I have the code of a sensor in keil. I couldnt understand this piece of the code, what is it trying to do with errors? How can I learn the meanings of codes?

[mert]

[Petter Myhre]

For sd_ble_gatts_service_changed() you can have a look at ble_gatts.h:

 * @retval ::NRF_SUCCESS Successfully queued the Service Changed indication for transmission.
 * @retval ::BLE_ERROR_INVALID_CONN_HANDLE Invalid Connection Handle.
 * @retval ::NRF_ERROR_NOT_SUPPORTED Service Changed not enabled at initialization. See @ref
 *                                   sd_ble_cfg_set and @ref ble_gatts_cfg_service_changed_t.
 * @retval ::NRF_ERROR_INVALID_STATE One or more of the following is true:
 *                                   - Invalid Connection State
 *                                   - Notifications and/or indications not enabled in the CCCD
 *                                   - An ATT_MTU exchange is ongoing
 * @retval ::NRF_ERROR_INVALID_PARAM Invalid parameter(s) supplied.