Math operation

[maritto]

Hi!
I've got a problem, I'm working with 12F series and I need to use a lot of variables.
In order to store temperature values like 25.5 (just with a decimal), an integer with a decimal, I use a "int16" not a "float" (because it uses 4bytes!).
So when I work with values like 250, 365, 379, those mean 25.0, 36.5 and 37.9

When I store those values in the internal EEPROM, I use this function:


void write_rom(){
write_eeprom(0,rom_p0);
write_eeprom(1,rom_p1);
read_rom();
}

void read_rom(){
rom_p0=read_eeprom(0);
rom_p1=read_eeprom(1);
temp_ref=(int16)(rom_p0*10) + rom_p1;
}

and I read it, to ensure, that the value has been stored.

So at position 0 I store (for example) "36", and at the position 1 I store "5", when I read it I get "36" and "5", so temp_ref=(36*10) + 5 = 365.
But I don't get that value!

If I put an arbitrary value in temp_ref like:

temp_ref=360;

it works, but if I try to read the value from the memory (once the value has been stored), It doesn't work!

Please somebody help me!

Thanks!

[Douglas Kennedy]

You didn't say which wrong value you got. However the compiler will scan the operands of an arithmetic operation to find the lowest precision operand and control intermediate results to that precision. This will impact the final result if it exceeds 255 even if it is cast correctly. The static value 10 may well be the issue try 10L and see if it makes a difference

[Storic]

This may not be the answer you are looking for however if you are doing

[maritto]

OK, thanks!
When I use 10L, the program size is reduced, I don't know why!
But the problem persists when I use values above 30.0 (30 and 0).
When I read the EEPROM, and send that values trought the RS232, I get nothing!

this is a pice of the program:

void read_RS232(){

char orden=0;

if(kbhit())
switch((ord=getch()))
{
case 'S':
while(!kbhit()){}
rom_p0=getch();
while(!kbhit()){}
rom_p1=getch();

if((rom_p0<40))
write_rom();

break;

case 'B':
printf(" %d ; %d ; %d\n\r",(int)(temp/10),rom_p0,(int)(temp_ref/10));
break;
}

when i try, for example:

Send 'S', send value 11, send value 05. (11.5), then 'B', to get the response, I get nothing!

Don't know what's wrong!

Thanks 4 helping!

[maritto]

By the way, I always get 63 when the value is between 10 and 30 (the value of rom_p0 and rom_p1)

[maritto]

OK, the problem is that when I try to send a value between 10 and 30, the program sends 3F 3F.....> 63 63, I don't know why! I'm using Proteus to simulate it!
Thanks!

[SET]

[maritto]

OK!
Thanks a lot!
It is working!