]> git.zerfleddert.de Git - proxmark3-svn/blame - armsrc/lfsampling.c
fixing iso 14443b (issue #103):
[proxmark3-svn] / armsrc / lfsampling.c
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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"
10a8875c 15
0cd2a41a 16sample_config config = { 1, 8, 1, 95, 0 } ;
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17
18void 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 */
40void 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
54sample_config* getSamplingConfig()
55{
56 return &config;
57}
10a8875c 58
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59typedef struct {
60 uint8_t * buffer;
61 uint32_t numbits;
62 uint32_t position;
63} BitstreamOut;
64
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65/**
66 * @brief Pushes bit onto the stream
67 * @param stream
68 * @param bit
69 */
10a8875c 70void pushBit( BitstreamOut* stream, uint8_t bit)
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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}
10a8875c 78
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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**/
86void 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
123uint32_t DoAcquisition(uint8_t decimation, uint32_t bits_per_sample, bool averaging, int trigger_threshold,bool silent)
124{
125 //.
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126 uint8_t *dest = BigBuf_get_addr();
127 int bufsize = BigBuf_max_traceLen();
128
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129 memset(dest, 0, bufsize);
130
131 if(bits_per_sample < 1) bits_per_sample = 1;
132 if(bits_per_sample > 8) bits_per_sample = 8;
133
134 if(decimation < 1) decimation = 1;
135
136 // Use a bit stream to handle the output
137 BitstreamOut data = { dest , 0, 0};
138 int sample_counter = 0;
139 uint8_t sample = 0;
140 //If we want to do averaging
141 uint32_t sample_sum =0 ;
142 uint32_t sample_total_numbers =0 ;
143 uint32_t sample_total_saved =0 ;
144
145 while(!BUTTON_PRESS()) {
146 WDT_HIT();
147 if (AT91C_BASE_SSC->SSC_SR & AT91C_SSC_TXRDY) {
148 AT91C_BASE_SSC->SSC_THR = 0x43;
149 LED_D_ON();
150 }
151 if (AT91C_BASE_SSC->SSC_SR & AT91C_SSC_RXRDY) {
152 sample = (uint8_t)AT91C_BASE_SSC->SSC_RHR;
153 LED_D_OFF();
154 if (trigger_threshold > 0 && sample < trigger_threshold)
155 continue;
156
157 trigger_threshold = 0;
158 sample_total_numbers++;
159
160 if(averaging)
161 {
162 sample_sum += sample;
163 }
164 //Check decimation
165 if(decimation > 1)
166 {
167 sample_counter++;
168 if(sample_counter < decimation) continue;
169 sample_counter = 0;
170 }
171 //Averaging
172 if(averaging && decimation > 1) {
173 sample = sample_sum / decimation;
174 sample_sum =0;
175 }
176 //Store the sample
177 sample_total_saved ++;
178 if(bits_per_sample == 8){
179 dest[sample_total_saved-1] = sample;
180 data.numbits = sample_total_saved << 3;//Get the return value correct
181 if(sample_total_saved >= bufsize) break;
182 }
183 else{
184 pushBit(&data, sample & 0x80);
185 if(bits_per_sample > 1) pushBit(&data, sample & 0x40);
186 if(bits_per_sample > 2) pushBit(&data, sample & 0x20);
187 if(bits_per_sample > 3) pushBit(&data, sample & 0x10);
188 if(bits_per_sample > 4) pushBit(&data, sample & 0x08);
189 if(bits_per_sample > 5) pushBit(&data, sample & 0x04);
190 if(bits_per_sample > 6) pushBit(&data, sample & 0x02);
191 //Not needed, 8bps is covered above
192 //if(bits_per_sample > 7) pushBit(&data, sample & 0x01);
193 if((data.numbits >> 3) +1 >= bufsize) break;
194 }
195 }
196 }
197
198 if(!silent)
199 {
200 Dbprintf("Done, saved %d out of %d seen samples at %d bits/sample",sample_total_saved, sample_total_numbers,bits_per_sample);
201 Dbprintf("buffer samples: %02x %02x %02x %02x %02x %02x %02x %02x ...",
202 dest[0], dest[1], dest[2], dest[3], dest[4], dest[5], dest[6], dest[7]);
203 }
204 return data.numbits;
205}
206/**
207 * @brief Does sample acquisition, ignoring the config values set in the sample_config.
208 * This method is typically used by tag-specific readers who just wants to read the samples
209 * the normal way
210 * @param trigger_threshold
211 * @param silent
212 * @return number of bits sampled
213 */
214uint32_t DoAcquisition_default(int trigger_threshold, bool silent)
215{
216 return DoAcquisition(1,8,0,trigger_threshold,silent);
217}
218uint32_t DoAcquisition_config( bool silent)
219{
220 return DoAcquisition(config.decimation
221 ,config.bits_per_sample
222 ,config.averaging
223 ,config.trigger_threshold
224 ,silent);
225}
226
1fbf8956 227uint32_t ReadLF(bool activeField, bool silent)
31abe49f 228{
1fbf8956 229 if (!silent) printConfig();
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230 LFSetupFPGAForADC(config.divisor, activeField);
231 // Now call the acquisition routine
1fbf8956 232 return DoAcquisition_config(silent);
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233}
234
235/**
236* Initializes the FPGA for reader-mode (field on), and acquires the samples.
237* @return number of bits sampled
238**/
1fbf8956 239uint32_t SampleLF(bool printCfg)
31abe49f 240{
1fbf8956 241 return ReadLF(true, printCfg);
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242}
243/**
244* Initializes the FPGA for snoop-mode (field off), and acquires the samples.
245* @return number of bits sampled
246**/
247
248uint32_t SnoopLF()
249{
1fbf8956 250 return ReadLF(false, true);
31abe49f 251}
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