Add new miller decoder (not working yet)

Vastly improve timing through CPU cycle counting. Jitter is now like 40ns (the SSC_DATA edge detection fuzziness)  in 2 main clusters 4 CPU cycles (83ns) apart, plus an occasional glitch adding 4 CPU cycles in either direction


git-svn-id: https://svn.openpcd.org:2342/trunk@385 6dc7ffe9-61d6-0310-9af1-9938baff3ed1

9 files changed, 187 insertions, 35 deletions

diff --git a/openpicc/Makefile b/openpicc/Makefile
index e35dc27..92a7351 100644
--- a/openpicc/Makefile
+++ b/openpicc/Makefile
@@ -90,6 +90,7 @@ ARM_SRC= \
   application/usb_print.c \
   application/iso14443_layer3a.c \
   application/iso14443a_manchester.c \
+  application/iso14443a_miller.c \
   application/load_modulation.c \
   application/decoder_miller.c \
   application/decoder_nrzl.c \
diff --git a/openpicc/application/iso14443_layer3a.c b/openpicc/application/iso14443_layer3a.c
index 0b5ceaf..35152db 100644
--- a/openpicc/application/iso14443_layer3a.c
+++ b/openpicc/application/iso14443_layer3a.c
@@ -37,13 +37,14 @@
 #include "load_modulation.h"
 #include "decoder.h"
 #include "iso14443a_manchester.h"
+#include "iso14443a_miller.h"
 #include "led.h"
 
 static enum ISO14443_STATES state = STARTING_UP;
 const iso14443_frame ATQA_FRAME = {
 	TYPE_A,
 	{{STANDARD_FRAME, PARITY}},
-	2, 
+	2,
 	0, 0,
 	{4, 0},
 	{}
@@ -85,11 +86,11 @@ const iso14443_frame NULL_FRAME = {
 void iso14443_transmit(ssc_dma_tx_buffer_t *buf, int fdt, int div)
 {
 	tc_cdiv_set_divider(div);
-	if(fdt == ISO14443A_TRANSMIT_AT_NEXT_INTERVAL_0 ||
-		fdt == ISO14443A_TRANSMIT_AT_NEXT_INTERVAL_1) {
-			/* FIXME Implement */
-			return;
-		}
+	if(fdt == ISO14443A_TRANSMIT_AT_NEXT_INTERVAL_0) {
+		fdt = tc_fdt_get_next_slot(ISO14443A_FDT_SHORT_0, ISO14443A_FDT_SLOTLEN);
+	} else if (fdt == ISO14443A_TRANSMIT_AT_NEXT_INTERVAL_1) {
+		fdt = tc_fdt_get_next_slot(ISO14443A_FDT_SHORT_1, ISO14443A_FDT_SLOTLEN);
+	}
 	ssc_tx_fiq_fdt_cdiv = fdt -3*div -1;
 	tc_fdt_set(ssc_tx_fiq_fdt_cdiv -MAX_TF_FIQ_ENTRY_DELAY -MAX_TF_FIQ_OVERHEAD);
 	ssc_tx_fiq_fdt_ssc  = fdt -div +1;
@@ -162,7 +163,7 @@ static int prefill_buffer(ssc_dma_tx_buffer_t *dest, const iso14443_frame *src)
 	
 }
 
-static u_int8_t received_buffer[256];
+static iso14443_frame received_frame;
 
 static void enable_reception(enum ssc_mode mode) {
 	tc_fdt_set(0xff00);
@@ -307,6 +308,12 @@ void iso14443_layer3a_state_machine (void *pvParameters)
 								LAYER3_DEBUG(", woke up to send ATQA\n\r");
 								atqa_sent = 0;
 							}
+							if(1) {
+								DumpStringToUSB("Decoded: ");
+								iso14443a_decode_miller(&received_frame, buffer->data, buffer->len);
+								DumpBufferToUSB((char*)received_frame.data, 100);
+								DumpStringToUSB("\n\r");
+							}
 							/* For debugging, wait 1ms, then wait for another frame 
 							 * Normally we'd go to anticol from here*/
 							vTaskDelay(portTICK_RATE_MS);
@@ -320,12 +327,12 @@ void iso14443_layer3a_state_machine (void *pvParameters)
 						break;
 					case ACTIVE:
 					case ACTIVE_STAR:
-							if(0) {
+#if 0
 								DumpStringToUSB("Decoded: ");
 								decoder_decode(DECODER_MILLER, (const char*)buffer->data, buffer->len, received_buffer);
 								DumpBufferToUSB((char*)received_buffer, 100);
 								DumpStringToUSB("\n\r");
-							}
+#endif
 							/* Wait for another frame */
 							if(0) {
 								ssc_rx_mode_set(SSC_MODE_14443A_STANDARD);
@@ -336,7 +343,7 @@ void iso14443_layer3a_state_machine (void *pvParameters)
 								if(prefill_buffer(&ssc_tx_buffer, &NULL_FRAME)) {
 									usb_print_string_f("Sending response ...",0);
 									ssc_tx_buffer.state = PROCESSING;
-									iso14443_transmit(&ssc_tx_buffer, 1, 8);
+									iso14443_transmit(&ssc_tx_buffer, ISO14443A_TRANSMIT_AT_NEXT_INTERVAL_1, 8);
 									while( ssc_tx_buffer.state != FREE ) {
 										vTaskDelay(portTICK_RATE_MS);
 									}
diff --git a/openpicc/application/iso14443_layer3a.h b/openpicc/application/iso14443_layer3a.h
index 495ca2e..26a8a2d 100644
--- a/openpicc/application/iso14443_layer3a.h
+++ b/openpicc/application/iso14443_layer3a.h
@@ -16,21 +16,6 @@ enum ISO14443_STATES {
 };
 
 /******************** RX ************************************/
-/* Magic delay, don't know where it comes from */
-#define MAGIC_OFFSET -32
-/* Delay from modulation till detection in SSC_DATA */
-#define DETECTION_DELAY 11
-/* See fdt_timinig.dia for these values */
-#define MAX_TF_FIQ_ENTRY_DELAY 16
-#define MAX_TF_FIQ_OVERHEAD 75 /* guesstimate */ 
-extern volatile int fdt_offset;
-/* standard derived magic values */
-#define ISO14443A_FDT_SLOTLEN 128
-#define ISO14443A_FDT_OFFSET_1 84
-#define ISO14443A_FDT_OFFSET_0 20
-#define ISO14443A_FDT_SHORT_1	(ISO14443A_FDT_SLOTLEN*9 + ISO14443A_FDT_OFFSET_1 +fdt_offset +MAGIC_OFFSET -DETECTION_DELAY)
-#define ISO14443A_FDT_SHORT_0	(ISO14443A_FDT_SLOTLEN*9 + ISO14443A_FDT_OFFSET_0 +fdt_offset +MAGIC_OFFSET -DETECTION_DELAY)
-
 #ifdef FOUR_TIMES_OVERSAMPLING
 /* definitions for four-times oversampling */
 /* Sample values for the REQA and WUPA short frames */
@@ -82,6 +67,21 @@ extern volatile int fdt_offset;
 #endif
 
 /******************** TX ************************************/
+/* Magic delay, don't know where it comes from */
+#define MAGIC_OFFSET -32
+/* Delay from modulation till detection in SSC_DATA */
+#define DETECTION_DELAY 11
+/* See fdt_timinig.dia for these values */
+#define MAX_TF_FIQ_ENTRY_DELAY 16
+#define MAX_TF_FIQ_OVERHEAD 75 /* guesstimate */ 
+extern volatile int fdt_offset;
+/* standard derived magic values */
+#define ISO14443A_FDT_SLOTLEN 128
+#define ISO14443A_FDT_OFFSET_1 84
+#define ISO14443A_FDT_OFFSET_0 20
+#define ISO14443A_FDT_SHORT_1	(ISO14443A_FDT_SLOTLEN*9 + ISO14443A_FDT_OFFSET_1 +fdt_offset +MAGIC_OFFSET -DETECTION_DELAY)
+#define ISO14443A_FDT_SHORT_0	(ISO14443A_FDT_SLOTLEN*9 + ISO14443A_FDT_OFFSET_0 +fdt_offset +MAGIC_OFFSET -DETECTION_DELAY)
+
 /* in bytes, not counting parity */
 #define MAXIMUM_FRAME_SIZE 256
 
diff --git a/openpicc/application/iso14443a_manchester.c b/openpicc/application/iso14443a_manchester.c
index be4de21..4093d57 100644
--- a/openpicc/application/iso14443a_manchester.c
+++ b/openpicc/application/iso14443a_manchester.c
@@ -1,5 +1,6 @@
 /* ISO14443A Manchester encoder for OpenPICC
  * (C) 2006 by Harald Welte <hwelte@hmw-consulting.de>
+ * (C) 2007 by 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 
diff --git a/openpicc/application/iso14443a_miller.c b/openpicc/application/iso14443a_miller.c
new file mode 100644
index 0000000..deb9a8a
--- /dev/null
+++ b/openpicc/application/iso14443a_miller.c
@@ -0,0 +1,112 @@
+/* ISO14443A Manchester encoder for OpenPICC
+ * (C) 2007 by 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; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ */
+
+#include <openpicc.h>
+#include <FreeRTOS.h>
+
+#include <string.h>
+
+#include "iso14443_layer3a.h"
+#include "usb_print.h"
+#include "cmd.h"
+
+#ifdef FOUR_TIMES_OVERSAMPLING
+#define OVERSAMPLING_RATE	4
+
+/* definitions for four-times oversampling */
+#define SEQ_X	0x4
+#define SEQ_Y	0x0
+#define SEQ_Z	0x1
+#else
+#define OVERSAMPLING_RATE	2
+#define SEQ_X   0x2
+#define SEQ_Y   0x0
+#define SEQ_Z   0x1
+#endif
+
+enum miller_sequence {
+	SEQUENCE_X,
+	SEQUENCE_Y,
+	SEQUENCE_Z,
+};
+
+#define BIT_ENDMARKER -1
+
+int iso14443a_decode_miller(iso14443_frame *frame, 
+	const u_int8_t *sample_buf, const u_int16_t sample_buf_len)
+{
+	signed int i, j, bit = 0, last_bit = 0;
+	enum miller_sequence current_seq;
+	unsigned int bitpos = 0;
+	
+	memset(frame, 0, sizeof(frame));
+	frame->type = TYPE_A;
+	frame->parameters.a.parity = GIVEN_PARITY;
+	
+	for(i=0; i<sample_buf_len && bit != BIT_ENDMARKER; i++) {
+		for(j=0; j<(signed)(sizeof(sample_buf[0])*8)/OVERSAMPLING_RATE && bit != BIT_ENDMARKER; j++) {
+			int sample = (sample_buf[i]>>(j*OVERSAMPLING_RATE)) & ~(~0 << OVERSAMPLING_RATE);
+			switch(sample) {
+				case SEQ_X: current_seq = SEQUENCE_X; break;
+				case SEQ_Y: current_seq = SEQUENCE_Y; break;
+				case SEQ_Z: current_seq = SEQUENCE_Z; break;
+				default: current_seq = SEQUENCE_Y;
+			}
+			
+			switch(current_seq) {
+				case SEQ_X:
+				DumpStringToUSB("X");
+					bit = 1; break;
+				case SEQ_Y: /* Fall-through to SEQ_Z */
+				DumpStringToUSB("Y");
+					if(last_bit == 0) {
+						bit = BIT_ENDMARKER;
+						break;
+					}
+				case SEQ_Z:
+				DumpStringToUSB("Z");
+					bit = 0; break;
+			}
+			
+			switch(bit) {
+				case BIT_ENDMARKER:
+					bitpos--;
+					break;
+				case 0: /* Fall-through */
+				case 1: {
+					int bytepos = bitpos/9;
+					if(bitpos % 9 == 8) { /* Parity bit */
+						frame->parity[ bytepos/8 ] |= (bit<<(bytepos%8));
+					} else {
+						frame->data[ bytepos ] |= (bit<<(bitpos%9));
+					}
+				}
+			}
+			
+			last_bit = bit;
+			bitpos++;
+		}
+	}
+	
+	frame->numbytes = bitpos/9;
+	frame->numbits = bitpos%9;
+	DumpStringToUSB("\n\r");
+	
+	return 0;
+}
diff --git a/openpicc/application/iso14443a_miller.h b/openpicc/application/iso14443a_miller.h
new file mode 100644
index 0000000..dbd7f85
--- /dev/null
+++ b/openpicc/application/iso14443a_miller.h
@@ -0,0 +1,6 @@
+#ifndef ISO14443A_MILLER_H_
+#define ISO14443A_MILLER_H_
+
+extern int iso14443a_decode_miller(iso14443_frame *frame, const u_int8_t *sample_buf, const u_int16_t sample_buf_len); 
+
+#endif /*ISO14443A_MILLER_H_*/
diff --git a/openpicc/application/tc_fdt.c b/openpicc/application/tc_fdt.c
index 7413e11..2a306ef 100644
--- a/openpicc/application/tc_fdt.c
+++ b/openpicc/application/tc_fdt.c
@@ -50,16 +50,12 @@ void tc_fdt_set(u_int16_t count)
 	tcfdt->TC_RA = count;
 }
 
-void __ramfunc tc_fdt_set_to_next_slot(int last_bit)
+int tc_fdt_get_next_slot(int reference_time, int slotlen)
 {
-	int reference_time;
-	if(last_bit == 0) reference_time = ISO14443A_FDT_OFFSET_0;
-	else reference_time = ISO14443A_FDT_OFFSET_1;
-	
-	if(tcfdt->TC_SR & AT91C_TC_CLKSTA) 
+	/*if(tcfdt->TC_SR & AT91C_TC_CLKSTA) 
 		while(tcfdt->TC_CV != 0xFFFF && (tcfdt->TC_CV - reference_time) % 128 != 0);
-	tcfdt->TC_CCR = AT91C_TC_SWTRG;
-	tc_fdt_set(2*128);
+	tcfdt->TC_CCR = AT91C_TC_SWTRG;*/
+	return tcfdt->TC_CV + (slotlen-((tcfdt->TC_CV - reference_time) % slotlen)) + 3*slotlen; 
 }
 
 
diff --git a/openpicc/application/tc_fdt.h b/openpicc/application/tc_fdt.h
index 28e7e7e..6e89f51 100644
--- a/openpicc/application/tc_fdt.h
+++ b/openpicc/application/tc_fdt.h
@@ -5,6 +5,6 @@
 
 extern void tc_fdt_init(void);
 extern void tc_fdt_set(u_int16_t count);
-extern void __ramfunc tc_fdt_set_to_next_slot(int last_bit);
+extern int tc_fdt_get_next_slot(int reference_time, int slotlen);
 
 #endif
diff --git a/openpicc/os/boot/boot.s b/openpicc/os/boot/boot.s
index 0000479..c065a6d 100644
--- a/openpicc/os/boot/boot.s
+++ b/openpicc/os/boot/boot.s
@@ -250,10 +250,39 @@ my_fiq_handler:
                 ldr   r11, =ssc_tx_fiq_fdt_cdiv
                 ldr   r11, [r11]               /* r11 == ssc_tx_fiq_fdt_cdiv */
 
+/* Problem: LDR from the timer still takes too long and causes us to miss the exact time.
+ * Strategy: Spin on TC2 till we are very near the actual time. Then load the timer value, calculate
+ * the difference to the target, then do a countdown spin without reading the timer.
+ * 
+ * At 47.923200 MHz 7 processor cycles are 2 carrier cycles of the 13.56MHz carrier
+ */
+ .equ SUB_TIME, 20 /* subtract 20 carrier cycles == 70 processor cycles */
+ .equ ADD_TIME, (70-20) /* Add x processor cycles */
+ 
+ 				mov r8, #SUB_TIME
+ 				sub r11, r11, r8              
+
 .wait_for_fdt_cdiv:  
 				ldr   r8, [r12, #TC2_CV]
 				cmp   r8, r11
-				bmi   .wait_for_fdt_cdiv       /* spin while TC2.CV is less fdt_cdiv */
+				bmi   .wait_for_fdt_cdiv       /* spin while TC2.CV is less fdt_cdiv-SUB_TIM */
+				
+				ldr r8, [r12, #TC2_CV]
+				sub r11, r11, r8               /* r11 == fdt_cdiv-SUB_TIME - TC2.CV */
+				
+				mov r8, #0x07
+				mul r11, r8, r11               /* r11 = r11 * 7 */
+				mov r11, r11, ASR #1           /* r11 = r11 / 2 */
+				
+				mov r8, #ADD_TIME
+				add r11, r11, r8               /* r11 = r11 + ADD_TIME */
+				
+				mov r11, r11, ASR #2           /* r11 = r11 / 4   (4 is the number of cycles per loop run below) */
+				
+				mov r8, #1
+.wait_for_my_time:
+				subs r11, r11, r8
+				bge .wait_for_my_time
 				
 				str   r9, [r12, #TC_CCR]       /* SWTRG on TC0 */