Electronic – Inserting compile date/time into the code in XC8

microchippicxc8

I'm in the process of writing code for a real time clock, and I want to compile the code with constants for the date/time of compilation to burn onto the clock immediately upon programming.

I believe I have seen this done before, but my searches have proved fruitless. Is there some kind of compile time macro that would do this? Something like:

rtc.second = __COMPILE_SECOND;
rtc.minute = __COMPILE_MINUTE;
rtc.hour   = __COMPILE_HOUR;
rtc.date   = __COMPILE_DATE;
rtc.month  = __COMPILE_MONTH;
rtc.year   = __COMPILE_YEAR;

Best Answer

From the XC8 C Compiler Users Guide, page 229:-

5.14.3 Predefined Macros

__DATE__ to indicate the current date eg. May 21, 2004 
__TIME__ to indicate the current time eg. 08:06:31

You can parse these strings to get numbers compatible with your rtc, but what's the point of a real time clock that doesn't have the real time?

Anyway, look at this Stack Overflow Question for a way to do it.

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Basic code to switch LED for PIC18f4550 XC8 not working!

If you are running your code at 20Mhz, and if I remember correctly, the Fcyc was a Fosc/4 which would mean that you are running your code at 5Mhz.

At 5Mhz thats 200ns per instruction.

Your delay function is ~ 500*165 = 82500 cycles = 16.5ms. It's 'not working' could be that it IS working, but its just not working the way you might have expected. It's probably just toggling too fast for you to see.

Try changing your msdelay(..) to the following

void msdelay(unsigned int ms)
{
   unsingned int x;
   unsigned int z;
   for(x = 0; x < ms ; x++)
     for(z = 0; z < 5000;z++);
}

How did I get 5000 ?

Each cycle takes 200ns. So to get a delay of 500ms, first you can find out how much it is for 1ms \$ \frac{1ms}{200ns} = 5000\$

Now when you pass your parameter in ms, for each ms it will run 5000 times.

Hopefully that helps.

Electronic – Strategies for managing code size – PIC18 XC8

Here are some things I have done when using Microchips C18 compiler. Maybe the concepts will apply to your compiler: - declare each string one time. Put in a separate .c file and use a .h file to reference them. In other words don't duplicate display messages multiple times. - declare strings so that they go in rom. This wont help you with ROM (code space) but it will save memory. - write tight code. If several lines of code are duplicated, put them in a function. Copy / paste is not necessary an embedded programmers best friend. - like you already thought of, implement your own functions instead of including a library. I once saved a ton of space by creating my own itoa() function. Try not to use printf.

Best Answer

Related Solutions

Basic code to switch LED for PIC18f4550 XC8 not working!

Electronic – Strategies for managing code size – PIC18 XC8

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