ESP8266 Community Forum

- Sun May 21, 2017 5:54 pm #66167

A Wifi device does actually broadcast its presence

Interesting reading material, thanks @torntrousers!

Assumption is the mother of all f*ckups. At least: that's what I'm assuming.

- Mon May 22, 2017 1:12 pm #66194 Does anyone got the onSoftAPModeProbeRequestReceived event actually working?

I've tried the example in the GitHub repository (it's not included yet in the "Boards manager"-version), but I'm not getting any probe-events, while the connect- and disconnect-events work as expected.

Used a couple of different devices, including Android 5, Android 6 and IOS 7 (an old iPhone 4).
They all see the ESP, but the handler just isn't get called.

[EDIT]
It does actually work, but there's something wrong with the example: it only probes for the first 10 seconds, after which it disables the probe-event.

Will keep you updated.

Assumption is the mother of all f*ckups. At least: that's what I'm assuming.

- Mon May 22, 2017 8:36 pm #66200 My first try at a solution:

Code: Select all/*
    This sketch will try to keep a list of all devices in
    the vicinity by signaling probe requests it receives.

    When a device probes for AP's (and it's picked up by our ESP8266),
    the ESP will search a table to see if it's already known.
    If not: it is added to the list, if it's already known, the entry's
    timestanp will be updated.
    When a device is not seen for a certain amount of time, it is
    removed from the list again.


    Output to serial console:
    - When a new device is found
    - When an existing device has left (timed out)
   
    Input from serial console:
    - Any command (or just LF) will show a list of registered devices


    NOTE: This is my first sketch using C++ for the ESP8266 (in real
          life I'm actually a Pascal/Delphi programmer), so don't shoot
          me for any weird pieces of code.
          I hope to be as good as you in the near future.

    Code inspired by the WiFiEvents-example by Ivan Grokhotkov.
    This version of the code was written by Peter Luijer and
    is released into the public domain, or, at your option,
    CC0 licensed.
*/

#include <ESP8266WiFi.h>
#include <stdio.h>

typedef struct
  {
      uint8_t mac[6];
      int rssi;
      unsigned long ms;
  }  client_device;

const char* proberversion = "ESProber v.0.9b by QuickFix, (c)2017";
const int   maxdevices    = 255; // Max. number of devices to keep track off at a time
const int   listtimeout   = 120; // Consider device away if not seen for this numner of seconds
const char* ap_ssid       = "ESProber"; // Name for our AP
const char* ap_password   = "12345678"; // Password for our AP
                                 
WiFiEventHandler probeRequestHandler;
client_device devicelist[maxdevices];
String consolebuffer;

int adddevice(const uint8 mac[6], int rssi) {
  int d;
  d = -1; 
  int i;
  for (i = 0; i < maxdevices; i = i + 1) {
    if ((devicelist[i].mac[0] == 0) &&
        (devicelist[i].rssi == 0)) {
      d = i;
      devicelist[d].mac[0] = mac[0];
      devicelist[d].mac[1] = mac[1];
      devicelist[d].mac[2] = mac[2];
      devicelist[d].mac[3] = mac[3];
      devicelist[d].mac[4] = mac[4];
      devicelist[d].mac[5] = mac[5];
      devicelist[d].rssi   = rssi;
      devicelist[d].ms     = millis();
      break;
    }
  }
  return d;
}

void updatedevice(int index, int rssi) {
  devicelist[index].rssi = rssi;
  devicelist[index].ms   = millis();
}

void cleardevice(int index) {
  devicelist[index].mac[0] = 0;
  devicelist[index].rssi   = 0;
  devicelist[index].ms     = 0; 
}

void cleardevices() {
  int i;
  for (i = 0; i < maxdevices; i = i + 1) {
    cleardevice(i); 
  } 
}

int countdevices() {
  int d;
  d = 0; 
  int i;
  for (i = 0; i < maxdevices; i = i + 1) {
    if ((devicelist[i].mac[0] != 0) &&
        (devicelist[i].rssi != 0)) {
      d = d + 1;
    }
  }
  return d;
}

int finddevice(const uint8 mac[6]) {
  int d;
  d = -1; 
  int i;
  for (i = 0; i < maxdevices; i = i + 1) {
    if ((devicelist[i].mac[0] == mac[0]) &&
        (devicelist[i].mac[1] == mac[1]) &&
        (devicelist[i].mac[2] == mac[2]) &&
        (devicelist[i].mac[3] == mac[3]) &&
        (devicelist[i].mac[4] == mac[4]) &&
        (devicelist[i].mac[5] == mac[5])) {
      d = i;
      break;
    }   
  }
  return d;
}

void checklist() {
  int i; 
  for (i = 0; i < maxdevices; i = i + 1) {
    if ((devicelist[i].mac[0] != 0) &&
        (devicelist[i].rssi != 0) &&
        ((devicelist[i].ms + (listtimeout * 1000)) < millis())) {
      Serial.print("Device ");
      Serial.print(macToString(devicelist[i].mac));
      Serial.println(" has left");
      cleardevice(i);
    }
  }
}

void printlist() {
  int c;
  c = countdevices();
  Serial.println("");
  Serial.print(c); 
  Serial.print(" registered devices (prober running for ");
  Serial.print(millis() / 1000);
  Serial.println(" seconds):");
 
  if (c > 0) {
    int i;   
    for (i = 0; i < maxdevices; i = i + 1) {
      if ((devicelist[i].mac[0] != 0) &&
          (devicelist[i].rssi != 0))
      {
        Serial.print("MAC: ");
        Serial.print(macToString(devicelist[i].mac));
        Serial.print(" RSSI: ");
        Serial.print(devicelist[i].rssi);     
        Serial.print(" last seen ");
        Serial.print((millis() - devicelist[i].ms) / 1000);
        Serial.println(" seconds ago");
      }   
    }
  } 
}

String macToString(const uint8 mac[6]) {
  char buf[20];
  snprintf(buf, sizeof(buf), "%02x:%02x:%02x:%02x:%02x:%02x",
           mac[0], mac[1], mac[2], mac[3], mac[4], mac[5]);
  return String(buf);
}

void checkconsole() {
  char c;
 
  while (Serial.available() > 0) {
    c = Serial.read();
    if (c == '\n') {
      printlist();     
      consolebuffer = "";
    } else {
      consolebuffer +=c;
    }
  }
}

void setup() {
  Serial.begin(115200);
  Serial.println(proberversion); 
 
  Serial.println("Configuring wifi:");
  WiFi.mode(WIFI_AP);
 
  Serial.print("- SSID: ");
  Serial.println(ap_ssid);
  Serial.print("- Password: ");
  Serial.println(ap_password);
  WiFi.softAP(ap_ssid, ap_password);

  Serial.print("Maximum number of devices: ");
  Serial.println(maxdevices);
  cleardevices();
  Serial.print("Registration time-out (s): ");
  Serial.println(listtimeout);

  probeRequestHandler = WiFi.onSoftAPModeProbeRequestReceived(&onProbeRequest);
  Serial.println("Probing started");
}

void onProbeRequest(const WiFiEventSoftAPModeProbeRequestReceived& evt) {
  int i;
  i = finddevice(evt.mac);
  if (i < 0) {
    i = adddevice(evt.mac, evt.rssi);
    if (i < 0) {
      Serial.print("Unable to add new device to list");
    } else {
      Serial.print("New device found");
    }
    Serial.print(", MAC: ");
    Serial.print(macToString(evt.mac));
    Serial.print(" RSSI: ");
    Serial.println(evt.rssi);   
  } else {
    updatedevice(i, evt.rssi);
  }
}

void loop() {
  checklist();
  checkconsole(); 
  delay(10);
}

For the code to work, you'll need to have the latest ESP8266-library code from GitHub (the current release version in the Arduino Board Manager isn't up to date yet).

When compiled and flashed, you'll see output on the console similar to this:

Code: Select allESProber v.0.9b by QuickFix, (c)2017
Configuring wifi:
- SSID: ESProber
- Password: 12345678
Maximum number of devices: 255
Registration time-out (s): 120
Probing started
New device found, MAC: 2c:0e:3d:47:2d:bd RSSI: -68
New device found, MAC: b8:53:ac:9c:f1:99 RSSI: -80
Device 2c:0e:3d:47:2d:bd has left
New device found, MAC: 70:72:0d:3a:6b:e2 RSSI: -28
New device found, MAC: 54:60:09:79:4c:e6 RSSI: -78

To get a current list of registered devices, just send a LF on the console:

Code: Select all3 registered devices (prober running for 319 seconds):
MAC: e0:c7:67:36:47:f4 RSSI: -86 last seen 3 seconds ago
MAC: 54:60:09:79:4c:e6 RSSI: -87 last seen 24 seconds ago
MAC: bc:6e:64:83:b0:2a RSSI: -88 last seen 0 seconds ago

I know the code may look weird at places, but this is my first go at C++, since I'm actually a Pascal/Delphi developer in real life.
You're welcome to critize my code, but please be gentle.

Greetz,

Peter

Assumption is the mother of all f*ckups. At least: that's what I'm assuming.

- Wed May 24, 2017 1:52 am #66240

I know the code may look weird at places, but this is my first go at C++, since I'm actually a Pascal/Delphi developer in real life. You're welcome to critize my code, but please be gentle.

Looks fine to me.

I've wondered about how to do something useful with these probe events. Something like record the date/time of each device visit along with its closest RSSI, and have daily and weekly reporting to show who comes by and when?