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1 /*
2 * LEGIC RF simulation code
3 *
4 * (c) 2009 Henryk Plötz <henryk@ploetzli.ch>
5 */
6
7 #include <proxmark3.h>
8
9 #include "apps.h"
10 #include "legicrf.h"
11 #include "unistd.h"
12 #include "stdint.h"
13
14 static struct legic_frame {
15 int bits;
16 uint16_t data;
17 } current_frame;
18
19 static struct legic_frame queries[] = {
20 {7, 0x55}, /* 1010 101 */
21 };
22
23 static struct legic_frame responses[] = {
24 {6, 0x3b}, /* 1101 11 */
25 };
26
27 static void frame_send(uint16_t response, int bits)
28 {
29 #if 0
30 /* Use the SSC to send a response. 8-bit transfers, LSBit first, 100us per bit */
31 #else
32 /* Bitbang the response */
33 AT91C_BASE_PIOA->PIO_CODR = GPIO_SSC_DOUT;
34 AT91C_BASE_PIOA->PIO_OER = GPIO_SSC_DOUT;
35 AT91C_BASE_PIOA->PIO_PER = GPIO_SSC_DOUT;
36
37 /* Wait for the frame start */
38 while(AT91C_BASE_TC1->TC_CV < 490) ;
39
40 int i;
41 for(i=0; i<bits; i++) {
42 int nextbit = AT91C_BASE_TC1->TC_CV + 150;
43 int bit = response & 1;
44 response = response >> 1;
45 if(bit)
46 AT91C_BASE_PIOA->PIO_SODR = GPIO_SSC_DOUT;
47 else
48 AT91C_BASE_PIOA->PIO_CODR = GPIO_SSC_DOUT;
49 while(AT91C_BASE_TC1->TC_CV < nextbit) ;
50 }
51 AT91C_BASE_PIOA->PIO_CODR = GPIO_SSC_DOUT;
52 #endif
53 }
54
55 static void frame_respond(struct legic_frame const * const f)
56 {
57 LED_D_ON();
58 int i;
59 struct legic_frame *r = NULL;
60
61 for(i=0; i<sizeof(queries)/sizeof(queries[0]); i++) {
62 if(f->bits == queries[i].bits && f->data == queries[i].data) {
63 r = &responses[i];
64 break;
65 }
66 }
67
68 if(r != NULL) {
69 frame_send(r->data, r->bits);
70 LED_A_ON();
71 } else {
72 LED_A_OFF();
73 }
74
75 LED_D_OFF();
76 }
77
78 static void frame_append_bit(struct legic_frame * const f, int bit)
79 {
80 if(f->bits >= 15)
81 return; /* Overflow, won't happen */
82 f->data |= (bit<<f->bits);
83 f->bits++;
84 }
85
86 static int frame_is_empty(struct legic_frame const * const f)
87 {
88 return( f->bits <= 4 );
89 }
90
91 static void frame_handle(struct legic_frame const * const f)
92 {
93 if(f->bits == 6) {
94 /* Short path */
95 return;
96 }
97 if( !frame_is_empty(f) ) {
98 frame_respond(f);
99 }
100 }
101
102 static void frame_clean(struct legic_frame * const f)
103 {
104 f->data = 0;
105 f->bits = 0;
106 }
107
108 static void emit(int bit)
109 {
110 if(bit == -1) {
111 frame_handle(&current_frame);
112 frame_clean(&current_frame);
113 } else if(bit == 0) {
114 frame_append_bit(&current_frame, 0);
115 } else if(bit == 1) {
116 frame_append_bit(&current_frame, 1);
117 }
118 }
119
120 void LegicRfSimulate(void)
121 {
122 /* ADC path high-frequency peak detector, FPGA in high-frequency simulator mode,
123 * modulation mode set to 212kHz subcarrier. We are getting the incoming raw
124 * envelope waveform on DIN and should send our response on DOUT.
125 *
126 * The LEGIC RF protocol is pulse-pause-encoding from reader to card, so we'll
127 * measure the time between two rising edges on DIN, and no encoding on the
128 * subcarrier from card to reader, so we'll just shift out our verbatim data
129 * on DOUT, 1 bit is 100us. The time from reader to card frame is still unclear,
130 * seems to be 300us-ish.
131 */
132 SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
133 FpgaSetupSsc();
134 FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_SIMULATOR | FPGA_HF_SIMULATOR_MODULATE_212K);
135
136 /* Bitbang the receiver */
137 AT91C_BASE_PIOA->PIO_ODR = GPIO_SSC_DIN;
138 AT91C_BASE_PIOA->PIO_PER = GPIO_SSC_DIN;
139
140 /* Set up Timer 1 to use for measuring time between pulses. Since we're bit-banging
141 * this it won't be terribly accurate but should be good enough.
142 */
143 AT91C_BASE_PMC->PMC_PCER = (1 << AT91C_ID_TC1);
144 AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKDIS;
145 AT91C_BASE_TC1->TC_CMR = TC_CMR_TCCLKS_TIMER_CLOCK3;
146 AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
147 int old_level = 0;
148
149 /* At TIMER_CLOCK3 (MCK/32) */
150 #define BIT_TIME_1 150
151 #define BIT_TIME_0 90
152 #define BIT_TIME_FUZZ 20
153
154 int active = 0;
155 while(!BUTTON_PRESS()) {
156 int level = !!(AT91C_BASE_PIOA->PIO_PDSR & GPIO_SSC_DIN);
157 int time = AT91C_BASE_TC1->TC_CV;
158
159 if(level != old_level) {
160 if(level == 1) {
161 AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
162 if(time > (BIT_TIME_1-BIT_TIME_FUZZ) && time < (BIT_TIME_1+BIT_TIME_FUZZ)) {
163 /* 1 bit */
164 emit(1);
165 active = 1;
166 LED_B_ON();
167 } else if(time > (BIT_TIME_0-BIT_TIME_FUZZ) && time < (BIT_TIME_0+BIT_TIME_FUZZ)) {
168 /* 0 bit */
169 emit(0);
170 active = 1;
171 LED_B_ON();
172 } else if(active) {
173 /* invalid */
174 emit(-1);
175 active = 0;
176 LED_B_OFF();
177 }
178 }
179 }
180
181 if(time >= (BIT_TIME_1+BIT_TIME_FUZZ) && active) {
182 /* Frame end */
183 emit(-1);
184 active = 0;
185 LED_B_OFF();
186 }
187
188 if(time >= (20*BIT_TIME_1) && (AT91C_BASE_TC1->TC_SR & AT91C_TC_CLKSTA)) {
189 AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKDIS;
190 }
191
192
193 old_level = level;
194 WDT_HIT();
195 }
196 }
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