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Cend
Guest
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| Navigation Program (Problem with Int32 and float) |
 Posted: Mon Nov 13, 2006 9:48 pm |
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My Project is about creating a navigation program which used UTM Coordinates to find Azimuth angle and range.
Example UTM Coordinate
Waypoint[0][0]=669694 m; (Destination Easting)
Waypoint[0][1]=1531197 m; (Destination Northing)
Easting =673147 m; (Current Easting)
Northing =1518363 m; (Current Northing)
Here are my function to find Azimuth and Range
| Code: |
long NAV_Azimuth (int Waypointno)
{ long Azimuth;
int32 X,Y;
float Degree,Xf,Yf;
printf("WP Easting %ld \n\r",Waypoint[Waypointno][0]);
printf("Current Easting %ld \n\r",Easting);
printf("WP Northing %ld \n\r",Waypoint[Waypointno][1]);
printf("Current Northing %ld \n\r",Northing);
X=Waypoint[Waypointno][0]-Easting;
Y=Waypoint[Waypointno][1]-Northing;
printf("X= %ld \n\r",X);
printf("Y= %ld \n\r",Y);
Xf=(float)X;
Yf=(float)Y;
printf("Xf= %E \n\r",Xf);
printf("Yf= %E \n\r",Yf);
Degree=atan2(Xf,-Yf);
printf("Degree =%f Radians \n\r",Degree);
Azimuth=(Degree/3.1417)*1800;
return (Azimuth);
}
int32 NAV_Range (int Waypointno)
{ int32 Range,X,Y;
X=Waypoint[Waypointno][0]-Easting;
Y=Waypoint[Waypointno][1]-Northing;
Range=sqrt(pow((float)X,2)+pow((float)Y,2));
Return (Range);
}
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The first function Problem is when convert int32 to float the value change.
The second function Problem is square of X and Y Value is too high for
int32.
Any suggestion would be very appreciated |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Tue Nov 14, 2006 2:17 pm |
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| Quote: | | Problem is when convert int32 to float the value change |
Post a test program that shows the problem. Initialize an int32 variable
to a value. Convert it to float. Use printf to display it. Tell us what
value is displayed by printf.
Here is an example of a test program.
http://www.ccsinfo.com/forum/viewtopic.php?t=28780&start=1&highlight=test+program
Do the same thing, except post a program that shows your problem.
Also post the PIC that you are using and the compiler version. |
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Cend
Guest
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| Sorry |
| Posted: Tue Nov 14, 2006 8:29 pm |
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sorry for not giving you guys info here it is
I'm using PCH 3.249
I'm testing with PIC18F458 using Hyperterm
the result are
| Code: |
WP Easting 661101
Current Easting 673144
WP Northing 1515691
Current Northing 1518396
X= -12043
y= -2678
Xf= 4.294954E+09
Yf= 4.294963E+09
Degree =2.356196 radians
and Range =1779030016
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the problem is Xf does not equal to X
and Range is wrong |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Tue Nov 14, 2006 11:12 pm |
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I noticed that your values for X and Y are signed integers. In CCS,
an 'int32' is unsigned by default. This is different from normal C.
To declare a signed integer, you have to use 'signed int32'.
I made a test program as shown below, and declared X and Y as
signed int32 values. I compiled it with PCH vs. 3.249 and ran it
in the MPLAB simulator and used "UART1" for output.
Here are the results. It looks OK.
| Code: |
X= -12043
Y= -2678
Xf= -1.204299E+04
Yf= -2.677999E+03
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| Code: |
#include <18F452.h>
#fuses XT,NOWDT,NOPROTECT,BROWNOUT,PUT,NOLVP
#use delay(clock=4000000)
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7, ERRORS)
//=====================================
void main()
{
signed int32 X,Y;
float Xf,Yf;
X= -12043;
y= -2678;
printf("X= %ld \n\r",X);
printf("Y= %ld \n\r",Y);
Xf = (float)X;
Yf = (float)Y;
printf("Xf= %E \n\r",Xf);
printf("Yf= %E \n\r",Yf);
while(1);
} |
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