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Waiting for pulse to start (rising or falling edge) to start timing.

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This commit is contained in:
David A. Mellis
2008-11-08 21:31:12 +00:00
parent 542a64fac1
commit e79b319fd1
1 changed files with 5 additions and 0 deletions
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5
hardware/cores/arduino/wiring_pulse.c
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@ -44,6 +44,11 @@ unsigned long pulseIn(uint8_t pin, uint8_t state, unsigned long timeout)
unsigned long numloops = 0; unsigned long numloops = 0;
unsigned long maxloops = microsecondsToClockCycles(timeout) / 16; unsigned long maxloops = microsecondsToClockCycles(timeout) / 16;
// wait for any previous pulse to end
while ((*portInputRegister(port) & bit) == stateMask)
if (numloops++ == maxloops)
return 0;
// wait for the pulse to start // wait for the pulse to start
while ((*portInputRegister(port) & bit) != stateMask) while ((*portInputRegister(port) & bit) != stateMask)
if (numloops++ == maxloops) if (numloops++ == maxloops)