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lfsampling.c
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lfsampling.c
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//-----------------------------------------------------------------------------
// This code is licensed to you under the terms of the GNU GPL, version 2 or,
// at your option, any later version. See the LICENSE.txt file for the text of
// the license.
//-----------------------------------------------------------------------------
// Miscellaneous routines for low frequency sampling.
//-----------------------------------------------------------------------------
#include "proxmark3.h"
#include "apps.h"
#include "util.h"
#include "string.h"
#include "lfsampling.h"
#include "usb_cdc.h" // for usb_poll_validate_length
#include "fpgaloader.h"
sample_config config = { 1, 8, 1, 95, 0, 0 } ;
void printConfig()
{
Dbprintf("LF Sampling config: ");
Dbprintf(" [q] divisor: %d ", config.divisor);
Dbprintf(" [b] bps: %d ", config.bits_per_sample);
Dbprintf(" [d] decimation: %d ", config.decimation);
Dbprintf(" [a] averaging: %d ", config.averaging);
Dbprintf(" [t] trigger threshold: %d ", config.trigger_threshold);
Dbprintf(" [s] samples to skip: %d ", config.samples_to_skip);
}
/**
* Called from the USB-handler to set the sampling configuration
* The sampling config is used for std reading and snooping.
*
* Other functions may read samples and ignore the sampling config,
* such as functions to read the UID from a prox tag or similar.
*
* Values set to '0' implies no change (except for averaging, threshold, samples_to_skip)
* @brief setSamplingConfig
* @param sc
*/
void setSamplingConfig(uint8_t *config_data) {
sample_config *sc = (sample_config *)config_data;
if (sc->divisor != 0) config.divisor = sc->divisor;
if (sc->bits_per_sample != 0) config.bits_per_sample = sc->bits_per_sample;
if (sc->decimation != 0) config.decimation = sc->decimation;
if (sc->trigger_threshold != -1) config.trigger_threshold = sc->trigger_threshold;
if (sc->samples_to_skip != -1) config.samples_to_skip = sc->samples_to_skip;
config.averaging= sc->averaging;
if (config.bits_per_sample > 8) config.bits_per_sample = 8;
if (config.decimation < 1) config.decimation = 1;
printConfig();
}
sample_config* getSamplingConfig()
{
return &config;
}
typedef struct {
uint8_t * buffer;
uint32_t numbits;
uint32_t position;
} BitstreamOut;
/**
* @brief Pushes bit onto the stream
* @param stream
* @param bit
*/
void pushBit( BitstreamOut* stream, uint8_t bit)
{
int bytepos = stream->position >> 3; // divide by 8
int bitpos = stream->position & 7;
*(stream->buffer+bytepos) |= (bit > 0) << (7 - bitpos);
stream->position++;
stream->numbits++;
}
/**
* Setup the FPGA to listen for samples. This method downloads the FPGA bitstream
* if not already loaded, sets divisor and starts up the antenna.
* @param divisor : 1, 88> 255 or negative ==> 134.8 KHz
* 0 or 95 ==> 125 KHz
*
**/
void LFSetupFPGAForADC(int divisor, bool lf_field)
{
FpgaDownloadAndGo(FPGA_BITSTREAM_LF);
if ( (divisor == 1) || (divisor < 0) || (divisor > 255) )
FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 88); //134.8Khz
else if (divisor == 0)
FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 95); //125Khz
else
FpgaSendCommand(FPGA_CMD_SET_DIVISOR, divisor);
FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_ADC | (lf_field ? FPGA_LF_ADC_READER_FIELD : 0));
// Connect the A/D to the peak-detected low-frequency path.
SetAdcMuxFor(GPIO_MUXSEL_LOPKD);
// Give it a bit of time for the resonant antenna to settle.
SpinDelay(50);
// Now set up the SSC to get the ADC samples that are now streaming at us.
FpgaSetupSsc(FPGA_MAJOR_MODE_LF_ADC);
}
/**
* Does the sample acquisition. If threshold is specified, the actual sampling
* is not commenced until the threshold has been reached.
* This method implements decimation and quantization in order to
* be able to provide longer sample traces.
* Uses the following global settings:
* @param decimation - how much should the signal be decimated. A decimation of N means we keep 1 in N samples, etc.
* @param bits_per_sample - bits per sample. Max 8, min 1 bit per sample.
* @param averaging If set to true, decimation will use averaging, so that if e.g. decimation is 3, the sample
* value that will be used is the average value of the three samples.
* @param trigger_threshold - a threshold. The sampling won't commence until this threshold has been reached. Set
* to -1 to ignore threshold.
* @param silent - is true, now outputs are made. If false, dbprints the status
* @return the number of bits occupied by the samples.
*/
uint32_t DoAcquisition(uint8_t decimation, uint32_t bits_per_sample, bool averaging, int trigger_threshold, bool silent, int bufsize, int cancel_after, int samples_to_skip)
{
//.
uint8_t *dest = BigBuf_get_addr();
bufsize = (bufsize > 0 && bufsize < BigBuf_max_traceLen()) ? bufsize : BigBuf_max_traceLen();
//memset(dest, 0, bufsize); //creates issues with cmdread (marshmellow)
if(bits_per_sample < 1) bits_per_sample = 1;
if(bits_per_sample > 8) bits_per_sample = 8;
if(decimation < 1) decimation = 1;
// Use a bit stream to handle the output
BitstreamOut data = { dest , 0, 0};
int sample_counter = 0;
uint8_t sample = 0;
//If we want to do averaging
uint32_t sample_sum =0 ;
uint32_t sample_total_numbers =0 ;
uint32_t sample_total_saved =0 ;
uint32_t cancel_counter = 0;
uint32_t samples_skipped = 0;
while(!BUTTON_PRESS() && !usb_poll_validate_length() ) {
WDT_HIT();
if (AT91C_BASE_SSC->SSC_SR & AT91C_SSC_TXRDY) {
AT91C_BASE_SSC->SSC_THR = 0x43;
LED_D_ON();
}
if (AT91C_BASE_SSC->SSC_SR & AT91C_SSC_RXRDY) {
sample = (uint8_t)AT91C_BASE_SSC->SSC_RHR;
LED_D_OFF();
// threshold either high or low values 128 = center 0. if trigger = 178
if ((trigger_threshold > 0) && (sample < (trigger_threshold+128)) && (sample > (128-trigger_threshold))) { //
if (cancel_after > 0) {
cancel_counter++;
if (cancel_after == cancel_counter) break;
}
continue;
}
trigger_threshold = 0;
if (samples_to_skip > samples_skipped) {
samples_skipped++;
continue;
}
sample_total_numbers++;
if(averaging)
{
sample_sum += sample;
}
//Check decimation
if(decimation > 1)
{
sample_counter++;
if(sample_counter < decimation) continue;
sample_counter = 0;
}
//Averaging
if(averaging && decimation > 1) {
sample = sample_sum / decimation;
sample_sum =0;
}
//Store the sample
sample_total_saved ++;
if(bits_per_sample == 8){
dest[sample_total_saved-1] = sample;
data.numbits = sample_total_saved << 3;//Get the return value correct
if(sample_total_saved >= bufsize) break;
}
else{
pushBit(&data, sample & 0x80);
if(bits_per_sample > 1) pushBit(&data, sample & 0x40);
if(bits_per_sample > 2) pushBit(&data, sample & 0x20);
if(bits_per_sample > 3) pushBit(&data, sample & 0x10);
if(bits_per_sample > 4) pushBit(&data, sample & 0x08);
if(bits_per_sample > 5) pushBit(&data, sample & 0x04);
if(bits_per_sample > 6) pushBit(&data, sample & 0x02);
//Not needed, 8bps is covered above
//if(bits_per_sample > 7) pushBit(&data, sample & 0x01);
if((data.numbits >> 3) +1 >= bufsize) break;
}
}
}
if(!silent)
{
Dbprintf("Done, saved %d out of %d seen samples at %d bits/sample",sample_total_saved, sample_total_numbers,bits_per_sample);
Dbprintf("buffer samples: %02x %02x %02x %02x %02x %02x %02x %02x ...",
dest[0], dest[1], dest[2], dest[3], dest[4], dest[5], dest[6], dest[7]);
}
return data.numbits;
}
/**
* @brief Does sample acquisition, ignoring the config values set in the sample_config.
* This method is typically used by tag-specific readers who just wants to read the samples
* the normal way
* @param trigger_threshold
* @param silent
* @return number of bits sampled
*/
uint32_t DoAcquisition_default(int trigger_threshold, bool silent)
{
return DoAcquisition(1,8,0,trigger_threshold,silent,0,0,0);
}
uint32_t DoAcquisition_config(bool silent, int sample_size)
{
return DoAcquisition(config.decimation
,config.bits_per_sample
,config.averaging
,config.trigger_threshold
,silent
,sample_size
,0
,config.samples_to_skip);
}
uint32_t DoPartialAcquisition(int trigger_threshold, bool silent, int sample_size, int cancel_after) {
return DoAcquisition(1,8,0,trigger_threshold,silent,sample_size,cancel_after,0);
}
uint32_t ReadLF(bool activeField, bool silent, int sample_size)
{
if (!silent) printConfig();
LFSetupFPGAForADC(config.divisor, activeField);
// Now call the acquisition routine
return DoAcquisition_config(silent, sample_size);
}
/**
* Initializes the FPGA for reader-mode (field on), and acquires the samples.
* @return number of bits sampled
**/
uint32_t SampleLF(bool printCfg, int sample_size)
{
uint32_t ret = ReadLF(true, printCfg, sample_size);
FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
return ret;
}
/**
* Initializes the FPGA for snoop-mode (field off), and acquires the samples.
* @return number of bits sampled
**/
uint32_t SnoopLF()
{
uint32_t ret = ReadLF(false, true, 0);
FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
return ret;
}
/**
* acquisition of Cotag LF signal. Similar to other LF, since the Cotag has such long datarate RF/384
* and is Manchester?, we directly gather the manchester data into bigbuff
**/
#define COTAG_T1 384
#define COTAG_T2 (COTAG_T1>>1)
#define COTAG_ONE_THRESHOLD 128+30
#define COTAG_ZERO_THRESHOLD 128-30
#ifndef COTAG_BITS
#define COTAG_BITS 264
#endif
void doCotagAcquisition(size_t sample_size) {
uint8_t *dest = BigBuf_get_addr();
uint16_t bufsize = BigBuf_max_traceLen();
if ( bufsize > sample_size )
bufsize = sample_size;
dest[0] = 0;
uint8_t sample = 0, firsthigh = 0, firstlow = 0;
uint16_t i = 0;
while (!BUTTON_PRESS() && !usb_poll_validate_length() && (i < bufsize) ) {
WDT_HIT();
if (AT91C_BASE_SSC->SSC_SR & AT91C_SSC_TXRDY) {
AT91C_BASE_SSC->SSC_THR = 0x43;
LED_D_ON();
}
if (AT91C_BASE_SSC->SSC_SR & AT91C_SSC_RXRDY) {
sample = (uint8_t)AT91C_BASE_SSC->SSC_RHR;
LED_D_OFF();
// find first peak
if ( !firsthigh ) {
if (sample < COTAG_ONE_THRESHOLD)
continue;
firsthigh = 1;
}
if ( !firstlow ){
if (sample > COTAG_ZERO_THRESHOLD )
continue;
firstlow = 1;
}
++i;
if ( sample > COTAG_ONE_THRESHOLD)
dest[i] = 255;
else if ( sample < COTAG_ZERO_THRESHOLD)
dest[i] = 0;
else
dest[i] = dest[i-1];
}
}
}
uint32_t doCotagAcquisitionManchester() {
uint8_t *dest = BigBuf_get_addr();
uint16_t bufsize = BigBuf_max_traceLen();
if ( bufsize > COTAG_BITS )
bufsize = COTAG_BITS;
dest[0] = 0;
uint8_t sample = 0, firsthigh = 0, firstlow = 0;
uint16_t sample_counter = 0, period = 0;
uint8_t curr = 0, prev = 0;
uint16_t noise_counter = 0;
while (!BUTTON_PRESS() && !usb_poll_validate_length() && (sample_counter < bufsize) && (noise_counter < (COTAG_T1<<1)) ) {
WDT_HIT();
if (AT91C_BASE_SSC->SSC_SR & AT91C_SSC_TXRDY) {
AT91C_BASE_SSC->SSC_THR = 0x43;
LED_D_ON();
}
if (AT91C_BASE_SSC->SSC_SR & AT91C_SSC_RXRDY) {
sample = (uint8_t)AT91C_BASE_SSC->SSC_RHR;
LED_D_OFF();
// find first peak
if ( !firsthigh ) {
if (sample < COTAG_ONE_THRESHOLD) {
noise_counter++;
continue;
}
noise_counter = 0;
firsthigh = 1;
}
if ( !firstlow ){
if (sample > COTAG_ZERO_THRESHOLD ) {
noise_counter++;
continue;
}
noise_counter=0;
firstlow = 1;
}
// set sample 255, 0, or previous
if ( sample > COTAG_ONE_THRESHOLD){
prev = curr;
curr = 1;
}
else if ( sample < COTAG_ZERO_THRESHOLD) {
prev = curr;
curr = 0;
}
else {
curr = prev;
}
// full T1 periods,
if ( period > 0 ) {
--period;
continue;
}
dest[sample_counter] = curr;
++sample_counter;
period = COTAG_T1;
}
}
return sample_counter;
}