This make the communication not byte to byte controlled as I want it to be for my need. At the center, the Slave Arduino, with buttons, leds, and ldr for testing pin access. I realized that if I wanted to make an Arduino slave, when receiving from master, it actually reads from a buffer that is already previously received. I'm writing PortExtender, a library to convert an Arduino Pro Mini in a port expander and I ran into what seems to be a compatibility problem between Arduino and nodeMCU: I got different answers depending on who is the master (Arduino or nodeMCU). But let’s start with the problem found in the Wire. The wire more close to the hardware in a simple way. When the limitations were somehow fixed, even though the small number of modifications (it is somehow a sort of hacking of the library) I found that the my final result were so useful to me that I thought was worth to write a short article about it. The solution is to have a library that allow me to do things in the hard way. Then, when experimenting with a portability of a project in the Arduino environment, I started to trying the official Wire library, discovering some incompatibilities for my needs.

I have spent a lot of time on playing and later working on the I2C buses. I almost always used self developed libraries, both for learning and job requirement purposes.

Wire library alternatives