Motion Sensor triggering on its own

[Jan Gatzke]

I have solved this by reading the status of the HC-SR501 twice. Works finde for me.

 boolean tripped = digitalRead(DIGITAL_INPUT_SENSOR) == HIGH; 
        
  Serial.println(tripped);
  if (tripped==1){
    //wait
    delay(100);
    //read the pin again
    tripped = digitalRead(DIGITAL_INPUT_SENSOR) == HIGH; 
     if (tripped==1){
  gw.send(msg2.set(tripped?"1":"0"));  // Send tripped value to gw 
  }
  }

[robosensor]

The same problem for me. Different HC-SR501 sensors (connected to one of three nodes with this sensors) periodically entering "flood mode" with continuous sending 1/0 values. I suspect that this is power supply related problems.

[bjacobse]

I have for a sonar sensor (Ultrasonic Module HC-SR04) used in RPI and written in Python, used to measure 3 times and if all 3 measurements are same, then result is valid and data send. This is working perfect for me. You can create something similar for your Arduino

intdistance = 0

        distance = -1
        continueLoop = True
        log.debug("Loop until distance1 = distance2 = distance3")
        while(continueLoop):
            #distance = ser.read(size=3)
            distance = ser.readline()
            getValue1 =  distance.rstrip('\r\n')
            log.debug("distance1: %s", getValue1)

            distance = ser.readline()
            getValue2 =  distance.rstrip('\r\n')
            log.debug("distance2: %s", getValue2)

            distance = ser.readline()
            getValue3 =  distance.rstrip('\r\n')
            log.debug("distance3: %s", getValue3)

            distance == getValue1

            if  getValue1 == getValue2 and getValue2 == getValue3 :
                continueLoop = False

        intdistance = int(distance)
        log.info("distance: %d to be sent to Agocontrol", intdistance)

[Jan Gatzke]

@robosensor Have you tried to enable the ibternal pullup for the pin?

[robosensor]

@Jan-Gatzke said:

@robosensor Have you tried to enable the ibternal pullup for the pin?

Didn't read biss0001 datasheet, so I don't know is output pin 5V-compatible (for pullup) or not, so I didn't tried to enable internal pullup.

In any case I will try to check what happens with OUT pin of module during this 1/0 flood.

[ErrK]

Thanks @Jan-Gatzke it did not work for me this time.

I'm using a 5v Arduino Pro mini and when i measure the power on the HC-SR501 i get 3.71v.
When i measure the power on the VCC i get 3.69v and when i measure the RAW i get 5.43v.

Here you can se how everything is wired, I use the Easy/Newbie PCB by @sundberg84.

First i used the 5v cable to the raw on the PCB and then it did't work.
When I change to connect to the PWR then it works. Don't know why. Maybe @sundberg84 know why?

[sundberg84]

Hi @ErrK.

Work your way backwards with the multimeter. Are you powering with 5v there shouldnt be a drop to 3v. Check volt over arduino and then vcc output. As i said work you way backwards in the circuit.

I suspect a faulty hardware somewhere, measure the input and output on the voltage regulator on the arduino.

[Maciej Kulawik]

@ErrK In my case PIR switches into HIGH for some seconds (depending on potentiometer), so reading after 100ms will give the same value.

@ErrK Unfortunately my solution is not 100% reliable. For 2 of my nodes it works well, but for 3rd node (the same hardware, the same sketch, only PCB is a little bi different - previous version, but difference only in dimension) - pir is false triggerring almost each minute (sometimes with 2 minutes delay with false triggering). And I checked - it is not caused by NRF sending. I have no idea whats going on.

[rvendrame]

@Maciej-Kulawik , how are you powering the node? I had once a PIR false-triggering due power instabilities...

[fifipil909]

Hi,

i'm wanted to share my experience also with those sensor.
I had a lot of issue with false trigger when running on 3.3V. In my case the power was definitely the issue.
it's looks like sleeping the radio/mcu cause some noise on the voltage line.

I solve 100% of my false trigger issue when doing a small sleep, before enabling the sleep with interrupt.

gw.sleep(500);
gw.sleep(INTERRUPT,RISING, SLEEP_TIME);

[Maciej Kulawik]

@rvendrame I'm powering all with 2xAA baterries. On PIR I removed regulator. The problem with false trigerring is independent from voltage level. It is the same if I put old baterries (2,8V) or brand new (3,2V).
@fifipil909 I also suspect that it is somehow connected to powering noises and mcu sleeping. In my one case PIR is triggering each minute - and sleep time is also one minute.

[rvendrame]

@Maciej-Kulawik , maybe if you try to power the PIR with +5V for a while and watch the results? Don't forget to keep all GNDs inter-connected...

[Sweebee]

I'm also having this issue at 3V. It gets triggered if there is a (little) voltage drop. All my pirs only wake with an interrupt and no timer, then it works fine. But with a sleep timer it won't work the normal way.

At 5V everything works fine.

Maybe @fifipil909 's solution works.

[ahmedadelhosni]

I was testing the below sensor with 3.3v and it was reporting false status. It worked well with 5v. Although the site claims it works between 3 to 5 volts.
Maybe power issues

http://store.fut-electronics.com/products/pir-motion-sensor-module-adjustable-range

[Maciej Kulawik]

@ahmedadelhosni All those PIRs are built using the same chip. All all have 3,3v regulator onboard, so they always work with 3,3v. I don't understand why powering directly with 3,2v from battery makes so trouble.
Maybe this LDO regulator adds some additional stabilisation/filtering on power line, when powered with greater voltage...

[rvendrame]

@Maciej-Kulawik It can be that the on-board LDO needs more than 3.3v to activate. It maybe even dropping the voltage from batteries, and doing nothing but disturbing :-) Maybe it worth to remove it when running the circuit with 3V from batteries.

[Maciej Kulawik]

@rvendrame But I work only with pirs with ldo removed (and diode).

[rvendrame]

@Maciej-Kulawik if so, your PIR looks to need at least 3.3V, so the ~3V from 2xAA is not enough and it is causing instabilities (probably the same as reported by others here).

[ahmedadelhosni]

@Maciej-Kulawik I didnt know that info. Thanks.

[LastSamurai]

Did you guys get them working? I tried to power the pir sensor via the "H" pad directly with 3.3V from a boost converter (via a coin cell). Now I get random readings that I didn't have when using a stable 3.3V source. Any ideas how to solve this?
I haven't (yet) removed the voltage regulator on board. Perhaps that might help...