armsrc/lfsampling.c

   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("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
 123 uint32_t DoAcquisition(uint8_t decimation, uint32_t bits_per_sample, bool averaging, int trigger_threshold,bool silent)
 124 {
 125         //.
 126         uint8_t *dest = BigBuf_get_addr();
 127     int bufsize = BigBuf_max_traceLen();
 128
 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  */
 214 uint32_t DoAcquisition_default(int trigger_threshold, bool silent)
 215 {
 216         return DoAcquisition(1,8,0,trigger_threshold,silent);
 217 }
 218 uint32_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
 227 uint32_t ReadLF(bool activeField, bool silent)
 228 {
 229         if (!silent) printConfig();
 230         LFSetupFPGAForADC(config.divisor, activeField);
 231         // Now call the acquisition routine
 232         return DoAcquisition_config(silent);
 233 }
 234
 235 /**
 236 * Initializes the FPGA for reader-mode (field on), and acquires the samples.
 237 * @return number of bits sampled
 238 **/
 239 uint32_t SampleLF(bool printCfg)
 240 {
 241         return ReadLF(true, printCfg);
 242 }
 243 /**
 244 * Initializes the FPGA for snoop-mode (field off), and acquires the samples.
 245 * @return number of bits sampled
 246 **/
 247
 248 uint32_t SnoopLF()
 249 {
 250         return ReadLF(false, true);
 251 }