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pulseIn() pullup/down comment #538

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5 changes: 4 additions & 1 deletion cores/arduino/wiring_pulse.h
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Expand Up @@ -30,7 +30,10 @@
* before the start of the pulse. The pulseIn() function is not designed to detect
* high frequencies. The consequences of using this function to detect frequencies
* such as a 100KHz PWM signal could possibly cause a sketch to hang at the
* pulseIn() function call.
* pulseIn() function call. There is the chance a pin using pulseIn() could get
* into a floating voltage state causing the hanging issue. This should be prevented
* by using a pullup or pulldown resistor. pinMode(pin, INPUT_PULLUP) could also
* be used to keep this from happening.
*/
extern uint32_t pulseIn( uint32_t ulPin, uint32_t ulState, uint32_t ulTimeout = 1000000UL ) ;

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