int bits;
uint16_t data;
} current_frame;
+AT91PS_TC timer;
-static struct legic_frame queries[] = {
+static void setup_timer(void)
+{
+ /* Set up Timer 1 to use for measuring time between pulses. Since we're bit-banging
+ * this it won't be terribly accurate but should be good enough.
+ */
+ AT91C_BASE_PMC->PMC_PCER = (1 << AT91C_ID_TC1);
+ timer = AT91C_BASE_TC1;
+ timer->TC_CCR = AT91C_TC_CLKDIS;
+ timer->TC_CMR = TC_CMR_TCCLKS_TIMER_CLOCK3;
+ timer->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
+
+/* At TIMER_CLOCK3 (MCK/32) */
+#define RWD_TIME_1 150 /* RWD_TIME_PAUSE off, 80us on = 100us */
+#define RWD_TIME_0 90 /* RWD_TIME_PAUSE off, 40us on = 60us */
+#define RWD_TIME_PAUSE 30 /* 20us */
+#define RWD_TIME_FUZZ 20 /* rather generous 13us, since the peak detector + hysteresis fuzz quite a bit */
+#define TAG_TIME_BIT 150 /* 100us for every bit */
+#define TAG_TIME_WAIT 490 /* time from RWD frame end to tag frame start, experimentally determined */
+
+}
+
+#define FUZZ_EQUAL(value, target, fuzz) ((value) > ((target)-(fuzz)) && (value) < ((target)+(fuzz)))
+
+static const struct legic_frame queries[] = {
{7, 0x55}, /* 1010 101 */
};
-static struct legic_frame responses[] = {
+static const struct legic_frame responses[] = {
{6, 0x3b}, /* 1101 11 */
};
-static void frame_send(uint16_t response, int bits)
+/* Send a frame in tag mode, the FPGA must have been set up by
+ * LegicRfSimulate
+ */
+static void frame_send_tag(uint16_t response, int bits)
{
#if 0
/* Use the SSC to send a response. 8-bit transfers, LSBit first, 100us per bit */
AT91C_BASE_PIOA->PIO_PER = GPIO_SSC_DOUT;
/* Wait for the frame start */
- while(AT91C_BASE_TC1->TC_CV < 490) ;
+ while(timer->TC_CV < TAG_TIME_WAIT) ;
int i;
for(i=0; i<bits; i++) {
- int nextbit = AT91C_BASE_TC1->TC_CV + 150;
+ int nextbit = timer->TC_CV + TAG_TIME_BIT;
int bit = response & 1;
response = response >> 1;
if(bit)
AT91C_BASE_PIOA->PIO_SODR = GPIO_SSC_DOUT;
else
AT91C_BASE_PIOA->PIO_CODR = GPIO_SSC_DOUT;
- while(AT91C_BASE_TC1->TC_CV < nextbit) ;
+ while(timer->TC_CV < nextbit) ;
}
AT91C_BASE_PIOA->PIO_CODR = GPIO_SSC_DOUT;
#endif
}
-static void frame_respond(struct legic_frame const * const f)
+/* Send a frame in reader mode, the FPGA must have been set up by
+ * LegicRfReader
+ */
+static void frame_send_rwd(uint16_t data, int bits)
{
- LED_D_ON();
+ /* Start clock */
+ timer->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
+ while(timer->TC_CV > 1) ; /* Wait till the clock has reset */
+
int i;
- struct legic_frame *r = NULL;
+ for(i=0; i<bits; i++) {
+ int starttime = timer->TC_CV;
+ int pause_end = starttime + RWD_TIME_PAUSE, bit_end;
+ int bit = data & 1;
+ data = data >> 1;
+
+ if(bit) {
+ bit_end = starttime + RWD_TIME_1;
+ } else {
+ bit_end = starttime + RWD_TIME_0;
+ }
+
+ /* RWD_TIME_PAUSE time off, then some time on, so that the complete bit time is
+ * RWD_TIME_x, where x is the bit to be transmitted */
+ AT91C_BASE_PIOA->PIO_CODR = GPIO_SSC_DOUT;
+ while(timer->TC_CV < pause_end) ;
+ AT91C_BASE_PIOA->PIO_SODR = GPIO_SSC_DOUT;
+ while(timer->TC_CV < bit_end) ;
+ }
+
+ {
+ /* One final pause to mark the end of the frame */
+ int pause_end = timer->TC_CV + RWD_TIME_PAUSE;
+ AT91C_BASE_PIOA->PIO_CODR = GPIO_SSC_DOUT;
+ while(timer->TC_CV < pause_end) ;
+ AT91C_BASE_PIOA->PIO_SODR = GPIO_SSC_DOUT;
+ }
+
+ /* Reset the timer, to measure time until the start of the tag frame */
+ timer->TC_CCR = AT91C_TC_SWTRG;
+}
+
+/* Receive a frame from the card in reader emulation mode, the FPGA and
+ * timer must have been set up by LegicRfReader and frame_send_rwd.
+ *
+ * The LEGIC RF protocol from card to reader does not include explicit
+ * frame start/stop information or length information. The reader must
+ * know beforehand how many bits it wants to receive. (Notably: a card
+ * sending a stream of 0-bits is indistinguishable from no card present.)
+ *
+ * Receive methodology: There is a fancy correlator in hi_read_rx_xcorr, but
+ * I'm not smart enough to use it. Instead I have patched hi_read_tx to output
+ * the ADC signal with hysteresis on SSP_DIN. Bit-bang that signal and look
+ * for edges. Count the edges in each bit interval. If they are approximately
+ * 0 this was a 0-bit, if they are approximately equal to the number of edges
+ * expected for a 212kHz subcarrier, this was a 1-bit. For timing we use the
+ * timer that's still running from frame_send_rwd in order to get a synchronization
+ * with the frame that we just sent.
+ *
+ * FIXME: Because we're relying on the hysteresis to just do the right thing
+ * the range is severely reduced (and you'll probably also need a good antenna).
+ * So this should be fixed some time in the future for a proper receiver.
+ */
+static void frame_receive_rwd(struct legic_frame * const f, int bits)
+{
+ uint16_t the_bit = 1; /* Use a bitmask to save on shifts */
+ uint16_t data=0;
+ int i, old_level=0, edges=0;
+ int next_bit_at = TAG_TIME_WAIT;
+
+
+ if(bits > 16)
+ bits = 16;
+
+ AT91C_BASE_PIOA->PIO_ODR = GPIO_SSC_DIN;
+ AT91C_BASE_PIOA->PIO_PER = GPIO_SSC_DIN;
+
+ while(timer->TC_CV < next_bit_at) ;
+ next_bit_at += TAG_TIME_BIT;
+
+ for(i=0; i<bits; i++) {
+ edges = 0;
+ while(timer->TC_CV < next_bit_at) {
+ int level = (AT91C_BASE_PIOA->PIO_PDSR & GPIO_SSC_DIN);
+ if(level != old_level)
+ edges++;
+ old_level = level;
+ }
+ next_bit_at += TAG_TIME_BIT;
+
+ if(edges > 20 && edges < 60) { /* expected are 42 edges */
+ data |= the_bit;
+ }
+
+
+ the_bit <<= 1;
+ }
+
+ f->data = data;
+ f->bits = bits;
+}
+
+/* Figure out a response to a frame in tag mode */
+static void frame_respond_tag(struct legic_frame const * const f)
+{
+ LED_D_ON();
+ int i, r_size=0;
+ uint16_t r_data=0;
for(i=0; i<sizeof(queries)/sizeof(queries[0]); i++) {
if(f->bits == queries[i].bits && f->data == queries[i].data) {
- r = &responses[i];
+ r_data = responses[i].data;
+ r_size = responses[i].bits;
break;
}
}
- if(r != NULL) {
- frame_send(r->data, r->bits);
+ if(r_size != 0) {
+ frame_send_tag(r_data, r_size);
LED_A_ON();
} else {
LED_A_OFF();
return( f->bits <= 4 );
}
-static void frame_handle(struct legic_frame const * const f)
+/* Handle (whether to respond) a frame in tag mode */
+static void frame_handle_tag(struct legic_frame const * const f)
{
if(f->bits == 6) {
/* Short path */
return;
}
if( !frame_is_empty(f) ) {
- frame_respond(f);
+ frame_respond_tag(f);
}
}
f->bits = 0;
}
-static void emit(int bit)
+enum emit_mode {
+ EMIT_RWD, /* Emit in tag simulation mode, e.g. the source is the RWD */
+ EMIT_TAG /* Emit in reader simulation mode, e.g. the source is the TAG */
+};
+static void emit(enum emit_mode mode, int bit)
{
if(bit == -1) {
- frame_handle(¤t_frame);
+ if(mode == EMIT_RWD) {
+ frame_handle_tag(¤t_frame);
+ }
frame_clean(¤t_frame);
} else if(bit == 0) {
frame_append_bit(¤t_frame, 0);
AT91C_BASE_PIOA->PIO_ODR = GPIO_SSC_DIN;
AT91C_BASE_PIOA->PIO_PER = GPIO_SSC_DIN;
- /* Set up Timer 1 to use for measuring time between pulses. Since we're bit-banging
- * this it won't be terribly accurate but should be good enough.
- */
- AT91C_BASE_PMC->PMC_PCER = (1 << AT91C_ID_TC1);
- AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKDIS;
- AT91C_BASE_TC1->TC_CMR = TC_CMR_TCCLKS_TIMER_CLOCK3;
- AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
- int old_level = 0;
-
-/* At TIMER_CLOCK3 (MCK/32) */
-#define BIT_TIME_1 150
-#define BIT_TIME_0 90
-#define BIT_TIME_FUZZ 20
+ setup_timer();
+ int old_level = 0;
int active = 0;
+
while(!BUTTON_PRESS()) {
int level = !!(AT91C_BASE_PIOA->PIO_PDSR & GPIO_SSC_DIN);
- int time = AT91C_BASE_TC1->TC_CV;
+ int time = timer->TC_CV;
if(level != old_level) {
if(level == 1) {
- AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
- if(time > (BIT_TIME_1-BIT_TIME_FUZZ) && time < (BIT_TIME_1+BIT_TIME_FUZZ)) {
+ timer->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
+ if(FUZZ_EQUAL(time, RWD_TIME_1, RWD_TIME_FUZZ)) {
/* 1 bit */
- emit(1);
+ emit(EMIT_RWD, 1);
active = 1;
LED_B_ON();
- } else if(time > (BIT_TIME_0-BIT_TIME_FUZZ) && time < (BIT_TIME_0+BIT_TIME_FUZZ)) {
+ } else if(FUZZ_EQUAL(time, RWD_TIME_0, RWD_TIME_FUZZ)) {
/* 0 bit */
- emit(0);
+ emit(EMIT_RWD, 0);
active = 1;
LED_B_ON();
} else if(active) {
/* invalid */
- emit(-1);
+ emit(EMIT_RWD, -1);
active = 0;
LED_B_OFF();
}
}
}
- if(time >= (BIT_TIME_1+BIT_TIME_FUZZ) && active) {
+ if(time >= (RWD_TIME_1+RWD_TIME_FUZZ) && active) {
/* Frame end */
- emit(-1);
+ emit(EMIT_RWD, -1);
active = 0;
LED_B_OFF();
}
- if(time >= (20*BIT_TIME_1) && (AT91C_BASE_TC1->TC_SR & AT91C_TC_CLKSTA)) {
- AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKDIS;
+ if(time >= (20*RWD_TIME_1) && (timer->TC_SR & AT91C_TC_CLKSTA)) {
+ timer->TC_CCR = AT91C_TC_CLKDIS;
}
WDT_HIT();
}
}
+
+void LegicRfReader(void)
+{
+ SetAdcMuxFor(GPIO_MUXSEL_HIPKD);
+ FpgaSetupSsc();
+ FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_TX);
+
+ /* Bitbang the transmitter */
+ AT91C_BASE_PIOA->PIO_CODR = GPIO_SSC_DOUT;
+ AT91C_BASE_PIOA->PIO_OER = GPIO_SSC_DOUT;
+ AT91C_BASE_PIOA->PIO_PER = GPIO_SSC_DOUT;
+
+ setup_timer();
+
+ while(!BUTTON_PRESS()) {
+ /* Switch on carrier and let the tag charge for 1ms */
+ AT91C_BASE_PIOA->PIO_SODR = GPIO_SSC_DOUT;
+ SpinDelay(1);
+
+ LED_A_ON();
+ frame_send_rwd(queries[0].data, queries[0].bits);
+ LED_A_OFF();
+
+ frame_clean(¤t_frame);
+ LED_B_ON();
+ frame_receive_rwd(¤t_frame, responses[0].bits);
+ LED_B_OFF();
+
+ /* Switch off carrier, make sure tag is reset */
+ AT91C_BASE_PIOA->PIO_CODR = GPIO_SSC_DOUT;
+ SpinDelay(10);
+
+ WDT_HIT();
+ }
+
+}
projects / proxmark3-svn / blobdiff