proxmark3/fpga/hi_read_tx.v
bushing ba06a4b694 setting svn:eol-style=native on files, part 3
(should be done now, sorry)
2010-02-22 19:29:05 +00:00

89 lines
2.2 KiB
Verilog

//-----------------------------------------------------------------------------
// The way that we connect things when transmitting a command to an ISO
// 15693 tag, using 100% modulation only for now.
//
// Jonathan Westhues, April 2006
//-----------------------------------------------------------------------------
module hi_read_tx(
pck0, ck_1356meg, ck_1356megb,
pwr_lo, pwr_hi, pwr_oe1, pwr_oe2, pwr_oe3, pwr_oe4,
adc_d, adc_clk,
ssp_frame, ssp_din, ssp_dout, ssp_clk,
cross_hi, cross_lo,
dbg,
shallow_modulation
);
input pck0, ck_1356meg, ck_1356megb;
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;
input cross_hi, cross_lo;
output dbg;
input shallow_modulation;
// The high-frequency stuff. For now, for testing, just bring out the carrier,
// and allow the ARM to modulate it over the SSP.
reg pwr_hi;
reg pwr_oe1;
reg pwr_oe2;
reg pwr_oe3;
reg pwr_oe4;
always @(ck_1356megb or ssp_dout or shallow_modulation)
begin
if(shallow_modulation)
begin
pwr_hi <= ck_1356megb;
pwr_oe1 <= ~ssp_dout;
pwr_oe2 <= ~ssp_dout;
pwr_oe3 <= ~ssp_dout;
pwr_oe4 <= 1'b0;
end
else
begin
pwr_hi <= ck_1356megb & ssp_dout;
pwr_oe1 <= 1'b0;
pwr_oe2 <= 1'b0;
pwr_oe3 <= 1'b0;
pwr_oe4 <= 1'b0;
end
end
// Then just divide the 13.56 MHz clock down to produce appropriate clocks
// for the synchronous serial port.
reg [6:0] hi_div_by_128;
always @(posedge ck_1356meg)
hi_div_by_128 <= hi_div_by_128 + 1;
assign ssp_clk = hi_div_by_128[6];
reg [2:0] hi_byte_div;
always @(negedge ssp_clk)
hi_byte_div <= hi_byte_div + 1;
assign ssp_frame = (hi_byte_div == 3'b000);
// Implement a hysteresis to give out the received signal on
// ssp_din. Sample at fc.
assign adc_clk = ck_1356meg;
// ADC data appears on the rising edge, so sample it on the falling edge
reg after_hysteresis;
always @(negedge adc_clk)
begin
if(& adc_d[7:0]) after_hysteresis <= 1'b1;
else if(~(| adc_d[7:0])) after_hysteresis <= 1'b0;
end
assign ssp_din = after_hysteresis;
assign pwr_lo = 1'b0;
assign dbg = ssp_din;
endmodule