urgent help in Code!!!!

[caddybran1977]

we are using 8 bits and we tried
voltage = (x/255)*(5.0) and we got much larger numbers that had negative signs in front.
our range on x is 71 - 81
the original code is


while(1)
{
lcd_init();

lcd_goto(0) ;
lcd_puts("welcome " ) ;
lcd_goto(0x40);
x=read_a2d(1);
voltage=(x/255.0)*(5.0);
sprintf(outString,"A2D = %d.%d volts",voltage);
lcd_puts(outString);

}

}
so if i comment out voltage and display x my range is 71-81

 

[binzer]

we are using 8 bits and we tried
voltage = (x/255)*(5.0) and we got much larger numbers that had negative signs in front.
our range on x is 71 - 81

so if i comment out voltage and display x my range is 71-81

So what is your input voltage when you did that?? If I calculate it out it's about 1.3 - 1.5 volts.

Where did you get your calculation info??

Here is a snippet from one of my programs, no guarantee it will help.
{

ConvertADC();
while( BusyADC() );
reslta0 = ReadADC();
reslts0 = (reslta0+1)* .488; // Scale for 5Volts
// reslts0 = (reslta0+1)* 2.44; // Scale for 25Volts
}