Hi I am using ultra sonic sensors to detect any obstacle and i have connected their response to extenal interrupt0 of 8051. The problem is the sensors are very sensitive they trigger the interrupt even if there is an object very far. I want that external interrupt should trigger if it gets contineous pulse from sensors for 1 second. (I think it is called debounce operation). Is their any way i can do this. Thanks for your help
In my opinion you need to re-think your approach. If the sensor sees an object too far away, it will still see the object after 1 sec delay. You might want to consider a hardware approach external to the MCU. It can be as simple as a RC filter with a variable resistor and capacitor. Also, some of the 8051 family have built-in camparators and DACs so you can set the compare threshold and feed the comparator output back into the interrupt input. With the DAC, you can scale the input sensitivity. However, if your input is really just noise and not a true object sense, then the debounce you suggested might be a better approch. Have you put an oscillscope on the sensor out and determined if the sense level is a true sensor detection or noise.? Bradford
the commonh method is to start a timer at the same time as the output pulse. when the input pulse is detected stop the timer: time * k = distance. Erik
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