interfacing of PIR sensor.

I have an PIR sensor module BS1600 and i want to interface it with the microcontroller , but i dont know that the output of it is in TTL form or not as i want to give it to controller so that it can operate the relays connected to it.

What datasheet says ?

hello u can directly connect pir sensor to the controller
see dis document u can find the solution

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it gives a 5v output while it detects motion
so u can directly connect it to the controller

PIR is a relatively slow sensor that detects any infrared waves (heat from a body) . There may be many transitions before steady state unless it there is considerable hysteresis and filtering inside the sensor.

This device states > 5sec response time from a strong signal (IR) .. longer from a weak signal
Output is Logic level 3.3V high when active and 0V when inactive.

The spec indicates simple driving a relay with an NPN switch. but drive current is not stated. I would assume it is low current 100µA max so it can drive CPU input with 3.3 V logic ok. Use software to count when active for at least 1 second before accepting active state..
3.3V/100µA = 33KΩ equivalent load.

If using only a transistor switch current depends on Relay coil current and hFE or current gain when switched on.
Allow x20 current gain as reasonable target of transistor switch to drive into saturation. ( less gain if much higher currrent)
Dont forget clamp diodes are needed on relay coils.

thank you very much for your feedback , so according to you i can directly connect it to the controller ...i was having the same data sheet but was still confused as it was not clearly mentioned..

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hello, the data sheet says that it gives high/low level signal of 3.3v with high intensity..help me if you can or suggest other sensor..thank you..

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hello, the data sheet says that it gives high/low level signal of 3.3v with high intensity..help me if you can or suggest other sensor..thank you..

ppatel23 said:

thank you very much for your feedback , so according to you i can directly connect it to the controller ...i was having the same data sheet but was still confused as it was not clearly mentioned..

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hello, the data sheet says that it gives high/low level signal of 3.3v with high intensity..help me if you can or suggest other sensor..thank you..

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hello, the data sheet says that it gives high/low level signal of 3.3v with high intensity..help me if you can or suggest other sensor..thank you..

Click to expand...

At first I had my PIR module’s output connected directly to a pin of pic16F84A microcontroller and did not get proper result. My microcontroller was sensing only high output from the PIR module on all conditions. So I checked the output of the PIR module and found that when connected to a 5 volt supply, the output pin voltage was about 2.66 volts and after detecting a movement the output pin voltage was about 3.44 volts! According to the datasheet of pic16F84A, input low voltage should be 0.2VDD. So I have used a BC547B with the PIR output as a switch to provide proper logic levels to the microcontroller.

See How to interface PIR modules with PIC microcontrollers https://www.edaboard.com/blog/1436/For Picture, circuit, code ideas etc.

Hope this will help you. Thanks

i also meet the same problem with my PIR sensor. actually the output of the sensor is already correct, but when I connect to microcontroller, it goes high and low frequently even there is no movement.. is anyone can help? thanks.

mentoz said:

i also meet the same problem with my PIR sensor. actually the output of the sensor is already correct, but when I connect to microcontroller, it goes high and low frequently even there is no movement.. is anyone can help? thanks.

Click to expand...

how high and how low and how often? Can you observe any other changes?

Is there any change in Solar power or wind?
I suspect it may be sensitive to changes in background thermal energy, as it is a thermal sensor.

Is V+ clean and well regulated?

high is 3.2V and low is around o.3mV.
when I install PIR sensor without microcontroller it detects very well only when I move in front. but when I connect with microcontroller it goes low and high changing periodically every three second. I already use the transistor BC547 connect to out signal of sensor for active low based on this reference https://https://www.edaboard.com/blog/1436/ .
voltage already regulated constantly 5volt.