The received signal strength indicator (RSSI) measures the amount of power present in a radio signal. It is an approximate value for signal strength received on an antenna.
You can use the DB command to measure the RSSI on a device. DB returns the RSSI value measured in -dBm of the last packet the device received. This number can be misleading in multi-hop DigiMesh networks. The DB value only indicates the received signal strength of the last hop. If a transmission spans multiple hops, the DB value provides no indication of the overall transmission path, or the quality of the worst link, it only indicates the quality of the last link.
To determine the DB value in hardware:
Use the DIO10/RSSI/PWM0 module pin (pin 6 in through-hole, pin 7 in surface-mount). When the device receives data, it sets the RSSI PWM duty cycle to a value based on the RSSI of the packet it receives.
This value only indicates the quality of the last hop of a multi-hop transmission. You could connect this pin to an LED to indicate if the link is stable or not.