diff --git a/rtl/layer_code.sv b/rtl/layer_code.sv
index 0adf9bd..3268a58 100644
--- a/rtl/layer_code.sv
+++ b/rtl/layer_code.sv
@@ -16,9 +16,9 @@ module layer_code(
     input logic [3:0] wr_byte_en_in,
 
     input logic [7:0] t0h_cnt_in,
-    input logic [7:0] t0l_cnt_in,
+    input logic [7:0] t0s_cnt_in,
     input logic [7:0] t1h_cnt_in,
-    input logic [7:0] t1l_cnt_in,
+    input logic [7:0] t1s_cnt_in,
 
     output logic ws281x_code_out
 );
@@ -67,9 +67,9 @@ ws281x_conf ws281x_conf(
     .bit_data_in(bit_data),
 
     .t0h_cnt_in(t0h_cnt_in),
-    .t0l_cnt_in(t0l_cnt_in),
+    .t0s_cnt_in(t0s_cnt_in),
     .t1h_cnt_in(t1h_cnt_in),
-    .t1l_cnt_in(t1l_cnt_in),
+    .t1s_cnt_in(t1s_cnt_in),
 
     .tim_sum_out(tim_sum)
 );
diff --git a/rtl/layer_conf.sv b/rtl/layer_conf.sv
index 313debf..d36975d 100644
--- a/rtl/layer_conf.sv
+++ b/rtl/layer_conf.sv
@@ -14,9 +14,9 @@ module layer_conf(
     input logic [7:0] wr_data_in,
 
     output logic [7:0] t0h_cnt_out,
-    output logic [7:0] t0l_cnt_out,
+    output logic [7:0] t0s_cnt_out,
     output logic [7:0] t1h_cnt_out,
-    output logic [7:0] t1l_cnt_out
+    output logic [7:0] t1s_cnt_out
 );
 
 logic [7:0] t0h_cnt;
@@ -25,9 +25,9 @@ logic [7:0] t1h_cnt;
 logic [7:0] t1l_cnt;
 
 assign t0h_cnt_out = t0h_cnt;
-assign t0l_cnt_out = t0l_cnt;
+assign t0s_cnt_out = t0h_cnt + t0l_cnt;
 assign t1h_cnt_out = t1h_cnt;
-assign t1l_cnt_out = t1l_cnt;
+assign t1s_cnt_out = t1h_cnt + t1l_cnt;
 
 always_ff @(posedge clk_in or negedge rst_n_in)
 begin
diff --git a/rtl/top.sv b/rtl/top.sv
index 084135c..c64a0da 100644
--- a/rtl/top.sv
+++ b/rtl/top.sv
@@ -33,9 +33,9 @@ logic [5:0] wr_addr;
 logic [3:0] wr_byte_en;
 
 logic [7:0] t0h_cnt;
-logic [7:0] t0l_cnt;
+logic [7:0] t0s_cnt;
 logic [7:0] t1h_cnt;
-logic [7:0] t1l_cnt;
+logic [7:0] t1s_cnt;
 
 sys_ctrl sys_ctrl(
     .clk_in(clk_in),
@@ -81,9 +81,9 @@ layer_conf layer_conf(
     .wr_data_in(byte_data),
 
     .t0h_cnt_out(t0h_cnt),
-    .t0l_cnt_out(t0l_cnt),
+    .t0s_cnt_out(t0s_cnt),
     .t1h_cnt_out(t1h_cnt),
-    .t1l_cnt_out(t1l_cnt)
+    .t1s_cnt_out(t1s_cnt)
 );
 
 layer_code layer_code7(
@@ -97,9 +97,9 @@ layer_code layer_code7(
     .wr_byte_en_in(wr_byte_en),
 
     .t0h_cnt_in(t0h_cnt),
-    .t0l_cnt_in(t0l_cnt),
+    .t0s_cnt_in(t0s_cnt),
     .t1h_cnt_in(t1h_cnt),
-    .t1l_cnt_in(t1l_cnt),
+    .t1s_cnt_in(t1s_cnt),
 
     .ws281x_code_out(ws281x_code_out[7])
 );
@@ -115,9 +115,9 @@ layer_code layer_code6(
     .wr_byte_en_in(wr_byte_en),
 
     .t0h_cnt_in(t0h_cnt),
-    .t0l_cnt_in(t0l_cnt),
+    .t0s_cnt_in(t0s_cnt),
     .t1h_cnt_in(t1h_cnt),
-    .t1l_cnt_in(t1l_cnt),
+    .t1s_cnt_in(t1s_cnt),
 
     .ws281x_code_out(ws281x_code_out[6])
 );
@@ -133,9 +133,9 @@ layer_code layer_code5(
     .wr_byte_en_in(wr_byte_en),
 
     .t0h_cnt_in(t0h_cnt),
-    .t0l_cnt_in(t0l_cnt),
+    .t0s_cnt_in(t0s_cnt),
     .t1h_cnt_in(t1h_cnt),
-    .t1l_cnt_in(t1l_cnt),
+    .t1s_cnt_in(t1s_cnt),
 
     .ws281x_code_out(ws281x_code_out[5])
 );
@@ -151,9 +151,9 @@ layer_code layer_code4(
     .wr_byte_en_in(wr_byte_en),
 
     .t0h_cnt_in(t0h_cnt),
-    .t0l_cnt_in(t0l_cnt),
+    .t0s_cnt_in(t0s_cnt),
     .t1h_cnt_in(t1h_cnt),
-    .t1l_cnt_in(t1l_cnt),
+    .t1s_cnt_in(t1s_cnt),
 
     .ws281x_code_out(ws281x_code_out[4])
 );
@@ -169,9 +169,9 @@ layer_code layer_code3(
     .wr_byte_en_in(wr_byte_en),
 
     .t0h_cnt_in(t0h_cnt),
-    .t0l_cnt_in(t0l_cnt),
+    .t0s_cnt_in(t0s_cnt),
     .t1h_cnt_in(t1h_cnt),
-    .t1l_cnt_in(t1l_cnt),
+    .t1s_cnt_in(t1s_cnt),
 
     .ws281x_code_out(ws281x_code_out[3])
 );
@@ -187,9 +187,9 @@ layer_code layer_code2(
     .wr_byte_en_in(wr_byte_en),
 
     .t0h_cnt_in(t0h_cnt),
-    .t0l_cnt_in(t0l_cnt),
+    .t0s_cnt_in(t0s_cnt),
     .t1h_cnt_in(t1h_cnt),
-    .t1l_cnt_in(t1l_cnt),
+    .t1s_cnt_in(t1s_cnt),
 
     .ws281x_code_out(ws281x_code_out[2])
 );
@@ -205,9 +205,9 @@ layer_code layer_code1(
     .wr_byte_en_in(wr_byte_en),
 
     .t0h_cnt_in(t0h_cnt),
-    .t0l_cnt_in(t0l_cnt),
+    .t0s_cnt_in(t0s_cnt),
     .t1h_cnt_in(t1h_cnt),
-    .t1l_cnt_in(t1l_cnt),
+    .t1s_cnt_in(t1s_cnt),
 
     .ws281x_code_out(ws281x_code_out[1])
 );
@@ -223,9 +223,9 @@ layer_code layer_code0(
     .wr_byte_en_in(wr_byte_en),
 
     .t0h_cnt_in(t0h_cnt),
-    .t0l_cnt_in(t0l_cnt),
+    .t0s_cnt_in(t0s_cnt),
     .t1h_cnt_in(t1h_cnt),
-    .t1l_cnt_in(t1l_cnt),
+    .t1s_cnt_in(t1s_cnt),
 
     .ws281x_code_out(ws281x_code_out[0])
 );
diff --git a/rtl/ws281x_conf.sv b/rtl/ws281x_conf.sv
index f684d74..1f73bcd 100644
--- a/rtl/ws281x_conf.sv
+++ b/rtl/ws281x_conf.sv
@@ -13,18 +13,15 @@ module ws281x_conf(
     input logic bit_data_in,
 
     input logic [7:0] t0h_cnt_in,
-    input logic [7:0] t0l_cnt_in,
+    input logic [7:0] t0s_cnt_in,
     input logic [7:0] t1h_cnt_in,
-    input logic [7:0] t1l_cnt_in,
+    input logic [7:0] t1s_cnt_in,
 
     output logic [7:0] tim_sum_out
 );
 
 logic [7:0] tim_sum;
 
-wire [7:0] t0_sum = t0h_cnt_in + t0l_cnt_in;
-wire [7:0] t1_sum = t1h_cnt_in + t1l_cnt_in;
-
 assign tim_sum_out = tim_sum;
 
 always_ff @(posedge clk_in or negedge rst_n_in)
@@ -32,7 +29,7 @@ begin
     if (!rst_n_in) begin
         tim_sum <= 8'h00;
     end else begin
-        tim_sum <= bit_rdy_in ? (bit_data_in ? t1_sum : t0_sum) : tim_sum;
+        tim_sum <= bit_rdy_in ? (bit_data_in ? t1s_cnt_in : t0s_cnt_in) : tim_sum;
     end
 end
 
diff --git a/simulation/test_layer_code.sv b/simulation/test_layer_code.sv
index cc78580..1f04087 100644
--- a/simulation/test_layer_code.sv
+++ b/simulation/test_layer_code.sv
@@ -19,9 +19,9 @@ logic [7:0] wr_data_in;
 logic [3:0] wr_byte_en_in;
 
 logic [7:0] t0h_cnt_in;
-logic [7:0] t0l_cnt_in;
+logic [7:0] t0s_cnt_in;
 logic [7:0] t1h_cnt_in;
-logic [7:0] t1l_cnt_in;
+logic [7:0] t1s_cnt_in;
 
 logic ws281x_code_out;
 
@@ -36,9 +36,9 @@ layer_code test_layer_code(
     .wr_byte_en_in(wr_byte_en_in),
 
     .t0h_cnt_in(t0h_cnt_in),
-    .t0l_cnt_in(t0l_cnt_in),
+    .t0s_cnt_in(t0s_cnt_in),
     .t1h_cnt_in(t1h_cnt_in),
-    .t1l_cnt_in(t1l_cnt_in),
+    .t1s_cnt_in(t1s_cnt_in),
 
     .ws281x_code_out(ws281x_code_out)
 );
@@ -55,9 +55,9 @@ initial begin
 
     // Unit: 10 ns (2 clk)
     t0h_cnt_in <= 8'h01;
-    t0l_cnt_in <= 8'h7f;
+    t0s_cnt_in <= 8'h80;
     t1h_cnt_in <= 8'h7f;
-    t1l_cnt_in <= 8'h01;
+    t1s_cnt_in <= 8'h80;
 
     #2 rst_n_in <= 1'b1;
 end
diff --git a/simulation/test_layer_conf.sv b/simulation/test_layer_conf.sv
index 896ff7e..1375946 100644
--- a/simulation/test_layer_conf.sv
+++ b/simulation/test_layer_conf.sv
@@ -17,9 +17,9 @@ logic [5:0] wr_addr_in;
 logic [7:0] wr_data_in;
 
 logic [7:0] t0h_cnt_out;
-logic [7:0] t0l_cnt_out;
+logic [7:0] t0s_cnt_out;
 logic [7:0] t1h_cnt_out;
-logic [7:0] t1l_cnt_out;
+logic [7:0] t1s_cnt_out;
 
 layer_conf test_layer_conf(
     .clk_in(clk_in),
@@ -30,9 +30,9 @@ layer_conf test_layer_conf(
     .wr_data_in(wr_data_in),
 
     .t0h_cnt_out(t0h_cnt_out),
-    .t0l_cnt_out(t0l_cnt_out),
+    .t0s_cnt_out(t0s_cnt_out),
     .t1h_cnt_out(t1h_cnt_out),
-    .t1l_cnt_out(t1l_cnt_out)
+    .t1s_cnt_out(t1s_cnt_out)
 );
 
 initial begin
diff --git a/simulation/test_ws281x_conf.sv b/simulation/test_ws281x_conf.sv
index 431ec8b..31e5879 100644
--- a/simulation/test_ws281x_conf.sv
+++ b/simulation/test_ws281x_conf.sv
@@ -16,9 +16,9 @@ logic bit_rdy_in;
 logic bit_data_in;
 
 logic [7:0] t0h_cnt_in;
-logic [7:0] t0l_cnt_in;
+logic [7:0] t0s_cnt_in;
 logic [7:0] t1h_cnt_in;
-logic [7:0] t1l_cnt_in;
+logic [7:0] t1s_cnt_in;
 
 logic [7:0] tim_sum_out;
 
@@ -30,9 +30,9 @@ ws281x_conf test_ws281x_conf(
     .bit_data_in(bit_data_in),
 
     .t0h_cnt_in(t0h_cnt_in),
-    .t0l_cnt_in(t0l_cnt_in),
+    .t0s_cnt_in(t0s_cnt_in),
     .t1h_cnt_in(t1h_cnt_in),
-    .t1l_cnt_in(t1l_cnt_in),
+    .t1s_cnt_in(t1s_cnt_in),
 
     .tim_sum_out(tim_sum_out)
 );
@@ -46,9 +46,9 @@ initial begin
 
     // Unit: 10 ns (2 clk)
     t0h_cnt_in <= 8'h01;
-    t0l_cnt_in <= 8'h7f;
+    t0s_cnt_in <= 8'h80;
     t1h_cnt_in <= 8'hfe;
-    t1l_cnt_in <= 8'h01;
+    t1s_cnt_in <= 8'hff;
 
     #2 rst_n_in <= 1'b1;
 end