P89LPC932A1 pulse width measurement assembly program

/********************CCU_Capture.asm***************************
;Program function: Capture each level jump of a square wave, and use the captured value to calculate
the pulse width, duty cycle, period or other of the square wave.
;****************************************************************/

$NOMOD51
$INCLUDE(REG932.INC)

ICRAH_DAT1 DATA 41H ; High byte of the first capture value
ICRAL_DAT1 DATA 42H ; Low byte of the first capture value
ICRAH_DAT2 DATA 43H ; High byte of the second capture value
ICRAL_DAT2 DATA 44H ; Low byte of the second capture value
ICRAH_DAT3 DATA 45H ; High byte of the third capture value
ICRAL_DAT3 DATA 46H ; Low byte of the third capture value

CAP_FLAG1 BIT 10H ; first capture flag
CAP_FLAG2 BIT 11H ; second capture flag

KEY  BIT P0.0

  ORG 0000H
  AJMP MAIN
  ORG 005BH
  AJMP CCU_ISR
;---------------------------------------
;Function: Main function
;---------------------------------------
  ORG 0080H
MAIN:
  MOV P2M1,#40H ;Port setting
  MOV P2M2,#40H

  MOV ICRAL_DAT1,#00H
  MOV ICRAH_DAT1,#00H
  MOV ICRAL_DAT2,#00H
  MOV ICRAH_DAT2,#00H
  MOV ICRAL_DAT3,#00H
  MOV ICRAH_DAT3,#00H 
MAIN_LOOP: 
  JB KEY,$ ;Wait for the key to
  be pressed JNB KEY,$ ;Wait for the key to be released
  ACALL INI_CCU ;Initialize CCU and set interrupt
  ACALL DISP ;Output the captured value to display
  SJMP MAIN_LOOP
  RET
;--------------------------------------
;Function: CCU initialization
;--------------------------------------
INI_CCU:
  MOV TOR2H,#00H ;Set CCU to reload high byte
  MOV TOR2L,#00H ;Set CCU to reload low byte
  MOV TPCR2H,#00H ;Set CCU pre- scaling controller
  MOV TPCR2L,#5
 
  MOV CCCRA,#10H ;Set the capture comparison channel A working mode to rising edge capture
  MOV TICR2,#81H ;Set CCU interrupt enable controller
  SETB ECCU ;Open CCU interrupt
  SETB EA ;Open all interrupts
  MOV TCR20,#00000001B ;Set CCU working mode, increment count
  RET
;--------------------------------------
;Function: CCU interrupt service routine
;--------------------------------------
CCU_ISR:
  CLR EA

  MOV A,TISE2
  ANL A,#07H
  CJNE A,#07H,CAP ;Judge whether it is CCU timer interrupt
  ANL TIFR2,#7FH ;If yes, clear TIFR2 (interrupt flag) to 0
  MOV A,TISE2 
CAP: CJNE A,#06H,INTS_CEXT ;Judge whether it is the interrupt of input capture event A, if not, exit
  JB CAP_FLAG1,CAP2 ;Judge whether it is the second interrupt, if yes, jump
;------------------
CAP1:
  PUSH ACC
  MOV A,ICRAL
  MOV ICRAL_DAT1,A
  MOV A,ICRAH
  MOV ICRAH_DAT1,A
  SETB CAP_FLAG1 ;The first capture interrupt is completed
  MOV CCCRA,#00H ;Set the capture compare A channel working mode to falling edge capture
  POP ACC
  AJMP INTS_CEXT
;------------------
CAP2: 
  PUSH ACC
  JB CAP_FLAG2,CAP3 ; Check if it is the third interrupt? If yes, jump to CAP3.
  MOV A,ICRAL ; Save the value captured for the second time
  MOV ICRAL_DAT2,A
  MOV A,ICRAH
  MOV ICRAH_DAT2,A

  SETB CAP_FLAG2 ;The second capture interrupt is completed
  MOV CCCRA,#10H ;Set the capture comparison channel A working mode to rising edge capture
  POP ACC
  AJMP INTS_CEXT
;-------------------
CAP3:
  MOV TCR20,#00H ;Stop CCU timer counting
  PUSH ACC
  MOV A,ICRAL ;Save the third capture value
  MOV ICRAL_DAT3,A
  MOV A,ICRAH
  MOV ICRAH_DAT3,A

  CLR CAP_FLAG1 ; Clear capture completion bit
  CLR CAP_FLAG2
  POP ACC
; AJMP INTS_CEXT
;------------------------
INTS_CEXT:
  MOV TIFR2,#00H ; Clear capture interrupt flag bit to 0
  SETB EA
  RETI
;-------------------------------------
; Function: Please add your data processing program here
;-------------------------------------
DISP:
  ;...... Please add your own statement here, for example, high level pulse width = (ICRAH_DAT2, ICRAL_DAT2)-(ICRAH_DAT1, ICRAL_DAT1)
  ;...... Process the obtained data to obtain the required value
  ;...... and display or transmit it to the host computer

  RIGHT
;-----------------------------------
  END 
;*********** ****************************************************** *****