Help in 16F874 Programming

[Shamooooot]

NEED HELP PLEASE!!!:-(

int t;
unsigned int adcvalue;

//LCD pinout settings

sbit LCD_RS at Rc3_bit;
sbit LCD_EN at Rc5_bit;
sbit LCD_d0 at Rb0_bit;
sbit LCD_d1 at Rb1_bit;
sbit LCD_d2 at Rb2_bit;
sbit LCD_d3 at Rb3_bit;
sbit LCD_d4 at Rb4_bit;
sbit LCD_d5 at Rb5_bit;
sbit LCD_d6 at Rb6_bit;
sbit LCD_d7 at Rb7_bit;

//Pin direction

sbit LCD_RS_Direction at TRISc3_bit;
sbit LCD_EN_Direction at TRISc5_bit;
sbit LCD_d0_Direction at TRISB0_bit;
sbit LCD_d1_Direction at TRISB1_bit;
sbit LCD_d2_Direction at TRISB2_bit;
sbit LCD_d3_Direction at TRISB3_bit;
sbit LCD_d4_Direction at TRISB4_bit;
sbit LCD_d5_Direction at TRISB5_bit;
sbit LCD_d6_Direction at TRISB6_bit;
sbit LCD_d7_Direction at TRISB7_bit;

void main()
{
TRISA = 0xFF; // PORTA Input
LCD_Init();
LCD_out(1,4,"J.U.S.T");
delay_ms(100);
LCD_out(1,3,"Biomedical");
LCD_out(2,3,"Engineering");
delay_ms(100);
Lcd_Cmd(_LCD_CLEAR);
delay_ms(100);
LCD_out(1,4,"Done By");
LCD_out(2,3,"M.Juhair");
delay_ms(100);
Lcd_Cmd(_LCD_CLEAR);
LCD_out(1,4,"& M. Fahed");
LCD_out(2,3,"& A.Jroud");
delay_ms(100);
Lcd_Cmd(_LCD_CLEAR);
LCD_out(1,1,"Supervised By Dr.");
LCD_out(2,1,"Areen Al-Basheer");
delay_ms(100);
Lcd_Cmd(_LCD_CLEAR);

while (1) {
t = ADC_read(2); // get ADC value from 2nd channel
adcvalue=t;
}
if (adcvalue>>2) {
LCD_out(1,1,"RATE/MIN=(30)");
}
}

The Micro controller in the normal case it receives once Low and once high in ordered or not ordered intervals on its A2 input, and in each interval (in a minute for example) it shows the number of transition from low to high or vice versa. For example it shows on the screen:
RATE PER MIN = ("number of transitions")
OK…
but when input becomes low for 10 or more seconds, a clock starts on the screen and it counts for two minutes. Once input comes high to the PIN 2 the program back to it's normal mode for example "RATE PER MIN = (30)". But if the 2 minutes completed the screen shows:
WARNING !!!
Oxygenated Blood Problem
and a buzzer connected on D7 for example is activated

"My biggest concern is that I can't get the value on A2 input to compare it in an if statement with 2 volts for example
if (adcvalue>>2) {
LCD_out(1,1,"RATE/MIN=(30)");
} even though the condition is true"

Thanks in advance

 

[keith1200rs]

This

adcvalue>>2

shifts adcvalue right twice. It is not a comparison statement.

Keith

 

[Shamooooot]

Did it nothing happened ??
you mean like this:

if ( adcvalue>>2) {
LCD_out(1,1,"RATE/MIN=(30)");
}

 

[prateek.kumar]

Keith is right, he means that your if statement
"if (adcvalue>>2)" shifts value stored in adcvalue, 2 times right.

You should give this: "if (adcvalue>2)" it means if the value stored in adcvalue is greater than 2 then condition is true.

 

[Shamooooot]

well thank you but still the "RATE/MIN=(30)" doesn't displayed on the LCD even though the voltage on A2 input is more than 2 volt!!

 

[keith1200rs]

You need to trace the values through the code. What is the value of "t", for example? What is the value of "adcvalue"?

Also, I am not sure why you assign an "int" to an "unsigned int" but there may be type casting issues depending on the compiler. I would normally explicitly cast to be sure.

Keith.

 

[Shamooooot]

Dear keith
I am trying to assign t (and hence adcvalue) to the voltage input to the pin A2 of the PIC the Proteus shows this voltage to be between 2 and 3 volts which should satisfy the condition of the if-statement !!

 

[keith1200rs]

I don't know which compiler you are using so I don't know exactly what ADC_read(2) will return but I would normally expect an ADC value to be a hex value and certainly not in volts. As I said earlier, use the debugger to see what the value of t and adcvalue really is!

Keith.

 

[Shamooooot]

I am using MikroC...