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hi_get_trace.v
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hi_get_trace.v
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//-----------------------------------------------------------------------------
//
// piwi, Feb 2019
//-----------------------------------------------------------------------------
module hi_get_trace(
ck_1356megb,
adc_d, trace_enable, major_mode,
ssp_frame, ssp_din, ssp_clk
);
input ck_1356megb;
input [7:0] adc_d;
input trace_enable;
input [2:0] major_mode;
output ssp_frame, ssp_din, ssp_clk;
// clock divider
reg [6:0] clock_cnt;
always @(negedge ck_1356megb)
begin
clock_cnt <= clock_cnt + 1;
end
// sample at 13,56MHz / 8. The highest signal frequency (subcarrier) is 848,5kHz, i.e. in this case we oversample by a factor of 2
reg [2:0] sample_clock;
always @(negedge ck_1356megb)
begin
if (sample_clock == 3'd7)
sample_clock <= 3'd0;
else
sample_clock <= sample_clock + 1;
end
reg [11:0] addr;
reg [11:0] start_addr;
reg [2:0] previous_major_mode;
reg write_enable1;
reg write_enable2;
always @(negedge ck_1356megb)
begin
previous_major_mode <= major_mode;
if (major_mode == `FPGA_MAJOR_MODE_HF_GET_TRACE)
begin
write_enable1 <= 1'b0;
write_enable2 <= 1'b0;
if (previous_major_mode != `FPGA_MAJOR_MODE_HF_GET_TRACE) // just switched into GET_TRACE mode
addr <= start_addr;
if (clock_cnt == 7'd0)
begin
if (addr == 12'd3071)
addr <= 12'd0;
else
addr <= addr + 1;
end
end
else if (major_mode != `FPGA_MAJOR_MODE_OFF)
begin
if (trace_enable)
begin
if (addr[11] == 1'b0)
begin
write_enable1 <= 1'b1;
write_enable2 <= 1'b0;
end
else
begin
write_enable1 <= 1'b0;
write_enable2 <= 1'b1;
end
if (sample_clock == 3'b000)
begin
if (addr == 12'd3071)
begin
addr <= 12'd0;
write_enable1 <= 1'b1;
write_enable2 <= 1'b0;
end
else
addr <= addr + 1;
end
end
else
begin
write_enable1 <= 1'b0;
write_enable2 <= 1'b0;
start_addr <= addr;
end
end
else // major_mode == `FPGA_MAJOR_MODE_OFF
begin
write_enable1 <= 1'b0;
write_enable2 <= 1'b0;
if (previous_major_mode != `FPGA_MAJOR_MODE_OFF && previous_major_mode != `FPGA_MAJOR_MODE_HF_GET_TRACE) // just switched off
start_addr <= addr;
end
end
// (2+1)k RAM
reg [7:0] D_out1, D_out2;
reg [7:0] ram1 [2047:0];
reg [7:0] ram2 [1023:0];
always @(negedge ck_1356megb)
begin
if (write_enable1)
begin
ram1[addr[10:0]] <= adc_d;
D_out1 <= adc_d;
end
else
D_out1 <= ram1[addr[10:0]];
if (write_enable2)
begin
ram2[addr[9:0]] <= adc_d;
D_out2 <= adc_d;
end
else
D_out2 <= ram2[addr[9:0]];
end
// SSC communication to ARM
reg ssp_clk;
reg ssp_frame;
reg [7:0] shift_out;
always @(negedge ck_1356megb)
begin
if(clock_cnt[3:0] == 4'd0) // update shift register every 16 clock cycles
begin
if(clock_cnt[6:4] == 3'd0) // either load new value
begin
if (addr[11] == 1'b0)
shift_out <= D_out1;
else
shift_out <= D_out2;
end
else // or shift left
shift_out[7:1] <= shift_out[6:0];
end
ssp_clk <= ~clock_cnt[3]; // ssp_clk frequency = 13,56MHz / 16 = 847,5 kHz
if(clock_cnt[6:4] == 3'b000) // set ssp_frame for 0...31
ssp_frame <= 1'b1;
else
ssp_frame <= 1'b0;
end
assign ssp_din = shift_out[7];
endmodule