What does "#warning Using TIM_DIV256_CLOCK for longest timer" mean?

[mark-hahn]

I'm getting "#warning Using TIM_DIV256_CLOCK for longest timer" in my compiler output. What does this mean? How do I get rid of it? I always want my compiles to be clean of all warnings.

[khoih-prog]

The warnings were there for unsophisticated users to be aware of the effect of selecting the option.

If you're a sophisticated one, you must know how and where to get rid of it, by commenting out the #warning lines

ESP8266TimerInterrupt/src/ESP8266TimerInterrupt.h

Lines 121 to 137 in 8a00389

	#if ( defined(USING_TIM_DIV1) && USING_TIM_DIV1 )
	#warning Using TIM_DIV1_CLOCK for shortest and most accurate timer
	#define TIM_CLOCK_FREQ TIM_DIV1_CLOCK
	#define TIM_DIV TIM_DIV1
	#elif ( defined(USING_TIM_DIV16) && USING_TIM_DIV16 )
	#warning Using TIM_DIV16_CLOCK for medium time and medium accurate timer
	#define TIM_CLOCK_FREQ TIM_DIV16_CLOCK
	#define TIM_DIV TIM_DIV16
	#elif ( defined(USING_TIM_DIV256) && USING_TIM_DIV256 )
	#warning Using TIM_DIV256_CLOCK for longest timer but least accurate
	#define TIM_CLOCK_FREQ TIM_DIV256_CLOCK
	#define TIM_DIV TIM_DIV256
	#else
	#warning Default to using TIM_DIV256_CLOCK for longest timer but least accurate
	#define TIM_CLOCK_FREQ TIM_DIV256_CLOCK
	#define TIM_DIV TIM_DIV256
	#endif

[mark-hahn]

Thanks for the fast response.

I'm guess I'm unsophisticated so I don't know what it means and therefore I cannot be aware of the effect. What does the warning mean?

[mark-hahn]

never mind. I was confused by the word "but". I would have thought it should be "and".

[khoih-prog]

Using TIM_DIV1_CLOCK for shortest and most accurate timer

As the warning says, when you select TIM_DIV1_CLOCK, you have more accurate timer, but the longest possible ISR timer will be shorter (because of the number of bits, 32/64, used to count, uint32_t or uint64_t)

On the extreme side, Using TIM_DIV256_CLOCK for longest timer but least accurate means when you select TIM_DIV256_CLOCK, you have less accurate timer, but the longest possible ISR timer will be longest.

The selection depends on your use-case. First try the best TIM_DIV1_CLOCK, if not long enough, reduce gradually to USING_TIM_DIV16, then the worst USING_TIM_DIV256

[mark-hahn]

Thanks. (I wish there was a like button.)

[khoih-prog]

You're very welcome. Your words are more than enough.