Added an important notice.

[proxmark3-svn] / fpga / hi_iso14443a.v

diff --git a/fpga/hi_iso14443a.v b/fpga/hi_iso14443a.v
index 0f7325b681a920baba0f54f40dd30b7f408d7bc6..ec5aa75771023b75fe5b7ee0426b7aac4d5390db 100644 (file)
--- a/fpga/hi_iso14443a.v
+++ b/fpga/hi_iso14443a.v
@@ -35,7 +35,7 @@ reg ssp_frame;
 wire adc_clk;
 assign adc_clk = ck_1356meg;
 
-reg after_hysteresis, after_hysteresis_prev1, after_hysteresis_prev2, after_hysteresis_prev3, after_hysteresis_prev4;
+reg after_hysteresis, pre_after_hysteresis, after_hysteresis_prev1, after_hysteresis_prev2, after_hysteresis_prev3, after_hysteresis_prev4;
 reg [11:0] has_been_low_for;
 reg [8:0] saw_deep_modulation;
 reg [2:0] deep_counter;
@@ -45,6 +45,8 @@ always @(negedge adc_clk)
 begin
        if(& adc_d[7:6]) after_hysteresis <= 1'b1;                      // adc_d >= 196 (U >= 3,28V) -> after_hysteris = 1
     else if(~(| adc_d[7:4])) after_hysteresis <= 1'b0;  // if adc_d <= 15 (U <= 1,13V) -> after_hysteresis = 0
+
+       pre_after_hysteresis <= after_hysteresis;
        
        if(~(| adc_d[7:0]))                                                                     // if adc_d == 0 (U <= 0,94V)
        begin
@@ -122,6 +124,7 @@ reg mod_sig, mod_sig_coil;
 reg temp_buffer_reset;
 reg sendbit;
 reg [3:0] sub_carrier_cnt;
+reg[3:0] reader_falling_edge_time;
 
 // ADC data appears on the rising edge, so sample it on the falling edge
 always @(negedge adc_clk)
@@ -244,13 +247,40 @@ begin
                        sendbit = 1'b0;
        end
 
+
+
+       // check timing of a falling edge in reader signal
+       if (pre_after_hysteresis && ~after_hysteresis)
+               reader_falling_edge_time[3:0] <= negedge_cnt[3:0];
+
+
+
+       // sync clock to external reader's clock:
+       if (negedge_cnt[3:0] == 4'd13 && (mod_type == `SNIFFER || mod_type == `TAGSIM_MOD || mod_type == `TAGSIM_LISTEN))
+       begin
+               // adjust clock if necessary:
+               if (reader_falling_edge_time < 4'd8 && reader_falling_edge_time > 4'd1)
+               begin
+                       negedge_cnt <= negedge_cnt;                             // freeze time
+               end     
+               else if (reader_falling_edge_time == 4'd8)
+               begin
+                       negedge_cnt <= negedge_cnt + 1;                 // the desired state. Advance as usual;
+               end
+               else
+               begin
+                       negedge_cnt[3:0] <= 4'd15;                              // time warp
+               end
+               reader_falling_edge_time <= 4'd8;                       // only once per detected rising edge
+       end
+       
+
+
        //------------------------------------------------------------------------------------------------------------------------------------------
        // Prepare 8 Bits to communicate to ARM
-
-       // in SNIFFER mode: 4 Bits data sniffed as Tag, 4 Bits data sniffed as Reader
-       if(mod_type == `SNIFFER)
+       if (negedge_cnt == 7'd63)
        begin
-               if (negedge_cnt == 7'd63)
+               if (mod_type == `SNIFFER)
                begin
                        if(deep_modulation) // a reader is sending (or there's no field at all)
                        begin
@@ -259,34 +289,32 @@ begin
                        else
                        begin
                                to_arm <= {after_hysteresis_prev1,after_hysteresis_prev2,after_hysteresis_prev3,after_hysteresis_prev4,bit1,bit2,bit3,bit4};
-                       end
+                       end                     
                        negedge_cnt <= 0;
                end
                else
                begin
                        negedge_cnt <= negedge_cnt + 1;
                end
-       end
-       else
-       // other modes: 8 Bits info on queue delay
+       end     
+       else if(negedge_cnt == 7'd127)
        begin
-               if(negedge_cnt == 7'd127)
+               if (mod_type == `TAGSIM_MOD)
                begin
-                       if (mod_type == `TAGSIM_MOD)
-                       begin
-                               to_arm[7:0] <= {mod_sig_ptr[4:0], mod_sig_flip[3:1]};
-                       end
-                       else
-                       begin
-                               to_arm[7:0] <= 8'd0;
-                       end
+                       to_arm[7:0] <= {mod_sig_ptr[4:0], mod_sig_flip[3:1]};
                        negedge_cnt <= 0;
                end
                else
                begin
-                               negedge_cnt <= negedge_cnt + 1;
+                       to_arm[7:0] <= 8'd0;
+                       negedge_cnt <= negedge_cnt + 1;
                end
        end
+       else
+       begin
+               negedge_cnt <= negedge_cnt + 1;
+       end
+
        
     if(negedge_cnt == 7'd1)
        begin
@@ -303,7 +331,7 @@ begin
         after_hysteresis_prev3 <= after_hysteresis;
                bit3 <= curbit;
        end
-    if(negedge_cnt == 7'd47)
+    if(negedge_cnt == 7'd49)
        begin
         after_hysteresis_prev4 <= after_hysteresis;
                bit4 <= curbit;