Hello I have a problem....
I have been searching the internet for a long time how I can connect a "NodeMCU Esp8266" with an "Aurduino UNO" via "SPI". I can't find a tutorial that explains how to do this... There is one that explains it, but the problem is that there are several web pages that say that the "MOSI" and "MISO" cables must have resistances, but according to me the pins of the "Arduino UNO" emit 3.3V and not 5V.
In short, I need the code for the "Arduino UNO" and "Esp8266" to make a "SPI" communication to send a Hello World before doing something else and how to connect them physically (the "Arduino UNO" must be the Slave).