Direct Connection without internet/wifi

[iceiceninja]

Hardware: ESP-WROOM-32
Hello! I am new here and with ESP (and IOT) development in general. I am working on a project that involves a device that will float on the surface of the water, receive a command to go underwater and gather sensor data, then come back to the surface of the water and transmit that data to a nearby computer. At the location that this will be taking place, there is no internet/wifi access already set up. My question is, would it be possible for the computer to directly connect to this float and send/receive information? I have heard people say to set the ESP up as an access point and connect to it using the computer. Would this work? There is no routers nearby or anything of that nature so I was curious if I could just establish a direct connection with the esp when the float resurfaces. Thank you in advance for any assistance!

Extra info: The float won't be too far from the computer, max of around 20ft once it resurfaces. It will be encased in a water proof device and focused on reading sensor data when it goes underwater and then focused on transmitting that data once it surfaces again.

[AndrewWang]

You can use bluetooth, WiFi Direct or WiFi-AP mode.
But according to your demonstration, I think any of them is not suitable for you.
1. Bluetooth has an advantage of low power but poor in distance of communication.
2. WiFi Direct has the best effect of connection and communication but needs too much energy. I'm not sure if there is any limits of power in your scenario. Besides, P2P is not supported by ESP-IDF now. But I'm tending to implement this function and here is my repository. You can follow this repository. If there is any possibility you want to use this function, you can have a look and post some your advice or requirements.

https://github.com/AHWang2/ESP-WiFi-P2P-WiFi-Direct

3. WiFi-AP seems to be the most suitable one for you. But its process of connection is inconvenient. Also, it has a high power consumption.

[dexterwatts]

You can configure the ESP-WROOM-32 as a Wi-Fi Access Point, and your computer can connect directly to it. Once connected, you’ll be able to send commands and receive sensor data whenever the device resurfaces.

The key requirement on the computer side is having working Wi-Fi Network Adapters, so it can detect and connect to the ESP’s access point. Since your distance is only around 20ft, signal strength should be fine for basic data transfer in this scenario.

If you run into stability issues later, you can also consider ESP-NOW for more direct ESP-to-device communication, but AP mode is the simplest starting point.