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master
zhaohe 2 years ago
commit
bd773b8841
  1. 17
      .gitignore
  2. 58
      impl.tcl
  3. 60
      led_test.fdc
  4. 249
      led_test.pds
  5. 202
      source/async.v
  6. 44
      source/led_test.v
  7. 202
      source/source/async.v
  8. 35
      source/test.v

17
.gitignore

@ -0,0 +1,17 @@
sim/behav/work/_lib.qdb
generate_bitstream/
pango_sim_libraries/
sim/
place_route/
synthesize/
compile/
constraint_backup/
device_map/logbackup/
logbackup/
log/
pds.log
run.log
device_map/bak/
device_map/
report_timing/
ipcore/ram/ram.idf

58
impl.tcl

@ -0,0 +1,58 @@
#Generated by Fabric Compiler ( version 2021.1-SP7 <build 86875> ) at Fri Dec 8 16:54:29 2023
add_design "D:/workspace/fpga_demo/led_test/source/led_test.v"
set_arch -family Logos -device PGL22G -speedgrade -6 -package MBG324
compile -top_module led_test
add_constraint "D:/workspace/fpga_demo/led_test/led_test.fdc"
synthesize -ads -selected_syn_tool_opt 2
dev_map
pnr
pnr
pnr
pnr
pnr
pnr
synthesize -ads -selected_syn_tool_opt 2
dev_map
pnr
report_timing
gen_bit_stream
synthesize -ads -selected_syn_tool_opt 2
dev_map
pnr
report_timing
gen_bit_stream
add_design D:/workspace/fpga_demo/led_test/ipcore/clk_wiz_0/clk_wiz_0.idf
add_design D:/workspace/fpga_demo/led_test/ipcore/ram/ram.idf
remove_design -force D:/workspace/fpga_demo/led_test/ipcore/clk_wiz_0/clk_wiz_0.idf
gen_bit_stream
gen_bit_stream
gen_bit_stream
gen_bit_stream
set_arch -family Logos -device PGL22G -speedgrade -6 -package MBG324
compile -top_module led_test
synthesize -ads -selected_syn_tool_opt 2
dev_map
pnr
report_timing
gen_bit_stream
set_arch -family Logos -device PGL22G -speedgrade -6 -package MBG324
compile -top_module led_test
synthesize -ads -selected_syn_tool_opt 2
dev_map
pnr
report_timing
gen_bit_stream
set_arch -family Logos -device PGL22G -speedgrade -6 -package MBG324
compile -top_module led_test
set_arch -family Logos -device PGL22G -speedgrade -6 -package MBG324
compile -top_module led_test
synthesize -ads -selected_syn_tool_opt 2
dev_map
pnr
report_timing
gen_bit_stream
add_simulation "D:/workspace/fpga_demo/led_test/source/vtf_led.test.v"
remove_simulation -force "D:/workspace/fpga_demo/led_test/source/vtf_led.test.v"
add_simulation "D:/workspace/fpga_demo/led_test/source/test.v"
add_design "D:/workspace/fpga_demo/led_test/source/source/async.v"

60
led_test.fdc

@ -0,0 +1,60 @@
#define_attribute {p:led[3]} {PAP_IO_DIRECTION} {OUTPUT}
#define_attribute {p:led[3]} {PAP_IO_LOC} {U12}
#define_attribute {p:led[3]} {PAP_IO_VCCIO} {3.3}
#define_attribute {p:led[3]} {PAP_IO_STANDARD} {LVCMOS33}
#define_attribute {p:led[3]} {PAP_IO_DRIVE} {4}
#define_attribute {p:led[3]} {PAP_IO_SLEW} {SLOW}
#define_attribute {p:led[2]} {PAP_IO_DIRECTION} {OUTPUT}
#define_attribute {p:led[2]} {PAP_IO_LOC} {B5}
#define_attribute {p:led[2]} {PAP_IO_VCCIO} {3.3}
#define_attribute {p:led[2]} {PAP_IO_STANDARD} {LVCMOS33}
#define_attribute {p:led[2]} {PAP_IO_DRIVE} {4}
#define_attribute {p:led[2]} {PAP_IO_SLEW} {SLOW}
#define_attribute {p:led[1]} {PAP_IO_DIRECTION} {OUTPUT}
#define_attribute {p:led[1]} {PAP_IO_LOC} {U10}
#define_attribute {p:led[1]} {PAP_IO_VCCIO} {3.3}
#define_attribute {p:led[1]} {PAP_IO_STANDARD} {LVCMOS33}
#define_attribute {p:led[1]} {PAP_IO_DRIVE} {4}
#define_attribute {p:led[1]} {PAP_IO_SLEW} {SLOW}
define_attribute {p:led[0]} {PAP_IO_DIRECTION} {OUTPUT}
define_attribute {p:led[0]} {PAP_IO_LOC} {U10}
define_attribute {p:led[0]} {PAP_IO_VCCIO} {3.3}
define_attribute {p:led[0]} {PAP_IO_STANDARD} {LVCMOS33}
define_attribute {p:led[0]} {PAP_IO_DRIVE} {4}
define_attribute {p:led[0]} {PAP_IO_SLEW} {SLOW}
#define_attribute {p:rst_n} {PAP_IO_DIRECTION} {INPUT}
#define_attribute {p:rst_n} {PAP_IO_LOC} {U11}
#define_attribute {p:rst_n} {PAP_IO_VCCIO} {3.3}
#define_attribute {p:rst_n} {PAP_IO_STANDARD} {LVTTL33}
#define_attribute {p:sys_clk} {PAP_IO_DIRECTION} {INPUT}
#define_attribute {p:sys_clk} {PAP_IO_LOC} {V11}
#define_attribute {p:sys_clk} {PAP_IO_VCCIO} {3.3}
#define_attribute {p:sys_clk} {PAP_IO_STANDARD} {LVTTL33}
define_attribute {p:led[3]} {PAP_IO_DIRECTION} {OUTPUT}
define_attribute {p:led[3]} {PAP_IO_LOC} {V11}
define_attribute {p:led[3]} {PAP_IO_VCCIO} {3.3}
define_attribute {p:led[3]} {PAP_IO_STANDARD} {LVCMOS33}
define_attribute {p:led[3]} {PAP_IO_DRIVE} {4}
define_attribute {p:led[3]} {PAP_IO_SLEW} {SLOW}
define_attribute {p:led[2]} {PAP_IO_DIRECTION} {OUTPUT}
define_attribute {p:led[2]} {PAP_IO_LOC} {U11}
define_attribute {p:led[2]} {PAP_IO_VCCIO} {3.3}
define_attribute {p:led[2]} {PAP_IO_STANDARD} {LVCMOS33}
define_attribute {p:led[2]} {PAP_IO_DRIVE} {4}
define_attribute {p:led[2]} {PAP_IO_SLEW} {SLOW}
define_attribute {p:led[1]} {PAP_IO_DIRECTION} {OUTPUT}
define_attribute {p:led[1]} {PAP_IO_LOC} {V10}
define_attribute {p:led[1]} {PAP_IO_VCCIO} {3.3}
define_attribute {p:led[1]} {PAP_IO_STANDARD} {LVCMOS33}
define_attribute {p:led[1]} {PAP_IO_DRIVE} {4}
define_attribute {p:led[1]} {PAP_IO_SLEW} {SLOW}
define_attribute {p:rst_n} {PAP_IO_DIRECTION} {INPUT}
define_attribute {p:rst_n} {PAP_IO_LOC} {U12}
define_attribute {p:rst_n} {PAP_IO_VCCIO} {3.3}
define_attribute {p:rst_n} {PAP_IO_STANDARD} {LVTTL33}
define_attribute {p:sys_clk} {PAP_IO_DIRECTION} {INPUT}
define_attribute {p:sys_clk} {PAP_IO_LOC} {B5}
define_attribute {p:sys_clk} {PAP_IO_VCCIO} {3.3}
define_attribute {p:sys_clk} {PAP_IO_STANDARD} {LVTTL33}
#create_clock -name {} -period {10.000} -waveform {0.000 5.000}
#define_attribute {p:sys_clk} {PAP_IO_HYS_DRIVE_MODE} {NOHYS}

249
led_test.pds

@ -0,0 +1,249 @@
(_flow fab_demo "2021.1-SP7"
(_comment "Generated by Fabric Compiler (version on 2021.1-SP7<build 86875>) at Wed Dec 13 10:46:05 2023")
(_version "1.0.5")
(_status "initial")
(_project
)
(_task tsk_setup
(_widget wgt_select_arch
(_input
(_part
(_family Logos)
(_device PGL22G)
(_speedgrade -6)
(_package MBG324)
)
)
)
(_widget wgt_my_design_src
(_input
(_file "source/led_test.v" + "led_test"
(_format verilog)
(_timespec "2023-12-12T18:38:54")
)
(_file "source/source/async.v"
(_format verilog)
(_timespec "2023-12-13T10:42:04")
)
)
)
(_widget wgt_my_ips_src
)
(_widget wgt_import_logic_con_file
(_input
(_file "led_test.fdc"
(_format fdc)
(_timespec "2023-12-08T19:12:53")
)
)
)
(_widget wgt_edit_user_cons
(_attribute _click_to_run (_switch ON))
)
(_widget wgt_simulation
(_input
(_file "source/test.v" + "vtf_led_test"
(_format verilog)
(_timespec "2023-12-12T18:47:34")
)
)
)
)
(_task tsk_compile
(_command cmd_compile
(_gci_state (_integer 3))
(_db_output
(_file "compile/led_test_comp.adf"
(_format adif)
(_timespec "2023-12-12T18:39:06")
)
)
(_output
(_file "compile/led_test.cmr"
(_format verilog)
(_timespec "2023-12-12T18:39:06")
)
(_file "compile/cmr.db"
(_format text)
(_timespec "2023-12-12T18:39:06")
)
)
)
(_widget wgt_rtl_view
(_attribute _click_to_run (_switch ON))
)
)
(_task tsk_synthesis
(_command cmd_synthesize
(_gci_state (_integer 3))
(_option ads (_switch ON))
(_option selected_syn_tool_opt (_integer 2))
(_db_output
(_file "synthesize/led_test_syn.adf"
(_format adif)
(_timespec "2023-12-12T18:39:08")
)
)
(_output
(_file "synthesize/led_test_syn.vm"
(_format structural_verilog)
(_timespec "2023-12-12T18:39:08")
)
(_file "synthesize/led_test.snr"
(_format text)
(_timespec "2023-12-12T18:39:08")
)
(_file "synthesize/snr.db"
(_format text)
(_timespec "2023-12-12T18:39:09")
)
)
)
(_widget wgt_tech_view
(_attribute _click_to_run (_switch ON))
)
(_widget wgt_map_constraint
)
(_widget wgt_my_fic_src
)
(_widget wgt_inserter_gui_view
(_attribute _click_to_run (_switch ON))
)
)
(_task tsk_devmap
(_command cmd_devmap
(_gci_state (_integer 3))
(_db_output
(_file "device_map/led_test_map.adf"
(_format adif)
(_timespec "2023-12-12T18:39:11")
)
)
(_output
(_file "device_map/led_test_dmr.prt"
(_format text)
(_timespec "2023-12-12T18:39:11")
)
(_file "device_map/led_test.dmr"
(_format text)
(_timespec "2023-12-12T18:39:11")
)
(_file "device_map/dmr.db"
(_format text)
(_timespec "2023-12-12T18:39:11")
)
)
)
(_widget wgt_edit_placement_cons
(_attribute _click_to_run (_switch ON))
(_input
(_file "device_map/led_test.pcf"
(_format pcf)
(_timespec "2023-12-12T18:39:11")
)
)
)
(_widget wgt_edit_route_cons
(_attribute _click_to_run (_switch ON))
)
)
(_task tsk_pnr
(_command cmd_pnr
(_gci_state (_integer 3))
(_db_output
(_file "place_route/led_test_pnr.adf"
(_format adif)
(_timespec "2023-12-12T18:39:16")
)
)
(_output
(_file "place_route/led_test.prr"
(_format text)
(_timespec "2023-12-12T18:39:16")
)
(_file "place_route/led_test_prr.prt"
(_format text)
(_timespec "2023-12-12T18:39:16")
)
(_file "place_route/clock_utilization.txt"
(_format text)
(_timespec "2023-12-12T18:39:16")
)
(_file "place_route/led_test_plc.adf"
(_format adif)
(_timespec "2023-12-12T18:39:15")
)
(_file "place_route/led_test_pnr.netlist"
(_format text)
(_timespec "2023-12-12T18:39:16")
)
(_file "place_route/prr.db"
(_format text)
(_timespec "2023-12-12T18:39:16")
)
)
)
(_widget wgt_power_calculator
(_attribute _click_to_run (_switch ON))
)
(_widget wgt_timing_analysis
(_attribute _click_to_run (_switch ON))
)
(_command cmd_report_post_pnr_timing
(_gci_state (_integer 3))
(_attribute _auto_exe_lock (_switch OFF))
(_db_output
(_file "report_timing/led_test_rtp.adf"
(_format adif)
(_timespec "2023-12-12T18:39:19")
)
)
(_output
(_file "report_timing/led_test.rtr"
(_format text)
(_timespec "2023-12-12T18:39:19")
)
(_file "report_timing/rtr.db"
(_format text)
(_timespec "2023-12-12T18:39:19")
)
)
)
(_widget wgt_arch_browser
(_attribute _click_to_run (_switch ON))
)
(_command cmd_report_power
(_gci_state (_integer 0))
(_attribute _auto_exe_lock (_switch OFF))
(_attribute _auto_exe (_switch OFF))
)
(_command cmd_gen_netlist
(_gci_state (_integer 0))
(_attribute _auto_exe_lock (_switch OFF))
(_attribute _auto_exe (_switch OFF))
)
)
(_task tsk_gen_bitstream
(_command cmd_gen_bitstream
(_gci_state (_integer 3))
(_output
(_file "generate_bitstream/led_test.sbit"
(_format text)
(_timespec "2023-12-12T18:39:23")
)
(_file "generate_bitstream/led_test.smsk"
(_format text)
(_timespec "2023-12-12T18:39:23")
)
(_file "generate_bitstream/led_test.bgr"
(_format text)
(_timespec "2023-12-12T18:39:23")
)
(_file "generate_bitstream/bgr.db"
(_format text)
(_timespec "2023-12-12T18:39:23")
)
)
)
)
)

202
source/async.v

@ -0,0 +1,202 @@
////////////////////////////////////////////////////////
// RS-232 RX and TX module
// (c) fpga4fun.com & KNJN LLC - 2003 to 2016
// The RS-232 settings are fixed
// TX: 8-bit data, 2 stop, no-parity
// RX: 8-bit data, 1 stop, no-parity (the receiver can accept more stop bits of course)
//`define SIMULATION // in this mode, TX outputs one bit per clock cycle
// and RX receives one bit per clock cycle (for fast simulations)
////////////////////////////////////////////////////////
module async_transmitter(
input clk,
input TxD_start,
input [7:0] TxD_data,
output TxD,
output TxD_busy
);
// Assert TxD_start for (at least) one clock cycle to start transmission of TxD_data
// TxD_data is latched so that it doesn't have to stay valid while it is being sent
parameter ClkFrequency = 50000000; // 50MHz
parameter Baud = 115200;
generate
if(ClkFrequency<Baud*8 && (ClkFrequency % Baud!=0)) ASSERTION_ERROR PARAMETER_OUT_OF_RANGE("Frequency incompatible with requested Baud rate");
endgenerate
////////////////////////////////
`ifdef SIMULATION
wire BitTick = 1'b1; // output one bit per clock cycle
`else
wire BitTick;
BaudTickGen #(ClkFrequency, Baud) tickgen(.clk(clk), .enable(TxD_busy), .tick(BitTick));
`endif
reg [3:0] TxD_state = 0;
wire TxD_ready = (TxD_state==0);
assign TxD_busy = ~TxD_ready;
reg [7:0] TxD_shift = 0;
always @(posedge clk)
begin
if(TxD_ready & TxD_start)
TxD_shift <= TxD_data;
else
if(TxD_state[3] & BitTick)
TxD_shift <= (TxD_shift >> 1);
case(TxD_state)
4'b0000: if(TxD_start) TxD_state <= 4'b0100;
4'b0100: if(BitTick) TxD_state <= 4'b1000; // start bit
4'b1000: if(BitTick) TxD_state <= 4'b1001; // bit 0
4'b1001: if(BitTick) TxD_state <= 4'b1010; // bit 1
4'b1010: if(BitTick) TxD_state <= 4'b1011; // bit 2
4'b1011: if(BitTick) TxD_state <= 4'b1100; // bit 3
4'b1100: if(BitTick) TxD_state <= 4'b1101; // bit 4
4'b1101: if(BitTick) TxD_state <= 4'b1110; // bit 5
4'b1110: if(BitTick) TxD_state <= 4'b1111; // bit 6
4'b1111: if(BitTick) TxD_state <= 4'b0010; // bit 7
4'b0010: if(BitTick) TxD_state <= 4'b0011; // stop1
4'b0011: if(BitTick) TxD_state <= 4'b0000; // stop2
default: if(BitTick) TxD_state <= 4'b0000;
endcase
end
assign TxD = (TxD_state<4) | (TxD_state[3] & TxD_shift[0]); // put together the start, data and stop bits
endmodule
////////////////////////////////////////////////////////
module async_receiver(
input clk,
input RxD,
output reg RxD_data_ready = 0,
output reg [7:0] RxD_data = 0, // data received, valid only (for one clock cycle) when RxD_data_ready is asserted
// We also detect if a gap occurs in the received stream of characters
// That can be useful if multiple characters are sent in burst
// so that multiple characters can be treated as a "packet"
output RxD_idle, // asserted when no data has been received for a while
output reg RxD_endofpacket = 0 // asserted for one clock cycle when a packet has been detected (i.e. RxD_idle is going high)
);
parameter ClkFrequency = 25000000; // 25MHz
parameter Baud = 115200;
parameter Oversampling = 8; // needs to be a power of 2
// we oversample the RxD line at a fixed rate to capture each RxD data bit at the "right" time
// 8 times oversampling by default, use 16 for higher quality reception
generate
if(ClkFrequency<Baud*Oversampling) ASSERTION_ERROR PARAMETER_OUT_OF_RANGE("Frequency too low for current Baud rate and oversampling");
if(Oversampling<8 || ((Oversampling & (Oversampling-1))!=0)) ASSERTION_ERROR PARAMETER_OUT_OF_RANGE("Invalid oversampling value");
endgenerate
////////////////////////////////
reg [3:0] RxD_state = 0;
`ifdef SIMULATION
wire RxD_bit = RxD;
wire sampleNow = 1'b1; // receive one bit per clock cycle
`else
wire OversamplingTick;
BaudTickGen #(ClkFrequency, Baud, Oversampling) tickgen(.clk(clk), .enable(1'b1), .tick(OversamplingTick));
// synchronize RxD to our clk domain
reg [1:0] RxD_sync = 2'b11;
always @(posedge clk) if(OversamplingTick) RxD_sync <= {RxD_sync[0], RxD};
// and filter it
reg [1:0] Filter_cnt = 2'b11;
reg RxD_bit = 1'b1;
always @(posedge clk)
if(OversamplingTick)
begin
if(RxD_sync[1]==1'b1 && Filter_cnt!=2'b11) Filter_cnt <= Filter_cnt + 1'd1;
else
if(RxD_sync[1]==1'b0 && Filter_cnt!=2'b00) Filter_cnt <= Filter_cnt - 1'd1;
if(Filter_cnt==2'b11) RxD_bit <= 1'b1;
else
if(Filter_cnt==2'b00) RxD_bit <= 1'b0;
end
// and decide when is the good time to sample the RxD line
function integer log2(input integer v); begin log2=0; while(v>>log2) log2=log2+1; end endfunction
localparam l2o = log2(Oversampling);
reg [l2o-2:0] OversamplingCnt = 0;
always @(posedge clk) if(OversamplingTick) OversamplingCnt <= (RxD_state==0) ? 1'd0 : OversamplingCnt + 1'd1;
wire sampleNow = OversamplingTick && (OversamplingCnt==Oversampling/2-1);
`endif
// now we can accumulate the RxD bits in a shift-register
always @(posedge clk)
case(RxD_state)
4'b0000: if(~RxD_bit) RxD_state <= `ifdef SIMULATION 4'b1000 `else 4'b0001 `endif; // start bit found?
4'b0001: if(sampleNow) RxD_state <= 4'b1000; // sync start bit to sampleNow
4'b1000: if(sampleNow) RxD_state <= 4'b1001; // bit 0
4'b1001: if(sampleNow) RxD_state <= 4'b1010; // bit 1
4'b1010: if(sampleNow) RxD_state <= 4'b1011; // bit 2
4'b1011: if(sampleNow) RxD_state <= 4'b1100; // bit 3
4'b1100: if(sampleNow) RxD_state <= 4'b1101; // bit 4
4'b1101: if(sampleNow) RxD_state <= 4'b1110; // bit 5
4'b1110: if(sampleNow) RxD_state <= 4'b1111; // bit 6
4'b1111: if(sampleNow) RxD_state <= 4'b0010; // bit 7
4'b0010: if(sampleNow) RxD_state <= 4'b0000; // stop bit
default: RxD_state <= 4'b0000;
endcase
always @(posedge clk)
if(sampleNow && RxD_state[3]) RxD_data <= {RxD_bit, RxD_data[7:1]};
//reg RxD_data_error = 0;
always @(posedge clk)
begin
RxD_data_ready <= (sampleNow && RxD_state==4'b0010 && RxD_bit); // make sure a stop bit is received
//RxD_data_error <= (sampleNow && RxD_state==4'b0010 && ~RxD_bit); // error if a stop bit is not received
end
`ifdef SIMULATION
assign RxD_idle = 0;
`else
reg [l2o+1:0] GapCnt = 0;
always @(posedge clk) if (RxD_state!=0) GapCnt<=0; else if(OversamplingTick & ~GapCnt[log2(Oversampling)+1]) GapCnt <= GapCnt + 1'h1;
assign RxD_idle = GapCnt[l2o+1];
always @(posedge clk) RxD_endofpacket <= OversamplingTick & ~GapCnt[l2o+1] & &GapCnt[l2o:0];
`endif
endmodule
////////////////////////////////////////////////////////
// dummy module used to be able to raise an assertion in Verilog
module ASSERTION_ERROR();
endmodule
////////////////////////////////////////////////////////
module BaudTickGen(
input clk, enable,
output tick // generate a tick at the specified baud rate * oversampling
);
parameter ClkFrequency = 25000000;
parameter Baud = 115200;
parameter Oversampling = 1;
function integer log2(input integer v); begin log2=0; while(v>>log2) log2=log2+1; end endfunction
localparam AccWidth = log2(ClkFrequency/Baud)+8; // +/- 2% max timing error over a byte
reg [AccWidth:0] Acc = 0;
localparam ShiftLimiter = log2(Baud*Oversampling >> (31-AccWidth)); // this makes sure Inc calculation doesn't overflow
localparam Inc = ((Baud*Oversampling << (AccWidth-ShiftLimiter))+(ClkFrequency>>(ShiftLimiter+1)))/(ClkFrequency>>ShiftLimiter);
always @(posedge clk) if(enable) Acc <= Acc[AccWidth-1:0] + Inc[AccWidth:0]; else Acc <= Inc[AccWidth:0];
assign tick = Acc[AccWidth];
endmodule
////////////////////////////////////////////////////////

44
source/led_test.v

@ -0,0 +1,44 @@
`timescale 1ns/1ns
module led_test
(
sys_clk, // system clock 50Mhz on board
rst_n, // reset ,low active
led // LED,use for control the LED signal on board
);
input sys_clk;
input rst_n;
output [3:0] led;
//define the time counter
reg [31:0] timer;
reg [3:0] led;
always @(posedge sys_clk or negedge rst_n)
begin
if (~rst_n)
timer <= 32'd0; // when the reset signal valid,time counter clearing
else if (timer == 32'd199_9999_9) //4 seconds count(50M*4-1=199999999)
timer <= 32'd0; //count done,clearing the time counter
else
timer <= timer + 1'b1; //timer counter = timer counter + 1
end
always @(posedge sys_clk or negedge rst_n)
begin
if (~rst_n)
led <= 4'b0000; //when the reset signal active
else if (timer == 32'd49_999_9) //time counter count to 1st sec,LED1 Extinguish
led <= 4'b0001;
else if (timer == 32'd99_999_9) //time counter count to 2nd sec,LED2 Extinguish
begin
led <= 4'b0010;
end
else if (timer == 32'd149_999_9) //time counter count to 3nd sec,LED3 Extinguish
led <= 4'b0100;
else if (timer == 32'd199_999_9) //time counter count to 4nd sec,LED4 Extinguish
led <= 4'b1000;
end
endmodule

202
source/source/async.v

@ -0,0 +1,202 @@
////////////////////////////////////////////////////////
// RS-232 RX and TX module
// (c) fpga4fun.com & KNJN LLC - 2003 to 2016
// The RS-232 settings are fixed
// TX: 8-bit data, 2 stop, no-parity
// RX: 8-bit data, 1 stop, no-parity (the receiver can accept more stop bits of course)
//`define SIMULATION // in this mode, TX outputs one bit per clock cycle
// and RX receives one bit per clock cycle (for fast simulations)
////////////////////////////////////////////////////////
module async_transmitter(
input clk,
input TxD_start,
input [7:0] TxD_data,
output TxD,
output TxD_busy
);
// Assert TxD_start for (at least) one clock cycle to start transmission of TxD_data
// TxD_data is latched so that it doesn't have to stay valid while it is being sent
parameter ClkFrequency = 50000000; // 50MHz
parameter Baud = 115200;
generate
if(ClkFrequency<Baud*8 && (ClkFrequency % Baud!=0)) ASSERTION_ERROR PARAMETER_OUT_OF_RANGE("Frequency incompatible with requested Baud rate");
endgenerate
////////////////////////////////
`ifdef SIMULATION
wire BitTick = 1'b1; // output one bit per clock cycle
`else
wire BitTick;
BaudTickGen #(ClkFrequency, Baud) tickgen(.clk(clk), .enable(TxD_busy), .tick(BitTick));
`endif
reg [3:0] TxD_state = 0;
wire TxD_ready = (TxD_state==0);
assign TxD_busy = ~TxD_ready;
reg [7:0] TxD_shift = 0;
always @(posedge clk)
begin
if(TxD_ready & TxD_start)
TxD_shift <= TxD_data;
else
if(TxD_state[3] & BitTick)
TxD_shift <= (TxD_shift >> 1);
case(TxD_state)
4'b0000: if(TxD_start) TxD_state <= 4'b0100;
4'b0100: if(BitTick) TxD_state <= 4'b1000; // start bit
4'b1000: if(BitTick) TxD_state <= 4'b1001; // bit 0
4'b1001: if(BitTick) TxD_state <= 4'b1010; // bit 1
4'b1010: if(BitTick) TxD_state <= 4'b1011; // bit 2
4'b1011: if(BitTick) TxD_state <= 4'b1100; // bit 3
4'b1100: if(BitTick) TxD_state <= 4'b1101; // bit 4
4'b1101: if(BitTick) TxD_state <= 4'b1110; // bit 5
4'b1110: if(BitTick) TxD_state <= 4'b1111; // bit 6
4'b1111: if(BitTick) TxD_state <= 4'b0010; // bit 7
4'b0010: if(BitTick) TxD_state <= 4'b0011; // stop1
4'b0011: if(BitTick) TxD_state <= 4'b0000; // stop2
default: if(BitTick) TxD_state <= 4'b0000;
endcase
end
assign TxD = (TxD_state<4) | (TxD_state[3] & TxD_shift[0]); // put together the start, data and stop bits
endmodule
////////////////////////////////////////////////////////
module async_receiver(
input clk,
input RxD,
output reg RxD_data_ready = 0,
output reg [7:0] RxD_data = 0, // data received, valid only (for one clock cycle) when RxD_data_ready is asserted
// We also detect if a gap occurs in the received stream of characters
// That can be useful if multiple characters are sent in burst
// so that multiple characters can be treated as a "packet"
output RxD_idle, // asserted when no data has been received for a while
output reg RxD_endofpacket = 0 // asserted for one clock cycle when a packet has been detected (i.e. RxD_idle is going high)
);
parameter ClkFrequency = 25000000; // 25MHz
parameter Baud = 115200;
parameter Oversampling = 8; // needs to be a power of 2
// we oversample the RxD line at a fixed rate to capture each RxD data bit at the "right" time
// 8 times oversampling by default, use 16 for higher quality reception
generate
if(ClkFrequency<Baud*Oversampling) ASSERTION_ERROR PARAMETER_OUT_OF_RANGE("Frequency too low for current Baud rate and oversampling");
if(Oversampling<8 || ((Oversampling & (Oversampling-1))!=0)) ASSERTION_ERROR PARAMETER_OUT_OF_RANGE("Invalid oversampling value");
endgenerate
////////////////////////////////
reg [3:0] RxD_state = 0;
`ifdef SIMULATION
wire RxD_bit = RxD;
wire sampleNow = 1'b1; // receive one bit per clock cycle
`else
wire OversamplingTick;
BaudTickGen #(ClkFrequency, Baud, Oversampling) tickgen(.clk(clk), .enable(1'b1), .tick(OversamplingTick));
// synchronize RxD to our clk domain
reg [1:0] RxD_sync = 2'b11;
always @(posedge clk) if(OversamplingTick) RxD_sync <= {RxD_sync[0], RxD};
// and filter it
reg [1:0] Filter_cnt = 2'b11;
reg RxD_bit = 1'b1;
always @(posedge clk)
if(OversamplingTick)
begin
if(RxD_sync[1]==1'b1 && Filter_cnt!=2'b11) Filter_cnt <= Filter_cnt + 1'd1;
else
if(RxD_sync[1]==1'b0 && Filter_cnt!=2'b00) Filter_cnt <= Filter_cnt - 1'd1;
if(Filter_cnt==2'b11) RxD_bit <= 1'b1;
else
if(Filter_cnt==2'b00) RxD_bit <= 1'b0;
end
// and decide when is the good time to sample the RxD line
function integer log2(input integer v); begin log2=0; while(v>>log2) log2=log2+1; end endfunction
localparam l2o = log2(Oversampling);
reg [l2o-2:0] OversamplingCnt = 0;
always @(posedge clk) if(OversamplingTick) OversamplingCnt <= (RxD_state==0) ? 1'd0 : OversamplingCnt + 1'd1;
wire sampleNow = OversamplingTick && (OversamplingCnt==Oversampling/2-1);
`endif
// now we can accumulate the RxD bits in a shift-register
always @(posedge clk)
case(RxD_state)
4'b0000: if(~RxD_bit) RxD_state <= `ifdef SIMULATION 4'b1000 `else 4'b0001 `endif; // start bit found?
4'b0001: if(sampleNow) RxD_state <= 4'b1000; // sync start bit to sampleNow
4'b1000: if(sampleNow) RxD_state <= 4'b1001; // bit 0
4'b1001: if(sampleNow) RxD_state <= 4'b1010; // bit 1
4'b1010: if(sampleNow) RxD_state <= 4'b1011; // bit 2
4'b1011: if(sampleNow) RxD_state <= 4'b1100; // bit 3
4'b1100: if(sampleNow) RxD_state <= 4'b1101; // bit 4
4'b1101: if(sampleNow) RxD_state <= 4'b1110; // bit 5
4'b1110: if(sampleNow) RxD_state <= 4'b1111; // bit 6
4'b1111: if(sampleNow) RxD_state <= 4'b0010; // bit 7
4'b0010: if(sampleNow) RxD_state <= 4'b0000; // stop bit
default: RxD_state <= 4'b0000;
endcase
always @(posedge clk)
if(sampleNow && RxD_state[3]) RxD_data <= {RxD_bit, RxD_data[7:1]};
//reg RxD_data_error = 0;
always @(posedge clk)
begin
RxD_data_ready <= (sampleNow && RxD_state==4'b0010 && RxD_bit); // make sure a stop bit is received
//RxD_data_error <= (sampleNow && RxD_state==4'b0010 && ~RxD_bit); // error if a stop bit is not received
end
`ifdef SIMULATION
assign RxD_idle = 0;
`else
reg [l2o+1:0] GapCnt = 0;
always @(posedge clk) if (RxD_state!=0) GapCnt<=0; else if(OversamplingTick & ~GapCnt[log2(Oversampling)+1]) GapCnt <= GapCnt + 1'h1;
assign RxD_idle = GapCnt[l2o+1];
always @(posedge clk) RxD_endofpacket <= OversamplingTick & ~GapCnt[l2o+1] & &GapCnt[l2o:0];
`endif
endmodule
////////////////////////////////////////////////////////
// dummy module used to be able to raise an assertion in Verilog
module ASSERTION_ERROR();
endmodule
////////////////////////////////////////////////////////
module BaudTickGen(
input clk, enable,
output tick // generate a tick at the specified baud rate * oversampling
);
parameter ClkFrequency = 25000000;
parameter Baud = 115200;
parameter Oversampling = 1;
function integer log2(input integer v); begin log2=0; while(v>>log2) log2=log2+1; end endfunction
localparam AccWidth = log2(ClkFrequency/Baud)+8; // +/- 2% max timing error over a byte
reg [AccWidth:0] Acc = 0;
localparam ShiftLimiter = log2(Baud*Oversampling >> (31-AccWidth)); // this makes sure Inc calculation doesn't overflow
localparam Inc = ((Baud*Oversampling << (AccWidth-ShiftLimiter))+(ClkFrequency>>(ShiftLimiter+1)))/(ClkFrequency>>ShiftLimiter);
always @(posedge clk) if(enable) Acc <= Acc[AccWidth-1:0] + Inc[AccWidth:0]; else Acc <= Inc[AccWidth:0];
assign tick = Acc[AccWidth];
endmodule
////////////////////////////////////////////////////////

35
source/test.v

@ -0,0 +1,35 @@
`timescale 1ns / 1ns
//////////////////////////////////////////////////////////////////////////////////
// Module Name: vtf_led_test
//////////////////////////////////////////////////////////////////////////////////
module vtf_led_test;
// Inputs
reg sys_clk;
reg rst_n;
// Outputs
wire [3:0] led;
// Instantiate the Unit Under Test (UUT)
led_test uut (
.sys_clk(sys_clk),
.rst_n(rst_n),
.led(led)
);
initial begin
// Initialize Inputs
sys_clk = 0;
rst_n = 0;
// Wait 100 ns for global reset to finish
#1000;
rst_n = 1;
// Add stimulus here
#20000;
// $stop;
end
always #10 sys_clk = ~ sys_clk; //20ns
endmodule
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