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1 //-----------------------------------------------------------------------------
2 // This code is licensed to you under the terms of the GNU GPL, version 2 or,
3 // at your option, any later version. See the LICENSE.txt file for the text of
4 // the license.
5 //-----------------------------------------------------------------------------
6 // Miscellaneous routines for low frequency sampling.
7 //-----------------------------------------------------------------------------
8
9 #include "proxmark3.h"
10 #include "apps.h"
11 #include "util.h"
12 #include "string.h"
13
14 #include "lfsampling.h"
15
16 sample_config config = { 1, 8, 1, 95, 0 } ;
17
18 void printConfig()
19 {
20 Dbprintf("LF Sampling config: ");
21 Dbprintf(" [q] divisor: %d ", config.divisor);
22 Dbprintf(" [b] bps: %d ", config.bits_per_sample);
23 Dbprintf(" [d] decimation: %d ", config.decimation);
24 Dbprintf(" [a] averaging: %d ", config.averaging);
25 Dbprintf(" [t] trigger threshold: %d ", config.trigger_threshold);
26 }
27
28
29 /**
30 * Called from the USB-handler to set the sampling configuration
31 * The sampling config is used for std reading and snooping.
32 *
33 * Other functions may read samples and ignore the sampling config,
34 * such as functions to read the UID from a prox tag or similar.
35 *
36 * Values set to '0' implies no change (except for averaging)
37 * @brief setSamplingConfig
38 * @param sc
39 */
40 void setSamplingConfig(sample_config *sc)
41 {
42 if(sc->divisor != 0) config.divisor = sc->divisor;
43 if(sc->bits_per_sample!= 0) config.bits_per_sample= sc->bits_per_sample;
44 if(sc->decimation!= 0) config.decimation= sc->decimation;
45 if(sc->trigger_threshold != -1) config.trigger_threshold= sc->trigger_threshold;
46
47 config.averaging= sc->averaging;
48 if(config.bits_per_sample > 8) config.bits_per_sample = 8;
49 if(config.decimation < 1) config.decimation = 1;
50
51 printConfig();
52 }
53
54 sample_config* getSamplingConfig()
55 {
56 return &config;
57 }
58
59 typedef struct {
60 uint8_t * buffer;
61 uint32_t numbits;
62 uint32_t position;
63 } BitstreamOut;
64
65 /**
66 * @brief Pushes bit onto the stream
67 * @param stream
68 * @param bit
69 */
70 void pushBit( BitstreamOut* stream, uint8_t bit)
71 {
72 int bytepos = stream->position >> 3; // divide by 8
73 int bitpos = stream->position & 7;
74 *(stream->buffer+bytepos) |= (bit > 0) << (7 - bitpos);
75 stream->position++;
76 stream->numbits++;
77 }
78
79 /**
80 * Setup the FPGA to listen for samples. This method downloads the FPGA bitstream
81 * if not already loaded, sets divisor and starts up the antenna.
82 * @param divisor : 1, 88> 255 or negative ==> 134.8 KHz
83 * 0 or 95 ==> 125 KHz
84 *
85 **/
86 void LFSetupFPGAForADC(int divisor, bool lf_field)
87 {
88 FpgaDownloadAndGo(FPGA_BITSTREAM_LF);
89 if ( (divisor == 1) || (divisor < 0) || (divisor > 255) )
90 FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 88); //134.8Khz
91 else if (divisor == 0)
92 FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 95); //125Khz
93 else
94 FpgaSendCommand(FPGA_CMD_SET_DIVISOR, divisor);
95
96 FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_ADC | (lf_field ? FPGA_LF_ADC_READER_FIELD : 0));
97
98 // Connect the A/D to the peak-detected low-frequency path.
99 SetAdcMuxFor(GPIO_MUXSEL_LOPKD);
100 // Give it a bit of time for the resonant antenna to settle.
101 SpinDelay(50);
102 // Now set up the SSC to get the ADC samples that are now streaming at us.
103 FpgaSetupSsc();
104 }
105
106
107 /**
108 * Does the sample acquisition. If threshold is specified, the actual sampling
109 * is not commenced until the threshold has been reached.
110 * This method implements decimation and quantization in order to
111 * be able to provide longer sample traces.
112 * Uses the following global settings:
113 * @param decimation - how much should the signal be decimated. A decimation of N means we keep 1 in N samples, etc.
114 * @param bits_per_sample - bits per sample. Max 8, min 1 bit per sample.
115 * @param averaging If set to true, decimation will use averaging, so that if e.g. decimation is 3, the sample
116 * value that will be used is the average value of the three samples.
117 * @param trigger_threshold - a threshold. The sampling won't commence until this threshold has been reached. Set
118 * to -1 to ignore threshold.
119 * @param silent - is true, now outputs are made. If false, dbprints the status
120 * @return the number of bits occupied by the samples.
121 */
122 uint32_t DoAcquisition(uint8_t decimation, uint32_t bits_per_sample, bool averaging, int trigger_threshold, bool silent)
123 {
124 //.
125 uint8_t *dest = BigBuf_get_addr();
126 int bufsize = BigBuf_max_traceLen();
127
128 memset(dest, 0, bufsize);
129
130 if(bits_per_sample < 1) bits_per_sample = 1;
131 if(bits_per_sample > 8) bits_per_sample = 8;
132
133 if(decimation < 1) decimation = 1;
134
135 // Use a bit stream to handle the output
136 BitstreamOut data = { dest , 0, 0};
137 int sample_counter = 0;
138 uint8_t sample = 0;
139 //If we want to do averaging
140 uint32_t sample_sum =0 ;
141 uint32_t sample_total_numbers =0 ;
142 uint32_t sample_total_saved =0 ;
143
144 while(!BUTTON_PRESS()) {
145 WDT_HIT();
146 if (AT91C_BASE_SSC->SSC_SR & AT91C_SSC_TXRDY) {
147 AT91C_BASE_SSC->SSC_THR = 0x43;
148 LED_D_ON();
149 }
150 if (AT91C_BASE_SSC->SSC_SR & AT91C_SSC_RXRDY) {
151 sample = (uint8_t)AT91C_BASE_SSC->SSC_RHR;
152 LED_D_OFF();
153 // threshold either high or low values 128 = center 0. if trigger = 178
154 if ((trigger_threshold > 0) && (sample < (trigger_threshold+128)) && (sample > (128-trigger_threshold))) //
155 continue;
156
157 //if (trigger_threshold > 0 && sample < trigger_threshold) //
158 //continue;
159
160 trigger_threshold = 0;
161 sample_total_numbers++;
162
163 if(averaging)
164 {
165 sample_sum += sample;
166 }
167 //Check decimation
168 if(decimation > 1)
169 {
170 sample_counter++;
171 if(sample_counter < decimation) continue;
172 sample_counter = 0;
173 }
174 //Averaging
175 if(averaging && decimation > 1) {
176 sample = sample_sum / decimation;
177 sample_sum =0;
178 }
179 //Store the sample
180 sample_total_saved ++;
181 if(bits_per_sample == 8){
182 dest[sample_total_saved-1] = sample;
183 data.numbits = sample_total_saved << 3;//Get the return value correct
184 if(sample_total_saved >= bufsize) break;
185 }
186 else{
187 pushBit(&data, sample & 0x80);
188 if(bits_per_sample > 1) pushBit(&data, sample & 0x40);
189 if(bits_per_sample > 2) pushBit(&data, sample & 0x20);
190 if(bits_per_sample > 3) pushBit(&data, sample & 0x10);
191 if(bits_per_sample > 4) pushBit(&data, sample & 0x08);
192 if(bits_per_sample > 5) pushBit(&data, sample & 0x04);
193 if(bits_per_sample > 6) pushBit(&data, sample & 0x02);
194 //Not needed, 8bps is covered above
195 //if(bits_per_sample > 7) pushBit(&data, sample & 0x01);
196 if((data.numbits >> 3) +1 >= bufsize) break;
197 }
198 }
199 }
200
201 if(!silent)
202 {
203 Dbprintf("Done, saved %d out of %d seen samples at %d bits/sample",sample_total_saved, sample_total_numbers,bits_per_sample);
204 Dbprintf("buffer samples: %02x %02x %02x %02x %02x %02x %02x %02x ...",
205 dest[0], dest[1], dest[2], dest[3], dest[4], dest[5], dest[6], dest[7]);
206 }
207 return data.numbits;
208 }
209 /**
210 * @brief Does sample acquisition, ignoring the config values set in the sample_config.
211 * This method is typically used by tag-specific readers who just wants to read the samples
212 * the normal way
213 * @param trigger_threshold
214 * @param silent
215 * @return number of bits sampled
216 */
217 uint32_t DoAcquisition_default(int trigger_threshold, bool silent)
218 {
219 return DoAcquisition(1,8,0,trigger_threshold,silent);
220 }
221 uint32_t DoAcquisition_config( bool silent)
222 {
223 return DoAcquisition(config.decimation
224 ,config.bits_per_sample
225 ,config.averaging
226 ,config.trigger_threshold
227 ,silent);
228 }
229
230 uint32_t ReadLF(bool activeField, bool silent)
231 {
232 if (!silent) printConfig();
233 LFSetupFPGAForADC(config.divisor, activeField);
234 // Now call the acquisition routine
235 return DoAcquisition_config(silent);
236 }
237
238 /**
239 * Initializes the FPGA for reader-mode (field on), and acquires the samples.
240 * @return number of bits sampled
241 **/
242 uint32_t SampleLF(bool printCfg)
243 {
244 return ReadLF(true, printCfg);
245 }
246 /**
247 * Initializes the FPGA for snoop-mode (field off), and acquires the samples.
248 * @return number of bits sampled
249 **/
250
251 uint32_t SnoopLF()
252 {
253 return ReadLF(false, true);
254 }
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