proxmark3/fpga/hi_simulate.v
pwpiwi cd028159be implement 'hf iclass snoop -j'
* fix long option --jam
* make room for one more bit for FPGA minor mode
* new mode FPGA_HF_READER_MODE_SEND_JAM
* implement jamming in Handle15693SampleFromReader
2019-11-13 18:03:40 +01:00

146 lines
4.5 KiB
Verilog

//-----------------------------------------------------------------------------
// Pretend to be an ISO 14443 tag. We will do this by alternately short-
// circuiting and open-circuiting the antenna coil, with the tri-state
// pins.
//
// We communicate over the SSP, as a bitstream (i.e., might as well be
// unframed, though we still generate the word sync signal). The output
// (ARM -> FPGA) tells us whether to modulate or not. The input (FPGA
// -> ARM) is us using the A/D as a fancy comparator; this is with
// (software-added) hysteresis, to undo the high-pass filter.
//
// At this point only Type A is implemented. This means that we are using a
// bit rate of 106 kbit/s, or fc/128. Oversample by 4, which ought to make
// things practical for the ARM (fc/32, 423.8 kbits/s, ~50 kbytes/s)
//
// Jonathan Westhues, October 2006
//-----------------------------------------------------------------------------
module hi_simulate(
ck_1356meg,
pwr_lo, pwr_hi, pwr_oe1, pwr_oe2, pwr_oe3, pwr_oe4,
adc_d, adc_clk,
ssp_frame, ssp_din, ssp_dout, ssp_clk,
dbg,
mod_type
);
input ck_1356meg;
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;
output dbg;
input [3:0] mod_type;
assign adc_clk = ck_1356meg;
// The comparator with hysteresis on the output from the peak detector.
reg after_hysteresis;
reg [11:0] has_been_low_for;
always @(negedge adc_clk)
begin
if (& adc_d[7:5]) after_hysteresis <= 1'b1; // if (adc_d >= 224)
else if (~(| adc_d[7:5])) after_hysteresis <= 1'b0; // if (adc_d <= 31)
if (adc_d >= 224)
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
begin
has_been_low_for <= has_been_low_for + 1;
end
end
end
// Divide 13.56 MHz to produce various frequencies for SSP_CLK
// and modulation.
reg [8:0] ssp_clk_divider;
always @(negedge adc_clk)
ssp_clk_divider <= (ssp_clk_divider + 1);
reg ssp_clk;
always @(negedge adc_clk)
begin
if (mod_type == `FPGA_HF_SIMULATOR_MODULATE_424K_8BIT)
// Get bit every at 53KHz (every 8th carrier bit of 424kHz)
ssp_clk <= ~ssp_clk_divider[7];
else if (mod_type == `FPGA_HF_SIMULATOR_MODULATE_212K)
// Get next bit at 212kHz
ssp_clk <= ~ssp_clk_divider[5];
else
// Get next bit at 424Khz
ssp_clk <= ~ssp_clk_divider[4];
end
// Produce the byte framing signal; the phase of this signal
// is arbitrary, because it's just a bit stream in this module.
reg ssp_frame;
always @(negedge adc_clk)
begin
if (mod_type == `FPGA_HF_SIMULATOR_MODULATE_212K)
begin
if (ssp_clk_divider[8:5] == 4'd1)
ssp_frame <= 1'b1;
if (ssp_clk_divider[8:5] == 4'd5)
ssp_frame <= 1'b0;
end
else
begin
if (ssp_clk_divider[7:4] == 4'd1)
ssp_frame <= 1'b1;
if (ssp_clk_divider[7:4] == 4'd5)
ssp_frame <= 1'b0;
end
end
// Synchronize up the after-hysteresis signal, to produce DIN.
reg ssp_din;
always @(posedge ssp_clk)
ssp_din = after_hysteresis;
// Modulating carrier frequency is fc/64 (212kHz) to fc/16 (848kHz). Reuse ssp_clk divider for that.
reg modulating_carrier;
always @(*)
if (mod_type == `FPGA_HF_SIMULATOR_NO_MODULATION)
modulating_carrier <= 1'b0; // no modulation
else if (mod_type == `FPGA_HF_SIMULATOR_MODULATE_BPSK)
modulating_carrier <= ssp_dout ^ ssp_clk_divider[3]; // XOR means BPSK
else if (mod_type == `FPGA_HF_SIMULATOR_MODULATE_212K)
modulating_carrier <= ssp_dout & ssp_clk_divider[5]; // switch 212kHz subcarrier on/off
else if (mod_type == `FPGA_HF_SIMULATOR_MODULATE_424K || mod_type == `FPGA_HF_SIMULATOR_MODULATE_424K_8BIT)
modulating_carrier <= ssp_dout & ssp_clk_divider[4]; // switch 424kHz modulation on/off
else
modulating_carrier <= 1'b0; // yet unused
// Load modulation. Toggle only one of these, since we are already producing much deeper
// modulation than a real tag would.
assign pwr_hi = 1'b0; // HF antenna connected to GND
assign pwr_oe3 = 1'b0; // 10k Load
assign pwr_oe1 = 1'b0; // 33 Ohms Load
assign pwr_oe4 = modulating_carrier; // 33 Ohms Load
// This is all LF and doesn't matter
assign pwr_lo = 1'b0;
assign pwr_oe2 = 1'b0;
assign dbg = ssp_frame;
endmodule