51 single chip ultrasonic ranging program

Ultrasonic rangefinder microcontroller program

#include  
#define uchar unsigned char 
#define uint unsigned int 
#define ulong unsigned long 

extern void cs_t(void);

extern void delay(uint); 
extern void display(uchar*); 
data uchar testok; 
/*主程序*/ 
void main(void) 
{ 
data uchar dispram[5]; 
data uint i; 
data ulong time; 
P0 = 0xff; 
P2 = 0xff; 
TMOD = 0x11; 
IE = 0x80; 
while (1) 
  { 
  cs_t(); 
  delay(1); 
  testok = 0; 
  EX0 = 1; 
  ET0 = 1; 
  while (!testok) display(dispram); 
  if (1 == testok) 
    { 
    time = TH0; 
    time = (time<<8) | TL0; 
    time *=172; 
    time /= 10000; 
    dispram[0] = (uchar) (time % 10); 
    time /= 10; 
    dispram[1] = (uchar) (time % 10); 
    time /= 10; 
    dispram[2] = (uchar) (time % 10); 
    dispram[3] = (uchar) (time / 10); 
    if (0 == dispram[3]) dispram[3] = 17; 
    } else 
    { 
    dispram[0] = 16; 
    dispram[1] = 16; 
    dispram[2] = 16; 
    dispram[3] = 16; 
    } 
  for (i=0; i<300; i++) display(dispram); 
  } 
} 
// 
/*超声接收程序（外中断0）*/ 
void cs_r(void) interrupt 0 
{ 
 TR0 = 0; 
 ET0 = 0; 
 EX0 = 0; 
 testok = 1; 
} 

/*超时清除程序（内中断T0）*/ 
void overtime(void) interrupt 1 
{ 
 EX0 = 0; 
 TR0 = 0; 
 ET0 = 0; 
 testok = 2; 
} 

;-------------------------------------
;超声发生子程序（12M晶振38.5Hz）
;-------------------------------------
                    NAME     CS_T
?PR?CS_T?CS_T       SEGMENT  CODE
                    PUBLIC   CS_T
                    RSEG     ?PR?CS_T?CS_T
CS_T:               PUSH     ACC
                    MOV      TH0,   #00H
                    MOV      TL0,   #00H
                    MOV      A,     #4D
                    SETB     TR0
CS_T1:              CPL      P1.0
                    NOP
                    NOP
                    NOP
                    NOP
                    NOP
                    NOP
                    NOP
                    NOP
                    NOP
                    NOP
                    DJNZ     ACC,  CS_T1
                    POP      ACC
                    RET
;
                    END

;---------------------------------------
; Four-digit common anode LED dynamic scanning display program
; P0 is the segment code port, P2 is the bit select port ( low level is valid)
; The parameter is the string pointer to be displayed
;---------------------------------------
                                     NAME DISPLAY
?PR?_DISPLAY?DISPLAY SEGMENT CODE
?CO?_DISPLAY?DISPLAY SEGMENT DATA
                     EXTRN CODE (_DELAY)
                     PUBLIC _DISPLAY
                     RSEG ?CO?_DISPLAY?DISPLAY
?_DISPLAY?BYTE:      
       DISPBIT: DS 1
       DISPNUM: DS 1
                     RSEG ?PR?_DISPLAY?DISPLAY
_DISPLAY: PUSH ACC
                     PUSH DPH
                     PUSH DPL
                     PUSH PSW
                     INC DISPNUM
                     MOV A, DISPNUM
                     CJNE A, #4D, DISP1
DISP1: JC DISP2
                     MOV DISPNUM, #00H
                     MOV DISPBIT, #0FEH
DISP2: MOV A, R1
                     ADD A, DISPNUM
                     MOV R0, A
                     MOV A, @R0
                     MOV DPTR, #DISPTABLE
                     MOVC A, @A+DPTR
                     MOV P0, A
                     MOV A, DISPNUM
                     CJNE A, #2D, DISP3
                     CLR P0.7
DISP3: MOV P2, DISPBIT
                     MOV R6, #00H
                     MOV R 7, #0AH
                     LCALL _DELAY
                     MOV P0, #0FFH
                     MOV P2, #0FFH
                     MOV A, DISPBIT
                     RL A
                     MOV DISPBIT, A
                     POP PSW
                     POP DPL
                     POP DPH POP
                     ACC
                     RET
DISPTABLE:DB 0C0H,0F9H,0A4H,0B0H,99H,92H,82H,0F8H,80H,90H,88H,83H,0C6H,0A1H,86H,8EH,0BFH,0FFH
; "0", "1", "2", "3","4", "5","6","7", "8","9","A" ,"B","C", "D", "E","F", "-", " "
                     END

;-------------------------------------
; Delay 100 machine cycles * parameter (1~65535)
;-------------------------------------
                    NAME DELAY
?PR?_DELAY?DELAY SEGMENT CODE
                    PUBLIC _DELAY
                    RSEG ?PR?_DELAY?DELAY
_DELAY: PUSH ACC ;2
      MOV A, R7 ;1
                    JZ DELA1 ;2
             INC R6 ;1
DELA1: MOV R5, #50D ;2
                    DJNZ R5, $ ;2
                    DJNZ R7, DELA1 ;2
                    DJNZ R6, DELA1 ;2
                    POP ACC ;2
                    RET ;2
;
                    END