hamilc wrote: ↑
Mon Jul 16, 2018 1:03 pm
I still don't understand. lets forget that we are using the Wi-Fi "layer" and think of only using TCP/IP by itself. I am sure that using the basic TCP/IP routines one can communicate between Is without a router. I think when I mentioned WiFi that the conversation meant that we HAD to use Wi-Fi routines. Lets forget Wi-Fi and think about using the TCP/IP routines. There must be some software to do this.
Think about the old serial RS-232 days. There was no master or slave here. Both were always receiving/listening and then when one wanted to transmit then they did so.
You can think of it this way. With Ethernet, you physically connect a cord, before any TCP/IP can work between the units. Creating a wireless Access Point with one Pi and connecting the other to it, is the equivalent of connecting that physical cable.
More Detail: With wireless, its sending all over the place, it doesn't go from one unit to another like Ethernet (contained inside the cord). The pi's Wireless sends data omni directional and it has to be able to tell the difference between signals meant for it, and ones that are not (not to mention getting send receive timings right, so you don't miss packets). So in order to isolate what's yours, you tell both units who and how they are connecting to each other. That process is setting up a Access Point (can be Ad-Hoc or Infrastructure like a router) and connecting the other unit to it.
Something else you may want to think about, is buying a small cheap router like this, and have both units connect to that. Its a LOT simpler to setup, and can be mobile due to the USB power for the router, and its very small power usage (had one running for 5 days on a big USB battery bank). O it also greatly increases the range you can have between the units.
https://www.amazon.ca/GL-iNet-GL-MT300N ... words=inet