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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 const struct legic_frame queries[] = {
20 {7, 0x55}, /* 1010 101 */
21 };
22
23 static const 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, r_size;
59 uint16_t r_data;
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_data = responses[i].data;
64 r_size = responses[i].bits;
65 break;
66 }
67 }
68
69 if(r_size != 0) {
70 frame_send(r_data, r_size);
71 LED_A_ON();
72 } else {
73 LED_A_OFF();
74 }
75
76 LED_D_OFF();
77 }
78
79 static void frame_append_bit(struct legic_frame * const f, int bit)
80 {
81 if(f->bits >= 15)
82 return; /* Overflow, won't happen */
83 f->data |= (bit<<f->bits);
84 f->bits++;
85 }
86
87 static int frame_is_empty(struct legic_frame const * const f)
88 {
89 return( f->bits <= 4 );
90 }
91
92 static void frame_handle(struct legic_frame const * const f)
93 {
94 if(f->bits == 6) {
95 /* Short path */
96 return;
97 }
98 if( !frame_is_empty(f) ) {
99 frame_respond(f);
100 }
101 }
102
103 static void frame_clean(struct legic_frame * const f)
104 {
105 f->data = 0;
106 f->bits = 0;
107 }
108
109 static void emit(int bit)
110 {
111 if(bit == -1) {
112 frame_handle(&current_frame);
113 frame_clean(&current_frame);
114 } else if(bit == 0) {
115 frame_append_bit(&current_frame, 0);
116 } else if(bit == 1) {
117 frame_append_bit(&current_frame, 1);
118 }
119 }
120
121 void LegicRfSimulate(void)
122 {
123 /* ADC path high-frequency peak detector, FPGA in high-frequency simulator mode,
124 * modulation mode set to 212kHz subcarrier. We are getting the incoming raw
125 * envelope waveform on DIN and should send our response on DOUT.
126 *
127 * The LEGIC RF protocol is pulse-pause-encoding from reader to card, so we'll
128 * measure the time between two rising edges on DIN, and no encoding on the
129 * subcarrier from card to reader, so we'll just shift out our verbatim data
130 * on DOUT, 1 bit is 100us. The time from reader to card frame is still unclear,
131 * seems to be 300us-ish.
132 */
133 SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
134 FpgaSetupSsc();
135 FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_SIMULATOR | FPGA_HF_SIMULATOR_MODULATE_212K);
136
137 /* Bitbang the receiver */
138 AT91C_BASE_PIOA->PIO_ODR = GPIO_SSC_DIN;
139 AT91C_BASE_PIOA->PIO_PER = GPIO_SSC_DIN;
140
141 /* Set up Timer 1 to use for measuring time between pulses. Since we're bit-banging
142 * this it won't be terribly accurate but should be good enough.
143 */
144 AT91C_BASE_PMC->PMC_PCER = (1 << AT91C_ID_TC1);
145 AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKDIS;
146 AT91C_BASE_TC1->TC_CMR = TC_CMR_TCCLKS_TIMER_CLOCK3;
147 AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
148 int old_level = 0;
149
150 /* At TIMER_CLOCK3 (MCK/32) */
151 #define BIT_TIME_1 150
152 #define BIT_TIME_0 90
153 #define BIT_TIME_FUZZ 20
154
155 int active = 0;
156 while(!BUTTON_PRESS()) {
157 int level = !!(AT91C_BASE_PIOA->PIO_PDSR & GPIO_SSC_DIN);
158 int time = AT91C_BASE_TC1->TC_CV;
159
160 if(level != old_level) {
161 if(level == 1) {
162 AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
163 if(time > (BIT_TIME_1-BIT_TIME_FUZZ) && time < (BIT_TIME_1+BIT_TIME_FUZZ)) {
164 /* 1 bit */
165 emit(1);
166 active = 1;
167 LED_B_ON();
168 } else if(time > (BIT_TIME_0-BIT_TIME_FUZZ) && time < (BIT_TIME_0+BIT_TIME_FUZZ)) {
169 /* 0 bit */
170 emit(0);
171 active = 1;
172 LED_B_ON();
173 } else if(active) {
174 /* invalid */
175 emit(-1);
176 active = 0;
177 LED_B_OFF();
178 }
179 }
180 }
181
182 if(time >= (BIT_TIME_1+BIT_TIME_FUZZ) && active) {
183 /* Frame end */
184 emit(-1);
185 active = 0;
186 LED_B_OFF();
187 }
188
189 if(time >= (20*BIT_TIME_1) && (AT91C_BASE_TC1->TC_SR & AT91C_TC_CLKSTA)) {
190 AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKDIS;
191 }
192
193
194 old_level = level;
195 WDT_HIT();
196 }
197 }
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