Solar Fed Multilevel Inverter Program Output

/*
* File: main.c
* Author: Group No 7 (SRMGPC)
* Created on 21 May, 2020, 1:39 PM
*/
#define _XTAL_FREQ 10000000
#pragma config FOSC = HS // Oscillator Selection bits (HS oscillator)
#pragma config WDTE = OFF // Watchdog Timer Enable bit (WDT disabled)
#pragma config PWRTE = OFF      // Power-up Timer Enable bit (PWRT disabled)
#pragma config BOREN = ON       // Brown-out Reset Enable bit (BOR enabled)
#pragma config LVP = OFF        // Low-Voltage (Single-Supply) In-Circuit Serial Programming Enable bit (RB3 is digital I/O, HV on MCLR must be used for programming)
#pragma config CPD = OFF        // Data EEPROM Memory Code Protection bit (Data EEPROM code protection off)
#pragma config WRT = OFF        // Flash Program Memory Write Enable bits (Write protection off; all program memory may be written to by EECON control)
#pragma config CP = OFF
#include <xc.h>
int level = 0;
int main() {
    TRISB = 0x00;               // set PORT B for output
    PORTB = 0b01001000;         // pin 7 and pin 4 of PORT B is high
    OPTION_REG = 0b00000111;    // set the prescalar to 256
    TMR0 = 244;                 // register value calculated for 0.01 ms delay
    TMR0IE = 1;
    GIE = 1;                    //enable global interrupt
    PEIE = 1;
    while(1) {
        if(level == 6) {
            RB3 = !RB3;     //switching T1
            RB6 = !RB6;     //switching T4
             RB4 = !RB4;     //switching T2
            RB5 = !RB5;     //switching T3
        }
        RB0 = !RB0;         //switching S1
        if(level % 2 != 0) {
            RB1 = !RB1;     //switching S2
        }
        if(level % 4 == 0) {
            RB2 = !RB2;     //switching S3
        }
        level++;
        if(level > 15) {
            level = 0;
        }
    }
    return 0;
}
void __interrupt() timer_isr(void) {
    if(TMR0IF == 1) {   // set timer value on overflow
        TMR0 = 244;     //timer value decrease to 0
        TMR0IF = 0;     //reset the timer interrupt
    }
}