https://medium.com/jungletronics/pic-18-hello-world-o-f00275279cd0

unit_01_02_pushAndBlinkAnLED.c

/* Project: Unit 01 - IO
      Code: unit_01_02_pushAndBlinkAnLED.c

   Objective:   This project we're blinking an LED attached on PORTD's reg. bit 0
                while pressing a button on PORTB's reg. bit 0 (Momentary button);
                8 LEDs are connected to PORTD & 8 buttons are on PORTB of PIC18F4520 uC,
                running under 8 MHZ crystal (set sw1 dip = 9, LEDs on PORTD);
                
      Author:   microgenios, edited by J3

   PIC Lessons: How to Start to Program PIC 18 - Step-by-step for Beginners! by J3

   Hardware:    Development Boards (OPTIONS):
                   PicGenios:   PIC18F4520 chip   ( https://loja.microgenios.com.br/produto/kit-picgenios-pic18f4520-com-gravador-usb-microicd-licen-a-compilador-mikroc-pro-for-pic/23507 )
                   EasyPIC™ 7:  PIC18F45K22 chip  ( https://www.microchip.com/Developmenttools/ProductDetails/TMIK013 )
   Software:    Development Programmer/Debugger:
                                PICkit™ 2         ( http://ww1.microchip.com/downloads/en/DeviceDoc/PICkit%202%20v2.61.00%20Setup%20A.zip )
                          mikroProg suite for PIC ( https://www.mikroe.com/blog/mikroprog-suite-for-pic-version-2-3-1-released )
                          
        PDL:    is a free-format English-like text that describes the flow of control and data in a
                program. PDL is not a programming language. It is a collection of some keywords that enable
                a programmer to describe the operation of a program in a stepwise and logical manner:

              BEGIN
                  Pre-compilation Directives (config PORTB and PORTD as digital)
                  Configure PORTB register bit 0 as digital input (just one button)
                  Configure all PORTD as digital output (init all LED off)
                  DO FOREVER
                      IF Button on PORTB reg. bit 0 pressed THEN
                           Toggle LED on PORTD's pin 0 (use LAT buffer)
                           Wait .3s
                      ENDIF
                  ENDDO
              END

       Date:   Oct 2019
*/

void main() {
                       // For PIC18F45K22
#ifdef PIC18F45K22
       ANSELB = 0;     // Config all the PORTB's pins as digital
       ANSELD = 0;     // Config all the PORTD's pins as digital
                       // For PIC18F4520
#else
       ADCON1 |= 0X0F; // Config all ADC's pins as digital on PIC18F4520
#endif

  /* BEGINNING TO CODE FROM HERE! */
  // Button on PORTB RB0
  TRISB.RB0 = 1;       // Config RB0 as Input (1=I:)
  PORTB.RB0 = 1;       // Optional, the MCU do it automatically ;)

  // LEDs on PORTD RD0
  TRISD = 0;           // Config all PORTD's pins as Output (0=0:)
  PORTD = 0;           // Config all PORTD's pins as LOW,
                       // then all LEDs attached to it will be OFF;)

  /* Remember that all pin's are initialize as analogue,
     so we need to config ANSEL (PIC18F45K22) or ADCON1 (PIC18F4520);
     PLEASE GOTO init of this main routine and set directive like this:
     #ifdef/#else/#endif... */

  while(1)
        {              // Triggered by low level;
                       // Note: the LED keeps blinking while pressing the button :/
                       //(In the next project we're gonna deal w/ this issue ;)
           if(PORTB.RB0 == 0 )
          {
                       // Toggle LED on PORTD's pin 0; 
                       // Using the LAT buffer to avoid intermidiate status
                       // Read Modify Write Problem:
                       // https://download.mikroe.com/documents/compilers/mikroc/pic/help/rmw.htm
            PORTD.RD0 = ~ LATD.RD0;
            Delay_ms(300);
          }

        }
 }