My question is about the pullup resistors that may or may-not be on either board that I wish to connect to each other. On the Arduino I expect to use A4 for SDA and A5 for SCL. On the Pi4B I expect to use J8-Pin 3 (GPIO2) for SDA and J8-Pin 5 (GPIO3) for SCL.
What puzzles me is this business of the I2C bus needing pullup resistors. Specifically, do I need to put resistors in place on the 2 I2C lines OR Does one or both of the boards already have pullup resistors in place for use on the I2C bus?
Part of my problem is in knowing if I have to "enable" any pullup resistors using something like the "pinMode()" function on either board.
Or, is it as simple as just connecting the SDA and SCL pins together on the respective boards?
I prefer Python on the Pi4B and C on the Arduino.
The Pi4B will act as the 'controller' and "send a command" to the Arduino, while the Arduino will act as a receiver and then act upon the received command.
I won't need any special handling in case of a failure to communicate since this is all under control of a real person who will observe if it worked or not and then repeat the process upon detecting a failure. Thanks -- Ray