FPGAで遊ぶ　Lチカ

Basys3には、入力として16個のスイッチと5個のボタン、出力として16個のLEDと4個の7セグメントディスプレイが搭載されています。

FPGAで最後に遊んだのは、数年前なのでプログラミングの感覚を取り戻すためと、開発環境全体が正常かどうかをチェックするためお決まりのLチカをやってみました。

ソースファイルです。

---

module switch_dec1(
　　input CLK,
　　input RST,
　　input [15:0] SW,
　　output reg[15:0] LED
);

//12Hz Counter
reg[22:0] cnt;
always @(posedge CLK) begin
　　if(RST) cnt <= 1’h0;
　　else cnt <= cnt + 1’h1;
end

//Switch → LED
always @(cnt[22]) begin
　　if(cnt[22]) LED <= SW;
　　else LED <= 16’h00;
end

endmodule

---

約12Hzのクロックを作って、LEDをオンオフします。

制約ファイルです。

---

## Clock Signals
set_property PACKAGE_PIN W5 [get_ports {CLK}]
set_property IOSTANDARD LVCMOS33 [get_ports {CLK}]
create_clock -add -name sys_clk_pin -period 10.00 -waveform {0 5} [get_ports {CLK}]

## Switchs
set_property PACKAGE_PIN V17 [get_ports {SW[0]}]
set_property IOSTANDARD LVCMOS33 [get_ports {SW[0]}]
set_property PACKAGE_PIN V16 [get_ports {SW[1]}]
set_property IOSTANDARD LVCMOS33 [get_ports {SW[1]}]
set_property PACKAGE_PIN W16 [get_ports {SW[2]}]
set_property IOSTANDARD LVCMOS33 [get_ports {SW[2]}]
set_property PACKAGE_PIN W17 [get_ports {SW[3]}]
set_property IOSTANDARD LVCMOS33 [get_ports {SW[3]}]
set_property PACKAGE_PIN W15 [get_ports {SW[4]}]
set_property IOSTANDARD LVCMOS33 [get_ports {SW[4]}]
set_property PACKAGE_PIN V15 [get_ports {SW[5]}]
set_property IOSTANDARD LVCMOS33 [get_ports {SW[5]}]
set_property PACKAGE_PIN W14 [get_ports {SW[6]}]
set_property IOSTANDARD LVCMOS33 [get_ports {SW[6]}]
set_property PACKAGE_PIN W13 [get_ports {SW[7]}]
set_property IOSTANDARD LVCMOS33 [get_ports {SW[7]}]
set_property PACKAGE_PIN V2 [get_ports {SW[8]}]
set_property IOSTANDARD LVCMOS33 [get_ports {SW[8]}]
set_property PACKAGE_PIN T3 [get_ports {SW[9]}]
set_property IOSTANDARD LVCMOS33 [get_ports {SW[9]}]
set_property PACKAGE_PIN T2 [get_ports {SW[10]}]
set_property IOSTANDARD LVCMOS33 [get_ports {SW[10]}]
set_property PACKAGE_PIN R3 [get_ports {SW[11]}]
set_property IOSTANDARD LVCMOS33 [get_ports {SW[11]}]
set_property PACKAGE_PIN W2 [get_ports {SW[12]}]
set_property IOSTANDARD LVCMOS33 [get_ports {SW[12]}]
set_property PACKAGE_PIN U1 [get_ports {SW[13]}]
set_property IOSTANDARD LVCMOS33 [get_ports {SW[13]}]
set_property PACKAGE_PIN T1 [get_ports {SW[14]}]
set_property IOSTANDARD LVCMOS33 [get_ports {SW[14]}]
set_property PACKAGE_PIN R2 [get_ports {SW[15]}]
set_property IOSTANDARD LVCMOS33 [get_ports {SW[15]}]

## LED
sset_property PACKAGE_PIN U16 [get_ports {LED[0]}]
set_property IOSTANDARD LVCMOS33 [get_ports {LED[0]}]
set_property PACKAGE_PIN E19 [get_ports {LED[1]}]
set_property IOSTANDARD LVCMOS33 [get_ports {LED[1]}]
set_property PACKAGE_PIN U19 [get_ports {LED[2]}]
set_property IOSTANDARD LVCMOS33 [get_ports {LED[2]}]
set_property PACKAGE_PIN V19 [get_ports {LED[3]}]
set_property IOSTANDARD LVCMOS33 [get_ports {LED[3]}]
set_property PACKAGE_PIN W18 [get_ports {LED[4]}]
set_property IOSTANDARD LVCMOS33 [get_ports {LED[4]}]
set_property PACKAGE_PIN U15 [get_ports {LED[5]}]
set_property IOSTANDARD LVCMOS33 [get_ports {LED[5]}]
set_property PACKAGE_PIN U14 [get_ports {LED[6]}]
set_property IOSTANDARD LVCMOS33 [get_ports {LED[6]}]
set_property PACKAGE_PIN V14 [get_ports {LED[7]}]
set_property IOSTANDARD LVCMOS33 [get_ports {LED[7]}]
set_property PACKAGE_PIN V13 [get_ports {LED[8]}]
set_property IOSTANDARD LVCMOS33 [get_ports {LED[8]}]
set_property PACKAGE_PIN V3 [get_ports {LED[9]}]
set_property IOSTANDARD LVCMOS33 [get_ports {LED[9]}]
set_property PACKAGE_PIN W3 [get_ports {LED[10]}]
set_property IOSTANDARD LVCMOS33 [get_ports {LED[10]}]
set_property PACKAGE_PIN U3 [get_ports {LED[11]}]
set_property IOSTANDARD LVCMOS33 [get_ports {LED[11]}]
set_property PACKAGE_PIN P3 [get_ports {LED[12]}]
set_property IOSTANDARD LVCMOS33 [get_ports {LED[12]}]
set_property PACKAGE_PIN N3 [get_ports {LED[13]}]
set_property IOSTANDARD LVCMOS33 [get_ports {LED[13]}]
set_property PACKAGE_PIN P1 [get_ports {LED[14]}]
set_property IOSTANDARD LVCMOS33 [get_ports {LED[14]}]
set_property PACKAGE_PIN L1 [get_ports {LED[15]}]
set_property IOSTANDARD LVCMOS33 [get_ports {LED[15]}]

##Buttons
set_property PACKAGE_PIN U18 [get_ports {RST}]
set_property IOSTANDARD LVCMOS33 [get_ports {RST}]

---

テストベンチです。

簡単な回路では、テストベンチ無しでいきなりコンフィグすることが多いのですが、今回はリハビリのため作成しました。

---

module sim_sw_dec;

localparam STEP = 10;
reg clk;
reg rst;
reg[15:0] sw;
wire[15:0] led;

switch_dec1 switch_dec1(
.CLK (clk),
.RST (rst),
.SW (sw),
.LED (led)
);

always begin
clk = 0; #(STEP/2);
clk = 1; #(STEP/2);
end

initial begin
rst = 0;
#(STEP10); rst = 1; #(STEP10);
rst = 0;
sw = 16’h5555;
#(STEP*20000000);
$stop;
end

---

切り替え周波数が少し高かったようで、マレーシアの蛍みたいに忙しなく点滅しますが、正常に動作しました。