github/RRG-Proxmark3
1
0
Fork 0
mirror of https://github.com/RfidResearchGroup/proxmark3.git synced 2025-08-21 05:43:48 -07:00
Code Issues Projects Releases Packages Wiki Activity Actions 4

added LED signals (A -> signal_properties, B -> listening windows, C -> reading)

Browse source 
stabilized noise detection by ignoring first samples
This commit is contained in:
tharexde 2020-11-27 22:21:45 +01:00
commit 35404eb207
1 changed files with 30 additions and 4 deletions
Download patch file Download diff file Expand all files Collapse all files

32
armsrc/em4x50.c
View file

@ -12,6 +12,7 @@
#include "ticks.h"
#include "dbprint.h"
#include "lfadc.h"
#include "lfdemod.h"
#include "commonutil.h"
#include "em4x50.h"
#include "flashmem.h"
@ -191,6 +192,8 @@ static bool get_signalproperties(void) {
uint32_t sample_max_sum = 0;
memcpy(sample_max, 0x00, sizeof(sample_max));
LED_A_ON();
// wait until signal/noise > 1 (max. 32 periods)
for (int i = 0; i < T0 * no_periods; i++) {
@ -199,14 +202,17 @@ static bool get_signalproperties(void) {
// about 2 samples per bit period
wait_timer(T0 * EM4X50_T_TAG_HALF_PERIOD);
if (AT91C_BASE_SSC->SSC_RHR > noise) {
// ignore first samples
if ((i > SIGNAL_IGNORE_FIRST_SAMPLES) && (AT91C_BASE_SSC->SSC_RHR > noise)) {
signal_found = true;
break;
}
}
if (signal_found == false)
if (signal_found == false) {
LED_A_OFF();
return false;
}
// calculate mean maximum value of 32 periods, each period has a length of
// 3 single "full periods" to eliminate the influence of a listen window
@ -232,6 +238,8 @@ static bool get_signalproperties(void) {
gHigh = sample_ref + pct * (sample_max_mean - sample_ref) / 100;
gLow = sample_ref - pct * (sample_max_mean - sample_ref) / 100;
LED_A_OFF();
return true;
}
@ -295,6 +303,7 @@ static bool check_pulse_length(uint32_t pl, int length) {
// check if pulse length <pl> corresponds to given length <length>
return ((pl >= T0 * (length - EM4X50_TAG_TOLERANCE)) && (pl <= T0 * (length + EM4X50_TAG_TOLERANCE)));
}
static void em4x50_reader_send_bit(int bit) {
@ -405,6 +414,8 @@ static int find_double_listen_window(bool bcommand) {
int cnt_pulses = 0;
LED_B_ON();
while (cnt_pulses < EM4X50_T_WAITING_FOR_DBLLIW) {
// identification of listen window is done via evaluation of
@ -438,6 +449,8 @@ static int find_double_listen_window(bool bcommand) {
em4x50_reader_send_bit(0);
em4x50_reader_send_bit(0);
LED_B_OFF();
return true;
}
@ -445,6 +458,8 @@ static int find_double_listen_window(bool bcommand) {
if (check_pulse_length(get_pulse_length(), 3 * EM4X50_T_TAG_FULL_PERIOD)) {
LED_B_OFF();
// return although second listen window consists of one
// more bit period but this period is necessary for
// evaluating further pulse lengths
@ -455,6 +470,8 @@ static int find_double_listen_window(bool bcommand) {
cnt_pulses++;
}
LED_B_OFF();
return false;
}
@ -462,7 +479,11 @@ static bool find_em4x50_tag(void) {
// function is used to check wether a tag on the proxmark is an
// EM4x50 tag or not -> speed up "lf search" process
LED_B_ON();
return find_single_listen_window();
LED_B_OFF();
}
static int request_receive_mode(void) {
@ -537,6 +558,8 @@ static int get_word_from_bitstream(uint32_t *data) {
uint32_t pl = 0;
uint64_t word = 0x0;
LED_C_ON();
*data = 0x0;
// initial bit value depends on last pulse length of listen window
@ -607,14 +630,17 @@ static int get_word_from_bitstream(uint32_t *data) {
} else if (check_pulse_length(pl, 3 * EM4X50_T_TAG_FULL_PERIOD)) {
LED_C_OFF();
// pulse length of 3 indicates listen window -> clear last
// bit (= 0) and return (without parities)
word >>= 2;
return (extract_parities(word, data)) ? --cnt : 0;
}
}
LED_C_OFF();
return BUTTON_SINGLE_CLICK;
}