Yes, the RSSI values can be obtained either before or after connecting to the peripheral devices in the following ways.
Before connecting, there are two ways to obtain the RSSI value of the peripheral device:
1. Call the RBLE_GAP_Observation_Enable function to execute the scan and obtain it from the advertising report notification event RBLE_GAP_EVENT_ADVERTISING_REPORT_IND.
2. Call the RBLE_GAP_Device_Search function to execute the scan and obtain from the device search result notification event RBLE_GAP_EVENT_DEVICE_SEARCH_RESULT_IND.
After connecting, you can obtain the RSSI value of the designation remote device by doing the following:
1. Call the RBLE_GAP_Read_RSSI function to acquire from the RSSI acquisition completion event RBLE_GAP_EVENT_READ_RSSI_COMP.
For details of each function and event, refer to the following manual.
Bluetooth® Low Energy Protocol Stack API Reference Manual: Basics (R01UW0088)