diff --git a/EPD/EPD_service.c b/EPD/EPD_service.c
index 80fb9cd..2d89c5e 100644
--- a/EPD/EPD_service.c
+++ b/EPD/EPD_service.c
@@ -87,6 +87,13 @@ static void epd_update_display_mode(ble_epd_t * p_epd, display_mode_t mode)
     }
 }
 
+static void epd_send_time(ble_epd_t * p_epd)
+{
+    char buf[20] = {0};
+    snprintf(buf, 20, "t=%"PRIu32, timestamp());
+    ble_epd_string_send(p_epd, (uint8_t *)buf, strlen(buf));
+}
+
 static void epd_service_on_write(ble_epd_t * p_epd, uint8_t * p_data, uint16_t length)
 {
     NRF_LOG_DEBUG("[EPD]: on_write LEN=%d\n", length);
@@ -121,6 +128,7 @@ static void epd_service_on_write(ble_epd_t * p_epd, uint8_t * p_data, uint16_t l
               epd_config_write(&p_epd->config);
           }
           p_epd->epd = epd_init((epd_model_id_t)id);
+          epd_send_time(p_epd);
         } break;
 
       case EPD_CMD_CLEAR:
diff --git a/EPD/EPD_service.h b/EPD/EPD_service.h
index 5ed4ac5..2afcf77 100644
--- a/EPD/EPD_service.h
+++ b/EPD/EPD_service.h
@@ -13,7 +13,7 @@
 #ifndef __EPD_SERVICE_H
 #define __EPD_SERVICE_H
 
-#include <stdint.h>
+#include <inttypes.h>
 #include <stdbool.h>
 #include "ble.h"
 #include "ble_srv_common.h"