BLE Peripheral disconnects every 30 seconds when reading notification

Hi,

I have a BLE characteristic that is available in READ / NOTIFY mode.

我使用一个定制的ble_peripheral_app的基地my tests.

//characteristic
ble_uuid_from_string(xxx_UUID, &uuid);
ble_gatts_add_characteristic(&uuid, GATT_PROP_NOTIFY | GATT_PROP_READ, ATT_PERM_READ,
xxx_SIZE, 0, NULL, &service->xxx);
//descriptor
ble_uuid_create16(UUID_GATT_CLIENT_CHAR_CONFIGURATION, &uuid);
ble_gatts_add_descriptor(&uuid, ATT_PERM_RW, sizeof(uint16_t), 0,
&service->xxx_desc);

On a regular basis I am updating this value

if (m_conn_idx != BLE_CONN_IDX_INVALID) {
ble_gatts_send_event(m_conn_idx, type, GATT_EVENT_NOTIFICATION,
xxx_SIZE, &data);
}

Notification and read are working well for the first 30 seconds then my android application is disconnected.

I am using a setup similar to wrbl project for BLE configuration
#define BLE_ADV_INTERVAL (320)
#define BLE_CONN_FAST_INTV_MAX (15)
#define BLE_CONN_FAST_INTV_MIN (15)
#define BLE_CONN_SLOW_INTV_MAX (520)
#define BLE_CONN_SLOW_INTV_MIN (480)
#define BLE_MTU_SIZE (131)

Any idea on which setting I need to modify to ensure I can read my notification more than 30 seconds?

Thanks a lot,