diff --git a/top/e31x/e31x_core.v b/top/e31x/e31x_core.v
index 732534e..d797601 100644
--- a/top/e31x/e31x_core.v
+++ b/top/e31x/e31x_core.v
@@ -683,7 +683,8 @@ module e31x_core #(
    .pps                   (pps_radioclk),
    .tb_timestamp          (radio_time),
    .tb_timestamp_last_pps (),
-   .tb_period_ns_q32      ()
+   .tb_period_ns_q32      (),
+   .tb_changed            ()
   );
 
   /////////////////////////////////////////////////////////////////////////////
diff --git a/top/e320/e320_core.v b/top/e320/e320_core.v
index 3d1c857..83fb294 100644
--- a/top/e320/e320_core.v
+++ b/top/e320/e320_core.v
@@ -1021,7 +1021,8 @@ module e320_core #(
    .pps                   (pps_radioclk),
    .tb_timestamp          (radio_time),
    .tb_timestamp_last_pps (),
-   .tb_period_ns_q32      ()
+   .tb_period_ns_q32      (),
+   .tb_changed            ()
   );
 
 
diff --git a/top/n3xx/n3xx_core.v b/top/n3xx/n3xx_core.v
index 98b4333..f561378 100644
--- a/top/n3xx/n3xx_core.v
+++ b/top/n3xx/n3xx_core.v
@@ -1109,7 +1109,8 @@ module n3xx_core #(
    .pps                   (pps),
    .tb_timestamp          (radio_time),
    .tb_timestamp_last_pps (),
-   .tb_period_ns_q32      ()
+   .tb_period_ns_q32      (),
+   .tb_changed            ()
   );
 
 
diff --git a/top/x300/bus_int.v b/top/x300/bus_int.v
index e74b12e..12f3493 100644
--- a/top/x300/bus_int.v
+++ b/top/x300/bus_int.v
@@ -22,6 +22,7 @@ module bus_int #(
     output [3:0] sw_rst,
     // Timekeeper
     input                   pps,
+    output                  time_sync,
     // Block connections
     input                   ce_clk,
     input                   ce_rst,
@@ -545,7 +546,8 @@ module bus_int #(
      .pps                   (pps),
      .tb_timestamp          (radio_time_tb),
      .tb_timestamp_last_pps (radio_time_last_pps_tb),
-     .tb_period_ns_q32      (period_ns_q32_tb)
+     .tb_period_ns_q32      (period_ns_q32_tb),
+     .tb_changed            (time_sync)
    );
 
    // Latch state changes to SFP0+ pins.
diff --git a/top/x300/x300_core.v b/top/x300/x300_core.v
index f05893b..03a1cbb 100644
--- a/top/x300/x300_core.v
+++ b/top/x300/x300_core.v
@@ -250,6 +250,7 @@ module x300_core #(
    wire [63:0] s00_axi_rdata, s01_axi_rdata;
    wire [1:0]  s00_axi_rresp, s01_axi_rresp;
    wire [0:0]  s00_axi_ruser, s01_axi_ruser;
+   wire        time_sync;
 
 
    /////////////////////////////////////////////////////////////////////////////////
@@ -287,6 +288,7 @@ module x300_core #(
       .leds(led_misc), .sw_rst(sw_rst),
       // Timekeeper
       .pps(pps_rclk),
+      .time_sync(time_sync),
       // Block connections
       .ce_clk     (ce_clk),
       .ce_rst     (ce_rst),
@@ -609,7 +611,7 @@ module x300_core #(
        ) x300_fe_core_i (
          .clk(radio_clk), .reset(radio_rst),
          .set_stb(db_fe_set_stb[i]), .set_addr(db_fe_set_addr[i]), .set_data(db_fe_set_data[i]),
-         .time_sync(),
+         .time_sync(time_sync),
          .tx_stb(tx_stb_r[i]), .tx_data_in(tx_data_r[i]), .tx_data_out(tx_data_out_r[i]),
          .rx_stb(rx_stb_r[i]), .rx_data_in(rx_data_in_r[i]), .rx_data_out(rx_data_r[i])
        );
diff --git a/top/x400/x4xx_core_common.v b/top/x400/x4xx_core_common.v
index 633aa69..d2224f2 100644
--- a/top/x400/x4xx_core_common.v
+++ b/top/x400/x4xx_core_common.v
@@ -339,7 +339,8 @@ module x4xx_core_common #(
     .pps                   (pps_radioclk),
     .tb_timestamp          (radio_time),
     .tb_timestamp_last_pps (),
-    .tb_period_ns_q32      ()
+    .tb_period_ns_q32      (),
+    .tb_changed            ()
   );