input clk,
input wr, rd);
+ reg rdlatch = 0;
reg [7:0] odata;
// synthesis attribute ram_style of rom is block
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 rdlatch = 0;
+ reg [7:0] addrlatch = 0;
reg [7:0] brom [255:0];
initial $readmemh("bootstrap.hex", brom);
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 = brom[addrlatch];
+ always @(posedge clk) begin
+ rdlatch <= rd && decode;
+ addrlatch <= address[7:0];
+ 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;
+
+ reg rdlatch = 0, wrlatch = 0;
+ reg [15:0] addrlatch = 0;
+ reg [7:0] datalatch = 0;
+
+ reg [7:0] progaddrh, progaddrm, progaddrl;
+
+ 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);
+
+ assign cr_nOE = decode ? ~rdlatch : 1;
+ assign cr_nWE = decode ? ~wrlatch : 1;
+
+ assign cr_DQ = (~cr_nOE) ? 16'bzzzzzzzzzzzzzzzz : {8'b0, datalatch};
+ assign cr_A = (addrlatch[15:14] == 2'b00) ? /* extrom */ {9'b0,addrlatch[13:0]} :
+ (addrlatch[15:13] == 3'b101) ? {1'b1, 9'b0, addrlatch[12:0]} :
+ (addrlatch == ADDR_PROGDATA) ? {progaddrh[6:0], progaddrm[7:0], progaddrl[7:0]} :
+ 23'b0;
+
+ reg [7:0] regbuf;
+
+ always @(posedge clk) begin
+ case (address)
+ ADDR_PROGADDRH: if (wr) progaddrh <= data;
+ ADDR_PROGADDRM: if (wr) progaddrm <= data;
+ ADDR_PROGADDRL: if (wr) progaddrl <= data;
+ endcase
+ 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)
output serio,
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,
.wr(wr[1]),
.rd(rd[1]));
+`ifdef isim
ROM 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_nWR(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;
git.joshuawise.com / fpgaboy.git / blobdiff