X-Git-Url: http://git.zerfleddert.de/cgi-bin/gitweb.cgi/proxmark3-svn/blobdiff_plain/6658905f18a1eebc148836f26c731dea9c1377dc..351d6d17b3fa82a82b2205c69dcc024884d0b146:/fpga/hi_read_rx_xcorr.v

diff --git a/fpga/hi_read_rx_xcorr.v b/fpga/hi_read_rx_xcorr.v
index 253f5080..8233960f 100644
--- a/fpga/hi_read_rx_xcorr.v
+++ b/fpga/hi_read_rx_xcorr.v
@@ -1,165 +1,213 @@
-//-----------------------------------------------------------------------------
-//
-// Jonathan Westhues, April 2006
-//-----------------------------------------------------------------------------
-
-module hi_read_rx_xcorr(
-    pck0, ck_1356meg, ck_1356megb,
-    pwr_lo, pwr_hi, pwr_oe1, pwr_oe2, pwr_oe3, pwr_oe4,
-    adc_d, adc_clk,
-    ssp_frame, ssp_din, ssp_dout, ssp_clk,
-    cross_hi, cross_lo,
-    dbg,
-    xcorr_is_848, snoop
-);
-    input pck0, ck_1356meg, ck_1356megb;
-    output pwr_lo, pwr_hi, pwr_oe1, pwr_oe2, pwr_oe3, pwr_oe4;
-    input [7:0] adc_d;
-    output adc_clk;
-    input ssp_dout;
-    output ssp_frame, ssp_din, ssp_clk;
-    input cross_hi, cross_lo;
-    output dbg;
-    input xcorr_is_848, snoop;
-
-// Carrier is steady on through this, unless we're snooping.
-assign pwr_hi = ck_1356megb & (~snoop);
-assign pwr_oe1 = 1'b0;
-assign pwr_oe2 = 1'b0;
-assign pwr_oe3 = 1'b0;
-assign pwr_oe4 = 1'b0;
-
-reg ssp_clk;
-reg ssp_frame;
-
-reg fc_div_2;
-always @(posedge ck_1356meg)
-    fc_div_2 = ~fc_div_2;
-
-reg adc_clk;
-
-always @(xcorr_is_848 or fc_div_2 or ck_1356meg)
-    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_1356meg;
-    else
-        // The subcarrier frequency is fc/32; we will sample at fc/2, and
-        // the subcarrier will look identical.
-        adc_clk <= fc_div_2;
-
-// 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.
-reg after_hysteresis, after_hysteresis_prev;
-reg [11:0] has_been_low_for;
-always @(negedge adc_clk)
-begin
-    if(& adc_d[7:0]) after_hysteresis <= 1'b1;
-    else if(~(| adc_d[7:0])) after_hysteresis <= 1'b0;
-
-    if(after_hysteresis)
-    begin
-        has_been_low_for <= 7'b0;
-    end
-    else
-    begin
-        if(has_been_low_for == 12'd4095)
-        begin
-            has_been_low_for <= 12'd0;
-            after_hysteresis <= 1'b1;
-        end
-        else
-            has_been_low_for <= has_been_low_for + 1;
-    end
-end
-
-// Let us report a correlation every 4 subcarrier cycles, or 4*16 samples,
-// so we need a 6-bit counter.
-reg [5:0] corr_i_cnt;
-reg [5:0] corr_q_cnt;
-// And a couple of registers in which to accumulate the correlations.
-reg signed [15:0] corr_i_accum;
-reg signed [15:0] corr_q_accum;
-reg signed [7:0] corr_i_out;
-reg signed [7:0] corr_q_out;
-
-// ADC data appears on the rising edge, so sample it on the falling edge
-always @(negedge adc_clk)
-begin
-    // 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'd63)
-    begin
-        if(snoop)
-        begin
-            corr_i_out <= {corr_i_accum[12:6], after_hysteresis_prev};
-            corr_q_out <= {corr_q_accum[12:6], after_hysteresis};
-        end
-        else
-        begin
-            // Only correlations need to be delivered.
-            corr_i_out <= corr_i_accum[13:6];
-            corr_q_out <= corr_q_accum[13:6];
-        end
-
-        corr_i_accum <= adc_d;
-        corr_q_accum <= adc_d;
-        corr_q_cnt <= 4;
-        corr_i_cnt <= 0;
-    end
-    else
-    begin
-        if(corr_i_cnt[3])
-            corr_i_accum <= corr_i_accum - adc_d;
-        else
-            corr_i_accum <= corr_i_accum + adc_d;
-
-        if(corr_q_cnt[3])
-            corr_q_accum <= corr_q_accum - adc_d;
-        else
-            corr_q_accum <= corr_q_accum + adc_d;
-
-        corr_i_cnt <= corr_i_cnt + 1;
-        corr_q_cnt <= corr_q_cnt + 1;
-    end
-
-    // 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)
-        after_hysteresis_prev <= after_hysteresis;
-
-    // Then the result from last time is serialized and send out to the ARM.
-    // We get one report each cycle, and each report is 16 bits, so the
-    // ssp_clk should be the adc_clk divided by 64/16 = 4.
-
-    if(corr_i_cnt[1:0] == 2'b10)
-        ssp_clk <= 1'b0;
-
-    if(corr_i_cnt[1:0] == 2'b00)
-    begin
-        ssp_clk <= 1'b1;
-        // Don't shift if we just loaded new data, obviously.
-        if(corr_i_cnt != 7'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];
-        end
-    end
-
-    if(corr_i_cnt[5:2] == 4'b000 || corr_i_cnt[5:2] == 4'b1000)
-        ssp_frame = 1'b1;
-    else
-        ssp_frame = 1'b0;
-
-end
-
-assign ssp_din = corr_i_out[7];
-
-assign dbg = corr_i_cnt[3];
-
-// Unused.
-assign pwr_lo = 1'b0;
-
-endmodule
+//-----------------------------------------------------------------------------
+//
+// Jonathan Westhues, April 2006
+//-----------------------------------------------------------------------------
+
+module hi_read_rx_xcorr(
+    pck0, ck_1356meg, ck_1356megb,
+    pwr_lo, pwr_hi, pwr_oe1, pwr_oe2, pwr_oe3, pwr_oe4,
+    adc_d, adc_clk,
+    ssp_frame, ssp_din, ssp_dout, ssp_clk,
+    cross_hi, cross_lo,
+    dbg,
+    xcorr_is_848, snoop, xcorr_quarter_freq
+);
+    input pck0, ck_1356meg, ck_1356megb;
+    output pwr_lo, pwr_hi, pwr_oe1, pwr_oe2, pwr_oe3, pwr_oe4;
+    input [7:0] adc_d;
+    output adc_clk;
+    input ssp_dout;
+    output ssp_frame, ssp_din, ssp_clk;
+    input cross_hi, cross_lo;
+    output dbg;
+    input xcorr_is_848, snoop, xcorr_quarter_freq;
+
+// Carrier is steady on through this, unless we're snooping.
+assign pwr_hi = ck_1356megb & (~snoop);
+assign pwr_oe1 = 1'b0;
+assign pwr_oe3 = 1'b0;
+assign pwr_oe4 = 1'b0;
+// Unused.
+assign pwr_lo = 1'b0;
+assign pwr_oe2 = 1'b0;
+
+assign adc_clk = ck_1356megb;  // sample frequency is 13,56 MHz
+
+// 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.
+reg after_hysteresis, after_hysteresis_prev, after_hysteresis_prev_prev;
+reg [11:0] has_been_low_for;
+always @(negedge adc_clk)
+begin
+    if(& adc_d[7:0]) after_hysteresis <= 1'b1;
+    else if(~(| adc_d[7:0])) after_hysteresis <= 1'b0;
+
+    if(after_hysteresis)
+    begin
+        has_been_low_for <= 7'b0;
+    end
+    else
+    begin
+        if(has_been_low_for == 12'd4095)
+        begin
+            has_been_low_for <= 12'd0;
+            after_hysteresis <= 1'b1;
+        end
+        else
+            has_been_low_for <= has_been_low_for + 1;
+    end
+end
+
+
+// Let us report a correlation every 64 samples. I.e.
+// one Q/I pair after 4 subcarrier cycles for the 848kHz subcarrier,
+// one Q/I pair after 2 subcarrier cycles for the 424kHz subcarriers,
+// one Q/I pair for each subcarrier cyle for the 212kHz subcarrier.
+// We need a 6-bit counter for the timing.
+reg [5:0] corr_i_cnt;
+always @(negedge adc_clk)
+begin
+	corr_i_cnt <= corr_i_cnt + 1;
+end		
+
+// And a couple of registers in which to accumulate the correlations. From the 64 samples
+// we would add at most 32 times the difference between unmodulated and modulated signal. It should
+// be safe to assume that a tag will not be able to modulate the carrier signal by more than 25%.
+// 32 * 255 * 0,25 = 2040, which can be held in 11 bits. Add 1 bit for sign.
+// Temporary we might need more bits. For the 212kHz subcarrier we could possible add 32 times the
+// maximum signal value before a first subtraction would occur. 32 * 255 = 8160 can be held in 13 bits. 
+// Add one bit for sign -> need 14 bit registers but final result will fit into 12 bits.
+reg signed [13:0] corr_i_accum;
+reg signed [13:0] corr_q_accum;
+// we will report maximum 8 significant bits
+reg signed [7:0] corr_i_out;
+reg signed [7:0] corr_q_out;
+// clock and frame signal for communication to ARM
+reg ssp_clk;
+reg ssp_frame;
+
+
+// The subcarrier reference signals
+reg subcarrier_I;
+reg subcarrier_Q;
+
+always @(corr_i_cnt or xcorr_is_848 or xcorr_quarter_freq)
+begin
+	if (xcorr_is_848 & ~xcorr_quarter_freq)				// 848 kHz
+		begin
+			subcarrier_I = ~corr_i_cnt[3];
+			subcarrier_Q = ~(corr_i_cnt[3] ^ corr_i_cnt[2]);
+		end
+	else if (xcorr_is_848 & xcorr_quarter_freq)			// 212 kHz	
+		begin
+			subcarrier_I = ~corr_i_cnt[5];
+			subcarrier_Q = ~(corr_i_cnt[5] ^ corr_i_cnt[4]);
+		end
+	else
+		begin											// 424 kHz
+			subcarrier_I = ~corr_i_cnt[4];
+			subcarrier_Q = ~(corr_i_cnt[4] ^ corr_i_cnt[3]);
+		end
+end
+	
+// ADC data appears on the rising edge, so sample it on the falling edge
+always @(negedge adc_clk)
+begin
+    // 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 == 6'd0)
+    begin
+        if(snoop)
+        begin
+			// Send 7 most significant bits of tag signal (signed), plus 1 bit reader signal
+			if (corr_i_accum[13:11] == 3'b000 || corr_i_accum[13:11] == 3'b111) 
+				corr_i_out <= {corr_i_accum[11:5], after_hysteresis_prev_prev};
+			else // truncate to maximum value
+				if (corr_i_accum[13] == 1'b0)
+					corr_i_out <= {7'b0111111, after_hysteresis_prev_prev};
+				else
+					corr_i_out <= {7'b1000000, after_hysteresis_prev_prev};
+			if (corr_q_accum[13:11] == 3'b000 || corr_q_accum[13:11] == 3'b111) 
+				corr_q_out <= {corr_q_accum[11:5], after_hysteresis_prev};
+			else // truncate to maximum value
+				if (corr_q_accum[13] == 1'b0)
+					corr_q_out <= {7'b0111111, after_hysteresis_prev};
+				else
+					corr_q_out <= {7'b1000000, after_hysteresis_prev};
+			after_hysteresis_prev_prev <= after_hysteresis;
+        end
+        else
+        begin
+            // Send 8 bits of tag signal
+			if (corr_i_accum[13:11] == 3'b000 || corr_i_accum[13:11] == 3'b111) 
+				corr_i_out <= corr_i_accum[11:4];
+			else // truncate to maximum value
+				if (corr_i_accum[13] == 1'b0)
+					corr_i_out <= 8'b01111111;
+				else
+					corr_i_out <= 8'b10000000;
+			if (corr_q_accum[13:11] == 3'b000 || corr_q_accum[13:11] == 3'b111) 
+				corr_q_out <= corr_q_accum[11:4];
+			else // truncate to maximum value
+				if (corr_q_accum[13] == 1'b0)
+					corr_q_out <= 8'b01111111;
+				else
+					corr_q_out <= 8'b10000000;
+        end
+		// Initialize next correlation. 
+		// Both I and Q reference signals are high when corr_i_nct == 0. Therefore need to accumulate.
+        corr_i_accum <= $signed({1'b0,adc_d});
+        corr_q_accum <= $signed({1'b0,adc_d});
+    end
+    else
+    begin
+        if (subcarrier_I)
+            corr_i_accum <= corr_i_accum + $signed({1'b0,adc_d});
+        else
+            corr_i_accum <= corr_i_accum - $signed({1'b0,adc_d});
+
+        if (subcarrier_Q)
+            corr_q_accum <= corr_q_accum + $signed({1'b0,adc_d});
+        else
+            corr_q_accum <= corr_q_accum - $signed({1'b0,adc_d});
+
+    end
+
+	// for each Q/I pair report two reader signal samples when sniffing
+    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.
+    // We get one report each cycle, and each report is 16 bits, so the
+    // ssp_clk should be the adc_clk divided by 64/16 = 4.
+
+    if(corr_i_cnt[1:0] == 2'b10)
+        ssp_clk <= 1'b0;
+
+    if(corr_i_cnt[1:0] == 2'b00)
+    begin
+        ssp_clk <= 1'b1;
+        // Don't shift if we just loaded new data, obviously.
+        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];
+        end
+    end
+
+    // set ssp_frame signal for corr_i_cnt = 0..3
+    // (send one frame with 16 Bits)
+    if(corr_i_cnt[5:2] == 4'b0000)
+        ssp_frame = 1'b1;
+    else
+        ssp_frame = 1'b0;
+
+end
+
+assign ssp_din = corr_i_out[7];
+
+assign dbg = corr_i_cnt[3];
+
+endmodule