Hi.
Is there a way (application?) that can make a phone turn-on a gadget ? Perhaps using (transmitting) with its WiFi to a receiver ?

Example. Hitting 234 on a virtual keyboard and the WiFi receiver to close its relay number 2 during 34 seconds. No networking/routers involved. Direct phone-to-receiver gadget.
What is a range limit line-of-sight of such 2.4/5GHz wireless ? My WiFi sniffer/explorer shows links over 500m away -95dBm

Or, calling a phone number that will auto answer, listen and will turn-on "relay number 2 for 34 seconds" What would be the proper hardware as for a landline ?

 

ESP32 as a server is likely the quickest route.

 

You can create an app on the smartphone to send commands via bluetooth.

 

Hi.
Is there a way (application?) that can make a phone turn-on a gadget ? Perhaps using (transmitting) with its WiFi to a receiver ?

Example. Hitting 234 on a virtual keyboard and the WiFi receiver to close its relay number 2 during 34 seconds. No networking/routers involved. Direct phone-to-receiver gadget.
What is a range limit line-of-sight of such 2.4/5GHz wireless ? My WiFi sniffer/explorer shows links over 500m away -95dBm

Or, calling a phone number that will auto answer, listen and will turn-on "relay number 2 for 34 seconds" What would be the proper hardware as for a landline ?

Look at the Sonos app on a phone. That uses UDP to interact with the devices, take a look at the UPnP technology, that's what Sonos is based on.

https://en.wikipedia.org/wiki/Universal_Plug_and_Play

 

What I see from your Sonos suggestion is listening to music and using UPnP networking and internet. Nothing to do with anything I asked

A smart phone application that shows a keypad... you hit some keys... a WiFi gadget receives those and energizes/does what was intended to do.
The nearest in sounds; could be Saying a phrase or numbers instead of interfacing a keypad; and a WiFi gadget do a corresponding action to the words said.

Zero internet, zero routers, zero modems. Phone ----> to a wifi gadget that closes a relay.

 

Bluetooth is the way to go.

 

As suggested earlier ESP32 is a simple way to go or even one of the ESP8266 varieties. They can create a WiFi access point you connect to much like connecting to a router. From there you can create a web server that serves a web page or a standard socket program. The web server is the easiest as you only need your phone's web browser, but if you are feeling adventurous you could create an app to connect to a socket (extremely adventurous would probably be a better description). Either way no internet, modems, or routers involved.

 

Zero internet, zero routers, zero modems. Phone ----> to a wifi gadget that closes a relay.

Wifi sort of implies at least a local intranet and a router. There are devices that create that local wifi network that your phone can connect to. My OBD-II (automotive diagnostic) reader works that way and I think some smart home devices have a similar way to enable a connection during the setup process. You need to talk to it to tell it how to get on your local network.

But anyway, bluetooth and a custom app is likely your best option as others have noted. If you're not into app development, you may have to keep searching to find something on-the-shelf that is close to what you need.

I don't know what you're up to but I have a number of smart home devices in the house and they're very easily controlled with existing or custom apps. Getting that timing that you want could be a challenge but these canned solutions would at least make it very easy to identify all your switches. Turn lights on and off, etc. Turn on the coffee pot. Lower the thermostat. Open a window.

 

Thanks, geek. Do not know enough to understand the method proposed. If I can expand, the 'smart' phone has no internet provider; or if preferred, no browser to access a server or anything on the web.

Thanks, Wayneh... I can print directly via WiFi from my phone to my Brother laser printer in another room. There is no router, no wifi in my home, none. As far as I know, no bluetooth involved either in my phone (or it is off).
A random example below :

That is sort of the method am after. To turn on something using a phone WiFi.

Say I sail to an island in the middle of the Caribbean. My phone has no telephony service provider there. I want to turn on the lighthouse navigation beacon on the nearby cliff. Which has some wireless receiver gadget that responds/recognizes any phone with the application am after. Can be from another sailor nearby. Any other sailor with the application in their phone.

Correct, I do not know enough to understand all responses here. Am limited in knowledge about this.

 

@geekoftheweek has proposed a solution that meets your requirements.

The ESP32 can set up a WIFI access point that you connect to just like would connect to a router. No internet connection is required. And you then have a TCP/IP communication channel with all if its robust error checking and retries, so it is very high reliability.

The ESP32 then acts like a very limited web server. It can serve a single web page to your phone simply by pumping out a string of text (HTML). The browser in your phone puts up this web page, which can have buttons, text boxes, dropdown menus, etc. to enter the data for the device. When you press a send button, it sends a URL back to the server with the parameters you entered.

I know, because I did all this myself to control a lighting display with 40m of addressable RGB LED strips. Now, I connected through my home WIFI, but I could have made it a dedicated access point as well by changing one or two commands to the ESP8266 I used.

The beauty of this is that it works from any phone, tablet, PC or other device with no application code required.

I urge you to try to understand this solution, it is well worth it.

 

What I see from your Sonos suggestion is listening to music and using UPnP networking and internet. Nothing to do with anything I asked

A smart phone application that shows a keypad... you hit some keys... a WiFi gadget receives those and energizes/does what was intended to do.
The nearest in sounds; could be Saying a phrase or numbers instead of interfacing a keypad; and a WiFi gadget do a corresponding action to the words said.

Zero internet, zero routers, zero modems. Phone ----> to a wifi gadget that closes a relay.

UPnP is just a way of using WiFi to control devices, if you don't like the idea then write your own system.

 

@geekoftheweek has proposed a solution that meets your requirements.

The ESP32 can set up a WIFI access point that you connect to just like would connect to a router. No internet connection is required. And you then have a TCP/IP communication channel with all if its robust error checking and retries, so it is very high reliability.

The ESP32 then acts like a very limited web server. It can serve a single web page to your phone simply by pumping out a string of text (HTML). The browser in your phone puts up this web page, which can have buttons, text boxes, dropdown menus, etc. to enter the data for the device. When you press a send button, it sends a URL back to the server with the parameters you entered.

I know, because I did all this myself to control a lighting display with 40m of addressable RGB LED strips. Now, I connected through my home WIFI, but I could have made it a dedicated access point as well by changing one or two commands to the ESP8266 I used.

The beauty of this is that it works from any phone, tablet, PC or other device with no application code required.

I urge you to try to understand this solution, it is well worth it.

This is the way to go.

From your phone, you would connect to the ESP32 "wifi" network.

I'm not sure how you would go about it, but, once connected, the ESP32 could present a web page that allows you to enter your code. Once you enter the code it acts on it to turn on or off your device.

It would be limited by the strength of the ESP32 transmitter so not a whole lot of distance between ESP32 and phone.

 

I'm not in any way arguing against the proposed solution but I would point out that you could configure a standard wifi router to host a local network at the lighthouse, no internet required, that anyone with wifi could access. Anyone joining that network would then have access to anything on that network. This might free you from solving some of the issues (range?) that you may encounter with a DIY solution.

 

https://randomnerdtutorials.com/esp32-web-server-beginners-guide/

 

Another thing to look into is mDNS for the ESP32. Instead of having to remember an IP address to access web page you would give it a unique name like "light-relay" and use "light-relay.local" to access web page.

 

Good link, Lo_volt. Thanks.
Bought the ESP-WROOM-32 . There is many models that cannot discern the proper one. A popular one that showed lots of sales is coming, will see.