i am not getting the distance value in LCD for ultrasonic distance sensor

[yash_01]

i wanted to create a project using at89s52 for distance of an object measurement using ultrasonic sensor. so i wrote a code using keil and tried the simulation using proteus, i am getting "distance" as the output but the distance value isnt shown. what is wrong in the code?? my code is:

---

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
#include <reg51.h>
#define lcd_data P2
sbit rs=P1^0; //reg select
sbit rw=P1^1; //rewrite
sbit en=P1^2;  //enable
sbit trig=P1^3;
sbit echo=P1^4;
char distance;
char time;
int i=0,j=0;
char str[4];
 
void lcd_init();
void cmd(unsigned char a);
void dat(unsigned char b);
void show(unsigned char *s);
void lcd_delay();
 
void lcd_init()
{
    cmd(0x38);   //defining is first, the peripherals and the line
    cmd(0x0e);  
    cmd(0x01);
    cmd(0x06);  //entry mode - after refreshing we're ready to use it
    cmd(0x0c);  //defining cursor
    cmd(0x80);    // start from the first row first column
}
 
void cmd(unsigned char a)
{
    lcd_data=a;
    rs=0;   //registers select
    rw=0; // write mode
    en=1; //enabling writing to the registers, power should be on when in use
    lcd_delay();
    en=0;
}
 
void dat(unsigned char b)
{
    lcd_data=b;
    rs=1;
    rw=0;
    en=1;
      lcd_delay();
    en=0;
}
 
void show(unsigned char *s)
{
    while(*s) {
        dat(*s++);
    }
}
 
void lcd_delay(){
    int i;
    for (i=0;i<10000;i++){
    }
}
 
void send_pulse(){
    trig=1;
    TMOD = 0x01;
    TH0 = 0xff;
    TL0 = 0xf6;
    TR0 = 1;       
  while (TF0 == 0);
  TR0 = 0;      
    TF0 = 0;          
    trig=0;
}
 
unsigned char ultrasonic(){  //11.3m
    TMOD = 0x01;          
  TH0 = 0x00;           
  TL0 = 0x00;
    TR0=1;
    send_pulse();
    while (!echo);
    while (echo);
    TR0=0;
    time=(TH0 << 8) | TL0;
    return time/58;
}
 
void int_to_string(unsigned int num, unsigned char *buf) {
    int i = 0, j;
    unsigned char temp[4];
   
    // Convert each digit to a character
    if (num == 0) {
        buf[i++] = '0';
    } else {
        while (num > 0) {
            temp[i++] = (num % 10) + '0';
            num /= 10;
        }
    }
 
    // Reverse the order
    for (j = 0; j < i; j++) {
        buf[j] = temp[i - j - 1];
    }
    buf[I] = '\0'; // Null-terminate the string
}
 
void main(){
    lcd_init();
    cmd(0x80);
    show("Distance");
    while(1){
                    distance=ultrasonic();
              int_to_string(distance, str);
                    cmd(0xc0);
                    show (str);
                    lcd_delay();
                    cmd(0x01);
                    lcd_delay();
            
    }
}[/I]

---

 

[FvM]

the distance value isnt shown

Means what exactly? Empty second line, value of 0 displayed?
Many possible problems. I stopped reading the code when found that time is using an 8-bit (char) variable type, so most of the distance information is discarded.

 

[yash_01]

Means what exactly? Empty second line, value of 0 displayed?
Many possible problems. I stopped reading the code when found that time is using an 8-bit (char) variable type, so most of the distance information is discarded.

empty second line, thats the problem . abt the 8 bit char value, since im focusing on nearby distances,i expect my value to be lesser, within 8 bits. is int type required??

 

[FvM]

As time is divided by 58, 8 bit value for time is restricting distance to 0..4. Hardly what you want.

--- Updated Yesterday at 12:09 PM ---

Also this is surely wrong:

buf = '\0'; // Null-terminate the string

Looks like you have written the whole code from the scratch. That's instructive, but you should have a simulator or debugger that allows to execute the code interactively and find all errors.

 

[yash_01]

As time is divided by 58, 8 bit value for time is restricting distance to 0..4. Hardly what you want.

--- Updated Yesterday at 12:09 PM ---

Also this is surely wrong:

buf = '\0'; // Null-terminate the string

Looks like you have written the whole code from the scratch. That's instructive, but you should have a simulator or debugger that allows to execute the code interactively and find all errors.

i set my distance as 3cm in that case, but still am not getting the distance value in the second line

 

[FvM]

As stated, there are more issues. Error in int_to_string() is sufficient to get no result output.

 

[yash_01]

As stated, there are more issues. Error in int_to_string() is sufficient to get no result output.

what is the error in the int_to_string() ??

 

[FvM]

See post #4.

 

[Aussie Susan]

I don't know the Keil compiler but I'm pretty sure that your 'lcd_delay()' function will not do anything. Most of the compilers that I know of (even in the lowest level of optimisation) will replace this whole function with nothing. You are probably getting away with this in the simulator because (I assume) it doesn't care about actual delays in the simulated LCD.
Instead you should be using a delay function provided by the compiler or use a hardware timer (or use assembler that will not be optimised away).
I don't know the LCD you will actually be using, but I suggest that you look at the data sheet for it - many will require long(ish) delays during the initialisation that youy are not providing.
Does the code as you have shown it actually compile? The reason I ask is that line 105 uses an uppercase 'I' as the index which is not declared. (Elsewhere you use a lower case 'i' that is correct. I think this may be due to the forum thinking that this is the start of an italic block, going by the '[/I]' at the end of the code block.)
Susan