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reduced use of timers and synchronized read actions

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tharexde 2021-01-12 00:22:53 +01:00
commit 1f08512670
1 changed files with 37 additions and 31 deletions
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68
armsrc/em4x50.c
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@ -46,6 +46,7 @@
#define EM4X50_T_WAITING_FOR_SNGLLIW 140
#define EM4X50_TAG_TOLERANCE 8
#define EM4X50_ZERO_DETECTION 3
#define EM4X50_TAG_WORD 45
#define EM4X50_TAG_MAX_NO_BYTES 136
@ -60,15 +61,11 @@ int gHigh = 190;
int gLow = 60;
// a global parameter is needed to indicate whether a previous login was
// successful, so operations that require authentication may be performed
// successful, so operations that require authentication can be handled
bool gLogin = false;
// additionally a global variable to identify the WritePassword process
bool gWritePasswordProcess = false;
int gcount = 0;
int gcycles = 0;
int rm = 0;
static int em4x50_sim_send_listen_window(uint32_t *tag);
void catch_samples(void);
@ -812,35 +809,48 @@ static int wait_cycles(int maxperiods) {
return PM3_SUCCESS;
}
static int get_cycles(void) {
static uint8_t em4x50_sim_read_bit(void) {
int cycles = 0;
AT91C_BASE_TC0->TC_CCR = AT91C_TC_SWTRG;
while (AT91C_BASE_TC0->TC_CV < T0 * (EM4X50_T_TAG_FULL_PERIOD - 2)) {
while (cycles < EM4X50_T_TAG_FULL_PERIOD) {
// wait until reader field disappears
while (!(AT91C_BASE_PIOA->PIO_PDSR & GPIO_SSC_CLK));
// check again to minimize desynchronization
if (AT91C_BASE_TC0->TC_CV >= T0 * EM4X50_T_TAG_FULL_PERIOD)
break;
// reader field is off, reset timer TC0
AT91C_BASE_TC0->TC_CCR = AT91C_TC_SWTRG;
while (AT91C_BASE_PIOA->PIO_PDSR & GPIO_SSC_CLK);
// now check until reader switches on carrier field
while (AT91C_BASE_PIOA->PIO_PDSR & GPIO_SSC_CLK) {
// check if cycle (i.e. off -> on -> off) takes longer than T0
if (AT91C_BASE_TC0->TC_CV > T0 * EM4X50_ZERO_DETECTION) {
// gap detected; wait until reader field is switched on again
while (AT91C_BASE_PIOA->PIO_PDSR & GPIO_SSC_CLK);
// now we have a reference "position", from here it will take
// slightly less 32 cycles until the end of the bit period
wait_cycles(EM4X50_T_TAG_FULL_PERIOD - EM4X50_ZERO_DETECTION);
// end of bit period is reached; return with bit value "0"
// (cf. datasheet)
return 0;
}
}
// no gap detected, i.e. reader field is still up;
// continue with counting cycles
cycles++;
}
return cycles;
// reached 64 cycles (= EM4X50_T_TAG_FULL_PERIOD) -> return bit value "1"
return 1;
}
static uint8_t em4x50_sim_read_bit(void) {
int cond = EM4X50_T_TAG_FULL_PERIOD - EM4X50_TAG_TOLERANCE;
return (get_cycles() < cond) ? 0 : 1;
}
static uint8_t em4x50_sim_read_byte(void) {
uint8_t byte = 0;
@ -954,8 +964,7 @@ static int em4x50_sim_handle_login_command(uint32_t *tag) {
// read password
uint32_t password = 0;
bool pwd_ok = em4x50_sim_read_word(&password);
//Dbprintf("address = %08x", address);
wait_cycles(15);
//wait_cycles(15);
// processing pause time (corresponds to a "1" bit)
em4x50_sim_send_bit(1);
@ -1261,13 +1270,11 @@ static int em4x50_sim_handle_standard_read_command(uint32_t *tag) {
// reader requests receive mode (rm) by sending two zeros
static int check_rm_request(uint32_t *tag) {
int cond = EM4X50_T_TAG_FULL_PERIOD - EM4X50_TAG_TOLERANCE;
// look for first zero
if (get_cycles() < cond) {
if (em4x50_sim_read_bit() == 0) {
// look for second zero
if (get_cycles() < cond) {
if (em4x50_sim_read_bit() == 0) {
// if command before was EM4X50_COMMAND_WRITE_PASSWORD
// switch to separate process
@ -1569,7 +1576,6 @@ void em4x50_info(em4x50_data_t *etd) {
uint32_t addresses = 0x00002100; // read from fwr = 0 to lwr = 33 (0x21)
uint32_t words[EM4X50_NO_WORDS] = {0x0};
gcount = 0;
em4x50_setup_read();
if (get_signalproperties() && find_em4x50_tag()) {