`timescale 1ns / 1ps
-module ROM(
+module SimROM(
input [15:0] address,
inout [7:0] data,
input clk,
input wr, rd);
+ reg rdlatch = 0;
reg [7:0] odata;
- // synthesis attribute ram_style of rom is block
- reg [7:0] rom [1023:0];
+ reg [7:0] rom [32767:0];
initial $readmemh("rom.hex", rom);
wire decode = address[15:13] == 0;
- always @(posedge clk)
+ always @(posedge clk) begin
+ rdlatch <= rd && decode;
odata <= rom[address[10:0]];
- assign data = (rd && decode) ? odata : 8'bzzzzzzzz;
+ end
+ assign data = rdlatch ? odata : 8'bzzzzzzzz;
endmodule
module BootstrapROM(
input clk,
input wr, rd);
- reg [7:0] brom [255:0];
- initial $readmemh("bootstrap.hex", brom);
+ reg rdlatch = 0;
+ reg [7:0] addrlatch = 0;
+ reg romno = 0, romnotmp = 0;
+ reg [7:0] brom0 [255:0];
+ reg [7:0] brom1 [255:0];
+
+ initial $readmemh("fpgaboot.hex", brom0);
+ initial $readmemh("gbboot.hex", brom1);
+
+`ifdef isim
+ initial romno <= 1;
+`endif
wire decode = address[15:8] == 0;
- wire [7:0] odata = brom[address[7:0]];
- assign data = (rd && decode) ? odata : 8'bzzzzzzzz;
+ wire [7:0] odata = (romno == 0) ? brom0[addrlatch] : brom1[addrlatch];
+ always @(posedge clk) begin
+ rdlatch <= rd && decode;
+ addrlatch <= address[7:0];
+ if (wr && decode) romnotmp <= data[0];
+ if (rd && address == 16'h0000) romno <= romnotmp; /* Latch when the program restarts. */
+ end
+ assign data = rdlatch ? odata : 8'bzzzzzzzz;
endmodule
module MiniRAM(
reg [7:0] ram [127:0];
wire decode = (address >= 16'hFF80) && (address <= 16'hFFFE);
+ reg rdlatch = 0;
reg [7:0] odata;
- assign data = (rd && decode) ? odata : 8'bzzzzzzzz;
+ assign data = rdlatch ? odata : 8'bzzzzzzzz;
always @(posedge clk)
begin
- if (decode) // This has to go this way. The only way XST knows how to do
- begin // block ram is chip select, write enable, and always
+ rdlatch <= rd && decode;
+ if (decode) // This has to go this way. The only way XST knows how to do
+ begin // block ram is chip select, write enable, and always
if (wr) // reading. "else if rd" does not cut it ...
ram[address[6:0]] <= data;
odata <= ram[address[6:0]];
end
endmodule
+module CellularRAM(
+ input clk,
+ input [15:0] address,
+ inout [7:0] data,
+ input wr, rd,
+ output wire cr_nADV, cr_nCE, cr_nOE, cr_nWE, cr_CRE, cr_nLB, cr_nUB, cr_CLK,
+ output wire [22:0] cr_A,
+ inout [15:0] cr_DQ);
+
+ parameter ADDR_PROGADDRH = 16'hFF60;
+ parameter ADDR_PROGADDRM = 16'hFF61;
+ parameter ADDR_PROGADDRL = 16'hFF62;
+ parameter ADDR_PROGDATA = 16'hFF63;
+ parameter ADDR_MBC = 16'hFF64;
+
+ reg rdlatch = 0, wrlatch = 0;
+ reg [15:0] addrlatch = 0;
+ reg [7:0] datalatch = 0;
+
+ reg [7:0] progaddrh, progaddrm, progaddrl;
+
+ reg [22:0] progaddr;
+
+ reg [7:0] mbc_emul = 8'b00000101; // High bit is whether we're poking flash
+ // low 7 bits are the MBC that we are emulating
+
+ assign cr_nADV = 0; /* Addresses are always valid! :D */
+ assign cr_nCE = 0; /* The chip is enabled */
+ assign cr_nLB = 0; /* Lower byte is enabled */
+ assign cr_nUB = 0; /* Upper byte is enabled */
+ assign cr_CRE = 0; /* Data writes, not config */
+ assign cr_CLK = 0; /* Clock? I think not! */
+
+ wire decode = (addrlatch[15:14] == 2'b00) /* extrom */ || (addrlatch[15:13] == 3'b101) /* extram */ || (addrlatch == ADDR_PROGDATA);
+
+ reg [3:0] rambank = 0;
+ reg [8:0] rombank = 1;
+
+ assign cr_nOE = decode ? ~rdlatch : 1;
+ assign cr_nWE = (decode && ((addrlatch == ADDR_PROGDATA) || (mbc_emul[6:0] == 0))) ? ~wrlatch : 1;
+
+ assign cr_DQ = (~cr_nOE) ? 16'bzzzzzzzzzzzzzzzz : {8'b0, datalatch};
+ assign cr_A = (addrlatch[15:14] == 2'b00) ? /* extrom, home bank */ {9'b0,addrlatch[13:0]} :
+ (addrlatch[15:14] == 2'b01) ? /* extrom, paged bank */ {rombank, addrlatch[13:0]} :
+ (addrlatch[15:13] == 3'b101) ? /* extram */ {1'b1, 5'b0, rambank, addrlatch[12:0]} :
+ (addrlatch == ADDR_PROGDATA) ? progaddr :
+ 23'b0;
+
+ always @(posedge clk) begin
+ case (address)
+ ADDR_PROGADDRH: if (wr) progaddrh <= data;
+ ADDR_PROGADDRM: if (wr) progaddrm <= data;
+ ADDR_PROGADDRL: if (wr) progaddrl <= data;
+ ADDR_PROGDATA: if (rd || wr) begin
+ progaddr <= {progaddrh[6:0], progaddrm[7:0], progaddrl[7:0]};
+ {progaddrh[6:0], progaddrm[7:0], progaddrl[7:0]} <= {progaddrh[6:0], progaddrm[7:0], progaddrl[7:0]} + 23'b1;
+ end
+ ADDR_MBC: begin
+ mbc_emul <= data;
+ rambank <= 0;
+ rombank <= 1;
+ end
+ endcase
+
+ if (mbc_emul[6:0] == 5) begin
+ if ((address[15:12] == 4'h2) && wr)
+ rombank <= {rombank[8], data};
+ else if ((address[15:12] == 4'h3) && wr)
+ rombank <= {data[0], rombank[7:0]};
+ else if ((address[15:12] == 4'h4) && wr)
+ rambank <= data[3:0];
+ end
+
+ rdlatch <= rd;
+ wrlatch <= wr;
+ addrlatch <= address;
+ datalatch <= data;
+ end
+
+ assign data = (rdlatch && decode) ?
+ (addrlatch == ADDR_PROGADDRH) ? progaddrh :
+ (addrlatch == ADDR_PROGADDRM) ? progaddrm :
+ (addrlatch == ADDR_PROGADDRL) ? progaddrl :
+ cr_DQ
+ : 8'bzzzzzzzz;
+endmodule
+
module InternalRAM(
input [15:0] address,
inout [7:0] data,
// synthesis attribute ram_style of ram is block
reg [7:0] ram [8191:0];
- wire decode = address[15:13] == 3'b110;
+ wire decode = (address >= 16'hC000) && (address <= 16'hFDFF); /* This includes echo RAM. */
reg [7:0] odata;
- assign data = (rd && decode) ? odata : 8'bzzzzzzzz;
+ reg rdlatch = 0;
+ assign data = rdlatch ? odata : 8'bzzzzzzzz;
always @(posedge clk)
begin
- if (decode) // This has to go this way. The only way XST knows how to do
- begin // block ram is chip select, write enable, and always
+ rdlatch <= rd && decode;
+ if (decode) // This has to go this way. The only way XST knows how to do
+ begin // block ram is chip select, write enable, and always
if (wr) // reading. "else if rd" does not cut it ...
ram[address[12:0]] <= data;
odata <= ram[address[12:0]];
wire decode = address == 16'hFF51;
reg [7:0] odata;
- assign data = (rd && decode) ? odata : 8'bzzzzzzzz;
+ reg rdlatch = 0;
+ assign data = rdlatch ? odata : 8'bzzzzzzzz;
always @(posedge clk)
begin
+ rdlatch <= rd && decode;
if (decode && rd)
odata <= switches;
else if (decode && wr)
input [3:0] buttons,
output wire [7:0] leds,
output serio,
+ input serin,
output wire [3:0] digits,
output wire [7:0] seven,
+ output wire cr_nADV, cr_nCE, cr_nOE, cr_nWE, cr_CRE, cr_nLB, cr_nUB, cr_CLK,
+ output wire [22:0] cr_A,
+ inout [15:0] cr_DQ,
`endif
output wire hs, vs,
output wire [2:0] r, g,
wire [7:0] leds;
wire serio;
+ wire serin = 1;
wire [3:0] digits;
wire [7:0] seven;
wire [7:0] switches = 8'b0;
.wr(wr[1]),
.rd(rd[1]));
- ROM rom(
+`ifdef isim
+ SimROM rom(
.address(addr[0]),
.data(data[0]),
.clk(clk),
.wr(wr[0]),
.rd(rd[0]));
+`else
+ CellularRAM cellram(
+ .address(addr[0]),
+ .data(data[0]),
+ .clk(clk),
+ .wr(wr[0]),
+ .rd(rd[0]),
+ .cr_nADV(cr_nADV),
+ .cr_nCE(cr_nCE),
+ .cr_nOE(cr_nOE),
+ .cr_nWE(cr_nWE),
+ .cr_CRE(cr_CRE),
+ .cr_nLB(cr_nLB),
+ .cr_nUB(cr_nUB),
+ .cr_CLK(cr_CLK),
+ .cr_A(cr_A),
+ .cr_DQ(cr_DQ));
+`endif
wire lcdhs, lcdvs, lcdclk;
wire [2:0] lcdr, lcdg;
.vgar(r),
.vgag(g),
.vgab(b));
-
+
+ Switches sw(
+ .clk(clk),
+ .address(addr[0]),
+ .data(data[0]),
+ .wr(wr[0]),
+ .rd(rd[0]),
+ .ledout(leds),
+ .switches(switches)
+ );
+
AddrMon amon(
.clk(clk),
.addr(addr[0]),
(state == 2'b10) ? 4'b1000 :
4'b0100) );
- Switches sw(
- .clk(clk),
- .address(addr[0]),
- .data(data[0]),
- .wr(wr[0]),
- .rd(rd[0]),
- .ledout(leds),
- .switches(switches)
- );
-
UART nouart ( /* no u */
.clk(clk),
.addr(addr[0]),
.data(data[0]),
.wr(wr[0]),
.rd(rd[0]),
- .serial(serio)
+ .serial(serio),
+ .serialrx(serin)
);
InternalRAM ram(
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