I could use some help getting started...
Basically, I'm using a ESP-201 module just powered on to the default AP mode as a beacon.
A second ESP-201 or ESP-01 would by default have one GPIO pin set high, which would power a optoisolator. This same second ESP8266 module would monitor the signal strength of the beacon, and at a specific signal strength threshold, it would toggle a optoisolator off. This threshold would start higher than zero signal or "out of range".
A loop like this might work fine:
Set GPIO2 HIGH, Scan for ESP-201 AP beacon, check RSSI for beacon, If RSSI > -20dbm, Set GPIO2 LOW, else if RSSI < -20dbm, Set GPIO2 HIGH.
I don't know the syntax or process well for RSSI, so that is what I'm asking help with.
In case you're wondering what this is for, it is for a semi-autonomous robot that stays in range of the central beacon, in a circular pattern.