Interfacing AT89C51 with ultrasonic sensor and LCD

Code C - [expand]
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
#include<REGX51.h>
#include<intrins.h>// for using _nop_() function
#define port P2
#define dataport P0 
sfr16 DPTR =0x82;
sbit trig=P3^5;
sbit rs=port^0;
sbit rw=port^1;
sbit e=port^2;
 
 
void delay(unsigned int msec)
{
int i,j;
for(i=0;i<msec;i++)
    for(j=0;j<1275;j++);
}
 
void lcd_cmd(unsigned char item) // Function to send command to LCD
{
dataport = item;
rs= 0;
rw=0;
e=1;
delay(1);
e=0;
return;
}
 
void lcd_data(unsigned char item) // Function to send data to LCD
{
dataport = item;
rs= 1;
rw=0;
e=1;
delay(1);
e=0;
return;
}
 
void lcd_data_string(unsigned char *str) // Function to send string to LCD
{
int i=0;
while(str[i]!='\0')
{
  lcd_data(str[i]);
  i++;
  delay(1);
}
return;
}
 
void send_pulse(void) //to generate 10 microseconds delay
{
TH0=0x00;TL0=0x00; 
 trig=1;
 _nop_();_nop_();_nop_();_nop_();_nop_();
 _nop_();_nop_();_nop_();_nop_();_nop_();
 trig=0;
    
} 
 
unsigned int get_range(void)
{
 int range=0;
 int s;
 send_pulse();
 delay(40);//          generate a delay of 40 Milli seconds=40000 micro 
 DPH=TH0;DPL=TL0;  
 TH0=0xFF;TL0=0xFF;
 lcd_cmd(0x81);
 delay(2);
 lcd_data_string("output:");
 lcd_cmd(0x8a);
 if(DPTR<35000)
 {//actually you need to use 38000 but the sensor may not work at higher levels 
  range=DPTR/59;
  s=range/100;
  range=range%100;
  if(s!=0)
  {
  lcd_data(s+48);
  }
  else
  {
  lcd_cmd(0x06);
  s=range/10;
  range=range%10;
  lcd_data(s+48);
  lcd_data(range+48);
  lcd_data(' ');
  }
 }
 else 
 {
 range=0; // indicates that there is no obstacle in front of the sensor 
 lcd_cmd(0x06);
 lcd_data(0);
 }
 return range;
}
 
void main()
{
  lcd_cmd(0x38);
  lcd_cmd(0x0c);
  delay(2);
  lcd_cmd(0x01);
  delay(2);
  lcd_cmd(0x81);
  delay(2);
  lcd_data_string("start");
  delay(20);
  TMOD=0x09;//timer0 in 16 bit mode with gate enable
  TR0=1;//timer run enabled
  TH0=0x00;TL0=0x00;
 
  P3=0x04;//setting pin P3.2 
     
  
 while(1)
 { get_range();
   delay(2);   
 }
}