qmk_firmware/Projects/Magstripe/Magstripe.c

/*
             LUFA Library
     Copyright (C) Dean Camera, 2009.
              
  dean [at] fourwalledcubicle [dot] com
      www.fourwalledcubicle.com
*/

/*
  Copyright 2009  Denver Gingerich (denver [at] ossguy [dot] com)
  Copyright 2009  Dean Camera (dean [at] fourwalledcubicle [dot] com)

  Permission to use, copy, modify, and distribute this software
  and its documentation for any purpose and without fee is hereby
  granted, provided that the above copyright notice appear in all
  copies and that both that the copyright notice and this
  permission notice and warranty disclaimer appear in supporting
  documentation, and that the name of the author not be used in
  advertising or publicity pertaining to distribution of the
  software without specific, written prior permission.

  The author disclaim all warranties with regard to this
  software, including all implied warranties of merchantability
  and fitness.  In no event shall the author be liable for any
  special, indirect or consequential damages or any damages
  whatsoever resulting from loss of use, data or profits, whether
  in an action of contract, negligence or other tortious action,
  arising out of or in connection with the use or performance of
  this software.
*/
 
#include "Magstripe.h"

BitBuffer_t TrackDataBuffers[3];

USB_ClassInfo_HID_t Keyboard_HID_Interface =
	{
		.InterfaceNumber         = 0,

		.ReportINEndpointNumber  = KEYBOARD_EPNUM,
		.ReportINEndpointSize    = KEYBOARD_EPSIZE,
	};

int main(void)
{
	SetupHardware();
	
	for (uint8_t Buffer = 0; Buffer < 3; Buffer++)
	  BitBuffer_Init(&TrackDataBuffers[Buffer]);

	for (;;)
	{
		if (Magstripe_GetStatus() & MAG_CARDPRESENT)
		  ReadMagstripeData();

		USB_HID_USBTask(&Keyboard_HID_Interface);
		USB_USBTask();
	}
}

void SetupHardware(void)
{
	/* Disable watchdog if enabled by bootloader/fuses */
	MCUSR &= ~(1 << WDRF);
	wdt_disable();

	/* Disable clock division */
	clock_prescale_set(clock_div_1);

	/* Hardware Initialization */
	Magstripe_Init();
	USB_Init();
}

void ReadMagstripeData(void)
{
	/* Arrays to hold the buffer pointers, clock and data bit masks for the separate card tracks */
	const struct
	{
		uint8_t ClockMask;
		uint8_t DataMask;	
	} TrackInfo[] = {{MAG_T1_CLOCK, MAG_T1_DATA},
	                 {MAG_T2_CLOCK, MAG_T2_DATA},
	                 {MAG_T3_CLOCK, MAG_T3_DATA}};

	uint8_t Magstripe_Prev = 0;
	uint8_t Magstripe_LCL  = Magstripe_GetStatus();

	while (Magstripe_LCL & MAG_CARDPRESENT)
	{
		for (uint8_t Track = 0; Track < 3; Track++)
		{
			bool DataPinLevel      = ((Magstripe_LCL & TrackInfo[Track].DataMask) != 0);
			bool ClockPinLevel     = ((Magstripe_LCL & TrackInfo[Track].ClockMask) != 0);
			bool ClockLevelChanged = (((Magstripe_LCL ^ Magstripe_Prev) & TrackInfo[Track].ClockMask) != 0);
		
			if (ClockPinLevel && ClockLevelChanged)
			  BitBuffer_StoreNextBit(&TrackDataBuffers[Track], DataPinLevel);
		}

		Magstripe_Prev = Magstripe_LCL;
		Magstripe_LCL  = Magstripe_GetStatus();
	}
}

void EVENT_USB_ConfigurationChanged(void)
{
	USB_HID_ConfigureEndpoints(&Keyboard_HID_Interface);
}

void EVENT_USB_UnhandledControlPacket(void)
{
	USB_HID_ProcessControlPacket(&Keyboard_HID_Interface);
}

void EVENT_USB_StartOfFrame(void)
{
	USB_HID_RegisterStartOfFrame(&Keyboard_HID_Interface);
}

uint16_t CALLBACK_USB_HID_CreateNextHIDReport(USB_ClassInfo_HID_t* HIDInterfaceInfo, void* ReportData)
{
	static bool IsKeyReleaseReport;
	static bool IsNewlineReport;

	BitBuffer_t*               Buffer         = NULL;
	USB_KeyboardReport_Data_t* KeyboardReport = (USB_KeyboardReport_Data_t*)ReportData;
		
	/* Key reports must be interleaved with 0 Key Code reports to release the keys, or repeated keys will be ignored */
	IsKeyReleaseReport = !IsKeyReleaseReport;	

	if (IsKeyReleaseReport)
	{
		KeyboardReport->KeyCode = 0;
	}
	else if (IsNewlineReport)
	{
		IsNewlineReport = false;
		KeyboardReport->KeyCode = KEY_ENTER;
	}
	else
	{
		if (TrackDataBuffers[0].Elements)
		  Buffer = &TrackDataBuffers[0];
		else if (TrackDataBuffers[1].Elements)
		  Buffer = &TrackDataBuffers[1];			
		else if (TrackDataBuffers[2].Elements)
		  Buffer = &TrackDataBuffers[2];
		else
		  return 0;

		KeyboardReport->KeyCode = BitBuffer_GetNextBit(Buffer) ? KEY_1 : KEY_0;
		
		/* If buffer now empty, next report must be a newline to seperate track data */
		if (!(Buffer->Elements))
		  IsNewlineReport = true;
	}
	
	return sizeof(USB_KeyboardReport_Data_t);
}

void CALLBACK_USB_HID_ProcessReceivedHIDReport(USB_ClassInfo_HID_t* HIDInterfaceInfo, void* ReportData, uint16_t ReportSize)
{
	// Unused (but mandatory for the HID class driver) in this demo, since there are no Host->Device reports
}