per1234 and bigdinotech Use correct separator in keywords.txt
The Arduino IDE requires the use of a tab separator between the name and identifier. Without this tab the keyword is not highlighted.

Reference: https://github.com/arduino/Arduino/wiki/Arduino-IDE-1.5:-Library-specification#keywords
Latest commit 2227ce1 Sep 2, 2017

README.md

Enable debug interface on Serail1

  • Default disable the debug interface.

If you want to enable debug trace on Serial1 to debug corelib, follow these instructions.

  1. Shut down the IDE
  2. Go to Arduino15 directory
  • Windows: C:\Users\<user>\AppData\Roaming\Arduino15
  • OS X: ~/Library/Arduino15
  • Linux: ~/.arduino15
  1. Modify the platform.txt
  • Find compiler.c.flags and add -DCONFIGURE_DEBUG_CORELIB_ENABLED at the end of this line
  • Find compiler.cpp.flags and add -DCONFIGURE_DEBUG_CORELIB_ENABLED at the end of this line
  1. Initial Serial1 in your sketch
  • Add Serial1.begin(115200); in your setup()
  1. Adjust the output level at log_init function in log.c