X-Git-Url: http://git.zerfleddert.de/cgi-bin/gitweb.cgi/proxmark3-svn/blobdiff_plain/24fe4dffb49ca5c50983c54f1b1d51028c06390d..dcc10e5e310a9e652e698593b7ba34bacbdd2b80:/armsrc/legicrf.c

diff --git a/armsrc/legicrf.c b/armsrc/legicrf.c
index 00cb52b6..a8c0cd11 100644
--- a/armsrc/legicrf.c
+++ b/armsrc/legicrf.c
@@ -79,6 +79,108 @@ static void frame_send_tag(uint16_t response, int bits)
 #endif
 }
 
+/* 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)
+{
+	/* Start clock */
+	timer->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
+	while(timer->TC_CV > 1) ; /* Wait till the clock has reset */
+	
+	int i;
+	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)
 {
@@ -220,3 +322,39 @@ void LegicRfSimulate(void)
 		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(&current_frame);
+		LED_B_ON();
+		frame_receive_rwd(&current_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();
+	}
+	
+}