Using the query and interrupt method to generate timing pulse programming using the microcontroller timer T0

   Timer T0 is used to generate timing pulses. A positive pulse with a width of 2 machine cycles is generated every 2ms, and this timing sequence pulse signal is output by P1.0 (assuming the clock frequency is 6MHZ).

    Answer: First, find the initial value of timer T0. Since the clock frequency is 6MHZ, the machine cycle is 2µs.

    Because: t = (213-T0 initial value) ´ Machine cycle

    Therefore, when t=2ms, then: (213-T0 initial value) ´ 2´10-6=2´10-3

Solution: T0 initial value = 7096 = 11011101 11000B, where the upper 8 bits 11011101 B = DDH are assigned to TH0, and the lower 5 bits 11000B = 18H are assigned to TL0.

method one:

       Using the query working mode, the programming is as follows:

              ORG 0000H

              AJMP MAIN 

              ORG 0100H

    MAIN: CLR P1.0

              MOV TMOD, #00H; Set the working mode of T0 

            MOV TH0 , #0DDH ; send initial value to timer T0 

MOV TL0 , #18H

        SETB TR0; start T0 work

        LOOP: JNB TF0, $; $ is the current instruction pointer address

           CLR TF0        

           SETB P1.0; generates a 2µs positive pulse 

           CLR P1.0 

           MOV TH0 , #0DDH; reload TH0 and TL0

           MOV TL0 , #18H

           SJMP LOOP

           END

Method Two:

Using interrupt working mode, programming is as follows:

           ORG 0000H

           AJMP MAIN

           ORG 000BH

           AJMP T0INT 

           ORG 0100H

  MAIN:CLR P1.0

           MOV TH0 , #0DDH ; send initial value to timer T0

MOV TL0 , #18H 

        MOV IE , #82H; Enable T0 interrupt

           SETB TR0; Start T0

           SJMP$ 

   Interrupt service routine:

           ORG 0300H

 T0INT: SETB P1.0 

           CLR P1.0

           MOV TH0 , #0DDH; reload TH0 and TL0 

           MOV TL0 , #18H 

           RETI