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Code Issues Releases Activity

No longer disabling interrupts in delayMicroseconds(): http://code.google.com/p/arduino/issues/detail?id=67

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This commit is contained in:
David A. Mellis 2009-12-18 17:04:51 +00:00
parent 07a5160f3b
commit ba5935e273
1 changed files with 1 additions and 13 deletions
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14
hardware/arduino/cores/arduino/wiring.c
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@ -103,13 +103,9 @@ void delay(unsigned long ms)
; ;
} }
/* Delay for the given number of microseconds. Assumes a 8 or 16 MHz clock. /* Delay for the given number of microseconds. Assumes a 8 or 16 MHz clock. */
* Disables interrupts, which will disrupt the millis() function if used
* too frequently. */
void delayMicroseconds(unsigned int us) void delayMicroseconds(unsigned int us)
{ {
uint8_t oldSREG;
// calling avrlib's delay_us() function with low values (e.g. 1 or // calling avrlib's delay_us() function with low values (e.g. 1 or
// 2 microseconds) gives delays longer than desired. // 2 microseconds) gives delays longer than desired.
//delay_us(us); //delay_us(us);
@ -150,19 +146,11 @@ void delayMicroseconds(unsigned int us)
us--; us--;
#endif #endif
// disable interrupts, otherwise the timer 0 overflow interrupt that
// tracks milliseconds will make us delay longer than we want.
oldSREG = SREG;
cli();
// busy wait // busy wait
__asm__ __volatile__ ( __asm__ __volatile__ (
"1: sbiw %0,1" "\n\t" // 2 cycles "1: sbiw %0,1" "\n\t" // 2 cycles
"brne 1b" : "=w" (us) : "0" (us) // 2 cycles "brne 1b" : "=w" (us) : "0" (us) // 2 cycles
); );
// reenable interrupts.
SREG = oldSREG;
} }
void init() void init()