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proxmark3/fpga-xc2s30/hi_flite.v
iceman1001 bc46696dc4 unify license text
2022-03-20 09:31:53 +01:00

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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.
//-----------------------------------------------------------------------------
/*
This code demodulates and modulates signal as described in ISO/IEC 18092.
That includes packets used for Felica, NFC Tag 3, etc. (which do overlap)
simple envelope following algorithm is used (modification of fail0verflow LF one)
is used to combat some nasty aliasing effect with testing phone (envelope looked like sine wave)
Speeds supported: only 212 kbps (fc/64) for now. Todo: 414 kbps
though for reader, the selection has to come from ARM. modulation waits for market sprocket -doesn't really mean anything
mod_type: bits 210:
bit 2 : reader drive/power on/off
bit 1 : speed bit, 0 : 212, 1 :424
bit 0 : listen or modulate
*/
module hi_flite(
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 dbg = 0;
wire power = mod_type[2];
wire speed = mod_type[1];
wire disabl = mod_type[0];
// Most off, oe4 for modulation;
// Trying reader emulation (would presumably just require switching power on, but I am not sure)
assign pwr_lo = 1'b0;
assign pwr_oe2 = 1'b0;
// 512x64/fc -wait before ts0, 32768 ticks
// tslot: 256*64/fc
assign adc_clk = ck_1356meg;
///heuristic values for initial thresholds. seem to work OK
`define imin 70 // (13'd256)
`define imax 180 // (-13'd256)
`define ithrmin 91 // -13'd8
`define ithrmax 160 // 13'd8
`define min_bitdelay_212 8
//minimum values and corresponding thresholds
reg [8:0] curmin=`imin;
reg [8:0] curminthres=`ithrmin;
reg [8:0] curmaxthres=`ithrmax;
reg [8:0] curmax=`imax;
//signal state, 1-not modulated, 0 -modulated
reg after_hysteresis = 1'b1;
//state machine for envelope tracking
reg [1:0] state=1'd0;
//lower edge detected, trying to detect first bit of SYNC (b24d, 1011001001001101)
reg try_sync=1'b0;
//detected first sync bit, phase frozen
reg did_sync=0;
`define bithalf_212 32 // half-bit length for 212 kbit
`define bitmlen_212 63 // bit transition edge
`define bithalf_424 16 // half-bit length for 212 kbit
`define bitmlen_424 31 // bit transition edge
wire [7:0] bithalf = speed ? `bithalf_424 : `bithalf_212;
wire [7:0] bitmlen = speed ? `bitmlen_424 : `bitmlen_212;
//ssp clock and current values
reg ssp_clk;
reg ssp_frame;
reg curbit = 1'b0;
reg [7:0] fccount = 8'd0; // in-bit tick counter. Counts carrier cycles from the first lower edge detected, reset on every manchester bit detected
reg [7:0] tsinceedge = 8'd0;// ticks from last edge, desync if the valye is too large
reg zero = 1'b0; // Manchester first halfbit low second high corresponds to this value. It has been known to change. SYNC is used to set it
//ssp counter for transfer and framing
reg [8:0] ssp_cnt = 9'd0;
always @(posedge adc_clk)
ssp_cnt <= (ssp_cnt + 1);
//maybe change it so that ARM sends preamble as well.
//then: ready bits sent to ARM, 8 bits sent from ARM (all ones), then preamble (all zeros, presumably) - which starts modulation
always @(negedge adc_clk)
begin
//count fc/64 - transfer bits to ARM at the rate they are received
if( ((~speed) && (ssp_cnt[5:0] == 6'b000000)) || (speed && (ssp_cnt[4:0] == 5'b00000)))
begin
ssp_clk <= 1'b1;
ssp_din <= curbit;
end
if( ( (~speed) && (ssp_cnt[5:0] == 6'b100000)) ||(speed && ssp_cnt[4:0] == 5'b10000))
ssp_clk <= 1'b0;
//create frame pulses. TBH, I still don't know what they do exactly, but they are crucial for ARM->FPGA transfer. If the frame is in the beginning of the byte, transfer slows to a crawl for some reason
// took me a day to figure THAT out.
if(( (~speed) && (ssp_cnt[8:0] == 9'd31)) || (speed && ssp_cnt[7:0] == 8'd15))
begin
ssp_frame <= 1'b1;
end
if(( (~speed) && (ssp_cnt[8:0] == 9'b1011111)) || (speed &&ssp_cnt[7:0] == 8'b101111) )
begin
ssp_frame <= 1'b0;
end
end
//send current bit (detected in SNIFF mode or the one being modulated in MOD mode, 0 otherwise)
reg ssp_din;
//previous signal value, mostly to detect SYNC
reg prv = 1'b1;
// for simple error correction in mod/demod detection, use maximum of modded/demodded in given interval. Maybe 1 bit is extra? but better safe than sorry.
reg[7:0] mid = 8'd128;
// set TAGSIM__MODULATE on ARM if we want to write... (frame would get lost if done mid-frame...)
// start sending over 1s on ssp->arm when we start sending preamble
// reg sending = 1'b0; // are we actively modulating?
reg [11:0] bit_counts = 12'd0; // for timeslots. only support ts=0 for now, at 212 speed -512 fullbits from end of frame. One hopes. might remove those?
//we need some way to flush bit_counts triggers on mod_type changes don't compile
reg dlay;
always @(negedge adc_clk) // every data ping?
begin
//envelope follow code...
////////////
if (fccount == bitmlen)
begin
if ((~try_sync) && (adc_d < curminthres) && disabl )
begin
fccount <= 1;
end
else
begin
fccount <= 0;
end
dlay <= ssp_dout;
if (bit_counts > 768) // should be over ts0 now, without ARM interference... stop counting...
begin
bit_counts <= 0;
end
else
if (power)
bit_counts <= 0;
else
bit_counts <= bit_counts + 1;
end
else
begin
if((~try_sync) && (adc_d < curminthres) && disabl)
begin
fccount <= 1;
end
else
begin
fccount <= fccount + 1;
end
end
// rising edge
if (adc_d > curmaxthres)
begin
case (state)
0: begin
curmax <= adc_d > `imax? adc_d : `imax;
state <= 2;
end
1: begin
curminthres <= ((curmin >> 1) + (curmin >> 2) + (curmin >> 4) + (curmax >> 3) + (curmax >> 4)); //threshold: 0.1875 max + 0.8125 min
curmaxthres <= ((curmax >> 1) + (curmax >> 2) + (curmax >> 4) + (curmin >> 3) + (curmin >> 4));
curmax <= adc_d > 155 ? adc_d : 155; // to hopefully prevent overflow from spikes going up to 255
state <= 2;
end
2: begin
if (adc_d > curmax)
curmax <= adc_d;
end
default:
begin
end
endcase
after_hysteresis <= 1'b1;
if(try_sync)
tsinceedge <= 0;
end
else if (adc_d<curminthres) //falling edge
begin
case (state)
0: begin
curmin <= adc_d<`imin? adc_d :`imin;
state <= 1;
end
1: begin
if (adc_d<curmin)
curmin <= adc_d;
end
2: begin
curminthres <= ( (curmin >> 1) + (curmin >> 2) + (curmin >> 4) + (curmax >> 3) + (curmax >> 4));
curmaxthres <= ( (curmax >> 1) + (curmax >> 2) + (curmax >> 4) + (curmin >> 3) + (curmin >> 4));
curmin <= adc_d < `imin ? adc_d : `imin;
state <= 1;
end
default:
begin
end
endcase
after_hysteresis <= 0;
if (~try_sync ) //begin modulation, lower edge...
begin
try_sync <= 1;
fccount <= 1;
did_sync <= 0;
curbit <= 0;
mid <= 8'd127;
tsinceedge <= 0;
prv <= 1;
end
else
begin
tsinceedge <= 0;
end
end
else //stable state, low or high
begin
curminthres <= ( (curmin >> 1) + (curmin >> 2) + (curmin >> 4) + (curmax >> 3) + (curmax >> 4));
curmaxthres <= ( (curmax >> 1) + (curmax >> 2) + (curmax >> 4) + (curmin >> 3) + (curmin >> 4));
state <= 0;
if (try_sync )
begin
if (tsinceedge >= (128))
begin
//we might need to start counting... assuming ARM wants to reply to the frame.
bit_counts <= 1;// i think? 128 is about 2 bits passed... but 1 also works
try_sync <= 0;
did_sync <= 0;//desync
curmin <= `imin; //reset envelope
curmax <= `imax;
curminthres <= `ithrmin;
curmaxthres <= `ithrmax;
prv <= 1;
tsinceedge <= 0;
after_hysteresis <= 1'b1;
curbit <= 0;
mid <= 8'd128;
end
else
tsinceedge <= (tsinceedge + 1);
end
end
if (try_sync && tsinceedge < 128)
begin
//detect bits in their middle ssp sampling is in sync, so it would sample all bits in order
if (fccount == bithalf)
begin
if ((~did_sync) && ((prv == 1 && (mid > 128))||(prv == 0 && (mid <= 128))))
begin
//sync the Zero, and set curbit roperly
did_sync <= 1'b1;
zero <= ~prv;// 1-prv
curbit <= 1;
end
else
curbit <= (mid > 128) ? (~zero) : zero;
prv <= (mid > 128) ? 1 : 0;
if (adc_d > curmaxthres)
mid <= 8'd129;
else if (adc_d < curminthres)
mid <= 8'd127;
else
begin
if (after_hysteresis)
begin
mid <= 8'd129;
end
else
begin
mid <= 8'd127;
end
end
end
else
begin
if (fccount==bitmlen)
begin
// fccount <= 0;
prv <= (mid > 128) ? 1 : 0;
mid <= 128;
end
else
begin
// minimum-maximum calc
if(adc_d > curmaxthres)
mid <= mid + 1;
else if (adc_d < curminthres)
mid <= mid - 1;
else
begin
if (after_hysteresis)
begin
mid <= mid + 1;
end
else
begin
mid <= mid - 1;
end
end
end
end
end
else
begin
end
// sending <= 0;
end
//put modulation here to maintain the correct clock. Seems that some readers are sensitive to that
reg pwr_hi;
reg pwr_oe1;
reg pwr_oe3;
reg pwr_oe4;
wire mod = ((fccount >= bithalf) ^ dlay) & (~disabl);
always @(ck_1356meg or ssp_dout or power or disabl or mod)
begin
if (power)
begin
pwr_hi <= ck_1356meg;
pwr_oe1 <= 1'b0;//mod;
pwr_oe3 <= 1'b0;//mod;
pwr_oe4 <= mod;//1'b0;
end
else
begin
pwr_hi <= 1'b0;
pwr_oe1 <= 1'b0;
pwr_oe3 <= 1'b0;
pwr_oe4 <= mod;
end
end
endmodule
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