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fix another way
[proxmark3-svn] / fpga / hi_read_tx.v
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ba06a4b6 1//-----------------------------------------------------------------------------
2// The way that we connect things when transmitting a command to an ISO
3// 15693 tag, using 100% modulation only for now.
4//
5// Jonathan Westhues, April 2006
6//-----------------------------------------------------------------------------
7
8module hi_read_tx(
9 pck0, ck_1356meg, ck_1356megb,
10 pwr_lo, pwr_hi, pwr_oe1, pwr_oe2, pwr_oe3, pwr_oe4,
11 adc_d, adc_clk,
12 ssp_frame, ssp_din, ssp_dout, ssp_clk,
13 cross_hi, cross_lo,
14 dbg,
15 shallow_modulation
16);
17 input pck0, ck_1356meg, ck_1356megb;
18 output pwr_lo, pwr_hi, pwr_oe1, pwr_oe2, pwr_oe3, pwr_oe4;
19 input [7:0] adc_d;
20 output adc_clk;
21 input ssp_dout;
22 output ssp_frame, ssp_din, ssp_clk;
23 input cross_hi, cross_lo;
24 output dbg;
25 input shallow_modulation;
26
d372569b 27// low frequency outputs, not relevant
28assign pwr_lo = 1'b0;
29assign pwr_oe2 = 1'b0;
30
ba06a4b6 31// The high-frequency stuff. For now, for testing, just bring out the carrier,
32// and allow the ARM to modulate it over the SSP.
33reg pwr_hi;
34reg pwr_oe1;
ba06a4b6 35reg pwr_oe3;
36reg pwr_oe4;
d372569b 37
ba06a4b6 38always @(ck_1356megb or ssp_dout or shallow_modulation)
39begin
40 if(shallow_modulation)
41 begin
42 pwr_hi <= ck_1356megb;
d372569b 43 pwr_oe1 <= 1'b0;
44 pwr_oe3 <= 1'b0;
45 pwr_oe4 <= ~ssp_dout;
ba06a4b6 46 end
47 else
48 begin
49 pwr_hi <= ck_1356megb & ssp_dout;
50 pwr_oe1 <= 1'b0;
ba06a4b6 51 pwr_oe3 <= 1'b0;
52 pwr_oe4 <= 1'b0;
53 end
54end
55
d372569b 56
ba06a4b6 57// Then just divide the 13.56 MHz clock down to produce appropriate clocks
58// for the synchronous serial port.
59
60reg [6:0] hi_div_by_128;
61
62always @(posedge ck_1356meg)
63 hi_div_by_128 <= hi_div_by_128 + 1;
64
65assign ssp_clk = hi_div_by_128[6];
66
67reg [2:0] hi_byte_div;
68
69always @(negedge ssp_clk)
70 hi_byte_div <= hi_byte_div + 1;
71
72assign ssp_frame = (hi_byte_div == 3'b000);
73
74// Implement a hysteresis to give out the received signal on
75// ssp_din. Sample at fc.
76assign adc_clk = ck_1356meg;
77
78// ADC data appears on the rising edge, so sample it on the falling edge
79reg after_hysteresis;
80always @(negedge adc_clk)
81begin
82 if(& adc_d[7:0]) after_hysteresis <= 1'b1;
83 else if(~(| adc_d[7:0])) after_hysteresis <= 1'b0;
84end
85
86
87assign ssp_din = after_hysteresis;
88
ba06a4b6 89assign dbg = ssp_din;
90
91endmodule
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