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yosys/tests/iwls2005/simple_spi/simple_spi_top.v

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/////////////////////////////////////////////////////////////////////
//// ////
//// OpenCores MC68HC11E based SPI interface ////
//// ////
//// Author: Richard Herveille ////
//// richard@asics.ws ////
//// www.asics.ws ////
//// ////
/////////////////////////////////////////////////////////////////////
//// ////
//// Copyright (C) 2002 Richard Herveille ////
//// richard@asics.ws ////
//// ////
//// This source file may be used and distributed without ////
//// restriction provided that this copyright statement is not ////
//// removed from the file and that any derivative work contains ////
//// the original copyright notice and the associated disclaimer.////
//// ////
//// THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY ////
//// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED ////
//// TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS ////
//// FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL THE AUTHOR ////
//// OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, ////
//// INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES ////
//// (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE ////
//// GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR ////
//// BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF ////
//// LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT ////
//// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT ////
//// OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE ////
//// POSSIBILITY OF SUCH DAMAGE. ////
//// ////
/////////////////////////////////////////////////////////////////////
// CVS Log
//
// $Id: simple_spi_top.v,v 1.5 2004/02/28 15:59:50 rherveille Exp $
//
// $Date: 2004/02/28 15:59:50 $
// $Revision: 1.5 $
// $Author: rherveille $
// $Locker: $
// $State: Exp $
//
// Change History:
// $Log: simple_spi_top.v,v $
// Revision 1.5 2004/02/28 15:59:50 rherveille
// Fixed SCK_O generation bug.
// This resulted in a major rewrite of the serial interface engine.
//
// Revision 1.4 2003/08/01 11:41:54 rherveille
// Fixed some timing bugs.
//
// Revision 1.3 2003/01/09 16:47:59 rherveille
// Updated clkcnt size and decoding due to new SPR bit assignments.
//
// Revision 1.2 2003/01/07 13:29:52 rherveille
// Changed SPR bits coding.
//
// Revision 1.1.1.1 2002/12/22 16:07:15 rherveille
// Initial release
//
//
//
// Motorola MC68HC11E based SPI interface
//
// Currently only MASTER mode is supported
//
// synopsys translate_off
`include "timescale.v"
// synopsys translate_on
module simple_spi_top(
// 8bit WISHBONE bus slave interface
input wire clk_i, // clock
input wire rst_i, // reset (asynchronous active low)
input wire cyc_i, // cycle
input wire stb_i, // strobe
input wire [1:0] adr_i, // address
input wire we_i, // write enable
input wire [7:0] dat_i, // data input
output reg [7:0] dat_o, // data output
output reg ack_o, // normal bus termination
output reg inta_o, // interrupt output
// SPI port
output reg sck_o, // serial clock output
output wire mosi_o, // MasterOut SlaveIN
input wire miso_i // MasterIn SlaveOut
);
//
// Module body
//
reg [7:0] spcr; // Serial Peripheral Control Register ('HC11 naming)
wire [7:0] spsr; // Serial Peripheral Status register ('HC11 naming)
reg [7:0] sper; // Serial Peripheral Extension register
reg [7:0] treg, rreg; // Transmit/Receive register
// fifo signals
wire [7:0] rfdout;
reg wfre, rfwe;
wire rfre, rffull, rfempty;
wire [7:0] wfdout;
wire wfwe, wffull, wfempty;
// misc signals
wire tirq; // transfer interrupt (selected number of transfers done)
wire wfov; // write fifo overrun (writing while fifo full)
reg [1:0] state; // statemachine state
reg [2:0] bcnt;
//
// Wishbone interface
wire wb_acc = cyc_i & stb_i; // WISHBONE access
wire wb_wr = wb_acc & we_i; // WISHBONE write access
// dat_i
always @(posedge clk_i or negedge rst_i)
if (~rst_i)
begin
spcr <= #1 8'h10; // set master bit
sper <= #1 8'h00;
end
else if (wb_wr)
begin
if (adr_i == 2'b00)
spcr <= #1 dat_i | 8'h10; // always set master bit
if (adr_i == 2'b11)
sper <= #1 dat_i;
end
// write fifo
assign wfwe = wb_acc & (adr_i == 2'b10) & ack_o & we_i;
assign wfov = wfwe & wffull;
// dat_o
always @(posedge clk_i)
case(adr_i) // synopsys full_case parallel_case
2'b00: dat_o <= #1 spcr;
2'b01: dat_o <= #1 spsr;
2'b10: dat_o <= #1 rfdout;
2'b11: dat_o <= #1 sper;
endcase
// read fifo
assign rfre = wb_acc & (adr_i == 2'b10) & ack_o & ~we_i;
// ack_o
always @(posedge clk_i or negedge rst_i)
if (~rst_i)
ack_o <= #1 1'b0;
else
ack_o <= #1 wb_acc & !ack_o;
// decode Serial Peripheral Control Register
wire spie = spcr[7]; // Interrupt enable bit
wire spe = spcr[6]; // System Enable bit
wire dwom = spcr[5]; // Port D Wired-OR Mode Bit
wire mstr = spcr[4]; // Master Mode Select Bit
wire cpol = spcr[3]; // Clock Polarity Bit
wire cpha = spcr[2]; // Clock Phase Bit
wire [1:0] spr = spcr[1:0]; // Clock Rate Select Bits
// decode Serial Peripheral Extension Register
wire [1:0] icnt = sper[7:6]; // interrupt on transfer count
wire [1:0] spre = sper[1:0]; // extended clock rate select
wire [3:0] espr = {spre, spr};
// generate status register
wire wr_spsr = wb_wr & (adr_i == 2'b01);
reg spif;
always @(posedge clk_i)
if (~spe)
spif <= #1 1'b0;
else
spif <= #1 (tirq | spif) & ~(wr_spsr & dat_i[7]);
reg wcol;
always @(posedge clk_i)
if (~spe)
wcol <= #1 1'b0;
else
wcol <= #1 (wfov | wcol) & ~(wr_spsr & dat_i[6]);
assign spsr[7] = spif;
assign spsr[6] = wcol;
assign spsr[5:4] = 2'b00;
assign spsr[3] = wffull;
assign spsr[2] = wfempty;
assign spsr[1] = rffull;
assign spsr[0] = rfempty;
// generate IRQ output (inta_o)
always @(posedge clk_i)
inta_o <= #1 spif & spie;
//
// hookup read/write buffer fifo
fifo4 #(8)
rfifo(
.clk ( clk_i ),
.rst ( rst_i ),
.clr ( ~spe ),
.din ( treg ),
.we ( rfwe ),
.dout ( rfdout ),
.re ( rfre ),
.full ( rffull ),
.empty ( rfempty )
),
wfifo(
.clk ( clk_i ),
.rst ( rst_i ),
.clr ( ~spe ),
.din ( dat_i ),
.we ( wfwe ),
.dout ( wfdout ),
.re ( wfre ),
.full ( wffull ),
.empty ( wfempty )
);
//
// generate clk divider
reg [11:0] clkcnt;
always @(posedge clk_i)
if(spe & (|clkcnt & |state))
clkcnt <= #1 clkcnt - 11'h1;
else
case (espr) // synopsys full_case parallel_case
4'b0000: clkcnt <= #1 12'h0; // 2 -- original M68HC11 coding
4'b0001: clkcnt <= #1 12'h1; // 4 -- original M68HC11 coding
4'b0010: clkcnt <= #1 12'h3; // 16 -- original M68HC11 coding
4'b0011: clkcnt <= #1 12'hf; // 32 -- original M68HC11 coding
4'b0100: clkcnt <= #1 12'h1f; // 8
4'b0101: clkcnt <= #1 12'h7; // 64
4'b0110: clkcnt <= #1 12'h3f; // 128
4'b0111: clkcnt <= #1 12'h7f; // 256
4'b1000: clkcnt <= #1 12'hff; // 512
4'b1001: clkcnt <= #1 12'h1ff; // 1024
4'b1010: clkcnt <= #1 12'h3ff; // 2048
4'b1011: clkcnt <= #1 12'h7ff; // 4096
endcase
// generate clock enable signal
wire ena = ~|clkcnt;
// transfer statemachine
always @(posedge clk_i)
if (~spe)
begin
state <= #1 2'b00; // idle
bcnt <= #1 3'h0;
treg <= #1 8'h00;
wfre <= #1 1'b0;
rfwe <= #1 1'b0;
sck_o <= #1 1'b0;
end
else
begin
wfre <= #1 1'b0;
rfwe <= #1 1'b0;
case (state) //synopsys full_case parallel_case
2'b00: // idle state
begin
bcnt <= #1 3'h7; // set transfer counter
treg <= #1 wfdout; // load transfer register
sck_o <= #1 cpol; // set sck
if (~wfempty) begin
wfre <= #1 1'b1;
state <= #1 2'b01;
if (cpha) sck_o <= #1 ~sck_o;
end
end
2'b01: // clock-phase2, next data
if (ena) begin
sck_o <= #1 ~sck_o;
state <= #1 2'b11;
end
2'b11: // clock phase1
if (ena) begin
treg <= #1 {treg[6:0], miso_i};
bcnt <= #1 bcnt -3'h1;
if (~|bcnt) begin
state <= #1 2'b00;
sck_o <= #1 cpol;
rfwe <= #1 1'b1;
end else begin
state <= #1 2'b01;
sck_o <= #1 ~sck_o;
end
end
2'b10: state <= #1 2'b00;
endcase
end
assign mosi_o = treg[7];
// count number of transfers (for interrupt generation)
reg [1:0] tcnt; // transfer count
always @(posedge clk_i)
if (~spe)
tcnt <= #1 icnt;
else if (rfwe) // rfwe gets asserted when all bits have been transfered
if (|tcnt)
tcnt <= #1 tcnt - 2'h1;
else
tcnt <= #1 icnt;
assign tirq = ~|tcnt & rfwe;
endmodule
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