From e2e37bea66206adefbb2fc97fcbfb71c1a3cfbe7 Mon Sep 17 00:00:00 2001
From: henryk <henryk@6dc7ffe9-61d6-0310-9af1-9938baff3ed1>
Date: Fri, 14 Mar 2008 04:55:15 +0000
Subject: Add T/C based receiver code with integrated miller decoder Integrate
 T/C receiver into iso14443 layer 2a Add state field to iso14443_frame, rename
 ssc buffer state constants Sniffer seems to work with the new code

git-svn-id: https://svn.openpcd.org:2342/trunk@452 6dc7ffe9-61d6-0310-9af1-9938baff3ed1
---
 openpicc/Makefile                           |   5 +-
 openpicc/application/cmd.c                  |   4 +-
 openpicc/application/iso14443.h             |   9 ++
 openpicc/application/iso14443_layer2a.c     |  71 ++++++----
 openpicc/application/iso14443_layer2a.h     |  17 +--
 openpicc/application/iso14443_layer3a.c     |  24 ++--
 openpicc/application/iso14443_sniffer.c     |  37 ++---
 openpicc/application/iso14443a_diffmiller.c |  37 ++++-
 openpicc/application/iso14443a_diffmiller.h |   2 +
 openpicc/application/iso14443a_pretender.c  |   4 +-
 openpicc/application/main.c                 |   8 +-
 openpicc/application/openpicc.h             |   1 +
 openpicc/application/performance.c          |   5 +
 openpicc/application/ssc.c                  |  34 ++---
 openpicc/application/ssc.h                  |  22 +--
 openpicc/application/ssc_buffer.h           |  10 +-
 openpicc/application/tc_recv.c              | 213 ++++++++++++++++++++++++++++
 openpicc/application/tc_recv.h              |  21 +++
 openpicc/application/tc_sniffer.c           |   8 --
 19 files changed, 400 insertions(+), 132 deletions(-)
 create mode 100644 openpicc/application/tc_recv.c
 create mode 100644 openpicc/application/tc_recv.h

(limited to 'openpicc')

diff --git a/openpicc/Makefile b/openpicc/Makefile
index e70eab7..b4270ab 100644
--- a/openpicc/Makefile
+++ b/openpicc/Makefile
@@ -88,6 +88,7 @@ ARM_SRC= \
   application/tc_cdiv_sync.c \
   application/tc_fdt.c \
   application/tc_cdiv.c \
+  application/tc_recv.c \
   application/usb_print.c \
   application/iso14443_layer2a.c \
   application/iso14443a_manchester.c \
@@ -109,9 +110,9 @@ ARM_SRC= \
   os/core/MemMang/heap_2.c \
   os/usb/USB-CDC.c \
   os/usb/USBIsr.c \
-  application/tc_sniffer.c \
+  application/iso14443_sniffer.c \
+#  application/tc_sniffer.c \
 #  application/iso14443a_pretender.c \
-#  application/iso14443_sniffer.c \
 #  application/iso14443_layer3a.c
 
 #
diff --git a/openpicc/application/cmd.c b/openpicc/application/cmd.c
index 4d7d6b2..412a349 100644
--- a/openpicc/application/cmd.c
+++ b/openpicc/application/cmd.c
@@ -243,9 +243,9 @@ void prvExecCommand(u_int32_t cmd, portCHAR *args) {
 		case 'P':
 		    print_pio();
 		    break;
-		case 'R':
+/*		case 'R':
 			start_stop_sniffing();
-			break;
+			break;*/
 		case 'C':
 		    DumpStringToUSB(
 			" *****************************************************\n\r"
diff --git a/openpicc/application/iso14443.h b/openpicc/application/iso14443.h
index d3439d1..a2d7458 100644
--- a/openpicc/application/iso14443.h
+++ b/openpicc/application/iso14443.h
@@ -75,8 +75,17 @@
 #define MAXIMUM_FRAME_SIZE 256
 #define ISO14443A_MAX_RX_FRAME_SIZE_IN_BITS (MAXIMUM_FRAME_SIZE*9 +2)
 
+typedef enum {
+	FRAME_FREE=0,    /* Frame is free */
+	FRAME_PENDING,   /* Frame is currently filled by Rx */
+	FRAME_FULL,      /* Frame has been filled by Rx */
+	FRAME_PROCESSING,/* The frame is currently processed by the consumer */
+} iso14443_frame_state_t;
+
+
 typedef struct {
   enum { TYPE_A, TYPE_B } type;
+  iso14443_frame_state_t state;
   union {
   	struct {
   		enum { SHORT_FRAME, STANDARD_FRAME, AC_FRAME } format;
diff --git a/openpicc/application/iso14443_layer2a.c b/openpicc/application/iso14443_layer2a.c
index 91df6b9..65d5d6a 100644
--- a/openpicc/application/iso14443_layer2a.c
+++ b/openpicc/application/iso14443_layer2a.c
@@ -44,6 +44,7 @@
 #include "tc_fdt.h"
 #include "tc_cdiv.h"
 #include "tc_cdiv_sync.h"
+#include "tc_recv.h"
 #include "load_modulation.h"
 #include "clock_switch.h"
 #include "pio_irq.h"
@@ -58,6 +59,7 @@ static u_int8_t tx_pending=0;
 static u_int8_t rx_pending=0;
 static iso14443_receive_callback_t callback=NULL;
 static ssc_handle_t *ssc;
+static tc_recv_handle_t th;
 
 #ifdef FOUR_TIMES_OVERSAMPLING
 #define RX_DIVIDER 32
@@ -65,10 +67,9 @@ static ssc_handle_t *ssc;
 #define RX_DIVIDER 64
 #endif
 
-int iso14443_receive(iso14443_receive_callback_t _callback, ssc_dma_rx_buffer_t **buffer, unsigned int timeout)
+int iso14443_receive(iso14443_receive_callback_t _callback, iso14443_frame **frame, unsigned int timeout)
 {
-	ssc_dma_rx_buffer_t* _buffer = NULL;
-	int len;
+	iso14443_frame* _frame = NULL;
 	
 	if(rx_pending) {
 		return -EALREADY;
@@ -76,9 +77,9 @@ int iso14443_receive(iso14443_receive_callback_t _callback, ssc_dma_rx_buffer_t
 	rx_pending=1;
 	callback=_callback;
 	
-	if(ssc_recv(ssc, &_buffer, timeout) == 0) {
+	if(tc_recv_receive(th, &_frame, timeout) == 0) {
 		
-		if(_buffer == NULL) {
+		if(_frame == NULL) {
 			/* Can this happen? */
 			rx_pending=0;
 			callback=NULL;
@@ -86,25 +87,23 @@ int iso14443_receive(iso14443_receive_callback_t _callback, ssc_dma_rx_buffer_t
 		}
 		
 		portENTER_CRITICAL();
-		_buffer->state = PROCESSING;
+		_frame->state = FRAME_PROCESSING;
 		portEXIT_CRITICAL();
 		
-		len = _buffer->len_transfers;
-		
 		if(callback != NULL && !fast_receive) {
-			callback(_buffer, 0);
+			callback(NULL, _frame, 0);
 		}
 		
-		if(buffer != NULL) *buffer = _buffer;
+		if(frame != NULL) *frame = _frame;
 		else {
 			portENTER_CRITICAL();
-			_buffer->state = FREE;
+			_frame->state = FRAME_FREE;
 			portEXIT_CRITICAL();
 		}
 		
 		rx_pending=0;
 		callback=NULL;
-		return len;
+		return 0;
 	}
 	
 	/* Note: There is the remote chance of a race condition probability here if
@@ -185,7 +184,7 @@ u_int8_t iso14443_get_fast_receive(void)
 
 static void iso14443_ssc_callback(ssc_callback_reason reason, void *data)
 {
-	if(reason == CALLBACK_RX_FRAME_BEGIN) {
+	if(reason == SSC_CALLBACK_RX_FRAME_BEGIN) {
 		/* Busy loop for the frame end */
 		int *end_asserted = data, i=0;
 		for(i=0; i<96000; i++) 
@@ -197,20 +196,20 @@ static void iso14443_ssc_callback(ssc_callback_reason reason, void *data)
 		return;
 	}
 	
-	if(reason == CALLBACK_TX_FRAME_ENDED) {
+	if(reason == SSC_CALLBACK_TX_FRAME_ENDED) {
 		tx_pending = 0;
 	}
 	
-	if( reason == CALLBACK_RX_FRAME_ENDED && fast_receive ) {
+	if( reason == SSC_CALLBACK_RX_FRAME_ENDED && fast_receive ) {
 		clock_switch(CLOCK_SELECT_CARRIER); /* A Tx might be coming up */
 		
 		ssc_dma_rx_buffer_t *buffer = data;
 		if(callback != NULL)
-			callback(buffer, 1);
+			callback(buffer, NULL, 1);
 	}
 	
-	if( (reason == CALLBACK_RX_FRAME_ENDED && !tx_pending) || reason == CALLBACK_RX_STARTING 
-			|| reason == CALLBACK_TX_FRAME_ENDED ) {
+	if( (reason == SSC_CALLBACK_RX_FRAME_ENDED && !tx_pending) || reason == SSC_CALLBACK_RX_STARTING 
+			|| reason == SSC_CALLBACK_TX_FRAME_ENDED ) {
 		/* For regular SSC Rx we'd set the clock to
 		// clock_switch(CLOCK_SELECT_PLL);
 		 * however, the SSC Rx code is going to go away (at least for 14443-A)
@@ -226,16 +225,27 @@ static void iso14443_ssc_callback(ssc_callback_reason reason, void *data)
 		usb_print_set_default_flush(old);
 #endif
 	}
-	
 }
 
-static portBASE_TYPE iso14443_rx_FRAME_cb(u_int32_t pio, portBASE_TYPE xTaskWoken)
+static void iso14443_tc_recv_callback(tc_recv_callback_reason reason, void *data)
 {
-	(void)pio;
-	if(PRINT_DEBUG) usb_print_string_f("°", 0);  // DEBUG OUTPUT
-	if(AT91F_PIO_IsInputSet(AT91C_BASE_PIOA, OPENPICC_PIO_FRAME))
-		ssc_frame_started();
-	return xTaskWoken;
+	if( reason == TC_RECV_CALLBACK_RX_FRAME_ENDED && fast_receive ) {
+		clock_switch(CLOCK_SELECT_CARRIER); /* A Tx might be coming up */
+		
+		iso14443_frame *frame = data;
+		if(callback != NULL)
+			callback(NULL, frame, 1);
+	}
+	
+	if( (reason == TC_RECV_CALLBACK_RX_FRAME_ENDED && !tx_pending) ||
+			reason == TC_RECV_CALLBACK_SETUP ) {
+		/* For T/C Rx we set the clock to */
+		clock_switch(CLOCK_SELECT_CARRIER);
+		ssc_set_gate(1);
+		tc_fdt_set(0xff00);
+		tc_cdiv_set_divider(RX_DIVIDER);
+		tc_cdiv_sync_reset();
+	}
 }
 
 int iso14443_layer2a_init(u_int8_t enable_fast_receive)
@@ -251,14 +261,15 @@ int iso14443_layer2a_init(u_int8_t enable_fast_receive)
 	iso14443_set_fast_receive(enable_fast_receive);
 	pio_irq_init_once();
 	
-	if(pio_irq_register(OPENPICC_PIO_FRAME, &iso14443_rx_FRAME_cb) >= 0) {
-		if(PRINT_DEBUG) usb_print_string("FRAME irq registered\n\r"); // DEBUG OUTPUT
-	}
-	
-	ssc = ssc_open(1, 1, SSC_MODE_14443A, iso14443_ssc_callback);
+	ssc = ssc_open(0, 1, SSC_MODE_14443A, iso14443_ssc_callback);
 	if(ssc == NULL)
 		return -EIO;
 	
+	if(tc_recv_init(&th, 0, iso14443_tc_recv_callback) < 0) {
+		ssc_close(ssc);
+		return -EIO;
+	}
+	
 	load_mod_level(3);
 	
 	return 0;
diff --git a/openpicc/application/iso14443_layer2a.h b/openpicc/application/iso14443_layer2a.h
index 858af81..a8874d0 100644
--- a/openpicc/application/iso14443_layer2a.h
+++ b/openpicc/application/iso14443_layer2a.h
@@ -4,36 +4,37 @@
 #include "ssc_buffer.h"
 
 /* Callback type for iso14443_receive().
- * Parameter buffer is being passed a pointer to an SSC Rx buffer structure that this receive happened
- * on. You might want to pass this into iso14443a_decode_miller().
+ * Parameter buffer is either being passed a pointer to an SSC Rx buffer structure that this 
+ * receive happened on, or a fully decoded iso14443_frame. 
+ * If it's an SSC buffer you might want to pass this into iso14443a_decode_miller().
  * Parameter in_irq is true if the callback has been called while still in IRQ mode. It must then *NOT*
  * perform any calls that might upset the IRQ processing. Especially it may not call into FreeRTOS or
  * any parts of the applications that do.
  */
-typedef void (*iso14443_receive_callback_t)(ssc_dma_rx_buffer_t *buffer, u_int8_t in_irq);
+typedef void (*iso14443_receive_callback_t)(ssc_dma_rx_buffer_t *buffer, iso14443_frame *frame, u_int8_t in_irq);
 
 /* Wait for and receive a frame. Parameters callback and buffer are optional. If you omit them you'll lose
  * the received frame, obviously.
  * Parameter callback is a callback function that will be called for each received frame and might
  * then trigger a response.
- * Parameter buffer is an output pointer to a pointer to an SSC Rx buffer structure containing the
+ * Parameter frame is an output pointer to a pointer to an ISO14443 frame structure containing the
  * received frame.
  * Parameter timeout gives an optional timeout for the receive operation after which the receive will
  * be aborted. When timeout is 0 the receive will not time out.
  * This call will block until a frame is received or an exception happens. Obviously it must not be run
  * from IRQ context.
  * 
- * Warning: When you get a buffer from the function then its state is set to PROCESSING and you must 
- * FREE it yourself. However, you MUST NOT free a buffer from the callback.
+ * Warning: When you get a frame from the function then its state is set to SSC_PROCESSING and you must 
+ * SSC_FREE it yourself. However, you MUST NOT free a buffer or a frame from the callback.
  * 
  * Return values:
- * >= 0        Frame received, return value is buffer length (yes, 0 is a valid buffer length)
+ * = 0         Frame received
  * -ENETDOWN   PLL is not locked or PLL lock lost
  * -ETIMEDOUT  Receive timed out without receiving anything (usually not regarded an error condition)
  * -EBUSY      A Tx is currently running or pending; can't receive
  * -EALREADY   There's already an iso14443_receive() invocation running
  */
-extern int iso14443_receive(iso14443_receive_callback_t callback, ssc_dma_rx_buffer_t **buffer, unsigned int timeout);
+extern int iso14443_receive(iso14443_receive_callback_t callback, iso14443_frame **frame, unsigned int timeout);
 
 /*
  * Transmit a frame. Starts transmitting fdt carrier cycles after the end of the received frame.
diff --git a/openpicc/application/iso14443_layer3a.c b/openpicc/application/iso14443_layer3a.c
index daac8dd..132038e 100644
--- a/openpicc/application/iso14443_layer3a.c
+++ b/openpicc/application/iso14443_layer3a.c
@@ -158,8 +158,8 @@ void __ramfunc iso14443_layer3a_irq_ext(u_int32_t ssc_sr, enum ssc_mode ssc_mode
 		
 		if(send_atqa) {
 		vLedSetGreen(0);
-			if(ssc_tx_buffer.state == PREFILLED && ssc_tx_buffer.source == &ATQA_FRAME) {
-				ssc_tx_buffer.state = PROCESSING;
+			if(ssc_tx_buffer.state == SSC_PREFILLED && ssc_tx_buffer.source == &ATQA_FRAME) {
+				ssc_tx_buffer.state = SSC_PROCESSING;
 				vLedSetGreen(1);
 				iso14443_transmit(&ssc_tx_buffer, fdt, 8);
 				atqa_sent = 1;
@@ -174,8 +174,8 @@ void __ramfunc iso14443_layer3a_irq_ext(u_int32_t ssc_sr, enum ssc_mode ssc_mode
 #define FALSE (0!=0)
 static int prefill_buffer(ssc_dma_tx_buffer_t *dest, const iso14443_frame *src) {
 	portENTER_CRITICAL();
-	if(dest->state == FREE) {
-		dest->state = PROCESSING;
+	if(dest->state == SSC_FREE) {
+		dest->state = SSC_PROCESSING;
 		portEXIT_CRITICAL();
 		dest->source = (void*)src;
 		dest->len = sizeof(ssc_tx_buffer.data);
@@ -185,15 +185,15 @@ static int prefill_buffer(ssc_dma_tx_buffer_t *dest, const iso14443_frame *src)
 		if(ret>0) {
 			dest->len = ret;
 			portENTER_CRITICAL();
-			dest->state = PREFILLED;
+			dest->state = SSC_PREFILLED;
 			portEXIT_CRITICAL();
 		} else {
 			portENTER_CRITICAL();
-			dest->state = FREE;
+			dest->state = SSC_FREE;
 			portEXIT_CRITICAL();
 		}
 		return ret > 0;
-	} else if(dest->state == PREFILLED) {
+	} else if(dest->state == SSC_PREFILLED) {
 		portEXIT_CRITICAL();
 		return dest->source == src;
 	} else {
@@ -325,7 +325,7 @@ void iso14443_layer3a_state_machine (void *pvParameters)
 				vLedSetGreen(0);
 				vLedBlinkGreen();
 				portENTER_CRITICAL();
-				buffer->state = PROCESSING;
+				buffer->state = SSC_PROCESSING;
 				portEXIT_CRITICAL();
 				u_int32_t first_sample = *(u_int32_t*)buffer->data;
 				
@@ -392,16 +392,16 @@ void iso14443_layer3a_state_machine (void *pvParameters)
 								ssc_rx_start();
 							} else {
 								//vTaskDelay(portTICK_RATE_MS);
-								if(ssc_tx_buffer.source == &ATQA_FRAME) ssc_tx_buffer.state = FREE;
+								if(ssc_tx_buffer.source == &ATQA_FRAME) ssc_tx_buffer.state = SSC_FREE;
 								if(prefill_buffer(&ssc_tx_buffer, &NULL_FRAME)) {
 									usb_print_string_f("Sending response ...",0);
-									ssc_tx_buffer.state = PROCESSING;
+									ssc_tx_buffer.state = SSC_PROCESSING;
 									iso14443_transmit(&ssc_tx_buffer,
 										received_frame.parameters.a.last_bit==ISO14443A_LAST_BIT_0 ?
 										ISO14443A_TRANSMIT_AT_NEXT_INTERVAL_0 :
 										ISO14443A_TRANSMIT_AT_NEXT_INTERVAL_1, 
 									8);
-									while( ssc_tx_buffer.state != FREE ) {
+									while( ssc_tx_buffer.state != SSC_FREE ) {
 										vTaskDelay(portTICK_RATE_MS);
 									}
 									usb_print_string("done\n\r");
@@ -415,7 +415,7 @@ void iso14443_layer3a_state_machine (void *pvParameters)
 				}
 				
 				portENTER_CRITICAL();
-				buffer->state = FREE;
+				buffer->state = SSC_FREE;
 				portEXIT_CRITICAL();
 			}
 		} else vTaskDelay(portTICK_RATE_MS);
diff --git a/openpicc/application/iso14443_sniffer.c b/openpicc/application/iso14443_sniffer.c
index bc326b4..6d4a451 100644
--- a/openpicc/application/iso14443_sniffer.c
+++ b/openpicc/application/iso14443_sniffer.c
@@ -26,6 +26,7 @@
 #include <board.h>
 #include <task.h>
 #include <errno.h>
+#include <stdlib.h>
 
 #include "openpicc.h"
 #include "ssc_buffer.h"
@@ -37,12 +38,11 @@
 #include "cmd.h"
 #include "led.h"
 
-static iso14443_frame rx_frame;
+static iso14443_frame *rx_frame;
 
 void iso14443_sniffer (void *pvParameters)
 {
 	(void)pvParameters;
-	(void)rx_frame;
 	int res;
 	
 	/* Delay until USB print etc. are ready */
@@ -56,47 +56,30 @@ void iso14443_sniffer (void *pvParameters)
 		}
 	} while(res < 0);
 	
+	
+	//while(1) { static int i=0; vTaskDelay(10*portTICK_RATE_MS); vLedSetBrightness(LED_RED, abs(1000-i)); i=(i+8)%2000; }
+		
 	usb_print_string("Waiting for carrier. ");
 	while(iso14443_wait_for_carrier(1000 * portTICK_RATE_MS) != 0) {
 	}
 	usb_print_string("Carrier detected.\n\r");
 	
 	while(true) {
-		ssc_dma_rx_buffer_t *buffer = 0;
-		res = iso14443_receive(NULL, &buffer, 20000 * portTICK_RATE_MS);
+		res = iso14443_receive(NULL, &rx_frame, 20000 * portTICK_RATE_MS);
 		if(res >= 0) {
-#if 1
 			DumpStringToUSB("\n\r");
 			DumpTimeToUSB(xTaskGetTickCount());
 			usb_print_string(": Frame received, consists of ");
-			DumpUIntToUSB(res);
-			usb_print_string(" transfers (");
-			DumpUIntToUSB(buffer->reception_mode->transfersize_ssc);
-			usb_print_string(" bits from SSC each)\n\r                  ");
-			if(buffer->len_transfers < 200)
-				DumpBufferToUSB((char*)buffer->data, (buffer->len_transfers * buffer->reception_mode->transfersize_pdc)/8);
-			else {
-				DumpBufferToUSB((char*)buffer->data, (200 * buffer->reception_mode->transfersize_pdc)/8);
-				usb_print_string("...");
-			}
-			usb_print_string("\n\r                  ");
 			
-			iso14443a_decode_miller(&rx_frame, buffer);
-			
-			usb_print_string("Decodes to ");
-			DumpUIntToUSB(rx_frame.numbytes);
+			DumpUIntToUSB(rx_frame->numbytes);
 			usb_print_string(" bytes and ");
-			DumpUIntToUSB(rx_frame.numbits);
+			DumpUIntToUSB(rx_frame->numbits);
 			usb_print_string(" bits:  ");
-			DumpBufferToUSB((char*)rx_frame.data, rx_frame.numbytes + (rx_frame.numbits+7)/8 );
+			DumpBufferToUSB((char*)rx_frame->data, rx_frame->numbytes + (rx_frame->numbits+7)/8 );
 			usb_print_string("\n\r");
-#else
-			DumpUIntToUSB(buffer->len_transfers);
-			DumpStringToUSB("\n\r");
-#endif
 			
 			portENTER_CRITICAL();
-			buffer->state = FREE;
+			rx_frame->state = FRAME_FREE;
 			portEXIT_CRITICAL();
 		} else {
 			if(res != -ETIMEDOUT) {
diff --git a/openpicc/application/iso14443a_diffmiller.c b/openpicc/application/iso14443a_diffmiller.c
index a5acfc8..d73bf95 100644
--- a/openpicc/application/iso14443a_diffmiller.c
+++ b/openpicc/application/iso14443a_diffmiller.c
@@ -124,6 +124,7 @@ inline void start_frame(struct diffmiller_state * const state)
 	//memset(state->frame, 0, sizeof(*state->frame));
 	memset(state->frame, 0, (u_int32_t)&(((iso14443_frame*)0)->data) );
 	performance_set_checkpoint("start_frame after memset");
+	state->frame->state = FRAME_PENDING;
 }
 
 static inline void append_to_frame(struct diffmiller_state *const state,
@@ -171,7 +172,7 @@ static inline void end_frame(struct diffmiller_state * const state, const u_int3
 }
 
 #define PRINT_BIT(a) if(0){(void)a;}
-//#define PRINT_BIT(a) usb_print_string(a)
+//#define PRINT_BIT(a) usb_print_string_f(a,0)
 
 #define DO_BIT_0 { \
 	if(++counter==9) { \
@@ -194,10 +195,10 @@ static inline void end_frame(struct diffmiller_state * const state, const u_int3
 }
 
 #define DO_SYMBOL_X \
+	PRINT_BIT("(X)"); \
 	if(!in_frame) { \
 		if(last_bit == BIT_0) DO_BIT_0; \
 		error = 1; \
-		end_frame(state, counter); \
 		PRINT_BIT(" ERROR\n"); \
 		last_bit = BIT_ERROR; \
 		in_frame = 0; \
@@ -208,10 +209,10 @@ static inline void end_frame(struct diffmiller_state * const state, const u_int3
 	}
 
 #define DO_SYMBOL_Y \
+	PRINT_BIT("(Y)"); \
 	if(!in_frame) { \
 		if(last_bit == BIT_0) DO_BIT_0; \
 		error = 1; \
-		end_frame(state, counter); \
 		PRINT_BIT(" ERROR\n"); \
 		last_bit = BIT_ERROR; \
 		in_frame = 0; \
@@ -227,6 +228,7 @@ static inline void end_frame(struct diffmiller_state * const state, const u_int3
 	}
 
 #define DO_SYMBOL_Z \
+	PRINT_BIT("(Z)"); \
 	if(!in_frame) { \
 		if(last_bit == BIT_0) DO_BIT_0; \
 		counter = 0; \
@@ -308,11 +310,12 @@ int iso14443a_decode_diffmiller(struct diffmiller_state * const state, iso14443_
 		
 		if(state->flags.frame_finished)  {
 			state->flags.frame_finished = 0;
-			state->old_state = old_state;
+			state->old_state = sym_y;
 			state->last_bit = last_bit;
 			state->counter = counter;
 			state->flags.in_frame = in_frame;
 			state->flags.error = error;
+			state->frame = NULL;
 			performance_set_checkpoint("frame finished");
 			return 0;
 		}
@@ -327,6 +330,31 @@ int iso14443a_decode_diffmiller(struct diffmiller_state * const state, iso14443_
 	return -EBUSY;
 }
 
+int iso14443a_diffmiller_assert_frame_ended(struct diffmiller_state * const state, 
+		iso14443_frame * const frame)
+{
+	if(state == NULL || !state->initialized) return -EINVAL;
+	if(!state->flags.in_frame) return -EBUSY;
+	if(state->frame != NULL && state->frame != frame) return -EINVAL;
+	state->frame = frame;
+
+	end_frame(state, state->counter);
+	PRINT_BIT(" EOF2\n");
+	state->flags.in_frame = 0;
+	
+	if(state->flags.frame_finished)  {
+		state->flags.frame_finished = 0;
+		state->old_state = sym_y;
+		state->last_bit = BIT_EOF;
+		state->counter = 0;
+		state->frame = NULL;
+		performance_set_checkpoint("frame finished2");
+		return 0;
+	}
+	
+	return -EBUSY;
+}
+
 struct diffmiller_state *iso14443a_init_diffmiller(int pauses_count)
 {
 	if(_state.initialized) return NULL;
@@ -334,6 +362,7 @@ struct diffmiller_state *iso14443a_init_diffmiller(int pauses_count)
 	state->initialized = 1;
 	state->pauses_count = pauses_count;
 	state->frame = NULL;
+	state->old_state = sym_y;
 	state->flags.frame_finished = 0;
 	
 	return state;
diff --git a/openpicc/application/iso14443a_diffmiller.h b/openpicc/application/iso14443a_diffmiller.h
index f5336d6..7dc9c55 100644
--- a/openpicc/application/iso14443a_diffmiller.h
+++ b/openpicc/application/iso14443a_diffmiller.h
@@ -7,6 +7,8 @@ struct diffmiller_state;
 
 extern int iso14443a_decode_diffmiller(struct diffmiller_state *state, iso14443_frame *frame, 
 	const u_int32_t buffer[], unsigned int *offset, const unsigned int buflen);
+extern int iso14443a_diffmiller_assert_frame_ended(struct diffmiller_state * const state, 
+		iso14443_frame * const frame);
 extern struct diffmiller_state *iso14443a_init_diffmiller(int pauses_count);
 
 #endif /*ISO14443A_DIFFMILLER_H_*/
diff --git a/openpicc/application/iso14443a_pretender.c b/openpicc/application/iso14443a_pretender.c
index 64112d1..03fb12d 100644
--- a/openpicc/application/iso14443a_pretender.c
+++ b/openpicc/application/iso14443a_pretender.c
@@ -118,7 +118,7 @@ static void fast_receive_callback(ssc_dma_rx_buffer_t *buffer, u_int8_t in_irq)
 	
 	
 	if(tx_buffer != NULL) {
-		tx_buffer->state = FULL;
+		tx_buffer->state = SSC_FULL;
 		if(	iso14443_transmit(tx_buffer, fdt, 1, 0) < 0) {
 			usb_print_string_f("Tx failed ", 0);
 		}
@@ -229,7 +229,7 @@ prefill_failed:
 			}
 			
 			portENTER_CRITICAL();
-			buffer->state = FREE;
+			buffer->state = SSC_FREE;
 			portEXIT_CRITICAL();
 		} else {
 			if(res != -ETIMEDOUT) {
diff --git a/openpicc/application/main.c b/openpicc/application/main.c
index 8babafe..a082933 100644
--- a/openpicc/application/main.c
+++ b/openpicc/application/main.c
@@ -211,12 +211,12 @@ int main (void)
 	NULL, TASK_USB_PRIORITY, NULL);
     /*xTaskCreate (iso14443_layer3a_state_machine, (signed portCHAR *) "ISO14443A-3", TASK_ISO_STACK,
 	NULL, TASK_ISO_PRIORITY, NULL);*/
-    /*xTaskCreate (iso14443_sniffer, (signed portCHAR *) "ISO14443-SNIFF", TASK_ISO_STACK,
-	NULL, TASK_ISO_PRIORITY, NULL);*/
+    xTaskCreate (iso14443_sniffer, (signed portCHAR *) "ISO14443-SNIFF", TASK_ISO_STACK,
+	NULL, TASK_ISO_PRIORITY, NULL);
     /*xTaskCreate (iso14443a_pretender, (signed portCHAR *) "ISO14443A-PRETEND", TASK_ISO_STACK,
 	NULL, TASK_ISO_PRIORITY, NULL);*/
-    xTaskCreate (tc_sniffer, (signed portCHAR *) "RFID-SNIFFER", TASK_ISO_STACK,
-		 	NULL, TASK_ISO_PRIORITY, NULL);
+    /*xTaskCreate (tc_sniffer, (signed portCHAR *) "RFID-SNIFFER", TASK_ISO_STACK,
+		 	NULL, TASK_ISO_PRIORITY, NULL);*/
 
 	    
     xTaskCreate (vUSBCDCTask, (signed portCHAR *) "USB", TASK_USB_STACK,
diff --git a/openpicc/application/openpicc.h b/openpicc/application/openpicc.h
index b4d2b7a..17cb4ee 100644
--- a/openpicc/application/openpicc.h
+++ b/openpicc/application/openpicc.h
@@ -39,5 +39,6 @@ typedef int s_int32_t;
 #define DA_BASELINE 200
 
 #define DIV_ROUND_UP(a,b) ( (a+(b-1)) / b)
+#define MIN(a, b) ((a)>(b)?(b):(a))
 
 #endif/*__OPENPICC_H__*/
diff --git a/openpicc/application/performance.c b/openpicc/application/performance.c
index cffd094..4515f18 100644
--- a/openpicc/application/performance.c
+++ b/openpicc/application/performance.c
@@ -33,6 +33,7 @@ static u_int32_t overruns = 0;
 #define NUMBER_OF_CHECKPOINTS 20
 static struct performance_checkpoint checkpoints[NUMBER_OF_CHECKPOINTS];
 static int current_checkpoint;
+static int running=0;
 
 static void __ramfunc tc_perf_irq(void) __attribute__ ((naked));
 static void __ramfunc tc_perf_irq(void)
@@ -66,6 +67,7 @@ inline void performance_start(void)
 	memset(checkpoints, 0, sizeof(checkpoints));
 	current_checkpoint = 0;
 	overruns = 0;
+	running = 1;
 	tc_perf->TC_CCR = AT91C_TC_SWTRG | AT91C_TC_CLKEN;
 }
 
@@ -82,6 +84,7 @@ inline perf_time_t performance_get(void)
 inline perf_time_t performance_stop(void)
 {
 	perf_time_t result = performance_get();
+	running = 0;
 	tc_perf->TC_CCR = AT91C_TC_CLKDIS;
 	return result;
 }
@@ -105,6 +108,7 @@ perf_time_t performance_diff(perf_time_t a, perf_time_t b)
 
 void performance_set_checkpoint(const char * const description)
 {
+	if(!running) return;
 	if(current_checkpoint < NUMBER_OF_CHECKPOINTS) {
 		perf_time_t time = performance_get();
 		checkpoints[current_checkpoint++] = (struct performance_checkpoint){
@@ -116,6 +120,7 @@ void performance_set_checkpoint(const char * const description)
 
 void performance_stop_report(void)
 {
+	if(!running) return;
 	perf_time_t _now = performance_stop();
 	struct performance_checkpoint now = {
 			.time = _now,
diff --git a/openpicc/application/ssc.c b/openpicc/application/ssc.c
index e25d982..4da45ae 100644
--- a/openpicc/application/ssc.c
+++ b/openpicc/application/ssc.c
@@ -125,7 +125,7 @@ static int __ramfunc _ssc_rx_irq(u_int32_t orig_sr, int start_asserted, portBASE
 		sh->ssc->SSC_RCMR = (orig_rcmr & (~AT91C_SSC_START)) | (AT91C_SSC_START_CONTINOUS);
 		/* Receiving has started */
 		if(sh->callback != NULL) {
-			sh->callback(CALLBACK_RX_FRAME_BEGIN, &end_asserted);
+			sh->callback(SSC_CALLBACK_RX_FRAME_BEGIN, &end_asserted);
 			if(end_asserted)
 				sr = orig_sr | _ssc.ssc->SSC_SR;
 		}
@@ -147,9 +147,9 @@ static int __ramfunc _ssc_rx_irq(u_int32_t orig_sr, int start_asserted, portBASE
 		ssc_dma_rx_buffer_t *buffer = _unload_rx(sh);
 		if(buffer != NULL) {
 			if(sh->callback != NULL)
-				sh->callback(CALLBACK_RX_FRAME_ENDED, buffer);
+				sh->callback(SSC_CALLBACK_RX_FRAME_ENDED, buffer);
 
-			if(buffer->state != FREE) {
+			if(buffer->state != SSC_FREE) {
 				task_woken = xQueueSendFromISR(sh->rx_queue, &buffer, task_woken);
 			}
 		}
@@ -174,7 +174,7 @@ static int __ramfunc _ssc_rx_irq(u_int32_t orig_sr, int start_asserted, portBASE
 		} else {
 			sh->ssc->SSC_IDR = SSC_RX_IRQ_MASK;
 			sh->rx_running = 0;
-			sh->callback(CALLBACK_RX_STOPPED, sh);
+			sh->callback(SSC_CALLBACK_RX_STOPPED, sh);
 		}
 		
 	}
@@ -202,7 +202,7 @@ static void __ramfunc _ssc_tx_end(ssc_handle_t *sh, int is_an_abort)
 	AT91F_PDC_SetNextTx(sh->pdc, 0, 0);
 
 	if(sh->tx_buffer) {
-		sh->tx_buffer->state = FREE;
+		sh->tx_buffer->state = SSC_FREE;
 		sh->tx_running = 0;
 	}
 	
@@ -213,9 +213,9 @@ static void __ramfunc _ssc_tx_end(ssc_handle_t *sh, int is_an_abort)
 	
 	if(sh->callback) {
 		if(is_an_abort)
-			sh->callback(CALLBACK_TX_FRAME_ABORTED, sh->tx_buffer);
+			sh->callback(SSC_CALLBACK_TX_FRAME_ABORTED, sh->tx_buffer);
 		else
-			sh->callback(CALLBACK_TX_FRAME_ENDED, sh->tx_buffer);
+			sh->callback(SSC_CALLBACK_TX_FRAME_ENDED, sh->tx_buffer);
 	}
 		
 	sh->tx_buffer = NULL;
@@ -236,7 +236,7 @@ static int __ramfunc _ssc_tx_irq(u_int32_t sr, portBASE_TYPE task_woken)
 		sh->ssc->SSC_TCMR = (sh->ssc->SSC_TCMR & ~AT91C_SSC_START) | AT91C_SSC_START_CONTINOUS;
 
 		if(sh->callback) 
-			sh->callback(CALLBACK_TX_FRAME_BEGIN, NULL);
+			sh->callback(SSC_CALLBACK_TX_FRAME_BEGIN, NULL);
 	}
 	
 	if( sr & AT91C_SSC_TXEMPTY ) {
@@ -297,7 +297,7 @@ static __ramfunc int _reload_rx(ssc_handle_t *sh)
 		goto out;
 	}
 	
-	ssc_dma_rx_buffer_t *buffer = _get_buffer(FREE, PENDING);
+	ssc_dma_rx_buffer_t *buffer = _get_buffer(SSC_FREE, SSC_PENDING);
 	
 	if(buffer == NULL) {
 		ssc_metrics[METRIC_RX_OVERFLOWS].value++;
@@ -328,7 +328,7 @@ static __ramfunc ssc_dma_rx_buffer_t* _unload_rx(ssc_handle_t *sh)
 		rcr = sh->pdc->PDC_RCR;
 	AT91F_PDC_SetRx(sh->pdc, 0, 0);
 	sh->rx_buffer[0] = NULL;
-	buffer->state = FULL;
+	buffer->state = SSC_FULL;
 	
 	if(rcr == 0) {
 		buffer->flags.overflow = 1;
@@ -357,7 +357,7 @@ static __ramfunc ssc_dma_rx_buffer_t* _unload_rx(ssc_handle_t *sh)
 	
 	if((buffer->len_transfers - rcr) != (rpr - (unsigned int)buffer->data)*(buffer->reception_mode->transfersize_pdc/8)) {
 		ssc_metrics[METRIC_MANAGEMENT_ERRORS_3].value++;
-		buffer->state = FREE;
+		buffer->state = SSC_FREE;
 		return NULL;
 	}
 	
@@ -393,7 +393,7 @@ static void _ssc_start_rx(ssc_handle_t *sh)
 		 AT91C_SSC_CP1 | AT91C_SSC_ENDRX;
 	sh->rx_running = 1;
 	if(sh->callback != NULL)
-		sh->callback(CALLBACK_RX_STARTING, sh);
+		sh->callback(SSC_CALLBACK_RX_STARTING, sh);
 
 	// Actually enable reception
 	int dummy = sh->ssc->SSC_RHR; (void)dummy;
@@ -411,7 +411,7 @@ static void _ssc_stop_rx(ssc_handle_t *sh)
 	sh->ssc->SSC_IDR = SSC_RX_IRQ_MASK;
 	sh->rx_running = 0;
 	if(sh->callback != NULL)
-		sh->callback(CALLBACK_RX_STOPPED, sh);
+		sh->callback(SSC_CALLBACK_RX_STOPPED, sh);
 	taskEXIT_CRITICAL();
 }
 
@@ -556,7 +556,7 @@ static int _ssc_register_callback(ssc_handle_t *sh, ssc_callback_t _callback)
 	if(sh->callback != NULL) return -EBUSY;
 	sh->callback = _callback;
 	if(sh->callback != NULL) 
-		sh->callback(CALLBACK_SETUP, sh);
+		sh->callback(SSC_CALLBACK_SETUP, sh);
 	return 0;
 }
 
@@ -565,7 +565,7 @@ static int _ssc_unregister_callback(ssc_handle_t *sh, ssc_callback_t _callback)
 	if(!sh) return -EINVAL;
 	if(_callback == NULL || sh->callback == _callback) {
 		if(sh->callback != NULL) 
-			sh->callback(CALLBACK_TEARDOWN, sh);
+			sh->callback(SSC_CALLBACK_TEARDOWN, sh);
 		sh->callback = NULL;
 	}
 	return 0;
@@ -686,7 +686,7 @@ int ssc_send(ssc_handle_t* sh, ssc_dma_tx_buffer_t *buffer)
 	
 	AT91F_PDC_SetTx(sh->pdc, buffer->data, num_data);
 	AT91F_PDC_SetNextTx(sh->pdc, 0, 0);
-	buffer->state = PENDING;
+	buffer->state = SSC_PENDING;
 
 	sh->ssc->SSC_IER = AT91C_SSC_TXEMPTY | AT91C_SSC_TXSYN;
 	/* Enable DMA */
@@ -795,7 +795,7 @@ int ssc_get_metric(ssc_metric metric, char **description, int *value)
 			_value = 0;
 			int i;
 			for(i=0; i < SSC_DMA_BUFFER_COUNT; i++)
-				if(_rx_buffers[i].state == FREE) _value++;
+				if(_rx_buffers[i].state == SSC_FREE) _value++;
 			break;
 		case METRIC_MANAGEMENT_ERRORS:
 			_value = ssc_metrics[METRIC_MANAGEMENT_ERRORS_1].value +
diff --git a/openpicc/application/ssc.h b/openpicc/application/ssc.h
index 9edec64..e99d444 100644
--- a/openpicc/application/ssc.h
+++ b/openpicc/application/ssc.h
@@ -21,17 +21,17 @@ typedef enum {
 extern int ssc_get_metric(ssc_metric metric, char **description, int *value);
 
 typedef enum {
-	CALLBACK_RX_STARTING,       // *data is ssh_handle_t *sh
-	CALLBACK_RX_STOPPED,        // *data is ssh_handle_t *sh
-	CALLBACK_RX_FRAME_BEGIN,    // *data is int *end_asserted
-								//  may set *end_asserted = 1 to force tell the IRQ handler  
-								//  that you have detected the end of reception
-	CALLBACK_RX_FRAME_ENDED,    // *data is ssc_dma_rx_buffer *buffer
-	CALLBACK_TX_FRAME_BEGIN,
-	CALLBACK_TX_FRAME_ENDED,
-	CALLBACK_TX_FRAME_ABORTED,
-	CALLBACK_SETUP,             // *data is ssh_handle_t *sh
-	CALLBACK_TEARDOWN,          // *data is ssh_handle_t *sh
+	SSC_CALLBACK_RX_STARTING,       // *data is ssh_handle_t *sh
+	SSC_CALLBACK_RX_STOPPED,        // *data is ssh_handle_t *sh
+	SSC_CALLBACK_RX_FRAME_BEGIN,    // *data is int *end_asserted
+									//  may set *end_asserted = 1 to force tell the IRQ handler  
+									//  that you have detected the end of reception
+	SSC_CALLBACK_RX_FRAME_ENDED,    // *data is ssc_dma_rx_buffer *buffer
+	SSC_CALLBACK_TX_FRAME_BEGIN,
+	SSC_CALLBACK_TX_FRAME_ENDED,
+	SSC_CALLBACK_TX_FRAME_ABORTED,
+	SSC_CALLBACK_SETUP,             // *data is ssh_handle_t *sh
+	SSC_CALLBACK_TEARDOWN,          // *data is ssh_handle_t *sh
 } ssc_callback_reason;
 typedef void (*ssc_callback_t)(ssc_callback_reason reason, void *data);
 
diff --git a/openpicc/application/ssc_buffer.h b/openpicc/application/ssc_buffer.h
index 5365851..527ae46 100644
--- a/openpicc/application/ssc_buffer.h
+++ b/openpicc/application/ssc_buffer.h
@@ -15,11 +15,11 @@
 #endif
 
 typedef enum {
-	FREE=0,    /* Buffer is free */
-	PENDING,   /* Buffer has been given to the DMA controller and is currently being filled */
-	FULL,      /* DMA controller signalled that the buffer is full */
-	PROCESSING,/* The buffer is currently processed by the consumer (e.g. decoder) */
-	PREFILLED, /* The buffer has been prefilled for later usage (only used for TX) */
+	SSC_FREE=0,    /* Buffer is free */
+	SSC_PENDING,   /* Buffer has been given to the DMA controller and is currently being filled */
+	SSC_FULL,      /* DMA controller signalled that the buffer is full */
+	SSC_PROCESSING,/* The buffer is currently processed by the consumer (e.g. decoder) */
+	SSC_PREFILLED, /* The buffer has been prefilled for later usage (only used for TX) */
 } ssc_dma_buffer_state_t;
 
 enum ssc_mode {
diff --git a/openpicc/application/tc_recv.c b/openpicc/application/tc_recv.c
new file mode 100644
index 0000000..fa6b510
--- /dev/null
+++ b/openpicc/application/tc_recv.c
@@ -0,0 +1,213 @@
+/***************************************************************
+ *
+ * OpenPICC - ISO 14443 Layer 2 Type A  T/C based receiver code
+ * Implements a receiver using FDT Timer/Counter (TC2) and the
+ * FIQ to measure the number of carrier cycles between modulation
+ * pauses.
+ * 
+ * The timing measurements are given to the differential miller
+ * decoder on the fly to interleave reception and decoding. This
+ * means two things: a) The CPU will be held in an IRQ handler
+ * with IRQs disabled for the time of reception and b) The frame
+ * will already have been fully decoded to a iso14443_frame
+ * structure when reception ends.
+ * 
+ * Copyright 2008 Henryk Plötz <henryk@ploetzli.ch>
+ *
+ ***************************************************************
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; version 2.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License along
+    with this program; if not, write to the Free Software Foundation, Inc.,
+    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+
+*/
+
+#include <FreeRTOS.h>
+#include <openpicc.h>
+#include <errno.h>
+#include <string.h>
+
+#include <task.h>
+#include <queue.h>
+
+#include "tc_recv.h"
+
+#include "iso14443a_diffmiller.h"
+#include "usb_print.h"
+#include "pio_irq.h"
+#include "led.h"
+#include "cmd.h"
+
+struct tc_recv_handle {
+	u_int8_t initialized;
+	u_int8_t pauses_count;
+	struct diffmiller_state *decoder;
+	int current, next;
+	tc_recv_callback_t callback;
+	iso14443_frame *current_frame;
+	xQueueHandle rx_queue;
+};
+
+static struct tc_recv_handle _tc;
+
+#define BUFSIZE 1024
+typedef struct {
+	u_int32_t count;
+	u_int32_t data[BUFSIZE];
+} fiq_buffer_t;
+fiq_buffer_t fiq_buffers[2];
+
+fiq_buffer_t *tc_sniffer_next_buffer_for_fiq = 0;
+
+iso14443_frame rx_frames[TC_RECV_NUMBER_OF_FRAME_BUFFERS];
+
+#define REAL_FRAME_END 333 
+
+static int tc_recv_buffer_overruns = 0;
+
+static inline iso14443_frame *get_frame_buffer(tc_recv_handle_t th)
+{
+	if(th->current_frame) return th->current_frame;
+	unsigned int i; iso14443_frame *result;
+	for(i=0; i<sizeof(rx_frames)/sizeof(rx_frames[0]); i++) {
+		if(rx_frames[i].state == FRAME_FREE) {
+			result = &rx_frames[i];
+			result->state = FRAME_PENDING;
+			th->current_frame = result;
+			return result;
+		}
+	}
+	tc_recv_buffer_overruns++;
+	return NULL;
+}
+
+static portBASE_TYPE handle_frame(iso14443_frame *frame, portBASE_TYPE task_woken)
+{
+	if(_tc.callback) _tc.callback(TC_RECV_CALLBACK_RX_FRAME_ENDED, frame);
+	if(frame->state != FRAME_FREE) {
+		task_woken = xQueueSendFromISR(_tc.rx_queue, &frame, task_woken);
+	}
+	_tc.current_frame = NULL;
+	return task_woken;
+}
+
+static portBASE_TYPE handle_buffer(u_int32_t data[], unsigned int count, portBASE_TYPE task_woken)
+{
+	unsigned int offset = 0;
+	while(offset < count) {
+		iso14443_frame *rx_frame = get_frame_buffer(&_tc);
+		if(rx_frame == NULL) return task_woken;
+		int ret = iso14443a_decode_diffmiller(_tc.decoder, rx_frame, data, &offset, count);
+		if(ret == 0) {
+			task_woken = handle_frame(rx_frame, task_woken);
+		}
+	}
+	return task_woken;
+}
+
+static inline portBASE_TYPE flush_buffer(fiq_buffer_t *buffer, portBASE_TYPE task_woken)
+{
+	if(buffer->count > 0) {
+		if(buffer->count >= BUFSIZE) {
+			usb_print_string_f("Warning: Possible buffer overrun detected\n\r",0);
+			//overruns++;
+		}
+		buffer->count = MIN(buffer->count, BUFSIZE);
+		task_woken = handle_buffer(buffer->data, buffer->count, task_woken);
+		buffer->count = 0;
+	}
+	return task_woken;
+}
+
+#define NEXT_BUFFER(a) ((a+1)%(sizeof(fiq_buffers)/sizeof(fiq_buffers[0])))
+
+static portBASE_TYPE switch_buffers(portBASE_TYPE task_woken)
+{
+	_tc.next = NEXT_BUFFER(_tc.current);
+	task_woken = flush_buffer( &fiq_buffers[_tc.next] , task_woken);
+	
+	tc_sniffer_next_buffer_for_fiq = &fiq_buffers[_tc.current=_tc.next];
+	return task_woken;
+}
+
+static portBASE_TYPE tc_recv_irq(u_int32_t pio, portBASE_TYPE task_woken)
+{
+	(void)pio;
+	/* TODO There should be some emergency exit here to prevent the CPU from
+	 * spinning in the IRQ for excessive amounts of time. (Maximum transmission
+	 * time for 256 Byte frame is something like 21ms.)
+	 */ 
+	while(*AT91C_TC2_CV <= REAL_FRAME_END || 
+			fiq_buffers[NEXT_BUFFER(_tc.current)].count > 0 || 
+			fiq_buffers[_tc.current].count > 0) 
+		task_woken = switch_buffers(task_woken);
+	
+	if(*AT91C_TC2_CV > REAL_FRAME_END) {
+		iso14443_frame *rx_frame = get_frame_buffer(&_tc);
+		if(rx_frame == NULL) return task_woken;
+		int ret = iso14443a_diffmiller_assert_frame_ended(_tc.decoder, rx_frame);
+		if(ret == 0) {
+			task_woken = handle_frame(rx_frame, task_woken);
+		}
+	}
+	return task_woken;
+}
+
+
+int tc_recv_init(tc_recv_handle_t *_th, int pauses_count, tc_recv_callback_t callback)
+{
+	if(_tc.initialized) return -EBUSY;
+	tc_recv_handle_t th = &_tc;
+	
+	memset(fiq_buffers, 0, sizeof(fiq_buffers));
+	th->current = th->next = 0;
+	
+	memset(rx_frames, 0, sizeof(rx_frames));
+	th->current_frame = NULL;
+	
+	if(th->rx_queue == NULL) {
+		th->rx_queue = xQueueCreate(TC_RECV_NUMBER_OF_FRAME_BUFFERS, sizeof(iso14443_frame*));
+		if(th->rx_queue == NULL)
+			return -ENOMEM;
+	}
+	
+	th->pauses_count = pauses_count;
+	th->decoder = iso14443a_init_diffmiller(th->pauses_count);
+	if(!th->decoder) return -EBUSY;
+
+	// The change interrupt is going to be handled by the FIQ and our secondary IRQ handler 
+	AT91F_PIO_CfgInput(AT91C_BASE_PIOA, OPENPICC_SSC_DATA);
+	if( pio_irq_register(OPENPICC_SSC_DATA, &tc_recv_irq) < 0) 
+		return -EBUSY;
+	pio_irq_enable(OPENPICC_SSC_DATA);
+	
+	th->initialized = 1;
+	*_th = th;
+	
+	th->callback = callback;
+	if(th->callback) th->callback(TC_RECV_CALLBACK_SETUP, th);
+	
+	return 0;
+}
+
+int tc_recv_receive(tc_recv_handle_t th, iso14443_frame* *frame, unsigned int timeout)
+{
+	if(th == NULL) return -EINVAL;
+	if(!th->initialized) return -EINVAL;
+	
+	if(xQueueReceive(th->rx_queue, frame, timeout)){
+		if(*frame != NULL) return 0;
+		else return -EINTR;
+	}
+	
+	return -ETIMEDOUT;
+}
diff --git a/openpicc/application/tc_recv.h b/openpicc/application/tc_recv.h
new file mode 100644
index 0000000..4f2392b
--- /dev/null
+++ b/openpicc/application/tc_recv.h
@@ -0,0 +1,21 @@
+#ifndef TC_RECV_H_
+#define TC_RECV_H_
+
+#include "iso14443.h"
+
+#define TC_RECV_NUMBER_OF_FRAME_BUFFERS 10
+
+struct tc_recv_handle;
+typedef struct tc_recv_handle *tc_recv_handle_t;
+
+typedef enum {
+	TC_RECV_CALLBACK_RX_FRAME_ENDED,    // *data is iso14443_frame *frame
+	TC_RECV_CALLBACK_SETUP,             // *data is tc_recv_handle_t th
+	TC_RECV_CALLBACK_TEARDOWN,          // *data is tc_recv_handle_t th
+} tc_recv_callback_reason;
+typedef void (*tc_recv_callback_t)(tc_recv_callback_reason reason, void *data);
+
+extern int tc_recv_init(tc_recv_handle_t *th, int pauses_count, tc_recv_callback_t callback);
+extern int tc_recv_receive(tc_recv_handle_t th, iso14443_frame* *frame, unsigned int timeout);
+
+#endif /*TC_RECV_H_*/
diff --git a/openpicc/application/tc_sniffer.c b/openpicc/application/tc_sniffer.c
index 943a2ad..592b5a4 100644
--- a/openpicc/application/tc_sniffer.c
+++ b/openpicc/application/tc_sniffer.c
@@ -56,15 +56,7 @@ static xSemaphoreHandle data_semaphore;
 struct diffmiller_state *decoder;
 iso14443_frame rx_frame;
 
-#define BUFSIZE 1024
 #define WAIT_TICKS (20*portTICK_RATE_MS)
-typedef struct {
-	u_int32_t count;
-	u_int32_t data[BUFSIZE];
-} fiq_buffer_t;
-fiq_buffer_t fiq_buffers[2];
-
-fiq_buffer_t *tc_sniffer_next_buffer_for_fiq = 0;
 
 portBASE_TYPE currently_sniffing = 0;
 enum { NONE, REQUEST_START, REQUEST_STOP } request_change = REQUEST_START;
-- 
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