I want to make a project where it is necessary to communicate between several microcontrollers in the fastest way possible.
For that matter I have 10 micro-controllers whose names will be 1 ... 10:
I want 1 to receive a number as input (input from user), and send it to 2.
2 will receive the number and will add 10 to it, and send the results to 3.
And so each will add a number and send the results to the next micro-controller until it reaches 10.
10 will output the final output (the output should be the number 1 received as input + all the numbers that the other processors in the chain added).
I am looking to buy STM32F103C8 (blue pill) because they look both cheaper and also stronger (and they looked more supported) than Arduino (although I am open to suggestions for other micro-controllers including claims in favor of Arduino).
Now my question is how I connect the micro-controllers I have selected (or the suggested micro controllers) to each other in the fastest and most efficient way.
I'm not looking for suggestions like: add an Ethernet/Bluetooth module and communicate with it between the micro-controllers.
I'm looking for an explanation of how to connect them using a serial or I2C connection or something like that (and I would be happy if you could add a detailed guide on how exactly to do it, which legs to attach to etc., since I'm still relatively new at working with micro-controllers)