Homepoint VS esp-jumpstart

Have a look at Homepoint, which you can run on an ESP32 with a display, such as the M5Stack Core. I have created something similar with ESPHome, and I'm running this as a dashboard showing the value of a couple of sensors at home. ESPHome on the M5Stack Core makes for a lot of possibilities, see https://koen.vervloesem.eu/blog/you-can-now-use-the-m5stack-core-in-esphome/ for how to use it.

As mentioned above, on line 15, the app_driver.c is using the "JUMPSTART_BOARD" variable on the "include" section. When building, it will be replaced by "board_esp32_devkitc.h", therefore becoming "#include board_esp32_devkitc.h". If you remove it, there will be no value to be replaced, and the system will try to compile the file with a "#include JUMPSTART_BOARD", which is an invalid directive.

Think of it as a configuration file. In this case, "board_esp32_devkitc.h" is the configuration for the ESP32 DevKit-C Board. For this board, it is using the GPIO 27 as output. What if you need to build the system for this board and for a different board where the GPIO 27 is already in use or, not even has that GPIO? With a configuration file you just need to pass and argument to the build system and it will use the correct configuration. Without it you'll probably need to clutter you source files with "#ifdef", which would work, but would be worse to maintain, especially if you need to add a third or more boards.