizeof(_desc_str) / sizeof(_desc_str[0]) - 1; // -1 for string type if (chr_count > max_count) chr_count = max_count; // Convert ASCII string into UTF-16 for (size_t i = 0; i < chr_count; i++) { _desc_str[1 + i] = str[i]; } break; } // first byte is length (including header), second byte is string type _desc_str[0] = (uint16_t) ((TUSB_DESC_STRING << 8) | (2 * chr_count + 2)); return _desc_str; }