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Implemented new FPGA mode for iclass tag simulation. Reduces arm-side size of transfer/memory by a factor of 8. Makes for easier arm-side encoding of messages, for when we start needing to do that on the fly instead of using precalculated messages

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This commit is contained in:
Martin Holst Swende 2015-01-15 15:16:34 +01:00
commit 645c960f61
4 changed files with 118 additions and 59 deletions
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39
fpga/hi_simulate.v
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@ -50,12 +50,38 @@ begin
else if(~(| adc_d[7:5])) after_hysteresis = 1'b0;
end
// Divide 13.56 MHz by 32 to produce the SSP_CLK
// The register is bigger to allow higher division factors of up to /128
reg [6:0] ssp_clk_divider;
reg [10:0] ssp_clk_divider;
always @(posedge adc_clk)
ssp_clk_divider <= (ssp_clk_divider + 1);
assign ssp_clk = ssp_clk_divider[4];
reg ssp_clk;
reg ssp_frame;
always @(negedge adc_clk)
begin
//If we're in 101, we only need a new bit every 8th carrier bit (53Hz). Otherwise, get next bit at 424Khz
if(mod_type == 3'b101)
begin
if(ssp_clk_divider[7:0] == 8'b00000000)
ssp_clk <= 1'b0;
if(ssp_clk_divider[7:0] == 8'b10000000)
ssp_clk <= 1'b1;
end
else
begin
if(ssp_clk_divider[4:0] == 5'd0)//[4:0] == 5'b00000)
ssp_clk <= 1'b1;
if(ssp_clk_divider[4:0] == 5'd16) //[4:0] == 5'b10000)
ssp_clk <= 1'b0;
end
end
//assign ssp_clk = ssp_clk_divider[4];
// Divide SSP_CLK by 8 to produce the byte framing signal; the phase of
// this is arbitrary, because it's just a bitstream.
@ -69,12 +95,13 @@ reg [2:0] ssp_frame_divider_from_arm;
always @(negedge ssp_clk)
ssp_frame_divider_from_arm <= (ssp_frame_divider_from_arm + 1);
reg ssp_frame;
always @(ssp_frame_divider_to_arm or ssp_frame_divider_from_arm or mod_type)
if(mod_type == 3'b000) // not modulating, so listening, to ARM
ssp_frame = (ssp_frame_divider_to_arm == 3'b000);
else
ssp_frame = (ssp_frame_divider_from_arm == 3'b000);
ssp_frame = (ssp_frame_divider_from_arm == 3'b000);
// Synchronize up the after-hysteresis signal, to produce DIN.
reg ssp_din;
@ -90,7 +117,7 @@ always @(mod_type or ssp_clk or ssp_dout)
modulating_carrier <= ssp_dout ^ ssp_clk_divider[3]; // XOR means BPSK
else if(mod_type == 3'b010)
modulating_carrier <= ssp_dout & ssp_clk_divider[5]; // switch 212kHz subcarrier on/off
else if(mod_type == 3'b100)
else if(mod_type == 3'b100 || mod_type == 3'b101)
modulating_carrier <= ssp_dout & ssp_clk_divider[4]; // switch 424kHz modulation on/off
else
modulating_carrier <= 1'b0; // yet unused
@ -106,7 +133,7 @@ assign pwr_oe4 = modulating_carrier;
// This one is always on, so that we can watch the carrier.
assign pwr_oe3 = 1'b0;
assign dbg = after_hysteresis;
assign dbg = modulating_carrier;
//reg dbg;
//always @(ssp_dout)
// dbg <= ssp_dout;