Merge pull request #319 from Proxmark/iceman1001-patch-2

[proxmark3-svn] / fpga / hi_read_rx_xcorr.v

diff --git a/fpga/hi_read_rx_xcorr.v b/fpga/hi_read_rx_xcorr.v
index 4a5de5536c64cffc2233db2d77ab9bc433672d10..80e363275fd6ed6ab6f56c369e1b42827852022b 100644 (file)
--- a/fpga/hi_read_rx_xcorr.v
+++ b/fpga/hi_read_rx_xcorr.v
@@ -28,22 +28,19 @@ assign pwr_oe1 = 1'b0;
 assign pwr_oe3 = 1'b0;
 assign pwr_oe4 = 1'b0;
 
-(* clock_signal = "yes" *) reg fc_div_2;
+// Clock divider
+reg [0:0] fc_divider;
 always @(negedge ck_1356megb)
-    fc_div_2 <= fc_div_2 + 1;
-
-(* clock_signal = "yes" *) reg adc_clk;
-always @(xcorr_is_848, ck_1356megb, fc_div_2)
-if (xcorr_is_848)
-       // The subcarrier frequency is fc/16; we will sample at fc, so that 
-       // means the subcarrier is 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 1 1 ...
-       adc_clk <= ck_1356megb;
-else
-    // The subcarrier frequency is fc/32; we will sample at fc/2, and
-    // the subcarrier will look identical.
-    adc_clk <= fc_div_2;
-
-       
+    fc_divider <= fc_divider + 1;
+wire fc_div2 = fc_divider[0];
+
+reg adc_clk;
+always @(ck_1356megb)
+       if (xcorr_is_848)
+               adc_clk <= ck_1356megb;
+       else
+               adc_clk <= fc_div2;
+
 // When we're a reader, we just need to do the BPSK demod; but when we're an
 // eavesdropper, we also need to pick out the commands sent by the reader,
 // using AM. Do this the same way that we do it for the simulated tag.
@@ -85,20 +82,23 @@ reg ssp_clk;
 reg ssp_frame;
 
 
+always @(negedge adc_clk)
+begin
+               corr_i_cnt <= corr_i_cnt + 1;
+end            
+               
 
 // ADC data appears on the rising edge, so sample it on the falling edge
 always @(negedge adc_clk)
 begin
-    corr_i_cnt <= corr_i_cnt + 1;
-
     // These are the correlators: we correlate against in-phase and quadrature
     // versions of our reference signal, and keep the (signed) result to
     // send out later over the SSP.
-    if(corr_i_cnt == 7'd0)
+    if(corr_i_cnt == 6'd0)
     begin
         if(snoop)
         begin
-                       // 7 most significant bits of tag signal (signed), 1 bit reader signal:
+                       // Send only 7 most significant bits of tag signal (signed), LSB is reader signal:
             corr_i_out <= {corr_i_accum[13:7], after_hysteresis_prev_prev};
             corr_q_out <= {corr_q_accum[13:7], after_hysteresis_prev};
                        after_hysteresis_prev_prev <= after_hysteresis;
@@ -129,7 +129,7 @@ begin
 
     // The logic in hi_simulate.v reports 4 samples per bit. We report two
     // (I, Q) pairs per bit, so we should do 2 samples per pair.
-    if(corr_i_cnt == 6'd31)
+    if(corr_i_cnt == 6'd32)
         after_hysteresis_prev <= after_hysteresis;
 
     // Then the result from last time is serialized and send out to the ARM.
@@ -143,7 +143,7 @@ begin
     begin
         ssp_clk <= 1'b1;
         // Don't shift if we just loaded new data, obviously.
-        if(corr_i_cnt != 7'd0)
+        if(corr_i_cnt != 6'd0)
         begin
             corr_i_out[7:0] <= {corr_i_out[6:0], corr_q_out[7]};
             corr_q_out[7:1] <= corr_q_out[6:0];