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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 "lfsampling.h"
10
11sample_config config = { 1, 8, 1, 95, 0 } ;
12
13void printConfig() {
14 Dbprintf("LF Sampling config: ");
15 Dbprintf(" [q] divisor: %d ", config.divisor);
16 Dbprintf(" [b] bps: %d ", config.bits_per_sample);
17 Dbprintf(" [d] decimation: %d ", config.decimation);
18 Dbprintf(" [a] averaging: %d ", config.averaging);
19 Dbprintf(" [t] trigger threshold: %d ", config.trigger_threshold);
20}
21
22
23/**
24 * Called from the USB-handler to set the sampling configuration
25 * The sampling config is used for std reading and snooping.
26 *
27 * Other functions may read samples and ignore the sampling config,
28 * such as functions to read the UID from a prox tag or similar.
29 *
30 * Values set to '0' implies no change (except for averaging)
31 * @brief setSamplingConfig
32 * @param sc
33 */
34void setSamplingConfig(sample_config *sc) {
35 if(sc->divisor != 0) config.divisor = sc->divisor;
36 if(sc->bits_per_sample != 0) config.bits_per_sample = sc->bits_per_sample;
37 if(sc->decimation != 0) config.decimation = sc->decimation;
38 if(sc->trigger_threshold != -1) config.trigger_threshold = sc->trigger_threshold;
39
40 config.averaging = sc->averaging;
41 if(config.bits_per_sample > 8) config.bits_per_sample = 8;
42 if(config.decimation < 1) config.decimation = 1;
43
44 printConfig();
45}
46
47sample_config* getSamplingConfig() {
48 return &config;
49}
50
51typedef struct {
52 uint8_t * buffer;
53 uint32_t numbits;
54 uint32_t position;
55} BitstreamOut;
56
57/**
58 * @brief Pushes bit onto the stream
59 * @param stream
60 * @param bit
61 */
62void pushBit( BitstreamOut* stream, uint8_t bit) {
63 int bytepos = stream->position >> 3; // divide by 8
64 int bitpos = stream->position & 7;
65 *(stream->buffer+bytepos) |= (bit > 0) << (7 - bitpos);
66 stream->position++;
67 stream->numbits++;
68}
69
70/**
71* Setup the FPGA to listen for samples. This method downloads the FPGA bitstream
72* if not already loaded, sets divisor and starts up the antenna.
73* @param divisor : 1, 88> 255 or negative ==> 134.8 KHz
74* 0 or 95 ==> 125 KHz
75*
76**/
77void LFSetupFPGAForADC(int divisor, bool lf_field) {
78 FpgaDownloadAndGo(FPGA_BITSTREAM_LF);
79 if ( (divisor == 1) || (divisor < 0) || (divisor > 255) )
80 FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 88); //134.8Khz
81 else if (divisor == 0)
82 FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 95); //125Khz
83 else
84 FpgaSendCommand(FPGA_CMD_SET_DIVISOR, divisor);
85
86 FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_ADC | (lf_field ? FPGA_LF_ADC_READER_FIELD : 0));
87
88 // Connect the A/D to the peak-detected low-frequency path.
89 SetAdcMuxFor(GPIO_MUXSEL_LOPKD);
90 // 50ms for the resonant antenna to settle.
91 SpinDelay(50);
92 // Now set up the SSC to get the ADC samples that are now streaming at us.
93 FpgaSetupSsc();
94 // start a 1.5ticks is 1us
95 StartTicks();
96}
97
98/**
99 * Does the sample acquisition. If threshold is specified, the actual sampling
100 * is not commenced until the threshold has been reached.
101 * This method implements decimation and quantization in order to
102 * be able to provide longer sample traces.
103 * Uses the following global settings:
104 * @param decimation - how much should the signal be decimated. A decimation of N means we keep 1 in N samples, etc.
105 * @param bits_per_sample - bits per sample. Max 8, min 1 bit per sample.
106 * @param averaging If set to true, decimation will use averaging, so that if e.g. decimation is 3, the sample
107 * value that will be used is the average value of the three samples.
108 * @param trigger_threshold - a threshold. The sampling won't commence until this threshold has been reached. Set
109 * to -1 to ignore threshold.
110 * @param silent - is true, now outputs are made. If false, dbprints the status
111 * @return the number of bits occupied by the samples.
112 */
113uint32_t DoAcquisition(uint8_t decimation, uint32_t bits_per_sample, bool averaging, int trigger_threshold,bool silent) {
114 //bigbuf, to hold the aquired raw data signal
115 uint8_t *dest = BigBuf_get_addr();
116 uint16_t bufsize = BigBuf_max_traceLen();
117
118 //BigBuf_Clear_ext(false); //creates issues with cmdread (marshmellow)
119
120 if(bits_per_sample < 1) bits_per_sample = 1;
121 if(bits_per_sample > 8) bits_per_sample = 8;
122
123 if(decimation < 1) decimation = 1;
124
125 // Use a bit stream to handle the output
126 BitstreamOut data = { dest , 0, 0};
127 int sample_counter = 0;
128 uint8_t sample = 0;
129 //If we want to do averaging
130 uint32_t sample_sum =0 ;
131 uint32_t sample_total_numbers =0 ;
132 uint32_t sample_total_saved =0 ;
133
134 while(!BUTTON_PRESS() && !usb_poll_validate_length() ) {
135 WDT_HIT();
136 if (AT91C_BASE_SSC->SSC_SR & AT91C_SSC_TXRDY) {
137 AT91C_BASE_SSC->SSC_THR = 0x43;
138 LED_D_ON();
139 }
140 if (AT91C_BASE_SSC->SSC_SR & AT91C_SSC_RXRDY) {
141 sample = (uint8_t)AT91C_BASE_SSC->SSC_RHR;
142 LED_D_OFF();
143 // threshold either high or low values 128 = center 0. if trigger = 178
144 if ((trigger_threshold > 0) && (sample < (trigger_threshold+128)) && (sample > (128-trigger_threshold))) //
145 continue;
146
147 trigger_threshold = 0;
148 sample_total_numbers++;
149
150 if(averaging)
151 {
152 sample_sum += sample;
153 }
154 //Check decimation
155 if(decimation > 1)
156 {
157 sample_counter++;
158 if(sample_counter < decimation) continue;
159 sample_counter = 0;
160 }
161 //Averaging
162 if(averaging && decimation > 1) {
163 sample = sample_sum / decimation;
164 sample_sum =0;
165 }
166 //Store the sample
167 sample_total_saved ++;
168 if(bits_per_sample == 8){
169 dest[sample_total_saved-1] = sample;
170 data.numbits = sample_total_saved << 3;//Get the return value correct
171 if(sample_total_saved >= bufsize) break;
172 }
173 else{
174 pushBit(&data, sample & 0x80);
175 if(bits_per_sample > 1) pushBit(&data, sample & 0x40);
176 if(bits_per_sample > 2) pushBit(&data, sample & 0x20);
177 if(bits_per_sample > 3) pushBit(&data, sample & 0x10);
178 if(bits_per_sample > 4) pushBit(&data, sample & 0x08);
179 if(bits_per_sample > 5) pushBit(&data, sample & 0x04);
180 if(bits_per_sample > 6) pushBit(&data, sample & 0x02);
181 //Not needed, 8bps is covered above
182 //if(bits_per_sample > 7) pushBit(&data, sample & 0x01);
183 if((data.numbits >> 3) +1 >= bufsize) break;
184 }
185 }
186 }
187
188 if(!silent)
189 {
190 Dbprintf("Done, saved %d out of %d seen samples at %d bits/sample",sample_total_saved, sample_total_numbers,bits_per_sample);
191 Dbprintf("buffer samples: %02x %02x %02x %02x %02x %02x %02x %02x ...",
192 dest[0], dest[1], dest[2], dest[3], dest[4], dest[5], dest[6], dest[7]);
193 }
194 return data.numbits;
195}
196/**
197 * @brief Does sample acquisition, ignoring the config values set in the sample_config.
198 * This method is typically used by tag-specific readers who just wants to read the samples
199 * the normal way
200 * @param trigger_threshold
201 * @param silent
202 * @return number of bits sampled
203 */
204uint32_t DoAcquisition_default(int trigger_threshold, bool silent) {
205 return DoAcquisition(1,8,0,trigger_threshold,silent);
206}
207uint32_t DoAcquisition_config( bool silent) {
208 return DoAcquisition(config.decimation
209 ,config.bits_per_sample
210 ,config.averaging
211 ,config.trigger_threshold
212 ,silent);
213}
214
215uint32_t ReadLF(bool activeField, bool silent) {
216 if (!silent)
217 printConfig();
218 LFSetupFPGAForADC(config.divisor, activeField);
219 return DoAcquisition_config(silent);
220}
221
222/**
223* Initializes the FPGA for reader-mode (field on), and acquires the samples.
224* @return number of bits sampled
225**/
226uint32_t SampleLF(bool printCfg) {
227 return ReadLF(true, printCfg);
228}
229/**
230* Initializes the FPGA for snoop-mode (field off), and acquires the samples.
231* @return number of bits sampled
232**/
233uint32_t SnoopLF() {
234 return ReadLF(false, true);
235}
236
237/**
238* acquisition of T55x7 LF signal. Similart to other LF, but adjusted with @marshmellows thresholds
239* the data is collected in BigBuf.
240**/
241void doT55x7Acquisition(size_t sample_size) {
242
243 #define T55xx_READ_UPPER_THRESHOLD 128+40 // 60 grph
244 #define T55xx_READ_LOWER_THRESHOLD 128-40 // -60 grph
245 #define T55xx_READ_TOL 2
246
247 uint8_t *dest = BigBuf_get_addr();
248 uint16_t bufsize = BigBuf_max_traceLen();
249
250 if ( bufsize > sample_size )
251 bufsize = sample_size;
252
253 uint8_t curSample = 0, lastSample = 0;
254 uint16_t i = 0, skipCnt = 0;
255 bool startFound = false;
256 bool highFound = false;
257 bool lowFound = false;
258
259 while(!BUTTON_PRESS() && !usb_poll_validate_length() && skipCnt < 1000 && (i < bufsize) ) {
260 WDT_HIT();
261 if (AT91C_BASE_SSC->SSC_SR & AT91C_SSC_TXRDY) {
262 AT91C_BASE_SSC->SSC_THR = 0x43;
263 LED_D_ON();
264 }
265 if (AT91C_BASE_SSC->SSC_SR & AT91C_SSC_RXRDY) {
266 curSample = (uint8_t)AT91C_BASE_SSC->SSC_RHR;
267 LED_D_OFF();
268
269 // skip until the first high sample above threshold
270 if (!startFound && curSample > T55xx_READ_UPPER_THRESHOLD) {
271 //if (curSample > lastSample)
272 // lastSample = curSample;
273 highFound = true;
274 } else if (!highFound) {
275 skipCnt++;
276 continue;
277 }
278 // skip until the first Low sample below threshold
279 if (!startFound && curSample < T55xx_READ_LOWER_THRESHOLD) {
280 //if (curSample > lastSample)
281 lastSample = curSample;
282 lowFound = true;
283 } else if (!lowFound) {
284 skipCnt++;
285 continue;
286 }
287
288 // skip until first high samples begin to change
289 if (startFound || curSample > T55xx_READ_LOWER_THRESHOLD + T55xx_READ_TOL){
290 // if just found start - recover last sample
291 if (!startFound) {
292 dest[i++] = lastSample;
293 startFound = true;
294 }
295 // collect samples
296 dest[i++] = curSample;
297 }
298 }
299 }
300}
301
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