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- Vistumbler is wireless network scanner written in AutoIT for Windows. The main purpose of vistumbler is to map and visualize the access points arount you based on the wireless and gps data collected. 7, and vista.Net framework v4 is required. Uses the Windows Native Wifi API or netsh to find access points and get wireless information.
- WiFi Scanner is the most feature rich and complete WiFi scanning app on the app store and is a great tool for personal use and for IT professionals. Programs for query ″wifi scanner 2.7″ NetSpot: WiFi survey & wireless scanner.
WiFi Scanner is the most feature rich and complete WiFi scanning app on the app store and is a great tool for personal use and for IT professionals. Programs for query ″wifi scanner 2.7″ NetSpot: WiFi survey & wireless scanner.
To connect a mobile phone to a hot spot, you typically open Wi-Fi settings app, list available networks and then pick the hot spot you need. You can also list the networks with ESP8266 and here is how.
This example shows the bare minimum code we need to check for the list of available networks.
Disconnect¶
To start with, enable module in station mode and then disconnect.
Running WiFi.disconnect() is to shut down a connection to an access point that module may have automatically made using previously saved credentials.
Scan for Networks¶
After some delay to let the module disconnect, go to scanning for available networks:
Now just check if returned n if greater than 0 and list found networks:
This is that simple.
Complete Example¶
The sketch should have obligatory #include<ESP8266WiFi.h> and looks as follows:
Example in Action¶
Upload this sketch to ESP module and open a serial monitor. If there are access points around (sure there are) you will see a similar list repeatedly printed out:
When looking for the text scanstart... displayed, you will notice that it takes noticeable time for the following text nnetwork(s)found to show up. This is because execution of WiFi.scanNetworks() takes time and our program is waiting for it to complete before moving to the next line of code. What if at the same time we would like ESP to run time critical process (e.g. animation)that should not be disturbed?
It turns out that this is fairly easy to do by scanning networks in async mode.
Check it out in next example below that will also demonstrate printing out other parameters of available networks besides SSID.
What we like to do, is to trigger process of scanning for networks and then return to executing code inside the loop(). Once scanning is complete, at a convenient time, we will check the list of networks. The “time critical process” will be simulated by a blinking LED at 250ms period.
We would like the blinking pattern not be disturbed at any time.
No delay()¶
To implement such functionality we should refrain from using any delay() inside the loop(). Instead we will define period when to trigger particular action. Then inside loop() we will check millis() (internal clock that counts milliseconds) and fire the action if the period expires.
Please check how this is done in BlinkWithoutDelay.ino example sketch. Identical technique can be used to periodically trigger scanning for Wi-Fi networks.
Setup¶
First we should define scanning period and internal variable lastScanMillis that will hold time when the last scan has been made.
When to Start¶
Then inside the loop() we will check if SCAN_PERIOD expired, so it is time to fire next scan:
Please note that WiFi.scanNetworks(true) has an extra parameter true that was not present in previous example above. This is an instruction to scan in asynchronous mode, i.e. trigger scanning process, do not wait for result (processing will be done in background) and move to the next line of code. We need to use asynchronous mode otherwise 250ms LED blinking pattern would be disturbed as scanning takes longer than 250ms.
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Check When Done¶
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Finally we should periodically check for scan completion to print out the result once ready. To do so, we will use function WiFi.scanComplete(), that upon completion returns the number of found networks. If scanning is still in progress it returns -1. If scanning has not been triggered yet, it would return -2.
Please note function WiFi.scanDelete() that is deleting scanning result from memory, so it is not printed out over and over again on each loop() run.
Complete Example¶
Complete sketch is below. The code inside setup() is the same as described in previous example except for an additional pinMode() to configure the output pin for LED.
Example in Action¶
Upload above sketch to ESP module and open a serial monitor. You should see similar list printed out every 5 seconds:
Check the LED. It should be blinking undisturbed four times per second.
The scan class API provides comprehensive set of methods to do scanning in both synchronous as well as in asynchronous mode. Therefore we can easy implement code that is doing scanning in background without disturbing other processes running on ESP8266 module.
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For the list of functions provided to manage scan mode please refer to the Scan Class documentation.