[Open-graphics] Help with specs on TV chip?
Nicholas
nova at macintoshclub.com
Fri Oct 6 21:25:44 EDT 2006
> In another thread, I posted this module. Here it is again:
>
> module FDDRRSE(Q, C0, C1, CE, D0, D1, R, S);
> output Q;
> reg Q;
> input C0, C1, CE, D0, D1, R, S;
> always @(posedge C0) Q <= D0;
> always @(posedge C1) Q <= D1;
> endmodule
> Add this to your test module that wraps the video module.
All right, I fixed that. I'll be sure to keep this module around from
now on :-).
I now control the DVI sync signals in my module, and it should produce
the right waveform now. I can actually use = and <= properly now,
instead of dreading what each one means :-)
The one thing is that I don't control the data at all. I plan on just
making one of two changes:
1) making gen_head0_signals module merge into head0_video_out,
2) making r,g,b into wires which are then controlled from
gen_head0_signals.
Which is a better idea? I would prefer (2) because that way people only
have to deal with gen_head0_signals and there is a semi-abstraction
barrier between the modules, but either one should work fine.
Also note that the output that is fixed is at 2652768 seconds (since the
rest is just a full frame, which takes a while).
and appended is the modules themselves.
nick
module test_head0;
//simple test interface
wire clkout,clk2out,resetout;
reg clock, clock_2x,reset;
initial begin
clock = 0;
forever begin
clock = !clock;
#2;
end
end
initial begin
clock_2x = 0;
forever begin
clock_2x = !clock_2x;
#1;
end
end
initial begin
$dumpfile( "testDVI.vcd" );
$dumpvars;
reset = 0;
#100;
reset = 1;
#3000000;
$finish;
end
assign clkout=clock;
assign clk2out=clock_2x;
assign resetout=reset;
gen_head0_signals u0(clkout, clk2out,resetout);
endmodule
module gen_head0_signals(
clock,
clock_2x,
reset);
input clock,clock_2x,reset;
wire clock,clock_2x,reset;
wire hsync,vsync,de;module test_head0;
//simple test interface
wire clkout,clk2out,resetout;
reg clock, clock_2x,reset;
initial begin
clock = 0;
forever begin
clock = !clock;
#2;
end
end
initial begin
clock_2x = 0;
forever begin
clock_2x = !clock_2x;
#1;
end
end
initial begin
$dumpfile( "testDVI.vcd" );
$dumpvars;
reset = 0;
#100;
reset = 1;
#3000000;
$finish;
end
assign clkout=clock;
assign clk2out=clock_2x;
assign resetout=reset;
gen_head0_signals u0(clkout, clk2out,resetout);
endmodule
module gen_head0_signals(
clock,
clock_2x,
reset);
input clock,clock_2x,reset;
wire clock,clock_2x,reset;
wire hsync,vsync,de;
reg hs,vs,en;
assign hsync=hs;
assign vsync=vs;
assign de=en;
head0_video_out u0(clock,clock_2x,reset,hsync,vsync,de,,,,,,,,,,);
// 800 X 600 @ 60Hz with a 40.000MHz pixel clock
parameter H_ACTIVE = 800, // pixels
H_FRONT_PORCH = 40, // pixels
H_SYNCH = 128, // pixels
H_BACK_PORCH = 88, // pixels
H_TOTAL = 1056, // pixels
V_ACTIVE = 600, // lines
V_FRONT_PORCH = 1, // lines
V_SYNCH = 4, // lines
V_BACK_PORCH = 23, // lines
V_TOTAL = 628; // lines
parameter SYNC_STATE=1'b1,
PORCH_STATE=1'b0,
DATA_STATE=2'b00;
reg [9:0] vert; //current vertical scanline location
reg [11:0] horiz; //current pixel in scanline
reg [1:0] hstate; //horizontal and vertical states
reg [1:0] vstate; //so it is easier to ref them.
always @(posedge clock or negedge reset)
begin
if (!reset) begin
reg hs,vs,en;
assign hsync=hs;
assign vsync=vs;
assign de=en;
head0_video_out u0(clock,clock_2x,reset,hsync,vsync,de,,,,,,,,,,);
// 800 X 600 @ 60Hz with a 40.000MHz pixel clock
parameter H_ACTIVE = 800, // pixels
H_FRONT_PORCH = 40, // pixels
H_SYNCH = 128, // pixels
H_BACK_PORCH = 88, // pixels
H_TOTAL = 1056, // pixels
V_ACTIVE = 600, // lines
V_FRONT_PORCH = 1, // lines
V_SYNCH = 4, // lines
V_BACK_PORCH = 23, // lines
V_TOTAL = 628; // lines
parameter SYNC_STATE=1'b1,
PORCH_STATE=1'b0,
DATA_STATE=2'b00;
reg [9:0] vert; //current vertical scanline location
reg [11:0] horiz; //current pixel in scanline
reg [1:0] hstate; //horizontal and vertical states
reg [1:0] vstate; //so it is easier to ref them.
always @(posedge clock or negedge reset)
begin
if (!reset) begin
vert<=0;
horiz<=0;
hstate<=0;
vstate<=0;
en<=1'b0;
end else begin
horiz <= horiz + 1;
case (horiz)
H_TOTAL-1:
begin
hstate <= 0;
horiz <=0;
vert=vert + 1;
//because the blocking
//occurs one time-delta
//later, it misses when
//vert is tested and then
//it is switched next time
//around.
end
H_SYNCH + H_FRONT_PORCH + H_ACTIVE-1:
begin
hstate <= 3;
end
H_FRONT_PORCH + H_ACTIVE-1:
begin
hstate <= 2;
end
H_ACTIVE-1:
begin
hstate <= 1;
end
endcase
end
end
always @(hstate or vstate)
begin
//now all the states are correct:
//0) Active - White.
//1) Front Porch.
//2) Sync signal. 0.
//3) Back Porch.
//now all is ready.
//insert here the code to make colors based
//on the various values.
//example: just sync signals.
if (vstate==2) //sync state
begin
vs<=SYNC_STATE;
en<=1'b0;
end
if (hstate==2) //sync state
begin
hs<=SYNC_STATE;
en<=1'b0;
end
if (hstate==1 || hstate==3) //porch state
begin
hs<=PORCH_STATE;
en<=1'b0;
end
if (vstate==1 || vstate==3) //vertporch state
begin
vs<=PORCH_STATE;
en<=1'b0;
end
if (hstate==0 && vstate==0) //draw state
begin
{hs,vs}<=DATA_STATE;
en<=1'b1;
end
end
always @(posedge clock)
begin
//Now set up Vert in the same way...
case(vert)
V_TOTAL-1:
begin
if (horiz==H_TOTAL-1)
begin
vert <=0;
vstate <=0;
end
// new frame
end
V_SYNCH + V_FRONT_PORCH + V_ACTIVE-1:
begin
vstate <= 3;
end
V_FRONT_PORCH + V_ACTIVE-1:
begin
vstate <= 2;
end
V_ACTIVE-1:
begin
vstate <= 1;
end
endcase
end
endmodule
module head0_video_out(
clock,
clock_2x,
reset,
hsync,
vsync,
de,
// Common data pins
vid_data,
// Syncs and clock for analog interface
dac_hsync,
dac_vsync,
dac_de,
dac_clk,
// Syncs and clocks for DVI interface
dvi_m_clk,
dvi_s_clk,
dvi_hsync,
dvi_vsync,
dvi_de
);
input clock, clock_2x, reset,hsync,vsync,de;
output [29:0] vid_data;
output dac_hsync, dac_vsync, dac_de, dac_clk;
output dvi_m_clk, dvi_s_clk, dvi_hsync, dvi_vsync, dvi_de;
reg dac_hsync, dac_vsync, dac_de;
reg dvi_hsync, dvi_vsync, dvi_de;
// ----------
// Pixel data -- notice that we process two pixels per clock
reg [9:0] r0, g0, b0; // even pixel
reg [9:0] r1, g1, b1; // odd pixel
// And the syncs
wire hsync, vsync, de;
// ----------
// Dual-link DVI
// There are two DVI transmitters. One takes the even pixels, and
// the other takes the odd pixels. Each one takes data at double-
// data rate. On the rising edge, the master transmitter wants
// {r0[7:0], g0[7:4]}, and on the falling edge, {g0[3:0], b0[7:0]}.
// The slave transmitter wants the same for r1, g1, and b1.
wire [11:0] dvi_data_m_0 = {r0[9:2], g0[9:6]};
wire [11:0] dvi_data_m_1 = {g0[5:2], b0[9:2]};
wire [11:0] dvi_data_s_0 = {r1[9:2], g1[9:6]};
wire [11:0] dvi_data_s_1 = {g1[5:2], b1[9:2]};
// Now splice together the bits that go together in time.
// The lower 6 bits correspond to the extra analog precision,
// which are don't-cares for DVI.
wire [29:0] vid_data_dvi0 = {dvi_data_m_0, dvi_data_s_0, 6'b0};
wire [29:0] vid_data_dvi1 = {dvi_data_m_1, dvi_data_s_1, 6'b0};
// Since this is a DDR interface, it is convenient to use a DDR FF
// to provide the clock signal. IIRC, we want data0 to appear with
// the rising edge of the clock, so we want to produce it on the
// negative edge.
ddrff1 ff0 (.Q(dvi_m_clk), .C0(clock), .C1(~clock), .D0(1'b0),
.D1(1'b1), .OE(1'b1));
ddrff1 ff1 (.Q(dvi_s_clk), .C0(clock), .C1(~clock), .D0(1'b0),
.D1(1'b1), .OE(1'b1));
// Syncs for DVI
always @(posedge clock) begin
dvi_hsync <= hsync;
dvi_vsync <= vsync;
dvi_de <= de;
end
// Analog, 330MHz
// There is a single triple-DAC that takes one 30-bit pixel per clock,
// at the pixel rate. We can use DDR flipflops for the data (indeed, we
must
// because we use the same pins for DVI), but the clock signal has to be
twice
// as fast. This results in a radically different arrangement of bits
for
// analog. Additionally, logically, we have separated out the lower
pairs
// of bits for the 10-bit precision.
wire [24:0] dac_data_hi0 = {r0[9:2], g0[9:2], b0[9:2]};
wire [5:0] dac_data_lo0 = {r0[1:0], g0[1:0], b0[1:0]};
wire [24:0] dac_data_hi1 = {r1[9:2], g1[9:2], b1[9:2]};
wire [5:0] dac_data_lo1 = {r1[1:0], g1[1:0], b1[1:0]};
// Splice together in order
wire [29:0] vid_data_dac0 = {dac_data_hi0, dac_data_lo0};
wire [29:0] vid_data_dac1 = {dac_data_hi1, dac_data_lo1};
// There is a single clock signal, but at twice the rate, so here we
// use a 2x clock that will be generated from a DCM.
// Did I get the polarity right?
ddrff1 ff2 (.Q(dac_clk), .C0(clock_2x), .C1(~clock_2x), .D0(1'b0),
.D1(1'b1), .OE(1'b1));
// Syncs for Analog
// In actuality, we'll want to replace these with shift registers.
// DVI transmitters take syncs, but with analog, our sync signals go
// directly to the connector, while the video data itself has a few
// cycles of latency through the DAC. We need to delay the syncs
// to line up with the data. In OGA, we'll make this delay variable.
always @(posedge clock) begin
dac_hsync <= hsync;
dac_vsync <= vsync;
dac_de <= de;
end
// Now, select the data for DVI or analog and connect to the I/O drivers
wire using_dvi = 1;
wire [29:0] vid_data0 = using_dvi ? vid_data_dvi0 : vid_data_dac0;
wire [29:0] vid_data1 = using_dvi ? vid_data_dvi1 : vid_data_dac1;
ddrff30 ff3 (.Q(vid_data), .C0(clock), .C1(~clock),
.D0(vid_data0), .D1(vid_data1), .OE(1'b1));
endmodule
module FDDRRSE(Q, C0, C1, CE, D0, D1, R, S);
output Q;
reg Q;
input C0, C1, CE, D0, D1, R, S;
always @(posedge C0) Q <= D0;
always @(posedge C1) Q <= D1;
endmodule
// For convenience, instantiate sets of DDR flipflops. You can
basically
// ignore this.
module ddrff1(Q, C0, C1, D0, D1, OE);
input C0, C1, D0, D1, OE;
output Q;
wire R;
FDDRRSE ff0 (.Q(R), .C0(C0), .C1(C1), .CE(1'b1), .D0(D0), .D1(D1),
.R(1'b0), .S(1'b0));
assign Q = OE ? R : 1'bz;
endmodule
module ddrff4(Q, C0, C1, D0, D1, OE);
input C0, C1, OE;
input [3:0] D0, D1;
output [3:0] Q;
ddrff1 ff0
(.Q(Q[0]), .C0(C0), .C1(C1), .D0(D0[0]), .D1(D1[0]), .OE(OE));
ddrff1 ff1
(.Q(Q[1]), .C0(C0), .C1(C1), .D0(D0[1]), .D1(D1[1]), .OE(OE));
ddrff1 ff2
(.Q(Q[2]), .C0(C0), .C1(C1), .D0(D0[2]), .D1(D1[2]), .OE(OE));
ddrff1 ff3
(.Q(Q[3]), .C0(C0), .C1(C1), .D0(D0[3]), .D1(D1[3]), .OE(OE));
endmodule
module ddrff30(Q, C0, C1, D0, D1, OE);
input C0, C1, OE;
input [29:0] D0, D1;
output [29:0] Q;
ddrff4 ff0 (.Q(Q[ 3: 0]), .C0(C0), .C1(C1), .D0(D0[ 3: 0]), .D1(D1[ 3:
0]), .OE(OE));
ddrff4 ff1 (.Q(Q[ 7: 4]), .C0(C0), .C1(C1), .D0(D0[ 7: 4]), .D1(D1[ 7:
4]), .OE(OE));
ddrff4 ff2 (.Q(Q[11: 8]), .C0(C0), .C1(C1), .D0(D0[11: 8]), .D1(D1[11:
8]), .OE(OE));
ddrff4 ff3 (.Q(Q[15:12]), .C0(C0), .C1(C1), .D0(D0[15:12]),
.D1(D1[15:12]), .OE(OE));
ddrff4 ff4 (.Q(Q[19:16]), .C0(C0), .C1(C1), .D0(D0[19:16]),
.D1(D1[19:16]), .OE(OE));
ddrff4 ff5 (.Q(Q[23:20]), .C0(C0), .C1(C1), .D0(D0[23:20]),
.D1(D1[23:20]), .OE(OE));
ddrff4 ff6 (.Q(Q[27:24]), .C0(C0), .C1(C1), .D0(D0[27:24]),
.D1(D1[27:24]), .OE(OE));
ddrff1 ff7
(.Q(Q[28]), .C0(C0), .C1(C1), .D0(D0[28]), .D1(D1[28]), .OE(OE));
ddrff1 ff8
(.Q(Q[29]), .C0(C0), .C1(C1), .D0(D0[29]), .D1(D1[29]), .OE(OE));
endmodule
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