picorv32/spiflash/top.v

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2017-07-29 10:01:39 -04:00
module top (
input clk,
output trap,
input [31:0] gpio_i,
output reg [31:0] gpio_o,
output spi_cs,
output spi_sclk,
output spi_mosi,
input spi_miso
);
parameter integer MEM_WORDS = 256;
parameter [31:0] STACKADDR = (4*MEM_WORDS); // end of memory
parameter [31:0] PROGADDR_RESET = 32'h 8010_0000; // 1 MB into flash
reg [5:0] reset_cnt = 0;
wire resetn = &reset_cnt;
always @(posedge clk) begin
reset_cnt <= reset_cnt + !resetn;
end
wire mem_valid;
wire mem_instr;
reg mem_ready;
wire [31:0] mem_addr;
wire [31:0] mem_wdata;
wire [3:0] mem_wstrb;
reg [31:0] mem_rdata;
wire spimem_ready;
wire [31:0] spimem_rdata;
picorv32 #(
.STACKADDR(STACKADDR),
.PROGADDR_RESET(PROGADDR_RESET)
) cpu (
.clk (clk ),
.resetn (resetn ),
.trap (trap ),
.mem_valid (mem_valid ),
.mem_instr (mem_instr ),
.mem_ready (mem_ready || spimem_ready),
.mem_addr (mem_addr ),
.mem_wdata (mem_wdata ),
.mem_wstrb (mem_wstrb ),
.mem_rdata (spimem_ready ? spimem_rdata : mem_rdata )
);
spimemio spimemio (
.clk(clk),
.resetn(resetn),
.valid (mem_valid && mem_addr[31:30] == 2'b10),
.ready (spimem_ready),
.addr (mem_addr[23:0]),
.rdata (spimem_rdata),
.spi_cs (spi_cs ),
.spi_sclk (spi_sclk),
.spi_mosi (spi_mosi),
.spi_miso (spi_miso)
);
reg [31:0] memory [0:MEM_WORDS-1];
always @(posedge clk) begin
mem_ready <= 0;
if (mem_valid && !mem_ready) begin
if (mem_addr < 4*MEM_WORDS) begin
mem_ready <= 1;
mem_rdata <= memory[mem_addr >> 2];
if (mem_wstrb[0]) memory[mem_addr >> 2][ 7: 0] <= mem_wdata[ 7: 0];
if (mem_wstrb[1]) memory[mem_addr >> 2][15: 8] <= mem_wdata[15: 8];
if (mem_wstrb[2]) memory[mem_addr >> 2][23:16] <= mem_wdata[23:16];
if (mem_wstrb[3]) memory[mem_addr >> 2][31:24] <= mem_wdata[31:24];
end
if (mem_addr == 32'h c000_0000) begin
mem_ready <= 1;
mem_rdata <= gpio_i;
if (mem_wstrb[0]) gpio_o[ 7: 0] <= mem_wdata[ 7: 0];
if (mem_wstrb[1]) gpio_o[15: 8] <= mem_wdata[15: 8];
if (mem_wstrb[2]) gpio_o[23:16] <= mem_wdata[23:16];
if (mem_wstrb[3]) gpio_o[31:24] <= mem_wdata[31:24];
end
end
end
endmodule