usb_device.c

   1 /* USB Keyboard Plus Debug Channel Example for Teensy USB Development Board
   2  * http://www.pjrc.com/teensy/usb_keyboard.html
   3  * Copyright (c) 2009 PJRC.COM, LLC
   4  *
   5  * Permission is hereby granted, free of charge, to any person obtaining a copy
   6  * of this software and associated documentation files (the "Software"), to deal
   7  * in the Software without restriction, including without limitation the rights
   8  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
   9  * copies of the Software, and to permit persons to whom the Software is
  10  * furnished to do so, subject to the following conditions:
  11  *
  12  * The above copyright notice and this permission notice shall be included in
  13  * all copies or substantial portions of the Software.
  14  *
  15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  16  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  18  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  19  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  20  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  21  * THE SOFTWARE.
  22  */
  23
  24 #include <avr/pgmspace.h>
  25 #include <avr/interrupt.h>
  26 #include "usb_device.h"
  27 #include "usb_keyboard.h"
  28 #include "usb_debug.h"
  29
  30
  31 /**************************************************************************
  32  *
  33  *  Configurable Options
  34  *
  35  **************************************************************************/
  36
  37 // You can change these to give your code its own name.
  38 #define STR_MANUFACTURER        L"MfgName"
  39 #define STR_PRODUCT             L"Keyboard"
  40
  41
  42 // Mac OS-X and Linux automatically load the correct drivers.  On
  43 // Windows, even though the driver is supplied by Microsoft, an
  44 // INF file is needed to load the driver.  These numbers need to
  45 // match the INF file.
  46 #define VENDOR_ID               0x16C0
  47 #define PRODUCT_ID              0x047D
  48
  49
  50 // USB devices are supposed to implment a halt feature, which is
  51 // rarely (if ever) used.  If you comment this line out, the halt
  52 // code will be removed, saving 102 bytes of space (gcc 4.3.0).
  53 // This is not strictly USB compliant, but works with all major
  54 // operating systems.
  55 #define SUPPORT_ENDPOINT_HALT
  56
  57
  58
  59 /**************************************************************************
  60  *
  61  *  Endpoint Buffer Configuration
  62  *
  63  **************************************************************************/
  64
  65 #define ENDPOINT0_SIZE          32
  66
  67 static const uint8_t PROGMEM endpoint_config_table[] = {
  68         0,
  69         0,
  70         1, EP_TYPE_INTERRUPT_IN,  EP_SIZE(KEYBOARD_SIZE) | KEYBOARD_BUFFER,
  71         1, EP_TYPE_INTERRUPT_IN,  EP_SIZE(DEBUG_TX_SIZE) | DEBUG_TX_BUFFER
  72 };
  73
  74
  75 /**************************************************************************
  76  *
  77  *  Descriptor Data
  78  *
  79  **************************************************************************/
  80
  81 // Descriptors are the data that your computer reads when it auto-detects
  82 // this USB device (called "enumeration" in USB lingo).  The most commonly
  83 // changed items are editable at the top of this file.  Changing things
  84 // in here should only be done by those who've read chapter 9 of the USB
  85 // spec and relevant portions of any USB class specifications!
  86
  87
  88 static uint8_t PROGMEM device_descriptor[] = {
  89         18,                                     // bLength
  90         1,                                      // bDescriptorType
  91         0x00, 0x02,                             // bcdUSB
  92         0,                                      // bDeviceClass
  93         0,                                      // bDeviceSubClass
  94         0,                                      // bDeviceProtocol
  95         ENDPOINT0_SIZE,                         // bMaxPacketSize0
  96         LSB(VENDOR_ID), MSB(VENDOR_ID),         // idVendor
  97         LSB(PRODUCT_ID), MSB(PRODUCT_ID),       // idProduct
  98         0x00, 0x01,                             // bcdDevice
  99         1,                                      // iManufacturer
 100         2,                                      // iProduct
 101         0,                                      // iSerialNumber
 102         1                                       // bNumConfigurations
 103 };
 104
 105 // Keyboard Protocol 1, HID 1.11 spec, Appendix B, page 59-60
 106 static uint8_t PROGMEM keyboard_hid_report_desc[] = {
 107         0x05, 0x01,          // Usage Page (Generic Desktop),
 108         0x09, 0x06,          // Usage (Keyboard),
 109         0xA1, 0x01,          // Collection (Application),
 110         0x75, 0x01,          //   Report Size (1),
 111         0x95, 0x08,          //   Report Count (8),
 112         0x05, 0x07,          //   Usage Page (Key Codes),
 113         0x19, 0xE0,          //   Usage Minimum (224),
 114         0x29, 0xE7,          //   Usage Maximum (231),
 115         0x15, 0x00,          //   Logical Minimum (0),
 116         0x25, 0x01,          //   Logical Maximum (1),
 117         0x81, 0x02,          //   Input (Data, Variable, Absolute), ;Modifier byte
 118         0x95, 0x01,          //   Report Count (1),
 119         0x75, 0x08,          //   Report Size (8),
 120         0x81, 0x03,          //   Input (Constant),                 ;Reserved byte
 121         0x95, 0x05,          //   Report Count (5),
 122         0x75, 0x01,          //   Report Size (1),
 123         0x05, 0x08,          //   Usage Page (LEDs),
 124         0x19, 0x01,          //   Usage Minimum (1),
 125         0x29, 0x05,          //   Usage Maximum (5),
 126         0x91, 0x02,          //   Output (Data, Variable, Absolute), ;LED report
 127         0x95, 0x01,          //   Report Count (1),
 128         0x75, 0x03,          //   Report Size (3),
 129         0x91, 0x03,          //   Output (Constant),                 ;LED report padding
 130         0x95, 0x06,          //   Report Count (6),
 131         0x75, 0x08,          //   Report Size (8),
 132         0x15, 0x00,          //   Logical Minimum (0),
 133         0x25, 0x68,          //   Logical Maximum(104),
 134         0x05, 0x07,          //   Usage Page (Key Codes),
 135         0x19, 0x00,          //   Usage Minimum (0),
 136         0x29, 0x68,          //   Usage Maximum (104),
 137         0x81, 0x00,          //   Input (Data, Array),
 138         0xc0                 // End Collection
 139 };
 140
 141 static uint8_t PROGMEM debug_hid_report_desc[] = {
 142         0x06, 0x31, 0xFF,                       // Usage Page 0xFF31 (vendor defined)
 143         0x09, 0x74,                             // Usage 0x74
 144         0xA1, 0x53,                             // Collection 0x53
 145         0x75, 0x08,                             // report size = 8 bits
 146         0x15, 0x00,                             // logical minimum = 0
 147         0x26, 0xFF, 0x00,                       // logical maximum = 255
 148         0x95, DEBUG_TX_SIZE,                    // report count
 149         0x09, 0x75,                             // usage
 150         0x81, 0x02,                             // Input (array)
 151         0xC0                                    // end collection
 152 };
 153
 154 #define CONFIG1_DESC_SIZE        (9+9+9+7+9+9+7)
 155 #define KEYBOARD_HID_DESC_OFFSET (9+9)
 156 #define DEBUG_HID_DESC_OFFSET    (9+9+9+7+9)
 157 static uint8_t PROGMEM config1_descriptor[CONFIG1_DESC_SIZE] = {
 158         // configuration descriptor, USB spec 9.6.3, page 264-266, Table 9-10
 159         9,                                      // bLength;
 160         2,                                      // bDescriptorType;
 161         LSB(CONFIG1_DESC_SIZE),                 // wTotalLength
 162         MSB(CONFIG1_DESC_SIZE),
 163         2,                                      // bNumInterfaces
 164         1,                                      // bConfigurationValue
 165         0,                                      // iConfiguration
 166         0xC0,                                   // bmAttributes
 167         50,                                     // bMaxPower
 168         // interface descriptor, USB spec 9.6.5, page 267-269, Table 9-12
 169         9,                                      // bLength
 170         4,                                      // bDescriptorType
 171         KEYBOARD_INTERFACE,                     // bInterfaceNumber
 172         0,                                      // bAlternateSetting
 173         1,                                      // bNumEndpoints
 174         0x03,                                   // bInterfaceClass (0x03 = HID)
 175         0x01,                                   // bInterfaceSubClass (0x01 = Boot)
 176         0x01,                                   // bInterfaceProtocol (0x01 = Keyboard)
 177         0,                                      // iInterface
 178         // HID interface descriptor, HID 1.11 spec, section 6.2.1
 179         9,                                      // bLength
 180         0x21,                                   // bDescriptorType
 181         0x11, 0x01,                             // bcdHID
 182         0,                                      // bCountryCode
 183         1,                                      // bNumDescriptors
 184         0x22,                                   // bDescriptorType
 185         sizeof(keyboard_hid_report_desc),       // wDescriptorLength
 186         0,
 187         // endpoint descriptor, USB spec 9.6.6, page 269-271, Table 9-13
 188         7,                                      // bLength
 189         5,                                      // bDescriptorType
 190         KEYBOARD_ENDPOINT | 0x80,               // bEndpointAddress
 191         0x03,                                   // bmAttributes (0x03=intr)
 192         KEYBOARD_SIZE, 0,                       // wMaxPacketSize
 193         1,                                      // bInterval
 194         // interface descriptor, USB spec 9.6.5, page 267-269, Table 9-12
 195         9,                                      // bLength
 196         4,                                      // bDescriptorType
 197         DEBUG_INTERFACE,                        // bInterfaceNumber
 198         0,                                      // bAlternateSetting
 199         1,                                      // bNumEndpoints
 200         0x03,                                   // bInterfaceClass (0x03 = HID)
 201         0x00,                                   // bInterfaceSubClass
 202         0x00,                                   // bInterfaceProtocol
 203         0,                                      // iInterface
 204         // HID interface descriptor, HID 1.11 spec, section 6.2.1
 205         9,                                      // bLength
 206         0x21,                                   // bDescriptorType
 207         0x11, 0x01,                             // bcdHID
 208         0,                                      // bCountryCode
 209         1,                                      // bNumDescriptors
 210         0x22,                                   // bDescriptorType
 211         sizeof(debug_hid_report_desc),          // wDescriptorLength
 212         0,
 213         // endpoint descriptor, USB spec 9.6.6, page 269-271, Table 9-13
 214         7,                                      // bLength
 215         5,                                      // bDescriptorType
 216         DEBUG_TX_ENDPOINT | 0x80,               // bEndpointAddress
 217         0x03,                                   // bmAttributes (0x03=intr)
 218         DEBUG_TX_SIZE, 0,                       // wMaxPacketSize
 219         1                                       // bInterval
 220 };
 221
 222 // If you're desperate for a little extra code memory, these strings
 223 // can be completely removed if iManufacturer, iProduct, iSerialNumber
 224 // in the device desciptor are changed to zeros.
 225 struct usb_string_descriptor_struct {
 226         uint8_t bLength;
 227         uint8_t bDescriptorType;
 228         int16_t wString[];
 229 };
 230 static struct usb_string_descriptor_struct PROGMEM string0 = {
 231         4,
 232         3,
 233         {0x0409}
 234 };
 235 static struct usb_string_descriptor_struct PROGMEM string1 = {
 236         sizeof(STR_MANUFACTURER),
 237         3,
 238         STR_MANUFACTURER
 239 };
 240 static struct usb_string_descriptor_struct PROGMEM string2 = {
 241         sizeof(STR_PRODUCT),
 242         3,
 243         STR_PRODUCT
 244 };
 245
 246 // This table defines which descriptor data is sent for each specific
 247 // request from the host (in wValue and wIndex).
 248 static struct descriptor_list_struct {
 249         uint16_t        wValue;     // descriptor type
 250         uint16_t        wIndex;
 251         const uint8_t   *addr;
 252         uint8_t         length;
 253 } PROGMEM descriptor_list[] = {
 254         // DEVICE descriptor
 255         {0x0100, 0x0000, device_descriptor, sizeof(device_descriptor)},
 256         // CONFIGURATION descriptor
 257         {0x0200, 0x0000, config1_descriptor, sizeof(config1_descriptor)},
 258         // HID REPORT
 259         {0x2200, KEYBOARD_INTERFACE, keyboard_hid_report_desc, sizeof(keyboard_hid_report_desc)},
 260         {0x2100, KEYBOARD_INTERFACE, config1_descriptor+KEYBOARD_HID_DESC_OFFSET, 9},
 261         // HID REPORT
 262         {0x2200, DEBUG_INTERFACE, debug_hid_report_desc, sizeof(debug_hid_report_desc)},
 263         {0x2100, DEBUG_INTERFACE, config1_descriptor+DEBUG_HID_DESC_OFFSET, 9},
 264         // STRING descriptor
 265         {0x0300, 0x0000, (const uint8_t *)&string0, 4},
 266         {0x0301, 0x0409, (const uint8_t *)&string1, sizeof(STR_MANUFACTURER)},
 267         {0x0302, 0x0409, (const uint8_t *)&string2, sizeof(STR_PRODUCT)}
 268 };
 269 #define NUM_DESC_LIST (sizeof(descriptor_list)/sizeof(struct descriptor_list_struct))
 270
 271
 272 /**************************************************************************
 273  *
 274  *  Variables - these are the only non-stack RAM usage
 275  *
 276  **************************************************************************/
 277
 278 // zero when we are not configured, non-zero when enumerated
 279 static volatile uint8_t usb_configuration=0;
 280
 281
 282 /**************************************************************************
 283  *
 284  *  Public Functions - these are the API intended for the user
 285  *
 286  **************************************************************************/
 287
 288
 289 // initialize USB
 290 void usb_init(void)
 291 {
 292         HW_CONFIG();
 293         USB_FREEZE();                           // enable USB
 294         PLL_CONFIG();                           // config PLL
 295         while (!(PLLCSR & (1<<PLOCK))) ;        // wait for PLL lock
 296         USB_CONFIG();                           // start USB clock
 297         UDCON = 0;                              // enable attach resistor
 298         usb_configuration = 0;
 299         UDIEN = (1<<EORSTE)|(1<<SOFE);
 300         sei();
 301 }
 302
 303 // return 0 if the USB is not configured, or the configuration
 304 // number selected by the HOST
 305 uint8_t usb_configured(void)
 306 {
 307         return usb_configuration;
 308 }
 309
 310
 311
 312 /**************************************************************************
 313  *
 314  *  Private Functions - not intended for general user consumption....
 315  *
 316  **************************************************************************/
 317
 318
 319
 320 // USB Device Interrupt - handle all device-level events
 321 // the transmit buffer flushing is triggered by the start of frame
 322 //
 323 ISR(USB_GEN_vect)
 324 {
 325         uint8_t intbits, t, i;
 326         static uint8_t div4=0;
 327
 328         intbits = UDINT;
 329         UDINT = 0;
 330         if (intbits & (1<<EORSTI)) {
 331                 UENUM = 0;
 332                 UECONX = 1;
 333                 UECFG0X = EP_TYPE_CONTROL;
 334                 UECFG1X = EP_SIZE(ENDPOINT0_SIZE) | EP_SINGLE_BUFFER;
 335                 UEIENX = (1<<RXSTPE);
 336                 usb_configuration = 0;
 337         }
 338         if ((intbits & (1<<SOFI)) && usb_configuration) {
 339                 t = debug_flush_timer;
 340                 if (t) {
 341                         debug_flush_timer = -- t;
 342                         if (!t) {
 343                                 UENUM = DEBUG_TX_ENDPOINT;
 344                                 while ((UEINTX & (1<<RWAL))) {
 345                                         UEDATX = 0;
 346                                 }
 347                                 UEINTX = 0x3A;
 348                         }
 349                 }
 350                 if (keyboard_idle_config && (++div4 & 3) == 0) {
 351                         UENUM = KEYBOARD_ENDPOINT;
 352                         if (UEINTX & (1<<RWAL)) {
 353                                 keyboard_idle_count++;
 354                                 if (keyboard_idle_count == keyboard_idle_config) {
 355                                         keyboard_idle_count = 0;
 356                                         UEDATX = keyboard_modifier_keys;
 357                                         UEDATX = 0;
 358                                         for (i=0; i<6; i++) {
 359                                                 UEDATX = keyboard_keys[i];
 360                                         }
 361                                         UEINTX = 0x3A;
 362                                 }
 363                         }
 364                 }
 365         }
 366 }
 367
 368
 369
 370 // Misc functions to wait for ready and send/receive packets
 371 static inline void usb_wait_in_ready(void)
 372 {
 373         while (!(UEINTX & (1<<TXINI))) ;
 374 }
 375 static inline void usb_send_in(void)
 376 {
 377         UEINTX = ~(1<<TXINI);
 378 }
 379 static inline void usb_wait_receive_out(void)
 380 {
 381         while (!(UEINTX & (1<<RXOUTI))) ;
 382 }
 383 static inline void usb_ack_out(void)
 384 {
 385         UEINTX = ~(1<<RXOUTI);
 386 }
 387
 388
 389
 390 // USB Endpoint Interrupt - endpoint 0 is handled here.  The
 391 // other endpoints are manipulated by the user-callable
 392 // functions, and the start-of-frame interrupt.
 393 //
 394 ISR(USB_COM_vect)
 395 {
 396         uint8_t intbits;
 397         const uint8_t *list;
 398         const uint8_t *cfg;
 399         uint8_t i, n, len, en;
 400         uint8_t bmRequestType;
 401         uint8_t bRequest;
 402         uint16_t wValue;
 403         uint16_t wIndex;
 404         uint16_t wLength;
 405         uint16_t desc_val;
 406         const uint8_t *desc_addr;
 407         uint8_t desc_length;
 408
 409         UENUM = 0;
 410         intbits = UEINTX;
 411         if (intbits & (1<<RXSTPI)) {
 412                 bmRequestType = UEDATX;
 413                 bRequest = UEDATX;
 414                 wValue = UEDATX;
 415                 wValue |= (UEDATX << 8);
 416                 wIndex = UEDATX;
 417                 wIndex |= (UEDATX << 8);
 418                 wLength = UEDATX;
 419                 wLength |= (UEDATX << 8);
 420                 UEINTX = ~((1<<RXSTPI) | (1<<RXOUTI) | (1<<TXINI));
 421                 if (bRequest == GET_DESCRIPTOR) {
 422                         list = (const uint8_t *)descriptor_list;
 423                         for (i=0; ; i++) {
 424                                 if (i >= NUM_DESC_LIST) {
 425                                         UECONX = (1<<STALLRQ)|(1<<EPEN);  //stall
 426                                         return;
 427                                 }
 428                                 desc_val = pgm_read_word(list);
 429                                 if (desc_val != wValue) {
 430                                         list += sizeof(struct descriptor_list_struct);
 431                                         continue;
 432                                 }
 433                                 list += 2;
 434                                 desc_val = pgm_read_word(list);
 435                                 if (desc_val != wIndex) {
 436                                         list += sizeof(struct descriptor_list_struct)-2;
 437                                         continue;
 438                                 }
 439                                 list += 2;
 440                                 desc_addr = (const uint8_t *)pgm_read_word(list);
 441                                 list += 2;
 442                                 desc_length = pgm_read_byte(list);
 443                                 break;
 444                         }
 445                         len = (wLength < 256) ? wLength : 255;
 446                         if (len > desc_length) len = desc_length;
 447                         do {
 448                                 // wait for host ready for IN packet
 449                                 do {
 450                                         i = UEINTX;
 451                                 } while (!(i & ((1<<TXINI)|(1<<RXOUTI))));
 452                                 if (i & (1<<RXOUTI)) return;    // abort
 453                                 // send IN packet
 454                                 n = len < ENDPOINT0_SIZE ? len : ENDPOINT0_SIZE;
 455                                 for (i = n; i; i--) {
 456                                         UEDATX = pgm_read_byte(desc_addr++);
 457                                 }
 458                                 len -= n;
 459                                 usb_send_in();
 460                         } while (len || n == ENDPOINT0_SIZE);
 461                         return;
 462                 }
 463                 if (bRequest == SET_ADDRESS) {
 464                         usb_send_in();
 465                         usb_wait_in_ready();
 466                         UDADDR = wValue | (1<<ADDEN);
 467                         return;
 468                 }
 469                 if (bRequest == SET_CONFIGURATION && bmRequestType == 0) {
 470                         usb_configuration = wValue;
 471                         usb_send_in();
 472                         cfg = endpoint_config_table;
 473                         for (i=1; i<5; i++) {
 474                                 UENUM = i;
 475                                 en = pgm_read_byte(cfg++);
 476                                 UECONX = en;
 477                                 if (en) {
 478                                         UECFG0X = pgm_read_byte(cfg++);
 479                                         UECFG1X = pgm_read_byte(cfg++);
 480                                 }
 481                         }
 482                         UERST = 0x1E;
 483                         UERST = 0;
 484                         return;
 485                 }
 486                 if (bRequest == GET_CONFIGURATION && bmRequestType == 0x80) {
 487                         usb_wait_in_ready();
 488                         UEDATX = usb_configuration;
 489                         usb_send_in();
 490                         return;
 491                 }
 492
 493                 if (bRequest == GET_STATUS) {
 494                         usb_wait_in_ready();
 495                         i = 0;
 496                         #ifdef SUPPORT_ENDPOINT_HALT
 497                         if (bmRequestType == 0x82) {
 498                                 UENUM = wIndex;
 499                                 if (UECONX & (1<<STALLRQ)) i = 1;
 500                                 UENUM = 0;
 501                         }
 502                         #endif
 503                         UEDATX = i;
 504                         UEDATX = 0;
 505                         usb_send_in();
 506                         return;
 507                 }
 508                 #ifdef SUPPORT_ENDPOINT_HALT
 509                 if ((bRequest == CLEAR_FEATURE || bRequest == SET_FEATURE)
 510                   && bmRequestType == 0x02 && wValue == 0) {
 511                         i = wIndex & 0x7F;
 512                         if (i >= 1 && i <= MAX_ENDPOINT) {
 513                                 usb_send_in();
 514                                 UENUM = i;
 515                                 if (bRequest == SET_FEATURE) {
 516                                         UECONX = (1<<STALLRQ)|(1<<EPEN);
 517                                 } else {
 518                                         UECONX = (1<<STALLRQC)|(1<<RSTDT)|(1<<EPEN);
 519                                         UERST = (1 << i);
 520                                         UERST = 0;
 521                                 }
 522                                 return;
 523                         }
 524                 }
 525                 #endif
 526                 if (wIndex == KEYBOARD_INTERFACE) {
 527                         if (bmRequestType == 0xA1) {
 528                                 if (bRequest == HID_GET_REPORT) {
 529                                         usb_wait_in_ready();
 530                                         UEDATX = keyboard_modifier_keys;
 531                                         UEDATX = 0;
 532                                         for (i=0; i<6; i++) {
 533                                                 UEDATX = keyboard_keys[i];
 534                                         }
 535                                         usb_send_in();
 536                                         return;
 537                                 }
 538                                 if (bRequest == HID_GET_IDLE) {
 539                                         usb_wait_in_ready();
 540                                         UEDATX = keyboard_idle_config;
 541                                         usb_send_in();
 542                                         return;
 543                                 }
 544                                 if (bRequest == HID_GET_PROTOCOL) {
 545                                         usb_wait_in_ready();
 546                                         UEDATX = keyboard_protocol;
 547                                         usb_send_in();
 548                                         return;
 549                                 }
 550                         }
 551                         if (bmRequestType == 0x21) {
 552                                 if (bRequest == HID_SET_REPORT) {
 553                                         usb_wait_receive_out();
 554                                         keyboard_leds = UEDATX;
 555                                         usb_ack_out();
 556                                         usb_send_in();
 557                                         return;
 558                                 }
 559                                 if (bRequest == HID_SET_IDLE) {
 560                                         keyboard_idle_config = (wValue >> 8);
 561                                         keyboard_idle_count = 0;
 562                                         //usb_wait_in_ready();
 563                                         usb_send_in();
 564                                         return;
 565                                 }
 566                                 if (bRequest == HID_SET_PROTOCOL) {
 567                                         keyboard_protocol = wValue;
 568                                         //usb_wait_in_ready();
 569                                         usb_send_in();
 570                                         return;
 571                                 }
 572                         }
 573                 }
 574                 if (wIndex == DEBUG_INTERFACE) {
 575                         if (bRequest == HID_GET_REPORT && bmRequestType == 0xA1) {
 576                                 len = wLength;
 577                                 do {
 578                                         // wait for host ready for IN packet
 579                                         do {
 580                                                 i = UEINTX;
 581                                         } while (!(i & ((1<<TXINI)|(1<<RXOUTI))));
 582                                         if (i & (1<<RXOUTI)) return;    // abort
 583                                         // send IN packet
 584                                         n = len < ENDPOINT0_SIZE ? len : ENDPOINT0_SIZE;
 585                                         for (i = n; i; i--) {
 586                                                 UEDATX = 0;
 587                                         }
 588                                         len -= n;
 589                                         usb_send_in();
 590                                 } while (len || n == ENDPOINT0_SIZE);
 591                                 return;
 592                         }
 593                 }
 594         }
 595         UECONX = (1<<STALLRQ) | (1<<EPEN);      // stall
 596 }
 597
 598