CCS C Programming Basics

Device Definition File

• A CCS C program begins with pre-processor directives like #include, #fuses, and #use delay.
• The directive #include includes the system header file 18F452.H, which is essential for specifying the Special Function Registers (SFRs).
• This device-specific file also holds the values to be written to these registers.

Fuses

• The #fuses directive allows configuration of the PIC microcontroller's fuse settings.
• Example settings explained:
  • HS: High-speed crystal or resonator used for the clock.
  • NOWDT: Disables the watchdog timer, preventing it from resetting the PIC unexpectedly.
  • NOBROWNOUT: Deactivates the brown-out detector, which protects the microcontroller from low voltage conditions.
  • NOPROTECT: Disables code protection, allowing the code to be read from memory.
  • PUT: Enables the power-on timer function.

Delays

• Delay functions in CCS C include delay_us() and delay_ms(), which introduce delays measured in microseconds and milliseconds respectively.
• These functions rely on the clock frequency to calculate the appropriate number of machine cycles for accurate timing.
• The directive #use delay(clock=20000000) defines a clock frequency of 20 MHz for the PIC microcontroller.

Multiple Source Code Files

• CCS C does not facilitate separate compilation and linking of different source code files.
• To enhance code organization and reuse, commonly-used library functions can be stored in separate files.
• The directive #include "lcd.c" incorporates the lcd.c library file into the current file, ensuring that it is available during compilation.
• Although this method of including library files can be less efficient due to repeated compilation, typical compilation times for PIC programs remain short, usually just a few seconds.