Projects/Magstripe/Magstripe.c

   1 /*
   2              LUFA Library
   3      Copyright (C) Dean Camera, 2009.
   4
   5   dean [at] fourwalledcubicle [dot] com
   6       www.fourwalledcubicle.com
   7 */
   8
   9 /*
  10   Copyright 2009  Denver Gingerich (denver [at] ossguy [dot] com)
  11   Copyright 2009  Dean Camera (dean [at] fourwalledcubicle [dot] com)
  12
  13   Permission to use, copy, modify, and distribute this software
  14   and its documentation for any purpose and without fee is hereby
  15   granted, provided that the above copyright notice appear in all
  16   copies and that both that the copyright notice and this
  17   permission notice and warranty disclaimer appear in supporting
  18   documentation, and that the name of the author not be used in
  19   advertising or publicity pertaining to distribution of the
  20   software without specific, written prior permission.
  21
  22   The author disclaim all warranties with regard to this
  23   software, including all implied warranties of merchantability
  24   and fitness.  In no event shall the author be liable for any
  25   special, indirect or consequential damages or any damages
  26   whatsoever resulting from loss of use, data or profits, whether
  27   in an action of contract, negligence or other tortious action,
  28   arising out of or in connection with the use or performance of
  29   this software.
  30 */
  31
  32 /** \file
  33  *
  34  *  Main source file for the MagStripe application. This file contains the code which drives
  35  *  the USB keyboard interface from the magnetic card stripe reader device.
  36  */
  37
  38 #include "Magstripe.h"
  39
  40 /* Scheduler Task List */
  41 TASK_LIST
  42 {
  43         { .Task = USB_USBTask          , .TaskStatus = TASK_STOP },
  44         { .Task = USB_Keyboard_Report  , .TaskStatus = TASK_STOP },
  45         { .Task = Magstripe_Read       , .TaskStatus = TASK_STOP },
  46 };
  47
  48 /* Global Variables */
  49 /** Indicates if the device is using Report Protocol mode, instead of Boot Protocol mode. Boot Protocol mode
  50  *  is a special reporting mode used by compatible PC BIOS to support USB keyboards before a full OS and USB
  51  *  driver has been loaded, by using predefined report structures indicated in the USB HID standard.
  52  */
  53 bool UsingReportProtocol = true;
  54
  55 /** Total idle period in milliseconds set by the host via a SetIdle request, used to silence the report endpoint
  56  *  until the report data changes or the idle period elapsed. Generally used to implement hardware key repeats, or
  57  *  by some BIOS to reduce the number of reports when in Boot Protocol mode.
  58  */
  59 uint8_t IdleCount = 0;
  60
  61 /** Milliseconds remaining counter for the HID class SetIdle and GetIdle requests, used to silence the report
  62  *  endpoint for an amount of time indicated by the host or until the report changes.
  63  */
  64 uint16_t IdleMSRemaining = 0;
  65
  66 /** Circular buffer to hold the read bits from track 1 of the inserted magnetic card. */
  67 BitBuffer_t Track1Data;
  68
  69 /** Circular buffer to hold the read bits from track 2 of the inserted magnetic card. */
  70 BitBuffer_t Track2Data;
  71
  72 /** Circular buffer to hold the read bits from track 3 of the inserted magnetic card. */
  73 BitBuffer_t Track3Data;
  74
  75 /** Delay counter between successive key strokes. This is to prevent the OS from ignoring multiple keys in a short
  76  *  period of time due to key repeats. Two milliseconds works for most OSes.
  77  */
  78 uint8_t KeyDelayRemaining;
  79
  80
  81 /** Main program entry point. This routine configures the hardware required by the application, then
  82  *  starts the scheduler to run the application tasks.
  83  */
  84 int main(void)
  85 {
  86         /* Disable watchdog if enabled by bootloader/fuses */
  87         MCUSR &= ~(1 << WDRF);
  88         wdt_disable();
  89
  90         /* Disable clock division */
  91         clock_prescale_set(clock_div_1);
  92
  93         /* Hardware Initialization */
  94         Magstripe_Init();
  95
  96         /* Buffer Initialization */
  97         BitBuffer_Init(&Track1Data);
  98         BitBuffer_Init(&Track2Data);
  99         BitBuffer_Init(&Track3Data);
 100
 101         /* Millisecond timer initialization, with output compare interrupt enabled for the idle timing */
 102         OCR0A  = 0xFA;
 103         TCCR0A = (1 << WGM01);
 104         TCCR0B = ((1 << CS01) | (1 << CS00));
 105         TIMSK0 = (1 << OCIE0A);
 106
 107         /* Initialize Scheduler so that it can be used */
 108         Scheduler_Init();
 109
 110         /* Initialize USB Subsystem */
 111         USB_Init();
 112
 113         /* Scheduling - routine never returns, so put this last in the main function */
 114         Scheduler_Start();
 115 }
 116
 117 /** Event handler for the USB_Connect event. This starts the USB task. */
 118 void EVENT_USB_Connect(void)
 119 {
 120         /* Start USB management task */
 121         Scheduler_SetTaskMode(USB_USBTask, TASK_RUN);
 122 }
 123
 124 /** Event handler for the USB_Disconnect event. This stops the USB and keyboard report tasks. */
 125 void EVENT_USB_Disconnect(void)
 126 {
 127         /* Stop running keyboard reporting, card reading and USB management tasks */
 128         Scheduler_SetTaskMode(USB_Keyboard_Report, TASK_STOP);
 129         Scheduler_SetTaskMode(USB_USBTask, TASK_STOP);
 130         Scheduler_SetTaskMode(Magstripe_Read, TASK_STOP);
 131 }
 132
 133 /** Event handler for the USB_ConfigurationChanged event. This configures the device's endpoints ready
 134  *  to relay reports to the host, and starts the keyboard report task.
 135  */
 136 void EVENT_USB_ConfigurationChanged(void)
 137 {
 138         /* Setup Keyboard Keycode Report Endpoint */
 139         Endpoint_ConfigureEndpoint(KEYBOARD_EPNUM, EP_TYPE_INTERRUPT,
 140                                        ENDPOINT_DIR_IN, KEYBOARD_EPSIZE,
 141                                    ENDPOINT_BANK_SINGLE);
 142
 143         /* Default to report protocol on connect */
 144         UsingReportProtocol = true;
 145
 146         /* Start Keyboard reporting and card reading tasks */
 147         Scheduler_SetTaskMode(USB_Keyboard_Report, TASK_RUN);
 148         Scheduler_SetTaskMode(Magstripe_Read, TASK_RUN);
 149 }
 150
 151 /** Event handler for the USB_UnhandledControlPacket event. This is used to catch standard and class specific
 152  *  control requests that are not handled internally by the USB library, so that they can be handled appropriately
 153  *  for the application.
 154  */
 155 void EVENT_USB_UnhandledControlPacket(void)
 156 {
 157         /* Handle HID Class specific requests */
 158         switch (USB_ControlRequest.bRequest)
 159         {
 160                 case REQ_GetReport:
 161                         if (USB_ControlRequest.bmRequestType == (REQDIR_DEVICETOHOST | REQTYPE_CLASS | REQREC_INTERFACE))
 162                         {
 163                                 USB_KeyboardReport_Data_t KeyboardReportData;
 164
 165                                 /* Create the next keyboard report for transmission to the host */
 166                                 GetNextReport(&KeyboardReportData);
 167
 168                                 Endpoint_ClearSETUP();
 169
 170                                 /* Write the report data to the control endpoint */
 171                                 Endpoint_Write_Control_Stream_LE(&KeyboardReportData, sizeof(KeyboardReportData));
 172
 173                                 /* Finalize the stream transfer to send the last packet or clear the host abort */
 174                                 Endpoint_ClearOUT();
 175                         }
 176
 177                         break;
 178                 case REQ_GetProtocol:
 179                         if (USB_ControlRequest.bmRequestType == (REQDIR_DEVICETOHOST | REQTYPE_CLASS | REQREC_INTERFACE))
 180                         {
 181                                 Endpoint_ClearSETUP();
 182
 183                                 /* Write the current protocol flag to the host */
 184                                 Endpoint_Write_Byte(UsingReportProtocol);
 185
 186                                 /* Send the flag to the host */
 187                                 Endpoint_ClearIN();
 188
 189                                 /* Acknowledge status stage */
 190                                 while (!(Endpoint_IsOUTReceived()));
 191                                 Endpoint_ClearOUT();
 192                         }
 193
 194                         break;
 195                 case REQ_SetProtocol:
 196                         if (USB_ControlRequest.bmRequestType == (REQDIR_HOSTTODEVICE | REQTYPE_CLASS | REQREC_INTERFACE))
 197                         {
 198                                 Endpoint_ClearSETUP();
 199
 200                                 /* Set or clear the flag depending on what the host indicates that the current Protocol should be */
 201                                 UsingReportProtocol = (USB_ControlRequest.wValue != 0x0000);
 202
 203                                 /* Acknowledge status stage */
 204                                 while (!(Endpoint_IsINReady()));
 205                                 Endpoint_ClearIN();
 206                         }
 207
 208                         break;
 209                 case REQ_SetIdle:
 210                         if (USB_ControlRequest.bmRequestType == (REQDIR_HOSTTODEVICE | REQTYPE_CLASS | REQREC_INTERFACE))
 211                         {
 212                                 Endpoint_ClearSETUP();
 213
 214                                 /* Get idle period in MSB */
 215                                 IdleCount = (USB_ControlRequest.wValue >> 8);
 216
 217                                 /* Acknowledge status stage */
 218                                 while (!(Endpoint_IsINReady()));
 219                                 Endpoint_ClearIN();
 220                         }
 221
 222                         break;
 223                 case REQ_GetIdle:
 224                         if (USB_ControlRequest.bmRequestType == (REQDIR_DEVICETOHOST | REQTYPE_CLASS | REQREC_INTERFACE))
 225                         {
 226                                 Endpoint_ClearSETUP();
 227
 228                                 /* Write the current idle duration to the host */
 229                                 Endpoint_Write_Byte(IdleCount);
 230
 231                                 /* Send the flag to the host */
 232                                 Endpoint_ClearIN();
 233
 234                                 /* Acknowledge status stage */
 235                                 while (!(Endpoint_IsOUTReceived()));
 236                                 Endpoint_ClearOUT();
 237                         }
 238
 239                         break;
 240         }
 241 }
 242
 243 /** ISR for the timer 0 compare vector. This ISR fires once each millisecond, and decrements the counter indicating
 244  *  the number of milliseconds left to idle (not send the host reports) if the device has been instructed to idle
 245  *  by the host via a SetIdle class specific request.
 246  */
 247 ISR(TIMER0_COMPA_vect, ISR_BLOCK)
 248 {
 249         /* One millisecond has elapsed, decrement the idle time remaining counter if it has not already elapsed */
 250         if (IdleMSRemaining)
 251           IdleMSRemaining--;
 252
 253         if (KeyDelayRemaining)
 254           KeyDelayRemaining--;
 255 }
 256
 257 /** Constructs a keyboard report indicating the currently pressed keyboard keys to the host.
 258  *
 259  *  \param ReportData  Pointer to a USB_KeyboardReport_Data_t report structure where the resulting report should
 260  *                     be stored
 261  *
 262  *  \return Boolean true if the current report is different to the previous report, false otherwise
 263  */
 264 bool GetNextReport(USB_KeyboardReport_Data_t* ReportData)
 265 {
 266         static bool OddReport   = false;
 267         static bool MustRelease = false;
 268
 269         BitBuffer_t* Buffer     = NULL;
 270
 271         /* Clear the report contents */
 272         memset(ReportData, 0, sizeof(USB_KeyboardReport_Data_t));
 273
 274         /* Get the next non-empty track data buffer */
 275         if (Track1Data.Elements)
 276           Buffer = &Track1Data;
 277         else if (Track2Data.Elements)
 278           Buffer = &Track2Data;
 279         else if (Track3Data.Elements)
 280           Buffer = &Track3Data;
 281
 282         if (Buffer != NULL)
 283         {
 284                 /* Toggle the odd report number indicator */
 285                 OddReport   = !OddReport;
 286
 287                 /* Set the flag indicating that a null report must eventually be sent to release all pressed keys */
 288                 MustRelease = true;
 289
 290                 /* Only send the next key on odd reports, so that they are interspersed with null reports to release keys */
 291                 if (OddReport)
 292                 {
 293                         /* Set the report key code to the key code for the next data bit */
 294                         ReportData->KeyCode = BitBuffer_GetNextBit(Buffer) ? KEY_1 : KEY_0;
 295
 296                         /* If buffer is now empty, a new line must be sent instead of the terminating bit */
 297                         if (!(Buffer->Elements))
 298                         {
 299                                 /* Set the keycode to the code for an enter key press */
 300                                 ReportData->KeyCode = KEY_ENTER;
 301                         }
 302                 }
 303
 304                 return true;
 305         }
 306         else if (MustRelease)
 307         {
 308                 /* Leave key code to null (0), to release all pressed keys */
 309                 return true;
 310         }
 311
 312         return false;
 313 }
 314
 315 /** Task to read out data from inserted magnetic cards and place the separate track data into their respective
 316  *  data buffers for later sending to the host as keyboard key presses.
 317  */
 318 TASK(Magstripe_Read)
 319 {
 320         /* Arrays to hold the buffer pointers, clock and data bit masks for the separate card tracks */
 321         const struct
 322         {
 323                 BitBuffer_t* Buffer;
 324                 uint8_t      ClockMask;
 325                 uint8_t      DataMask;
 326         } TrackInfo[] = {{&Track1Data, MAG_T1_CLOCK, MAG_T1_DATA},
 327                          {&Track2Data, MAG_T2_CLOCK, MAG_T2_DATA},
 328                          {&Track3Data, MAG_T3_CLOCK, MAG_T3_DATA}};
 329
 330         /* Previous magnetic card control line' status, for later comparison */
 331         uint8_t Magstripe_Prev = 0;
 332
 333         /* Buffered current card reader control line' status */
 334         uint8_t Magstripe_LCL  = Magstripe_GetStatus();
 335
 336         /* Exit the task early if no card is present in the reader */
 337         if (!(Magstripe_LCL & MAG_CARDPRESENT))
 338           return;
 339
 340         /* Read out card data while a card is present */
 341         while (Magstripe_LCL & MAG_CARDPRESENT)
 342         {
 343                 /* Read out the next bit for each track of the card */
 344                 for (uint8_t Track = 0; Track < 3; Track++)
 345                 {
 346                         /* Current data line status for the current card track */
 347                         bool DataLevel    = ((Magstripe_LCL & TrackInfo[Track].DataMask) != 0);
 348
 349                         /* Current clock line status for the current card track */
 350                         bool ClockLevel   = ((Magstripe_LCL & TrackInfo[Track].ClockMask) != 0);
 351
 352                         /* Current track clock transition check */
 353                         bool ClockChanged = (((Magstripe_LCL ^ Magstripe_Prev) & TrackInfo[Track].ClockMask) != 0);
 354
 355                         /* Sample the next bit on the falling edge of the track's clock line, store key code into the track's buffer */
 356                         if (ClockLevel && ClockChanged)
 357                           BitBuffer_StoreNextBit(TrackInfo[Track].Buffer, DataLevel);
 358                 }
 359
 360                 /* Retain the current card reader control line states for later edge detection */
 361                 Magstripe_Prev = Magstripe_LCL;
 362
 363                 /* Retrieve the new card reader control line states */
 364                 Magstripe_LCL  = Magstripe_GetStatus();
 365         }
 366
 367         /* Add terminators to the end of each track buffer */
 368         BitBuffer_StoreNextBit(&Track1Data, 0);
 369         BitBuffer_StoreNextBit(&Track2Data, 0);
 370         BitBuffer_StoreNextBit(&Track3Data, 0);
 371 }
 372
 373 /** Task for the magnetic card reading and keyboard report generation. This task waits until a card is inserted,
 374  *  then reads off the card data and sends it to the host as a series of keyboard key presses via keyboard reports.
 375  */
 376 TASK(USB_Keyboard_Report)
 377 {
 378         USB_KeyboardReport_Data_t KeyboardReportData;
 379         bool                      SendReport = false;
 380
 381         /* Check if the USB system is connected to a host */
 382         if (USB_IsConnected)
 383         {
 384                 /* Select the Keyboard Report Endpoint */
 385                 Endpoint_SelectEndpoint(KEYBOARD_EPNUM);
 386
 387                 /* Check if Keyboard Endpoint Ready for Read/Write */
 388                 if (Endpoint_IsReadWriteAllowed())
 389                 {
 390                         /* Only fetch the next key to send once the period between key presses has elapsed */
 391                         if (!(KeyDelayRemaining))
 392                         {
 393                                 /* Create the next keyboard report for transmission to the host */
 394                                 SendReport = GetNextReport(&KeyboardReportData);
 395                         }
 396
 397                         /* Check if the idle period is set and has elapsed */
 398                         if (IdleCount && !(IdleMSRemaining))
 399                         {
 400                                 /* Idle period elapsed, indicate that a report must be sent */
 401                                 SendReport = true;
 402
 403                                 /* Reset the idle time remaining counter, must multiply by 4 to get the duration in milliseconds */
 404                                 IdleMSRemaining = (IdleCount << 2);
 405                         }
 406
 407                         /* Write the keyboard report if a report is to be sent to the host */
 408                         if (SendReport)
 409                         {
 410                                 /* Write Keyboard Report Data */
 411                                 Endpoint_Write_Stream_LE(&KeyboardReportData, sizeof(USB_KeyboardReport_Data_t));
 412
 413                                 /* Finalize the stream transfer to send the last packet */
 414                                 Endpoint_ClearIN();
 415
 416                                 /* Reset the key delay period counter */
 417                                 KeyDelayRemaining = 2;
 418                         }
 419                 }
 420         }
 421 }