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ljb
Joined: 19 Nov 2003
Posts: 30
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| struct within a struct |
 Posted: Wed Jul 28, 2004 9:31 am |
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The first struct maintains the running date and time. The second struct is a record with a time stamp. How do I include the datetime format within the record structure?
struct datetime{
int8 Yrs;
int8 Mth;
int8 Day;
int8 Hrs;
int8 Min;
int8 Sec;
}dtm, *dp=&dtm;
struct rec{
long rc;
//datetime format here ****************
long ChData[MaxChans];
int8 St;
}drec, *rp=&drec;
Many thanks in advance
Les |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Wed Jul 28, 2004 1:20 pm |
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| Quote: | | How do I include the datetime format within the record structure? |
See the code below for an example of how I did it in one program.
For more examples, search Google for this string:
"structures within structures" int char
| Code: | #include <16F877.H>
#fuses XT, NOWDT, NOPROTECT, BROWNOUT, PUT, NOLVP
#use delay(clock = 4000000)
#use rs232(baud = 9600, xmit=PIN_C6, rcv=PIN_C7, ERRORS)
typedef struct
{
char c_month; // 1-12 month
char c_date; // 1-31 date
char c_year; // 00-99 year (based on year 2000)
char c_hours; // 0-23 hours
char c_minutes; // 0-59 minutes
}T_DATE_TIME;
// In this structure, bit fields are used to store tenths (ie., .0 to .9) of
// a minute, for latitude and longitude. The compiler stores them in 1 byte.
typedef struct
{
char c_latitude_degrees; // 0 to 90 degrees
char c_latitude_minutes; // 0 to 59 minutes, N/S in bit 7, 1 = South.
char c_longitude_degrees; // 0 to 180 degrees
char c_longitude_minutes; // 0 to 59 minutes, E/W in bit 7, 1 = West.
char nib_longitude_tenths:4; // 0 to 9 tenths of a minute (Long. in low nibble)
char nib_latitude_tenths:4; // 0 to 0 tenths of a minute (Lat. in high nibble)
}T_LAT_LONG;
// Next, combine the above types into the trip record structure.
typedef struct
{ // Size in bytes must be = 16
char c_duration; // 1
T_DATE_TIME starting_date_time; // 5
T_LAT_LONG starting_position; // 5
T_LAT_LONG ending_position; // 5
}T_TRIP_RECORD;
// Create one instance of the trip record. We'll temporarily
// store data here before we read or write to FRAM.
T_TRIP_RECORD gt_trip_record;
//====================================
main()
{
gt_trip_record.starting_date_time.c_month = 6;
while(1);
} |
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ljb
Joined: 19 Nov 2003
Posts: 30
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| structures eating rom space |
| Posted: Thu Jul 29, 2004 3:06 am |
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Using a 16f876, when I grouped associated vars into a structure as below.
typedef struct{
int8 Yrs;
int8 Mth;
int8 Day;
int8 Hrs;
int8 Min;
int8 Sec;
}datetime;
datetime *dp;
the available rom space reduced by 5%. After adding another struct the rom space reduced again by a similar amount.
The prog works fine, but I can't figure out why the rom space should be reduced so dramaticaly when its only memory locations that are being pointed to.
please help, as I'm going to end up with a prog full of structures and very little code. Am I doing something wrong?
Cheers
Les |
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Gerrit
Joined: 15 Sep 2003
Posts: 58
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| Posted: Thu Jul 29, 2004 3:12 am |
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How mutch ram is availible in *.lst file
ram used / 0.percentage
ex. RAM used: 247 (67%) at main() level
total ram ~ 247 / 0.67 => 368 bytes
I'm not sure but did you use
#device *=16
Gerrit |
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