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Pololu 38 kHz IR Proximity Sensor - reaction speed?

Pololu 38 kHz IR Proximity Sensor, Fixed Gain, Low Brightness
Hi, I was wondering if there was a known “reaction time” for the Pololu 38 kHz IR Proximity Sensors?

(not sure if “reaction time” is the correct way to describe it)

I am using a couple of these sensors for a game to detect an object being thrown passed the sensor. The sensor will detect the object when placed in front of it, but often misses when the object is moving at high speed. I am working on my microcontroller code to increase polling speed of the input pins, but I also wondered if there was a known minimum reaction time for the sensor. In other words, is there a minimum amount of time (barring the speed of light :-)) that an object needs to be detected for in order to trigger the sensor? Could the objects being thrown passed the sensor be moving too fast?

Thank you,

Hello, J.

Yes, there is going to be some minimum amount of time that an object needs to be in front of the sensor in order for it to trigger, but I think this is going to have more to do with ensuring that enough IR light will be reflected by they object as opposed to the sensor’s reaction time (the sensor’s datasheet, which is available on the product page under the “Resources” tab has some data about that). With that in mind, I expect the time value you are looking for to be highly dependent on various aspects of your specific application, such as how reflective your object is to IR light, its size, and far away it is from the sensor.

Another possibility is that your microcontroller might not be sampling the sensor output fast enough to pick up the brief detection. You might be able to determine if this is the case by monitoring the sensor output with a oscilloscope, and if that is the problem, using an interrupt instead of polling the sensor output might help.

- Patrick