Bootloaders/DFU/BootloaderDFU.c

   1 /*
   2              LUFA Library
   3      Copyright (C) Dean Camera, 2010.
   4
   5   dean [at] fourwalledcubicle [dot] com
   6       www.fourwalledcubicle.com
   7 */
   8
   9 /*
  10   Copyright 2010  Dean Camera (dean [at] fourwalledcubicle [dot] com)
  11
  12   Permission to use, copy, modify, distribute, and sell this
  13   software and its documentation for any purpose is hereby granted
  14   without fee, provided that the above copyright notice appear in
  15   all copies and that both that the copyright notice and this
  16   permission notice and warranty disclaimer appear in supporting
  17   documentation, and that the name of the author not be used in
  18   advertising or publicity pertaining to distribution of the
  19   software without specific, written prior permission.
  20
  21   The author disclaim all warranties with regard to this
  22   software, including all implied warranties of merchantability
  23   and fitness.  In no event shall the author be liable for any
  24   special, indirect or consequential damages or any damages
  25   whatsoever resulting from loss of use, data or profits, whether
  26   in an action of contract, negligence or other tortious action,
  27   arising out of or in connection with the use or performance of
  28   this software.
  29 */
  30
  31 /** \file
  32  *
  33  *  Main source file for the DFU class bootloader. This file contains the complete bootloader logic.
  34  */
  35
  36 #define  INCLUDE_FROM_BOOTLOADER_C
  37 #include "BootloaderDFU.h"
  38
  39 /** Flag to indicate if the bootloader is currently running in secure mode, disallowing memory operations
  40  *  other than erase. This is initially set to the value set by SECURE_MODE, and cleared by the bootloader
  41  *  once a memory erase has completed.
  42  */
  43 bool IsSecure      = SECURE_MODE;
  44
  45 /** Flag to indicate if the bootloader should be running, or should exit and allow the application code to run
  46  *  via a soft reset. When cleared, the bootloader will abort, the USB interface will shut down and the application
  47  *  jumped to via an indirect jump to location 0x0000 (or other location specified by the host).
  48  */
  49 bool RunBootloader = true;
  50
  51 /** Flag to indicate if the bootloader is waiting to exit. When the host requests the bootloader to exit and
  52  *  jump to the application address it specifies, it sends two sequential commands which must be properly
  53  *  acknowledged. Upon reception of the first the RunBootloader flag is cleared and the WaitForExit flag is set,
  54  *  causing the bootloader to wait for the final exit command before shutting down.
  55  */
  56 bool WaitForExit = false;
  57
  58 /** Current DFU state machine state, one of the values in the DFU_State_t enum. */
  59 uint8_t DFU_State = dfuIDLE;
  60
  61 /** Status code of the last executed DFU command. This is set to one of the values in the DFU_Status_t enum after
  62  *  each operation, and returned to the host when a Get Status DFU request is issued.
  63  */
  64 uint8_t DFU_Status = OK;
  65
  66 /** Data containing the DFU command sent from the host. */
  67 DFU_Command_t SentCommand;
  68
  69 /** Response to the last issued Read Data DFU command. Unlike other DFU commands, the read command
  70  *  requires a single byte response from the bootloader containing the read data when the next DFU_UPLOAD command
  71  *  is issued by the host.
  72  */
  73 uint8_t ResponseByte;
  74
  75 /** Pointer to the start of the user application. By default this is 0x0000 (the reset vector), however the host
  76  *  may specify an alternate address when issuing the application soft-start command.
  77  */
  78 AppPtr_t AppStartPtr = (AppPtr_t)0x0000;
  79
  80 /** 64-bit flash page number. This is concatenated with the current 16-bit address on USB AVRs containing more than
  81  *  64KB of flash memory.
  82  */
  83 uint8_t Flash64KBPage = 0;
  84
  85 /** Memory start address, indicating the current address in the memory being addressed (either FLASH or EEPROM
  86  *  depending on the issued command from the host).
  87  */
  88 uint16_t StartAddr = 0x0000;
  89
  90 /** Memory end address, indicating the end address to read to/write from in the memory being addressed (either FLASH
  91  *  of EEPROM depending on the issued command from the host).
  92  */
  93 uint16_t EndAddr = 0x0000;
  94
  95
  96 /** Main program entry point. This routine configures the hardware required by the bootloader, then continuously
  97  *  runs the bootloader processing routine until instructed to soft-exit, or hard-reset via the watchdog to start
  98  *  the loaded application code.
  99  */
 100 int main(void)
 101 {
 102         /* Configure hardware required by the bootloader */
 103         SetupHardware();
 104
 105         /* Run the USB management task while the bootloader is supposed to be running */
 106         while (RunBootloader || WaitForExit)
 107           USB_USBTask();
 108
 109         /* Reset configured hardware back to their original states for the user application */
 110         ResetHardware();
 111
 112         /* Start the user application */
 113         AppStartPtr();
 114 }
 115
 116 /** Configures all hardware required for the bootloader. */
 117 void SetupHardware(void)
 118 {
 119         /* Disable watchdog if enabled by bootloader/fuses */
 120         MCUSR &= ~(1 << WDRF);
 121         wdt_disable();
 122
 123         /* Disable clock division */
 124         clock_prescale_set(clock_div_1);
 125
 126         /* Relocate the interrupt vector table to the bootloader section */
 127         MCUCR = (1 << IVCE);
 128         MCUCR = (1 << IVSEL);
 129
 130         /* Initialize the USB subsystem */
 131         USB_Init();
 132 }
 133
 134 /** Resets all configured hardware required for the bootloader back to their original states. */
 135 void ResetHardware(void)
 136 {
 137         /* Shut down the USB subsystem */
 138         USB_ShutDown();
 139
 140         /* Relocate the interrupt vector table back to the application section */
 141         MCUCR = (1 << IVCE);
 142         MCUCR = 0;
 143 }
 144
 145 /** Event handler for the USB_UnhandledControlRequest event. This is used to catch standard and class specific
 146  *  control requests that are not handled internally by the USB library (including the DFU commands, which are
 147  *  all issued via the control endpoint), so that they can be handled appropriately for the application.
 148  */
 149 void EVENT_USB_Device_UnhandledControlRequest(void)
 150 {
 151         /* Get the size of the command and data from the wLength value */
 152         SentCommand.DataSize = USB_ControlRequest.wLength;
 153
 154         switch (USB_ControlRequest.bRequest)
 155         {
 156                 case DFU_DNLOAD:
 157                         Endpoint_ClearSETUP();
 158
 159                         /* Check if bootloader is waiting to terminate */
 160                         if (WaitForExit)
 161                         {
 162                                 /* Bootloader is terminating - process last received command */
 163                                 ProcessBootloaderCommand();
 164
 165                                 /* Indicate that the last command has now been processed - free to exit bootloader */
 166                                 WaitForExit = false;
 167                         }
 168
 169                         /* If the request has a data stage, load it into the command struct */
 170                         if (SentCommand.DataSize)
 171                         {
 172                                 while (!(Endpoint_IsOUTReceived()))
 173                                 {
 174                                         if (USB_DeviceState == DEVICE_STATE_Unattached)
 175                                           return;
 176                                 }
 177
 178                                 /* First byte of the data stage is the DNLOAD request's command */
 179                                 SentCommand.Command = Endpoint_Read_Byte();
 180
 181                                 /* One byte of the data stage is the command, so subtract it from the total data bytes */
 182                                 SentCommand.DataSize--;
 183
 184                                 /* Load in the rest of the data stage as command parameters */
 185                                 for (uint8_t DataByte = 0; (DataByte < sizeof(SentCommand.Data)) &&
 186                                      Endpoint_BytesInEndpoint(); DataByte++)
 187                                 {
 188                                         SentCommand.Data[DataByte] = Endpoint_Read_Byte();
 189                                         SentCommand.DataSize--;
 190                                 }
 191
 192                                 /* Process the command */
 193                                 ProcessBootloaderCommand();
 194                         }
 195
 196                         /* Check if currently downloading firmware */
 197                         if (DFU_State == dfuDNLOAD_IDLE)
 198                         {
 199                                 if (!(SentCommand.DataSize))
 200                                 {
 201                                         DFU_State = dfuIDLE;
 202                                 }
 203                                 else
 204                                 {
 205                                         /* Throw away the filler bytes before the start of the firmware */
 206                                         DiscardFillerBytes(DFU_FILLER_BYTES_SIZE);
 207
 208                                         /* Throw away the packet alignment filler bytes before the start of the firmware */
 209                                         DiscardFillerBytes(StartAddr % FIXED_CONTROL_ENDPOINT_SIZE);
 210
 211                                         /* Calculate the number of bytes remaining to be written */
 212                                         uint16_t BytesRemaining = ((EndAddr - StartAddr) + 1);
 213
 214                                         if (IS_ONEBYTE_COMMAND(SentCommand.Data, 0x00))        // Write flash
 215                                         {
 216                                                 /* Calculate the number of words to be written from the number of bytes to be written */
 217                                                 uint16_t WordsRemaining = (BytesRemaining >> 1);
 218
 219                                                 union
 220                                                 {
 221                                                         uint16_t Words[2];
 222                                                         uint32_t Long;
 223                                                 } CurrFlashAddress                 = {.Words = {StartAddr, Flash64KBPage}};
 224
 225                                                 uint32_t CurrFlashPageStartAddress = CurrFlashAddress.Long;
 226                                                 uint8_t  WordsInFlashPage          = 0;
 227
 228                                                 while (WordsRemaining--)
 229                                                 {
 230                                                         /* Check if endpoint is empty - if so clear it and wait until ready for next packet */
 231                                                         if (!(Endpoint_BytesInEndpoint()))
 232                                                         {
 233                                                                 Endpoint_ClearOUT();
 234
 235                                                                 while (!(Endpoint_IsOUTReceived()))
 236                                                                 {
 237                                                                         if (USB_DeviceState == DEVICE_STATE_Unattached)
 238                                                                           return;
 239                                                                 }
 240                                                         }
 241
 242                                                         /* Write the next word into the current flash page */
 243                                                         boot_page_fill(CurrFlashAddress.Long, Endpoint_Read_Word_LE());
 244
 245                                                         /* Adjust counters */
 246                                                         WordsInFlashPage      += 1;
 247                                                         CurrFlashAddress.Long += 2;
 248
 249                                                         /* See if an entire page has been written to the flash page buffer */
 250                                                         if ((WordsInFlashPage == (SPM_PAGESIZE >> 1)) || !(WordsRemaining))
 251                                                         {
 252                                                                 /* Commit the flash page to memory */
 253                                                                 boot_page_write(CurrFlashPageStartAddress);
 254                                                                 boot_spm_busy_wait();
 255
 256                                                                 /* Check if programming incomplete */
 257                                                                 if (WordsRemaining)
 258                                                                 {
 259                                                                         CurrFlashPageStartAddress = CurrFlashAddress.Long;
 260                                                                         WordsInFlashPage          = 0;
 261
 262                                                                         /* Erase next page's temp buffer */
 263                                                                         boot_page_erase(CurrFlashAddress.Long);
 264                                                                         boot_spm_busy_wait();
 265                                                                 }
 266                                                         }
 267                                                 }
 268
 269                                                 /* Once programming complete, start address equals the end address */
 270                                                 StartAddr = EndAddr;
 271
 272                                                 /* Re-enable the RWW section of flash */
 273                                                 boot_rww_enable();
 274                                         }
 275                                         else                                                   // Write EEPROM
 276                                         {
 277                                                 while (BytesRemaining--)
 278                                                 {
 279                                                         /* Check if endpoint is empty - if so clear it and wait until ready for next packet */
 280                                                         if (!(Endpoint_BytesInEndpoint()))
 281                                                         {
 282                                                                 Endpoint_ClearOUT();
 283
 284                                                                 while (!(Endpoint_IsOUTReceived()))
 285                                                                 {
 286                                                                         if (USB_DeviceState == DEVICE_STATE_Unattached)
 287                                                                           return;
 288                                                                 }
 289                                                         }
 290
 291                                                         /* Read the byte from the USB interface and write to to the EEPROM */
 292                                                         eeprom_write_byte((uint8_t*)StartAddr, Endpoint_Read_Byte());
 293
 294                                                         /* Adjust counters */
 295                                                         StartAddr++;
 296                                                 }
 297                                         }
 298
 299                                         /* Throw away the currently unused DFU file suffix */
 300                                         DiscardFillerBytes(DFU_FILE_SUFFIX_SIZE);
 301                                 }
 302                         }
 303
 304                         Endpoint_ClearOUT();
 305
 306                         Endpoint_ClearStatusStage();
 307
 308                         break;
 309                 case DFU_UPLOAD:
 310                         Endpoint_ClearSETUP();
 311
 312                         while (!(Endpoint_IsINReady()))
 313                         {
 314                                 if (USB_DeviceState == DEVICE_STATE_Unattached)
 315                                   return;
 316                         }
 317
 318                         if (DFU_State != dfuUPLOAD_IDLE)
 319                         {
 320                                 if ((DFU_State == dfuERROR) && IS_ONEBYTE_COMMAND(SentCommand.Data, 0x01))       // Blank Check
 321                                 {
 322                                         /* Blank checking is performed in the DFU_DNLOAD request - if we get here we've told the host
 323                                            that the memory isn't blank, and the host is requesting the first non-blank address */
 324                                         Endpoint_Write_Word_LE(StartAddr);
 325                                 }
 326                                 else
 327                                 {
 328                                         /* Idle state upload - send response to last issued command */
 329                                         Endpoint_Write_Byte(ResponseByte);
 330                                 }
 331                         }
 332                         else
 333                         {
 334                                 /* Determine the number of bytes remaining in the current block */
 335                                 uint16_t BytesRemaining = ((EndAddr - StartAddr) + 1);
 336
 337                                 if (IS_ONEBYTE_COMMAND(SentCommand.Data, 0x00))            // Read FLASH
 338                                 {
 339                                         /* Calculate the number of words to be written from the number of bytes to be written */
 340                                         uint16_t WordsRemaining = (BytesRemaining >> 1);
 341
 342                                         union
 343                                         {
 344                                                 uint16_t Words[2];
 345                                                 uint32_t Long;
 346                                         } CurrFlashAddress = {.Words = {StartAddr, Flash64KBPage}};
 347
 348                                         while (WordsRemaining--)
 349                                         {
 350                                                 /* Check if endpoint is full - if so clear it and wait until ready for next packet */
 351                                                 if (Endpoint_BytesInEndpoint() == FIXED_CONTROL_ENDPOINT_SIZE)
 352                                                 {
 353                                                         Endpoint_ClearIN();
 354
 355                                                         while (!(Endpoint_IsINReady()))
 356                                                         {
 357                                                                 if (USB_DeviceState == DEVICE_STATE_Unattached)
 358                                                                   return;
 359                                                         }
 360                                                 }
 361
 362                                                 /* Read the flash word and send it via USB to the host */
 363                                                 #if (FLASHEND > 0xFFFF)
 364                                                         Endpoint_Write_Word_LE(pgm_read_word_far(CurrFlashAddress.Long));
 365                                                 #else
 366                                                         Endpoint_Write_Word_LE(pgm_read_word(CurrFlashAddress.Long));
 367                                                 #endif
 368
 369                                                 /* Adjust counters */
 370                                                 CurrFlashAddress.Long += 2;
 371                                         }
 372
 373                                         /* Once reading is complete, start address equals the end address */
 374                                         StartAddr = EndAddr;
 375                                 }
 376                                 else if (IS_ONEBYTE_COMMAND(SentCommand.Data, 0x02))       // Read EEPROM
 377                                 {
 378                                         while (BytesRemaining--)
 379                                         {
 380                                                 /* Check if endpoint is full - if so clear it and wait until ready for next packet */
 381                                                 if (Endpoint_BytesInEndpoint() == FIXED_CONTROL_ENDPOINT_SIZE)
 382                                                 {
 383                                                         Endpoint_ClearIN();
 384
 385                                                         while (!(Endpoint_IsINReady()))
 386                                                         {
 387                                                                 if (USB_DeviceState == DEVICE_STATE_Unattached)
 388                                                                   return;
 389                                                         }
 390                                                 }
 391
 392                                                 /* Read the EEPROM byte and send it via USB to the host */
 393                                                 Endpoint_Write_Byte(eeprom_read_byte((uint8_t*)StartAddr));
 394
 395                                                 /* Adjust counters */
 396                                                 StartAddr++;
 397                                         }
 398                                 }
 399
 400                                 /* Return to idle state */
 401                                 DFU_State = dfuIDLE;
 402                         }
 403
 404                         Endpoint_ClearIN();
 405
 406                         Endpoint_ClearStatusStage();
 407                         break;
 408                 case DFU_GETSTATUS:
 409                         Endpoint_ClearSETUP();
 410
 411                         /* Write 8-bit status value */
 412                         Endpoint_Write_Byte(DFU_Status);
 413
 414                         /* Write 24-bit poll timeout value */
 415                         Endpoint_Write_Byte(0);
 416                         Endpoint_Write_Word_LE(0);
 417
 418                         /* Write 8-bit state value */
 419                         Endpoint_Write_Byte(DFU_State);
 420
 421                         /* Write 8-bit state string ID number */
 422                         Endpoint_Write_Byte(0);
 423
 424                         Endpoint_ClearIN();
 425
 426                         Endpoint_ClearStatusStage();
 427                         break;
 428                 case DFU_CLRSTATUS:
 429                         Endpoint_ClearSETUP();
 430
 431                         /* Reset the status value variable to the default OK status */
 432                         DFU_Status = OK;
 433
 434                         Endpoint_ClearStatusStage();
 435                         break;
 436                 case DFU_GETSTATE:
 437                         Endpoint_ClearSETUP();
 438
 439                         /* Write the current device state to the endpoint */
 440                         Endpoint_Write_Byte(DFU_State);
 441
 442                         Endpoint_ClearIN();
 443
 444                         Endpoint_ClearStatusStage();
 445                         break;
 446                 case DFU_ABORT:
 447                         Endpoint_ClearSETUP();
 448
 449                         /* Reset the current state variable to the default idle state */
 450                         DFU_State = dfuIDLE;
 451
 452                         Endpoint_ClearStatusStage();
 453                         break;
 454         }
 455 }
 456
 457 /** Routine to discard the specified number of bytes from the control endpoint stream. This is used to
 458  *  discard unused bytes in the stream from the host, including the memory program block suffix.
 459  *
 460  *  \param[in] NumberOfBytes  Number of bytes to discard from the host from the control endpoint
 461  */
 462 static void DiscardFillerBytes(uint8_t NumberOfBytes)
 463 {
 464         while (NumberOfBytes--)
 465         {
 466                 if (!(Endpoint_BytesInEndpoint()))
 467                 {
 468                         Endpoint_ClearOUT();
 469
 470                         /* Wait until next data packet received */
 471                         while (!(Endpoint_IsOUTReceived()))
 472                         {
 473                                 if (USB_DeviceState == DEVICE_STATE_Unattached)
 474                                   return;
 475                         }
 476                 }
 477                 else
 478                 {
 479                         Endpoint_Discard_Byte();
 480                 }
 481         }
 482 }
 483
 484 /** Routine to process an issued command from the host, via a DFU_DNLOAD request wrapper. This routine ensures
 485  *  that the command is allowed based on the current secure mode flag value, and passes the command off to the
 486  *  appropriate handler function.
 487  */
 488 static void ProcessBootloaderCommand(void)
 489 {
 490         /* Check if device is in secure mode */
 491         if (IsSecure)
 492         {
 493                 /* Don't process command unless it is a READ or chip erase command */
 494                 if (!(((SentCommand.Command == COMMAND_WRITE)             &&
 495                         IS_TWOBYTE_COMMAND(SentCommand.Data, 0x00, 0xFF)) ||
 496                            (SentCommand.Command == COMMAND_READ)))
 497                 {
 498                         /* Set the state and status variables to indicate the error */
 499                         DFU_State  = dfuERROR;
 500                         DFU_Status = errWRITE;
 501
 502                         /* Stall command */
 503                         Endpoint_StallTransaction();
 504
 505                         /* Don't process the command */
 506                         return;
 507                 }
 508         }
 509
 510         /* Dispatch the required command processing routine based on the command type */
 511         switch (SentCommand.Command)
 512         {
 513                 case COMMAND_PROG_START:
 514                         ProcessMemProgCommand();
 515                         break;
 516                 case COMMAND_DISP_DATA:
 517                         ProcessMemReadCommand();
 518                         break;
 519                 case COMMAND_WRITE:
 520                         ProcessWriteCommand();
 521                         break;
 522                 case COMMAND_READ:
 523                         ProcessReadCommand();
 524                         break;
 525                 case COMMAND_CHANGE_BASE_ADDR:
 526                         if (IS_TWOBYTE_COMMAND(SentCommand.Data, 0x03, 0x00))              // Set 64KB flash page command
 527                           Flash64KBPage = SentCommand.Data[2];
 528
 529                         break;
 530         }
 531 }
 532
 533 /** Routine to concatenate the given pair of 16-bit memory start and end addresses from the host, and store them
 534  *  in the StartAddr and EndAddr global variables.
 535  */
 536 static void LoadStartEndAddresses(void)
 537 {
 538         union
 539         {
 540                 uint8_t  Bytes[2];
 541                 uint16_t Word;
 542         } Address[2] = {{.Bytes = {SentCommand.Data[2], SentCommand.Data[1]}},
 543                         {.Bytes = {SentCommand.Data[4], SentCommand.Data[3]}}};
 544
 545         /* Load in the start and ending read addresses from the sent data packet */
 546         StartAddr = Address[0].Word;
 547         EndAddr   = Address[1].Word;
 548 }
 549
 550 /** Handler for a Memory Program command issued by the host. This routine handles the preparations needed
 551  *  to write subsequent data from the host into the specified memory.
 552  */
 553 static void ProcessMemProgCommand(void)
 554 {
 555         if (IS_ONEBYTE_COMMAND(SentCommand.Data, 0x00) ||                          // Write FLASH command
 556             IS_ONEBYTE_COMMAND(SentCommand.Data, 0x01))                            // Write EEPROM command
 557         {
 558                 /* Load in the start and ending read addresses */
 559                 LoadStartEndAddresses();
 560
 561                 /* If FLASH is being written to, we need to pre-erase the first page to write to */
 562                 if (IS_ONEBYTE_COMMAND(SentCommand.Data, 0x00))
 563                 {
 564                         union
 565                         {
 566                                 uint16_t Words[2];
 567                                 uint32_t Long;
 568                         } CurrFlashAddress = {.Words = {StartAddr, Flash64KBPage}};
 569
 570                         /* Erase the current page's temp buffer */
 571                         boot_page_erase(CurrFlashAddress.Long);
 572                         boot_spm_busy_wait();
 573                 }
 574
 575                 /* Set the state so that the next DNLOAD requests reads in the firmware */
 576                 DFU_State = dfuDNLOAD_IDLE;
 577         }
 578 }
 579
 580 /** Handler for a Memory Read command issued by the host. This routine handles the preparations needed
 581  *  to read subsequent data from the specified memory out to the host, as well as implementing the memory
 582  *  blank check command.
 583  */
 584 static void ProcessMemReadCommand(void)
 585 {
 586         if (IS_ONEBYTE_COMMAND(SentCommand.Data, 0x00) ||                          // Read FLASH command
 587         IS_ONEBYTE_COMMAND(SentCommand.Data, 0x02))                            // Read EEPROM command
 588         {
 589                 /* Load in the start and ending read addresses */
 590                 LoadStartEndAddresses();
 591
 592                 /* Set the state so that the next UPLOAD requests read out the firmware */
 593                 DFU_State = dfuUPLOAD_IDLE;
 594         }
 595         else if (IS_ONEBYTE_COMMAND(SentCommand.Data, 0x01))                       // Blank check FLASH command
 596         {
 597                 uint32_t CurrFlashAddress = 0;
 598
 599                 while (CurrFlashAddress < BOOT_START_ADDR)
 600                 {
 601                         /* Check if the current byte is not blank */
 602                         #if (FLASHEND > 0xFFFF)
 603                         if (pgm_read_byte_far(CurrFlashAddress) != 0xFF)
 604                         #else
 605                         if (pgm_read_byte(CurrFlashAddress) != 0xFF)
 606                         #endif
 607                         {
 608                                 /* Save the location of the first non-blank byte for response back to the host */
 609                                 Flash64KBPage = (CurrFlashAddress >> 16);
 610                                 StartAddr     = CurrFlashAddress;
 611
 612                                 /* Set state and status variables to the appropriate error values */
 613                                 DFU_State  = dfuERROR;
 614                                 DFU_Status = errCHECK_ERASED;
 615
 616                                 break;
 617                         }
 618
 619                         CurrFlashAddress++;
 620                 }
 621         }
 622 }
 623
 624 /** Handler for a Data Write command issued by the host. This routine handles non-programming commands such as
 625  *  bootloader exit (both via software jumps and hardware watchdog resets) and flash memory erasure.
 626  */
 627 static void ProcessWriteCommand(void)
 628 {
 629         if (IS_ONEBYTE_COMMAND(SentCommand.Data, 0x03))                            // Start application
 630         {
 631                 /* Indicate that the bootloader is terminating */
 632                 WaitForExit = true;
 633
 634                 /* Check if empty request data array - an empty request after a filled request retains the
 635                    previous valid request data, but initializes the reset */
 636                 if (!(SentCommand.DataSize))
 637                 {
 638                         if (SentCommand.Data[1] == 0x00)                                   // Start via watchdog
 639                         {
 640                                 /* Start the watchdog to reset the AVR once the communications are finalized */
 641                                 wdt_enable(WDTO_250MS);
 642                         }
 643                         else                                                               // Start via jump
 644                         {
 645                                 /* Load in the jump address into the application start address pointer */
 646                                 union
 647                                 {
 648                                         uint8_t  Bytes[2];
 649                                         AppPtr_t FuncPtr;
 650                                 } Address = {.Bytes = {SentCommand.Data[4], SentCommand.Data[3]}};
 651
 652                                 AppStartPtr = Address.FuncPtr;
 653
 654                                 /* Set the flag to terminate the bootloader at next opportunity */
 655                                 RunBootloader = false;
 656                         }
 657                 }
 658         }
 659         else if (IS_TWOBYTE_COMMAND(SentCommand.Data, 0x00, 0xFF))                 // Erase flash
 660         {
 661                 uint32_t CurrFlashAddress = 0;
 662
 663                 /* Clear the application section of flash */
 664                 while (CurrFlashAddress < BOOT_START_ADDR)
 665                 {
 666                         boot_page_erase(CurrFlashAddress);
 667                         boot_spm_busy_wait();
 668                         boot_page_write(CurrFlashAddress);
 669                         boot_spm_busy_wait();
 670
 671                         CurrFlashAddress += SPM_PAGESIZE;
 672                 }
 673
 674                 /* Re-enable the RWW section of flash as writing to the flash locks it out */
 675                 boot_rww_enable();
 676
 677                 /* Memory has been erased, reset the security bit so that programming/reading is allowed */
 678                 IsSecure = false;
 679         }
 680 }
 681
 682 /** Handler for a Data Read command issued by the host. This routine handles bootloader information retrieval
 683  *  commands such as device signature and bootloader version retrieval.
 684  */
 685 static void ProcessReadCommand(void)
 686 {
 687         const uint8_t BootloaderInfo[3] = {BOOTLOADER_VERSION, BOOTLOADER_ID_BYTE1, BOOTLOADER_ID_BYTE2};
 688         const uint8_t SignatureInfo[3]  = {AVR_SIGNATURE_1,    AVR_SIGNATURE_2,     AVR_SIGNATURE_3};
 689
 690         uint8_t DataIndexToRead = SentCommand.Data[1];
 691
 692         if (IS_ONEBYTE_COMMAND(SentCommand.Data, 0x00))                         // Read bootloader info
 693           ResponseByte = BootloaderInfo[DataIndexToRead];
 694         else if (IS_ONEBYTE_COMMAND(SentCommand.Data, 0x01))                    // Read signature byte
 695           ResponseByte = SignatureInfo[DataIndexToRead - 0x30];
 696 }