"sd_ble_gattc_write" and "BLE_GATTC_EVT_WRITE_RSP"

Question

I have a question about "sd_ble_gattc_write" and "BLE_GATTC_EVT_WRITE_RSP". 
 1) If "BLE_GATTC_EVT_WRITE_RSP" occurs, can you guarantee that the data has been written to the characteristic reliably? 2) Is "BLE_GATTC_EVT_WRITE_RSP" correct in recognition occurring at the connection interval timing after executing "sd_ble_gattc_write"? 3) Is there a case where "BLE_GATTC_EVT_WRITE_RSP" does not occur? 4) In that case, is it necessary to execute "sd_ble_gattc_write" again? 
 Thanking you in advance.

Jared · Accepted Answer

Hi, 
 
 You can determine if the characteristic has been successfully written to by waiting for the BLE_GATTC_EVT_WRITE_RSP event and see if the status of the event is a BLE_GATT_STATUS_SUCCESS. If the WRITE is not permitted a error code will be received with the BLE_GATTC_EVT_WRITE_RSP event. I've included sample code from the ble event handler in nrf_ble_ots_c file that shows how to check if the WRITE is success or not: 
 You can't set the number of re transmission, the device will continuously try to re transmit a packet until the connection times out. However, you can decide the connection timeout, most of our examples use the definition CONN_SUP_TIMEOUT to set the time out. See this post and this post . 
 
 regards 
 Jared 
 
 void nrf_ble_ots_c_on_ble_evt(ble_evt_t const * const p_ble_evt,
 void * p_context)
{
 nrf_ble_ots_c_t * p_ots_c;
 p_ots_c = (nrf_ble_ots_c_t*) p_context;

 VERIFY_MODULE_INITIALIZED_VOID();
 VERIFY_PARAM_NOT_NULL_VOID(p_ots_c);
 VERIFY_PARAM_NOT_NULL_VOID(p_ble_evt);

 switch (p_ble_evt->header.evt_id)
 {
 case BLE_GAP_EVT_DISCONNECTED:
 on_disconnect(p_ots_c, p_ble_evt);
 break;

 case BLE_GATTC_EVT_READ_RSP:
 on_read_rsp(p_ots_c, p_ble_evt);
 break;

 case BLE_GATTC_EVT_WRITE_RSP:
 if ((p_ble_evt->evt.gattc_evt.error_handle != BLE_GATT_HANDLE_INVALID)
 && (p_ble_evt->evt.gattc_evt.error_handle ==
 p_ots_c->service.object_action_cp_char.handle_value))
 {
 if (p_ble_evt->evt.gattc_evt.gatt_status == BLE_GATT_STATUS_ATTERR_CPS_CCCD_CONFIG_ERROR)
 {
 NRF_LOG_INFO("write to OACP failed, CCCD improperly configured, enable indications on OACP and try again");
 }
 else
 {
 NRF_LOG_INFO("BLE_GATTC_EVT_WRITE_RSP error handle: %x error response %x
",
 p_ble_evt->evt.gattc_evt.error_handle,
 p_ble_evt->evt.gattc_evt.gatt_status);
 }
 }
 break;

 default:
 break;
 }
 ots_c_l2cap_on_ble_evt(p_ots_c, p_ble_evt);
 ots_c_oacp_on_ble_evt(p_ots_c, p_ble_evt);
}

"sd_ble_gattc_write" and "BLE_GATTC_EVT_WRITE_RSP"

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