Timer interrupt in PIC16F877A working explained 

The calculation of the time delay is just great. Thank you!!

super bro Explanation.

Thank you, but. why is machine cycle equal to 4/20MHz ? where is 4 from ?

Thank you, it is very clear but how is it different, using the timer and using __delay_ms(300);

Best lecture. Lekin baaki comments kaha hai

Bro u r Pro

plz do interface with PC WINDOWS by c++ gcc concile + CAM BUS of 3 please

Sir this is my program but not working pls tell me the reason Unsigned long=i; void interrupt timer() { if(INTCONbits. TMR0IF==1) {i++; TMR0=236; INTCONbits. TMR0IF=0; }} void main() { TRISB=0; INTCONbits. GIE=1; INTCONbits. PEIE=1; INTCONbits. TMR0IE=1; OPTION_REG=0x27; TMR0=236; while(1) { if(i==1000) {PORTBbits.RB1=0; } if(i=2000) {PORTBbits.RB1=1; i=0;}} return;}