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72acba78 1//-----------------------------------------------------------------------------\r
2// For reading TI tags, we need to place the FPGA in pass through mode\r
3// and pass everything through to the ARM\r
4//-----------------------------------------------------------------------------\r
5\r
6module lo_passthru(\r
7 pck0, ck_1356meg, ck_1356megb,\r
8 pwr_lo, pwr_hi, pwr_oe1, pwr_oe2, pwr_oe3, pwr_oe4,\r
9 adc_d, adc_clk,\r
10 ssp_frame, ssp_din, ssp_dout, ssp_clk,\r
11 cross_hi, cross_lo,\r
8e7a6ce4 12 dbg, divisor\r
72acba78 13);\r
14 input pck0, ck_1356meg, ck_1356megb;\r
15 output pwr_lo, pwr_hi, pwr_oe1, pwr_oe2, pwr_oe3, pwr_oe4;\r
16 input [7:0] adc_d;\r
17 output adc_clk;\r
18 input ssp_dout;\r
19 output ssp_frame, ssp_din, ssp_clk;\r
20 input cross_hi, cross_lo;\r
21 output dbg;\r
8e7a6ce4 22 input [7:0] divisor;\r
72acba78 23\r
8e7a6ce4 24reg [7:0] pck_divider;\r
25reg ant_lo;\r
72acba78 26\r
8e7a6ce4 27// this task runs on the rising egde of pck0 clock (24Mhz) and creates ant_lo\r
28// which is high for (divisor+1) pck0 cycles and low for the same duration\r
29// ant_lo is therefore a 50% duty cycle clock signal with a frequency of\r
30// 12Mhz/(divisor+1) which drives the antenna as well as the ADC clock adc_clk\r
31always @(posedge pck0)\r
32begin\r
33 if(pck_divider == divisor[7:0])\r
34 begin\r
35 pck_divider <= 8'd0;\r
36 ant_lo = !ant_lo;\r
37 end\r
38 else\r
39 begin\r
40 pck_divider <= pck_divider + 1;\r
41 end\r
42end\r
43\r
44// the antenna is modulated when ssp_dout = 1, when 0 the\r
45// antenna drivers stop modulating and go into listen mode\r
72acba78 46assign pwr_oe3 = 1'b0;\r
8e7a6ce4 47assign pwr_oe1 = ssp_dout;\r
48assign pwr_oe2 = ssp_dout;\r
49assign pwr_oe4 = ssp_dout;\r
50assign pwr_lo = ant_lo && ssp_dout;\r
72acba78 51assign pwr_hi = 1'b0;\r
52assign adc_clk = 1'b0;\r
53assign ssp_din = cross_lo;\r
54assign dbg = cross_lo;\r
55\r
56endmodule\r
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