//-----------------------------------------------------------------------------
// 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 "lfsampling.h"
/*
Default LF config is set to:
decimation = 1 (we keep 1 out of 1 samples)
bits_per_sample = 8
averaging = YES
divisor = 95 (125khz)
trigger_threshold = 0
*/
sample_config config = { 1, 8, 1, 95, 0 } ;
void printConfig() {
Dbprintf("LF Sampling config");
Dbprintf(" [q] divisor.............%d (%d KHz)", config.divisor, 12000 / (config.divisor + 1));
Dbprintf(" [b] bps.................%d", config.bits_per_sample);
Dbprintf(" [d] decimation..........%d", config.decimation);
Dbprintf(" [a] averaging...........%s", (config.averaging) ? "Yes" : "No");
Dbprintf(" [t] trigger threshold...%d", config.trigger_threshold);
}
/**
* Called from the USB-handler to set the sampling configuration
* The sampling config is used for std reading and sniffing.
*
* 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)
* @brief setSamplingConfig
* @param sc
*/
void setSamplingConfig(sample_config *sc) {
if (sc->divisor != 0) config.divisor = sc->divisor;
if (sc->bits_per_sample != 0) config.bits_per_sample = sc->bits_per_sample;
if (sc->trigger_threshold != -1) config.trigger_threshold = sc->trigger_threshold;
config.decimation = (sc->decimation != 0) ? sc->decimation : 1;
config.averaging = sc->averaging;
if (config.bits_per_sample > 8) config.bits_per_sample = 8;
printConfig();
}
sample_config *getSamplingConfig() {
return &config;
}
struct BitstreamOut {
uint8_t *buffer;
uint32_t numbits;
uint32_t position;
};
/**
* @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);
// 50ms 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();
// start a 1.5ticks is 1us
StartTicks();
}
/**
* 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, uint32_t cancel_after) {
uint8_t *dest = BigBuf_get_addr();
bufsize = (bufsize > 0 && bufsize < BigBuf_max_traceLen()) ? bufsize : BigBuf_max_traceLen();
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;
while (!BUTTON_PRESS() && !usb_poll_validate_length()) {
WDT_HIT();
if (AT91C_BASE_SSC->SSC_SR & AT91C_SSC_RXRDY) {
sample = (uint8_t)AT91C_BASE_SSC->SSC_RHR;
// Testpoint 8 (TP8) can be used to trigger oscilliscope
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;
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;
// Get the return value correct
data.numbits = sample_total_saved << 3;
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);
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]);
}
// Ensure that DC offset removal and noise check is performed for any device-side processing
removeSignalOffset(dest, bufsize);
computeSignalProperties(dest, bufsize);
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);
}
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);
}
uint32_t DoPartialAcquisition(int trigger_threshold, bool silent, int sample_size, uint32_t cancel_after) {
return DoAcquisition(1, 8, 0, trigger_threshold, silent, sample_size, cancel_after);
}
uint32_t ReadLF(bool activeField, bool silent, int sample_size) {
if (!silent)
printConfig();
LFSetupFPGAForADC(config.divisor, activeField);
uint32_t ret = DoAcquisition_config(silent, sample_size);
FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
return ret;
}
/**
* Initializes the FPGA for reader-mode (field on), and acquires the samples.
* @return number of bits sampled
**/
uint32_t SampleLF(bool silent, int sample_size) {
BigBuf_Clear_ext(false);
return ReadLF(true, silent, sample_size);
}
/**
* Initializes the FPGA for sniffer-mode (field off), and acquires the samples.
* @return number of bits sampled
**/
uint32_t SniffLF() {
BigBuf_Clear_ext(false);
return ReadLF(false, true, 0);
}
/**
* acquisition of T55x7 LF signal. Similar to other LF, but adjusted with @marshmellows thresholds
* the data is collected in BigBuf.
**/
void doT55x7Acquisition(size_t sample_size) {
#define T55xx_READ_UPPER_THRESHOLD 128+60 // 60 grph
#define T55xx_READ_LOWER_THRESHOLD 128-60 // -60 grph
#define T55xx_READ_TOL 5
uint8_t *dest = BigBuf_get_addr();
uint16_t bufsize = BigBuf_max_traceLen();
if (bufsize > sample_size)
bufsize = sample_size;
uint8_t curSample = 0, lastSample = 0;
uint16_t i = 0, skipCnt = 0;
bool startFound = false;
bool highFound = false;
bool lowFound = false;
while (!BUTTON_PRESS() && !usb_poll_validate_length() && skipCnt < 1000 && (i < bufsize)) {
WDT_HIT();
if (AT91C_BASE_SSC->SSC_SR & AT91C_SSC_RXRDY) {
curSample = (uint8_t)AT91C_BASE_SSC->SSC_RHR;
LED_D_OFF();
// skip until the first high sample above threshold
if (!startFound && curSample > T55xx_READ_UPPER_THRESHOLD) {
//if (curSample > lastSample)
// lastSample = curSample;
highFound = true;
} else if (!highFound) {
skipCnt++;
continue;
}
// skip until the first low sample below threshold
if (!startFound && curSample < T55xx_READ_LOWER_THRESHOLD) {
//if (curSample > lastSample)
lastSample = curSample;
lowFound = true;
} else if (!lowFound) {
skipCnt++;
continue;
}
// skip until first high samples begin to change
if (startFound || curSample > T55xx_READ_LOWER_THRESHOLD + T55xx_READ_TOL) {
// if just found start - recover last sample
if (!startFound) {
dest[i++] = lastSample;
startFound = true;
}
// collect samples
dest[i++] = curSample;
}
}
}
}
/**
* acquisition of Cotag LF signal. Similart 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;
uint16_t noise_counter = 0;
while (!BUTTON_PRESS() && !usb_poll_validate_length() && (i < bufsize) && (noise_counter < (COTAG_T1 << 1))) {
WDT_HIT();
if (AT91C_BASE_SSC->SSC_SR & AT91C_SSC_RXRDY) {
sample = (uint8_t)AT91C_BASE_SSC->SSC_RHR;
// 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;
}
++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_RXRDY) {
sample = (uint8_t)AT91C_BASE_SSC->SSC_RHR;
// 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;
}