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Code Issues Releases Activity

Added pulseIn function to measure pulse durations.

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This commit is contained in:
David A. Mellis 2006-03-24 14:09:54 +00:00
parent c6d860ef00
commit 4f80fe1489
2 changed files with 34 additions and 0 deletions
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33
targets/arduino/wiring.c
View File

@ -366,6 +366,39 @@ void delayMicroseconds(unsigned int us)
sei();
}
/*
unsigned long pulseIn(int pin, int state)
{
unsigned long width = 0;
while (digitalRead(pin) == !state)
;
while (digitalRead(pin) != !state)
width++;
return width * 17 / 2; // convert to microseconds
}
*/
unsigned long pulseIn(int pin, int state)
{
unsigned long width = 0;
int r = port_to_input[digitalPinToPort(pin)];
int bit = digitalPinToBit(pin);
int mask = 1 << bit;
state = (!!state) << bit;
while ((_SFR_IO8(r) & mask) != state)
;
while ((_SFR_IO8(r) & mask) == state)
width++;
return width * (16000000UL / F_CPU) * 20 / 23;
}
int main(void)
{
// this needs to be called before setup() or some functions won't

1
targets/arduino/wiring.h
View File

@ -82,6 +82,7 @@ unsigned long millis(void);
void delay(unsigned long);
void delay_ms(unsigned short ms);
void delayMicroseconds(unsigned int us);
unsigned long pulseIn(int pin, int state);
void setup(void);
void loop(void);