__delay_cycles() question???

Two ideas for your implementation...

1. Use a timer rather than a software delay. This will allow you to enter a low-power mode (such as LPM3 or LPM0) while you are waiting, greatly reducing the power consumption of your system, or
2. Implement your own software delay function using some kind of loop statement that as the __delay_cycles() intrinsic function call at its core. This is better than a SW delay written in "pure" C since that one would be subject to all kinds of compiler optimizations and may result in different delays depending on your optimization level, compiler version, and compiler vendor...
   
   For example, you could do something like this:
   
   void delay_ms(unsigned int delay)
   {
       while (delay--)
       {
           __delay_cycles(PUT_CPU_CLOCK_SPEED_IN_HZ_DIVIDED_BY_1000_HERE);
       }
   }

Regards,
Andreas

Mike,

yes with the code there will be a small "offset" and "gain" error in the actual delay you get. The code is good to guarantee a certain minimum delay, with a very small error into the positive direction. That's why the delay inside the loop was chosen rather large ("ms"). If you need a dead-on delay, the best way would be using a timer. But if you for some reason still want to use SW delays, I would recommend coding a function in assembler rather than measuring the C function. You could compensate in the function itself for the "offset" and "gain" errors of the call and loop overhead. Also, our IDEs have cycle counter functions that you could use to analyze the delay function. But for SW delays, be aware that interrupts could kick in (if enabled) and change your resulting observable delay.

Regards,
Andreas