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proxmark3/fpga/hi_reader.v
Yann GASCUEL fa3c2e386b improve iso15 sniff quality
2024-01-24 13:59:12 +01:00

460 lines
15 KiB
Verilog
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//-----------------------------------------------------------------------------
// Copyright (C) Proxmark3 contributors. See AUTHORS.md for details.
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// See LICENSE.txt for the text of the license.
//-----------------------------------------------------------------------------
// with optional support for iso15 2sc mode slected with compiler define WITH_HF_15
module hi_reader(
input ck_1356meg,
input [7:0] adc_d,
input [1:0] subcarrier_frequency,
input [3:0] minor_mode,
input ssp_dout,
output ssp_din,
output reg ssp_frame,
output reg ssp_clk,
output adc_clk,
output pwr_lo,
output reg pwr_hi,
output reg pwr_oe1,
output pwr_oe2,
output pwr_oe3,
output reg pwr_oe4,
output debug
);
assign adc_clk = ck_1356meg; // 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
`ifdef WITH_HF_15_LOWSIGNAL
if (& adc_d[7:4]) after_hysteresis <= 1'b1;
else if (~(| adc_d[7:6])) after_hysteresis <= 1'b0;
`else
if (& adc_d[7:0]) after_hysteresis <= 1'b1;
else if (~(| adc_d[7:0])) after_hysteresis <= 1'b0;
`endif
if (after_hysteresis)
begin
has_been_low_for <= 12'd0;
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)
corr_i_cnt <= corr_i_cnt + 1;
`ifdef WITH_HF_15
reg [1:0] fskout = 2'd0;
reg last0 = 1'b0;
reg [7:0] avg = 8'd0;
reg [127:0] avg128 = 128'd0;
reg [7:0] diff16 = 8'd0;
reg [7:0] diff28 = 8'd0;
reg [7:0] diff32 = 8'd0;
reg [11:0] match16 = 12'd0;
reg [11:0] match32 = 12'd0;
reg [11:0] match28 = 12'd0;
always @(negedge adc_clk)
begin
if (corr_i_cnt[0] == 1'b0) // every 2 clock
avg = adc_d[7:1];
else
begin
avg = avg + adc_d[7:1];
if (corr_i_cnt[0] == 1'b1) // every 2 clock
begin
if (avg > avg128[63:56])
diff16 = avg - avg128[63:56];
else
diff16 = avg128[63:56] - avg;
if (avg > avg128[111:104])
diff28 = avg - avg128[111:104];
else
diff28 = avg128[111:104] - avg;
if (avg > avg128[127:120])
diff32 = avg - avg128[127:120];
else
diff32 = avg128[127:120] - avg;
avg128[127:8] = avg128[119:0];
avg128[7:0] = avg;
if (corr_i_cnt[4:1] == 4'b0000) // every 32 clock (8*4)
begin
match16 = diff16;
match28 = diff28;
match32 = diff32;
end
else
begin
match16 = match16 + diff16;
match28 = match28 + diff28;
match32 = match32 + diff32;
if (corr_i_cnt[4:1] == 4'b1111) // every 32 clock (8*4)
begin
last0 = (fskout == 2'b0);
if (match16 < 12'd64 && last0)
fskout = 2'b00; // not yet started
else if ((match16 | match28 | match32) == 12'b0)
fskout = 2'b00; // signal likely ended
else if (((match16 <= match28 + 12'd16) && (match16 <= match32+ 12'd16)) ||
(match28 <= 12'd16 && match32 <= 12'd16))
begin
if (!last0)
fskout = 2'b11; // 16 match better than 28 or 32 but already started
end
else
begin
if (match28 < match32)
begin
diff28 = match32 - match28;
diff16 = match16 - match28;
if (diff28*2 > diff16)
fskout = 2'b01;
else if (!last0)
begin
fskout = 2'b01;
end
end
else //if (match32 <= match28)
begin
diff32 = match28 - match32;
diff16 = match16 - match32;
if (diff32*2 > diff16)
fskout = 2'b10;
else if (!last0)
begin
fskout = 2'b10;
end
end
end
end
end
end
end
end
`endif
// 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;
// the amplitude of the subcarrier is sqrt(ci^2 + cq^2).
// approximate by amplitude = max(|ci|,|cq|) + 1/2*min(|ci|,|cq|)
reg [13:0] corr_amplitude, abs_ci, abs_cq, max_ci_cq;
reg [12:0] min_ci_cq_2; // min_ci_cq / 2
always @(*)
begin
if (corr_i_accum[13] == 1'b0)
abs_ci <= corr_i_accum;
else
abs_ci <= -corr_i_accum;
if (corr_q_accum[13] == 1'b0)
abs_cq <= corr_q_accum;
else
abs_cq <= -corr_q_accum;
if (abs_ci > abs_cq)
begin
max_ci_cq <= abs_ci;
min_ci_cq_2 <= abs_cq / 2;
end
else
begin
max_ci_cq <= abs_cq;
min_ci_cq_2 <= abs_ci / 2;
end
corr_amplitude <= max_ci_cq + min_ci_cq_2;
end
// The subcarrier reference signals
reg subcarrier_I;
reg subcarrier_Q;
always @(*)
begin
if (subcarrier_frequency == `FPGA_HF_READER_SUBCARRIER_848_KHZ)
begin
subcarrier_I = ~corr_i_cnt[3];
subcarrier_Q = ~(corr_i_cnt[3] ^ corr_i_cnt[2]);
end
else if (subcarrier_frequency == `FPGA_HF_READER_SUBCARRIER_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) results or the
// resulting amplitude to send out later over the SSP.
if (corr_i_cnt == 6'd0)
begin
if (minor_mode == `FPGA_HF_READER_MODE_SNIFF_AMPLITUDE)
begin
`ifdef WITH_HF_15
if (subcarrier_frequency == `FPGA_HF_READER_2SUBCARRIERS_424_484_KHZ)
begin
// send amplitude + 2 bits fsk (2sc) signal + 2 bits reader signal
corr_i_out <= corr_amplitude[13:6];
corr_q_out <= {corr_amplitude[5:2], fskout, after_hysteresis_prev_prev, after_hysteresis_prev};
end
else
`endif
begin
// send amplitude plus 2 bits reader signal
corr_i_out <= corr_amplitude[13:6];
corr_q_out <= {corr_amplitude[5:0], after_hysteresis_prev_prev, after_hysteresis_prev};
end
end
else if (minor_mode == `FPGA_HF_READER_MODE_SNIFF_IQ)
begin
// Send 7 most significant bits of in phase 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};
// Send 7 most significant bits of quadrature phase tag signal (signed), plus 1 bit reader signal
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};
end
else if (minor_mode == `FPGA_HF_READER_MODE_RECEIVE_AMPLITUDE)
begin
`ifdef WITH_HF_15
if (subcarrier_frequency == `FPGA_HF_READER_2SUBCARRIERS_424_484_KHZ)
begin
// send 2 bits fsk (2sc) signal + amplitude
corr_i_out <= {fskout, corr_amplitude[13:8]};
corr_q_out <= corr_amplitude[7:0];
end
else
`endif
begin
// send amplitude
corr_i_out <= {2'b00, corr_amplitude[13:8]};
corr_q_out <= corr_amplitude[7:0];
end
end
else if (minor_mode == `FPGA_HF_READER_MODE_RECEIVE_IQ)
begin
// Send 8 bits of in phase 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;
// Send 8 bits of quadrature phase tag signal
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
// for each Q/I pair report two reader signal samples when sniffing. Store the 1st.
after_hysteresis_prev_prev <= after_hysteresis;
// 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. Store the 2nd.
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.
// ssp_clk frequency = 13,56MHz / 4 = 3.39MHz
if (corr_i_cnt[1:0] == 2'b00)
begin
// 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
end
// ssp clock and frame signal for communication to and from ARM
// _____ _____ _____ _
// ssp_clk | |_____| |_____| |_____|
// _____
// ssp_frame ___| |____________________________
// ___________ ___________ ___________ _
// ssp_d_in X___________X___________X___________X_
//
// corr_i_cnt 0 1 2 3 4 5 6 7 8 9 10 11 12 ...
//
always @(negedge adc_clk)
begin
if (corr_i_cnt[1:0] == 2'b00)
ssp_clk <= 1'b1;
if (corr_i_cnt[1:0] == 2'b10)
ssp_clk <= 1'b0;
// set ssp_frame signal for corr_i_cnt = 1..3
// (send one frame with 16 Bits)
if (corr_i_cnt == 6'd1)
ssp_frame <= 1'b1;
if (corr_i_cnt == 6'd3)
ssp_frame <= 1'b0;
end
assign ssp_din = corr_i_out[7];
// a jamming signal
reg jam_signal;
reg [3:0] jam_counter;
always @(negedge adc_clk)
begin
if (corr_i_cnt == 6'd0)
begin
jam_counter <= jam_counter + 1;
jam_signal <= jam_counter[1] ^ jam_counter[3];
end
end
always @(*)
begin
pwr_oe1 = 1'b0;
pwr_oe4 = 1'b0;
if (minor_mode == `FPGA_HF_READER_MODE_SEND_SHALLOW_MOD)
begin
pwr_hi = ck_1356meg;
pwr_oe4 = ssp_dout;
end
else if (minor_mode == `FPGA_HF_READER_MODE_SEND_SHALLOW_MOD_RDV4)
begin
pwr_hi = ck_1356meg;
pwr_oe1 = ssp_dout;
end
else if (minor_mode == `FPGA_HF_READER_MODE_SEND_FULL_MOD)
begin
pwr_hi = ck_1356meg & ~ssp_dout;
pwr_oe4 = 1'b0;
end
else if (minor_mode == `FPGA_HF_READER_MODE_SEND_JAM)
begin
pwr_hi = ck_1356meg & jam_signal;
pwr_oe4 = 1'b0;
end
else if (minor_mode == `FPGA_HF_READER_MODE_SNIFF_IQ
|| minor_mode == `FPGA_HF_READER_MODE_SNIFF_AMPLITUDE
|| minor_mode == `FPGA_HF_READER_MODE_SNIFF_PHASE)
begin // all off
pwr_hi = 1'b0;
pwr_oe4 = 1'b0;
end
else // receiving from tag
begin
pwr_hi = ck_1356meg;
pwr_oe4 = 1'b0;
end
end
// unused
assign pwr_oe2 = 1'b0;
assign pwr_oe3 = 1'b0;
assign pwr_lo = 1'b0;
// Debug Output
assign debug = corr_i_cnt[3];
endmodule
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