ESP8266 in AP Mode -determining if a station is connected

Question

I have an ESP8266 running in AP mode using softAP and i want to conserve battery life. I am wanting to turn on wifi and advertise SSID for 20 seconds. If no station connects to the ssid within the 20 seconds, I want to go to sleep for 1 minute, otherwise I do not sleep.

My problem is that I cannot get "WiFi.softAPgetStationNum()" working. when I build i get a message that this is not part of ESP8266WiFi class. I have attached simplified code.

Can someone help me to achieve this please?

#include <ESP8266WiFi.h>
//WIFI Access point setup
const char* Ssid = "SSID";
const char* Password = "Password";
IPAddress ip(10,0,0,10);
IPAddress gateway(10,0,0,1);
IPAddress subnet(255,255,255,0);
WiFiServer server(80); // Set web server port number to 
80
// GPIO pins
const int output_set = 5;
int delay_loop=0;
void setup() 
{
 // Data Direction
 pinMode(output_set, OUTPUT);
 // Output initial Values
 digitalWrite(output_set, LOW);
 WiFi.softAPConfig(ip,gateway,subnet);
 WiFi.softAP(Ssid,Password);
 server.begin();
// check to see if a station is connected to this AP. If no station 
connected within 20 sec timeframe, go to sleep.
while (WiFi.softAPgetStationNum()==0) //loop here while no AP is connected to this station
{
 delay(1);
 delay_loop++;
 if (delay_loop>=20000) 
 {
 ESP.deepSleep(60e6); //go to sleep for 60 sec -wake pin externally connected to reset pin
 } 
}
}
void loop()
{
 digitalWrite(output_set, HIGH); //Flash led once station is connected
 delay(200);
 digitalWrite(output_set, LOW);
 delay(400); 
}

• Maximilian Gerhardt: Cannot reproduce. Above code builds fine for me in PlatformIO and in Arduino IDE 1.8.3 using Arduino-ESP8266 version 2.4.1 and ESP8266WiFi library version 1.0.0. What version are you using?
• Clayton Lines: Hi, thanks for your response, Arduino IDE Ver:1.8.5, ESP8266WiFi library Ver: 1.0.0. I am unsure what Arduino-ESP8266 v2.4.1 is? are you able to clarify this?
• Clayton Lines: I have: arduino.esp8266.com/stable/package_esp8266com_index.json added to my additional boards manager URL in preferences
• Maximilian Gerhardt: That URL is correct. What version does boardmanager say you have for esp8266? (Tools->Board->Board manager)
• Clayton Lines: it said 2.0.0, and I have now changed it to 2.4.1. My problem has now been solved. Thank you for your help with this. I continue to learn. Kudos.

Answer 1

Followup answer from comments:

The issue was an outdated version of the ESP8266-Arduino framework. The function WiFi.softAPgetStationNum() is available in 2.4.1

For the sake of completeness: The function itself is simply a wrapper for the Espressif non-os SDK function:

/**
 * Get the count of the Station / client that are connected to the softAP interface
 * @return Stations count
 */
uint8_t ESP8266WiFiAPClass::softAPgetStationNum() {
 return wifi_softap_get_station_num();
}

See Espressif Non-OS SDK API reference chapter 3.5.36.

That function should also be available on older framework versions. However, upgrading is the recommended way to use that function.