www.pudn.com > DE2_WEB.rar > timer_1.v, change:2006-04-18,size:6773b
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// turn off bogus verilog processor warnings
// altera message_off 10034 10035 10036 10037 10230
// synthesis translate_off
`timescale 1ns / 1ps
// synthesis translate_on
module timer_1 (
// inputs:
address,
chipselect,
clk,
reset_n,
write_n,
writedata,
// outputs:
irq,
readdata
)
;
output irq;
output [ 15: 0] readdata;
input [ 2: 0] address;
input chipselect;
input clk;
input reset_n;
input write_n;
input [ 15: 0] writedata;
wire clk_en;
wire control_continuous;
wire control_interrupt_enable;
reg [ 3: 0] control_register;
wire control_wr_strobe;
reg counter_is_running;
wire counter_is_zero;
wire [ 31: 0] counter_load_value;
reg [ 31: 0] counter_snapshot;
reg delayed_unxcounter_is_zeroxx0;
wire do_start_counter;
wire do_stop_counter;
reg force_reload;
reg [ 31: 0] internal_counter;
wire irq;
reg [ 15: 0] period_h_register;
wire period_h_wr_strobe;
reg [ 15: 0] period_l_register;
wire period_l_wr_strobe;
wire [ 15: 0] read_mux_out;
reg [ 15: 0] readdata;
wire snap_h_wr_strobe;
wire snap_l_wr_strobe;
wire [ 31: 0] snap_read_value;
wire snap_strobe;
wire start_strobe;
wire status_wr_strobe;
wire stop_strobe;
wire timeout_event;
reg timeout_occurred;
assign clk_en = 1;
always @(posedge clk or negedge reset_n)
begin
if (reset_n == 0)
internal_counter = 32'h1869F;
else if (counter_is_running || force_reload)
if (counter_is_zero || force_reload)
internal_counter = counter_load_value;
else
internal_counter = internal_counter - 1;
end
assign counter_is_zero = internal_counter == 0;
assign counter_load_value = {period_h_register,
period_l_register};
always @(posedge clk or negedge reset_n)
begin
if (reset_n == 0)
force_reload = 0;
else if (clk_en)
force_reload = period_h_wr_strobe || period_l_wr_strobe;
end
assign do_start_counter = start_strobe;
assign do_stop_counter = (stop_strobe ) ||
(force_reload ) ||
(counter_is_zero && ~control_continuous );
always @(posedge clk or negedge reset_n)
begin
if (reset_n == 0)
counter_is_running = 1'b0;
else if (clk_en)
if (do_start_counter)
counter_is_running = -1;
else if (do_stop_counter)
counter_is_running = 0;
end
//delayed_unxcounter_is_zeroxx0, which is an e_register
always @(posedge clk or negedge reset_n)
begin
if (reset_n == 0)
delayed_unxcounter_is_zeroxx0 = 0;
else if (clk_en)
delayed_unxcounter_is_zeroxx0 = counter_is_zero;
end
assign timeout_event = (counter_is_zero) & ~(delayed_unxcounter_is_zeroxx0);
always @(posedge clk or negedge reset_n)
begin
if (reset_n == 0)
timeout_occurred = 0;
else if (clk_en)
if (status_wr_strobe)
timeout_occurred = 0;
else if (timeout_event)
timeout_occurred = -1;
end
assign irq = timeout_occurred && control_interrupt_enable;
//s1, which is an e_avalon_slave
assign read_mux_out = ({16 {(address == 2)}} & period_l_register) |
({16 {(address == 3)}} & period_h_register) |
({16 {(address == 4)}} & snap_read_value[15 : 0]) |
({16 {(address == 5)}} & snap_read_value[31 : 16]) |
({16 {(address == 1)}} & control_register) |
({16 {(address == 0)}} & {counter_is_running,
timeout_occurred});
always @(posedge clk or negedge reset_n)
begin
if (reset_n == 0)
readdata = 0;
else if (clk_en)
readdata = read_mux_out;
end
assign period_l_wr_strobe = chipselect && ~write_n && (address == 2);
assign period_h_wr_strobe = chipselect && ~write_n && (address == 3);
always @(posedge clk or negedge reset_n)
begin
if (reset_n == 0)
period_l_register = 34463;
else if (period_l_wr_strobe)
period_l_register = writedata;
end
always @(posedge clk or negedge reset_n)
begin
if (reset_n == 0)
period_h_register = 1;
else if (period_h_wr_strobe)
period_h_register = writedata;
end
assign snap_l_wr_strobe = chipselect && ~write_n && (address == 4);
assign snap_h_wr_strobe = chipselect && ~write_n && (address == 5);
assign snap_strobe = snap_l_wr_strobe || snap_h_wr_strobe;
always @(posedge clk or negedge reset_n)
begin
if (reset_n == 0)
counter_snapshot = 0;
else if (snap_strobe)
counter_snapshot = internal_counter;
end
assign snap_read_value = counter_snapshot;
assign control_wr_strobe = chipselect && ~write_n && (address == 1);
always @(posedge clk or negedge reset_n)
begin
if (reset_n == 0)
control_register = 0;
else if (control_wr_strobe)
control_register = writedata[3 : 0];
end
assign stop_strobe = writedata[3] && control_wr_strobe;
assign start_strobe = writedata[2] && control_wr_strobe;
assign control_continuous = control_register[1];
assign control_interrupt_enable = control_register;
assign status_wr_strobe = chipselect && ~write_n && (address == 0);
endmodule