Motion Sensor triggering on its own

[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...

[Chakkie]

I have the same issue first when I tried to power the PIR with the VCC from the arduino mini pro 3.3V. It seems like the PIR does not work with 3.3V. Now I power the PIR directly from the 9V battery. Problem solved.

[fifipil909]

Hi,

False detection is only due to power stability issue.
Personnaly i remove the regulator and power the PIR without any boost on the VCC pin. Even below 2v the PIR continue working without any a single issue.

Did you try to do a small delay before sleeping with interupt ? See my post a bit upper.

For me it solve all my false trigger issue.

[m26872]

I know this thread's about hc-501. But I guess one can apply some of my hc-505 (mini-pir) experiences from here:
https://forum.mysensors.org/topic/2715/slim-node-as-a-mini-2aa-battery-pir-motion-sensor

[Fabien]

Same problem here every time m node wake-up I have a false trigger. With delay (@fifipil909) it's not better

[LastSamurai]

Mhm I still have strange results from my PIR sensor (doesn't even seem to be the wake up that influences them).
I have the pir with diode and voltage regulator removed powered by a boost converter with the low pass filter and a pull down resistor. Using a clean 3.3V worked though, but I really want to use batteries (with sometimes less than 3V). Directly powering the sensor with the 2.x V did not work either.
For one of the guys with working sensors: what is your exact setup? None of the tipps I found seem to work. I would really love to get one sensor running. Only idea I still have is to try with another sensor.

Here is the code I am currently using:

#include <MySensor.h>  
#include <SPI.h>

unsigned long SLEEP_TIME = 120000; // Sleep time between reports (in milliseconds)
#define DIGITAL_INPUT_SENSOR 3   // The digital input you attached your motion sensor.  (Only 2 and 3 generates interrupt!)
#define INTERRUPT DIGITAL_INPUT_SENSOR-2 // Usually the interrupt = pin -2 (on uno/nano anyway)
#define CHILD_ID 1   // Id of the sensor child

#ifdef DEBUG
#define DEBUG_SERIAL(x) Serial.begin(x)
#define DEBUG_PRINT(x) Serial.print(x)
#define DEBUG_PRINTLN(x) Serial.println(x)
#else
#define DEBUG_SERIAL(x)
#define DEBUG_PRINT(x) 
#define DEBUG_PRINTLN(x) 
#endif

MySensor gw;
// Initialize motion message
MyMessage msg(CHILD_ID, V_TRIPPED);

void setup()  
{  

  DEBUG_SERIAL(9600);    // <<<<<<<<<<<<<<<<<<<<<<<<<< Note BAUD_RATE in MySensors.h
  DEBUG_PRINTLN("Serial started");

  gw.begin();

  // Send the sketch version information to the gateway and Controller
  gw.sendSketchInfo("Motion Sensor Test", "24052016");

  pinMode(DIGITAL_INPUT_SENSOR, INPUT);      // sets the motion sensor digital pin as input
  // Register all sensors to gw (they will be created as child devices)
  gw.present(CHILD_ID, S_MOTION);
  
}

void loop()     
{     
  // Read digital motion value
  boolean tripped = digitalRead(DIGITAL_INPUT_SENSOR) == HIGH; 
  DEBUG_PRINT("Got tripped: ");
  DEBUG_PRINTLN(tripped);
        
  gw.send(msg.set(tripped?"1":"0"));  // Send tripped value to gw 
 
  DEBUG_PRINTLN("Sleeping till next interrupt");

  // Sleep until interrupt comes in on motion sensor. Send update every two minute. 
  //gw.sleep(INTERRUPT,CHANGE, SLEEP_TIME);
  // Sleep until interrupt comes in on motion sensor. Won't wake up otherwise
  gw.sleep(500);
  gw.sleep(INTERRUPT, CHANGE, 0);
  //gw.sleep(INTERRUPT, RISING, 0);
}

[LastSamurai]

Does anyone have an idea how to get the pir sensor running with a coin cell? Or perhaps if that doesn't work with 2 aa's? See my post above