I develop a serial comms system using AT commands and functions or classes.
I have carefully read and exercise with the Libraries section or the Arduino reference and also read the h and cpp of the Arduino site recommended libraries.
The Adafruit are example of well-done works. See https://docs.arduino.cc/learn/contributions/arduino-library-style-guide.
I studied libs from Mr. Olivier Staquet and Mr. Vittorio Esposito for SIM800L, both very well written and documented.
My point is to read and work with the use of classes with data streams, and O. Staquet lib seems to me very complex to start.
Any book or reading to start this topics from the groundup ?
I feel that learn classes and streams and grasp all the details will be a challenge!