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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, 88, 0 } ;
17
18 void printConfig()
19 {
20 Dbprintf("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 /**
67 * @brief Pushes bit onto the stream
68 * @param stream
69 * @param bit
70 */
71 void pushBit( BitstreamOut* stream, uint8_t bit)
72 {
73 int bytepos = stream->position >> 3; // divide by 8
74 int bitpos = stream->position & 7;
75 *(stream->buffer+bytepos) |= (bit > 0) << (7 - bitpos);
76 stream->position++;
77 stream->numbits++;
78 }
79
80 /**
81 * Setup the FPGA to listen for samples. This method downloads the FPGA bitstream
82 * if not already loaded, sets divisor and starts up the antenna.
83 * @param divisor : 1, 88> 255 or negative ==> 134.8 KHz
84 * 0 or 95 ==> 125 KHz
85 *
86 **/
87 void LFSetupFPGAForADC(int divisor, bool lf_field)
88 {
89 FpgaDownloadAndGo(FPGA_BITSTREAM_LF);
90 if ( (divisor == 1) || (divisor < 0) || (divisor > 255) )
91 FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 88); //134.8Khz
92 else if (divisor == 0)
93 FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 95); //125Khz
94 else
95 FpgaSendCommand(FPGA_CMD_SET_DIVISOR, divisor);
96
97 FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_ADC | (lf_field ? FPGA_LF_ADC_READER_FIELD : 0));
98
99 // Connect the A/D to the peak-detected low-frequency path.
100 SetAdcMuxFor(GPIO_MUXSEL_LOPKD);
101 // Give it a bit of time for the resonant antenna to settle.
102 SpinDelay(50);
103 // Now set up the SSC to get the ADC samples that are now streaming at us.
104 FpgaSetupSsc();
105 }
106
107
108 /**
109 * Does the sample acquisition. If threshold is specified, the actual sampling
110 * is not commenced until the threshold has been reached.
111 * This method implements decimation and quantization in order to
112 * be able to provide longer sample traces.
113 * Uses the following global settings:
114 * @param decimation - how much should the signal be decimated. A decimation of N means we keep 1 in N samples, etc.
115 * @param bits_per_sample - bits per sample. Max 8, min 1 bit per sample.
116 * @param averaging If set to true, decimation will use averaging, so that if e.g. decimation is 3, the sample
117 * value that will be used is the average value of the three samples.
118 * @param trigger_threshold - a threshold. The sampling won't commence until this threshold has been reached. Set
119 * to -1 to ignore threshold.
120 * @param silent - is true, now outputs are made. If false, dbprints the status
121 * @return the number of bits occupied by the samples.
122 */
123
124 uint32_t DoAcquisition(uint8_t decimation, uint32_t bits_per_sample, bool averaging, int trigger_threshold,bool silent)
125 {
126 //.
127 uint8_t *dest = BigBuf_get_addr();
128 int bufsize = BigBuf_max_traceLen();
129
130 memset(dest, 0, bufsize);
131
132 if(bits_per_sample < 1) bits_per_sample = 1;
133 if(bits_per_sample > 8) bits_per_sample = 8;
134
135 if(decimation < 1) decimation = 1;
136
137 // Use a bit stream to handle the output
138 BitstreamOut data = { dest , 0, 0};
139 int sample_counter = 0;
140 uint8_t sample = 0;
141 //If we want to do averaging
142 uint32_t sample_sum =0 ;
143 uint32_t sample_total_numbers =0 ;
144 uint32_t sample_total_saved =0 ;
145
146 while(!BUTTON_PRESS()) {
147 WDT_HIT();
148 if (AT91C_BASE_SSC->SSC_SR & AT91C_SSC_TXRDY) {
149 AT91C_BASE_SSC->SSC_THR = 0x43;
150 LED_D_ON();
151 }
152 if (AT91C_BASE_SSC->SSC_SR & AT91C_SSC_RXRDY) {
153 sample = (uint8_t)AT91C_BASE_SSC->SSC_RHR;
154 LED_D_OFF();
155 if (trigger_threshold > 0 && sample < trigger_threshold)
156 continue;
157
158 trigger_threshold = 0;
159 sample_total_numbers++;
160
161 if(averaging)
162 {
163 sample_sum += sample;
164 }
165 //Check decimation
166 if(decimation > 1)
167 {
168 sample_counter++;
169 if(sample_counter < decimation) continue;
170 sample_counter = 0;
171 }
172 //Averaging
173 if(averaging && decimation > 1) {
174 sample = sample_sum / decimation;
175 sample_sum =0;
176 }
177 //Store the sample
178 sample_total_saved ++;
179 if(bits_per_sample == 8){
180 dest[sample_total_saved-1] = sample;
181 data.numbits = sample_total_saved << 3;//Get the return value correct
182 if(sample_total_saved >= bufsize) break;
183 }
184 else{
185 pushBit(&data, sample & 0x80);
186 if(bits_per_sample > 1) pushBit(&data, sample & 0x40);
187 if(bits_per_sample > 2) pushBit(&data, sample & 0x20);
188 if(bits_per_sample > 3) pushBit(&data, sample & 0x10);
189 if(bits_per_sample > 4) pushBit(&data, sample & 0x08);
190 if(bits_per_sample > 5) pushBit(&data, sample & 0x04);
191 if(bits_per_sample > 6) pushBit(&data, sample & 0x02);
192 //Not needed, 8bps is covered above
193 //if(bits_per_sample > 7) pushBit(&data, sample & 0x01);
194 if((data.numbits >> 3) +1 >= bufsize) break;
195 }
196 }
197 }
198
199 if(!silent)
200 {
201 Dbprintf("Done, saved %d out of %d seen samples at %d bits/sample",sample_total_saved, sample_total_numbers,bits_per_sample);
202 Dbprintf("buffer samples: %02x %02x %02x %02x %02x %02x %02x %02x ...",
203 dest[0], dest[1], dest[2], dest[3], dest[4], dest[5], dest[6], dest[7]);
204 }
205 return data.numbits;
206 }
207 /**
208 * @brief Does sample acquisition, ignoring the config values set in the sample_config.
209 * This method is typically used by tag-specific readers who just wants to read the samples
210 * the normal way
211 * @param trigger_threshold
212 * @param silent
213 * @return number of bits sampled
214 */
215 uint32_t DoAcquisition_default(int trigger_threshold, bool silent)
216 {
217 return DoAcquisition(1,8,0,trigger_threshold,silent);
218 }
219 uint32_t DoAcquisition_config( bool silent)
220 {
221 return DoAcquisition(config.decimation
222 ,config.bits_per_sample
223 ,config.averaging
224 ,config.trigger_threshold
225 ,silent);
226 }
227
228 uint32_t ReadLF(bool activeField)
229 {
230 printConfig();
231 LFSetupFPGAForADC(config.divisor, activeField);
232 // Now call the acquisition routine
233 return DoAcquisition_config(false);
234 }
235
236 /**
237 * Initializes the FPGA for reader-mode (field on), and acquires the samples.
238 * @return number of bits sampled
239 **/
240 uint32_t SampleLF()
241 {
242 return ReadLF(true);
243 }
244 /**
245 * Initializes the FPGA for snoop-mode (field off), and acquires the samples.
246 * @return number of bits sampled
247 **/
248
249 uint32_t SnoopLF()
250 {
251 return ReadLF(false);
252 }
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