diff --git a/le_bas.c b/le_bas.c
index 6726edc..465eedb 100644
--- a/le_bas.c
+++ b/le_bas.c
@@ -14,17 +14,41 @@ extern "C"
 #include "nrf_log_ctrl.h"
 #include "nrf_log_default_backends.h"
 
-
 #include "nrf_sdh.h"
 #include "nrf_sdh_ble.h"
 #include "nrf_sdh_freertos.h"
 
 #include "ble_srv_common.h"
 
+#include "FreeRTOS.h"
+#include "task.h"
+
 #ifdef __cplusplus
 }
 #endif
 
-uint16_t bas_volt_read(void) {
-    return 3100;
-}
\ No newline at end of file
+static uint16_t volt = 3100;
+
+uint16_t bas_volt_read(void)
+{
+    return volt;
+}
+
+void battery_task(void *pArg)
+{
+    for (;;)
+    {
+        // battery psuedo code
+        vTaskDelay(pdMS_TO_TICKS(1000));
+        volt = volt ? volt - 1 : 3100;
+        
+        // update battery volt
+        extern void le_edc_bat_volt_update(uint16_t bat_volt);
+        le_edc_bat_volt_update(volt);
+    }
+}
+
+void bas_volt_init(void)
+{
+    xTaskCreate(battery_task, "bat_task", 160, NULL, 2, NULL);
+}
diff --git a/le_edc_srv.c b/le_edc_srv.c
index 7088c5a..8d794dc 100644
--- a/le_edc_srv.c
+++ b/le_edc_srv.c
@@ -2,6 +2,7 @@
 #if NRF_MODULE_ENABLED(BLE_EDC)
 
 #include "app_error.h"
+#include "ble_conn_state.h"
 #include "ble_gatts.h"
 #include "ble_srv_common.h"
 #include "nrf_sdh_ble.h"
@@ -37,16 +38,18 @@ typedef struct
     uint16_t battery_volt;
 } ble_edc_init_t;
 
-static ble_edc_t ble_edc;
+static ble_edc_t ble_edc = {
+    .conn_handle = BLE_CONN_HANDLE_INVALID,
+};
 
 static void on_connect(ble_edc_t *p_edc, ble_evt_t const *p_ble_evt)
 {
-    // TODO...
+    p_edc->conn_handle = p_ble_evt->evt.common_evt.conn_handle;
 }
 
 static void on_disconnect(ble_edc_t *p_edc, ble_evt_t const *p_ble_evt)
 {
-    // TODO...
+    p_edc->conn_handle = BLE_CONN_HANDLE_INVALID;
 }
 
 static void edc_ccc_update(ble_edc_t *p_edc, ble_evt_t const *p_ble_evt)
@@ -149,10 +152,51 @@ void le_edc_init(void)
     ble_edc_init_t edc_init;
     memset(&edc_init, 0x00, sizeof(edc_init));
 
+    extern void bas_volt_init(void);
+    bas_volt_init();
+
     extern uint16_t bas_volt_read(void);
     edc_init.battery_volt = bas_volt_read();
     ret_code_t err_code   = ble_edc_init(&edc_init);
     APP_ERROR_CHECK(err_code);
 }
 
+void le_edc_bat_volt_update(uint16_t bat_volt)
+{
+    ret_code_t err_code = NRF_SUCCESS;
+
+    if (bat_volt == ble_edc.bat_volt)
+    {
+        return;
+    }
+
+    // update database.
+    ble_gatts_value_t gatts_value = {
+        .p_value = (void *)&bat_volt,
+        .offset  = 0,
+        .len     = sizeof(bat_volt),
+    };
+    err_code = sd_ble_gatts_value_set(BLE_CONN_HANDLE_INVALID, ble_edc.bat_volt_handles.value_handle, &gatts_value);
+    APP_ERROR_CHECK(err_code);
+    ble_edc.bat_volt = bat_volt;
+
+    // send value if connected and notifying.
+    if (ble_edc.bat_volt_notify_en)
+    {
+        ble_gatts_hvx_params_t hvx_params = {
+            .handle = ble_edc.bat_volt_handles.value_handle,
+            .type   = BLE_GATT_HVX_NOTIFICATION,
+            .offset = gatts_value.offset,
+            .p_len  = &gatts_value.len,
+            .p_data = gatts_value.p_value,
+        };
+
+        if (ble_conn_state_status(ble_edc.conn_handle) == BLE_CONN_STATUS_CONNECTED)
+        {
+            err_code = sd_ble_gatts_hvx(ble_edc.conn_handle, &hvx_params);
+            APP_ERROR_CHECK(err_code);
+        }
+    }
+}
+
 #endif // NRF_MODULE_ENABLED(BLE_EDC)