PIR Motion triggers when switch pressed (Allmost Solved, waiting for testresults)

  • Contest Winner

    I'm having a lot of troubles combining my doorbell with a PIR motion sensor.

    When I trigger the doorbell from Domoticz, the chime is playing played and everything is alright.

    If how ever I press the door switch, the PIR motion sensor Pin also goes LOW. I've stripped my sensors completely from the code, but still the same problem. What am I doing wrong?

     * Sketch: Doorbell
     * Version: 1.0 April 2nd 2016
     * Author: by Theo
     * MySensors doorbell sensor. This sensor is a fully working doorbell, that is also connected to the MySensors network. Through MySensors you can:
     * - detect whether the doorbell has been pressed
     * - turn of the doorbell sound (for instance when you or your little child is sleeping.
     * - control the volume of the doorbell
     * The doorbell is designed around the HK592 which is a real cheap doorbell chip making a double ding dong sound. Other melody chips can be used, but you might
     * need to change the circuit. The HKxxx chips are hard to find. As an alternative you can us an UM348x IC. Which is also a melody chip. However, note that you
     * might not be able to interrupt a melody that's being played bij the UM chip. So in that case the doorbell will play a sound for a longer period as you might
     * like.
     * Design decision(s):
     * - Must use an melody chip as a source for playing sounds. Reason(s):
     *   1. I want to get to know more about electronic circuits (but just a personal driver)
     *   2. These chips only need a single signal to start playing. Thus it will simplyfy the Arduino code. No checking if we have to end the melody that's being
     *      played or what so ever.
     * - Don't use breakout boards that are able to play MP3's or any other soundboard. Reason(s):
     *   1. See reason 2 for previous decision
     *   2. It'll need extra hardware in terms of amplifier etc. This will raise the total costs of this doorbell.
     * Requirement(s):
     * 1. The total costs of the doorbell should be as low as possibel. Meaning cheaper than a doorbell sold at any store.
     * 2. Volume control is a must
     * 3. Silent mode is a must
     * 4. Reliability: Doorbell must be working at all times
     * 5. Power consumption must be as low as possible.
     * Revision history:
     * 1.1 April 12th 2016
     *   - added a motion sensor node, for my own convenience. I just needed one at the same spot as the doorbell. Comment #define USE_MOTION_SENSOR if you don't
     *     need one
     * 1.0 April second 2016
     *    - initial version
    // Uncomment following line if you want a PIR motion sensor. Use a mini PIR if you connect one to a pro Mini 3.3V. The mini has 3.3V output, the larger one has 5V
    #include <Bounce2.h>
    // ---------------------- constants definitions (pinouts etc)   -----------------------------
    #define DOORBELL_SWITCH_PIN  2 // Interrupt pin to which the doorbell switch is connected
    #define MOTION_SENSOR_PIN    7 // reserved for PIR sensor, which will be added later on after the doorbell is published on openhardware.io
    #define SOUND_PIN            17 // Pin to which the transistor for starting the doorbell sound is connected (Prob a BC547)
    #define DOUBLEPRESS_INTERVAL 2000 //8000 // The amount of milli seconds before a new press on the doorbell switch will trigger a new sound
    #define SILENTMODE_ON        1
    #define SILENTMODE_OFF       0
                                           // only the gateway is being informed of a press on the doorbell switch.
    // Variables
    unsigned long ignoreDoorbellSwitchDoublePressIntervall = 0; // The time in ms after which a doorbell switch will trigger a sound. Double press protection.
                                                                // it also discourages youngsters from pressing the doorbell and hiding.
    unsigned long dingdongStarted = 1;
    Bounce dbSwitchDebouncer = Bounce();
    Bounce motionsDebouncer = Bounce();
    // ---------------------- Sketch initialization   -----------------------------
    void setup() {
      Serial.begin( 115200 );
      Serial.println( "Starting...." );
      digitalWrite( DOORBELL_SWITCH_PIN, HIGH );
      pinMode( SOUND_PIN, OUTPUT );
      Serial.println( "Started" );
    void playDoorbellSound() {
      Serial.println( "Ding dong" );
      digitalWrite( SOUND_PIN, HIGH );
      dingdongStarted = millis();
    // ---------------------- main loop   -----------------------------
    void loop() {
      if ( motionsDebouncer.update()) {
        int value = motionsDebouncer.read();
        Serial.println( "Motion sensor is " + (String)value );
      if ( dbSwitchDebouncer.update() ) {
        if ( dbSwitchDebouncer.read() == LOW ) {
          unsigned long pressedTime = millis();
          if ( pressedTime > ignoreDoorbellSwitchDoublePressIntervall ) {
            ignoreDoorbellSwitchDoublePressIntervall = pressedTime + DOUBLEPRESS_INTERVAL;
              Serial.println( "Doorbell" );
      if ( dingdongStarted != 1 && dingdongStarted + 200 < millis() ) {
        dingdongStarted = 0; 
        digitalWrite( SOUND_PIN, LOW );
      delay( 50 ); // give the input pins some rest. Incomming messages are still being processed.

  • Contest Winner

    It looks like the obvioud (power issues). When I hookup an LED instead of the doorbell IC. It works like a charm. I'm gonna replace the 800mA for a 1A adapter. (Strange behaviour) 😉

    Nope. Meassured powered it's sufficient. Whenever I control the doorbell chime IC it triggers the PIR sensor. Which seems like it loses power or so. Would a capacitor help? And what value would you use for stabalizing a mini pir motion sensor 10uF?

  • Hero Member

    @TheoL What kind of PIR sensor are you using. Are you using a/the on--board regulator? These things are very sensitive @m26872 has written something about it too.

  • Contest Winner

    @AWI I'm using the hc sr505 datasheet. It's giving 3.3V on the output pin, which I thought would be perfect for the proMini.

    10uF cap didn't help.

    Also. Are you still in for a Dutch/Belgium MySensors Meetup?

  • Hero Member

    @TheoL If you are using the on-board regulator of the HC-505 for other purposes (I use it like that too) you are in for a lot of debugging.. only a capacitor won't help. I added a separate regulator for powering the pro-mini in the end..

    And still in for a NL/BE meeting if I can make it..

  • Contest Winner

    @AWI Hmm I'm gonna try that. It the moment I power the ProMini and the PirSensor directly from the power plug. I have a ld 33 for powering my door chime IC.

    I'll think I'm gonna give up the idea of hooking up a pir motion sensor for that Node. Just gonna build the housing for the door bell.

    I'll post a reminder in the meetup topic. I'm always in for good chats and beers 😉

  • Same problem here with HS SR505 mini and sensebender with CR123 for powering. After each transmit of temp/hum, there is false triggering from PIR sensor. I try with 470uF an 10nF caps but it doesn't work too

  • Contest Winner

    I've stripped out MySensors from the sketch and it gives the same result.

    I'll think I'll order one of these https://www.sparkfun.com/products/13285 or look for other less sensitive alternatives.

  • Hardware Contributor

    @Fabien When it's predictable, then why don't you just block the false trig like I do in http://forum.mysensors.org/topic/2715/slim-node-as-a-mini-2aa-battery-pir-motion-sensor ?

  • Contest Winner

    @m26872 I've thought about that. But the problem is that The Mini pir sensors starts with a 10 seconds period if signaling movement. So in my case if somebody pressed the door alarm switch I would have to stop monitoring movement in my hall way for 10 seconds.

    I'm gonna try a ProMini 5V to see if this has the same problems. If it solves my problem I just have to add a transistor to the circuit, just to trigger the door chime IC. Which is okay. I have a spare ProMini 5V that I'm not using anyway. I'll let you guys know what the out come is.

    Thus far I've discovered the following:

    1. Combining a PIR with the Door chime IC will trigger the door chime whenever I push the door button
    2. Combining a PIR with an LED instead of the door chime IC will not trigger the PIR sensor when pushing the button.

    So it looks like the PIN controlling the door chime IC is drawing to much power. Things I've tried:

    1. adding a transistor between the door chime IC and the arduino. No luck.
    2. Adding a 10 uF capacitor between the positive and negative pin of the pir sensor no look.

    Options I still have:

    • use a ProMini 5V with that I can use the normal PIR instead of the Mini. Which can be adjusted to raise the movement pin for just 2 seconds.
    • Search for an alternative motion sensor
    • Use batteries to power the door chime IC, make that a separate circuit. this looks okay. I think the doorbell chime ID will run for years on the batteries. They will mostly go empty by normal battery life time.

    I measured power usage and there's a huge peak in power consumption when the doorbell chime is being triggered and used. About 60 mA. As far as I've understood it. This shouldn't be a problem for the Arduino.

  • Contest Winner

    I have implemented the way with powering the door chime IC with batteries. I've used a good old BC548B for sending a trigger signal and it works great. With this I mean that the PIR sensor doesn't go high after a switch press.

    My conclussion is what @AWI already said, the PIR is very sensitive when I comes to power and peaks.

    I have one question before I'll go down this road. The data sheet of the HK592 says the following:
    Operating voltage min. 1.8
    Operating current 0.1 to 0.5 mA
    standby current 1 to 5 uA

    Anybody any Idea how long this IC will operate on two AA batteries?

  • Contest Winner

    I'm posting my progress. So that if I find the solution someone else might benefit from this.

    Battery powering the Chime IC works well. It doesn't interfere with the PIR. So I took the next step and added the my sensor code again. Next problem! Node stops receiving messages after a couple of minutes. Notice I powered the antenna directly from the ProMini 3.3V.

    Hmmm might this be caused by MySensors libraries?

    Anyway. Put a 100mA 3.3V regulator between the power adapter and the radio. And things looked great. Only this times the node took just 15 minutes before it stalled. Except for the motion notification to the gateway everything else stalls. Until I walk around the motion sensor a couple of times and then the node receives all messages send by the gateway. Hmzzzzi strange.

    Replaced the regulator with a LD33V with correct capacitors. Node is been running for a longer while. If this node stays stable, I'll hookup the door Chime ID to the LD33V as well.

    To be continued.

    The question is, why is the LD33V stabilizing the circuit. I'd like to know why, so that I can learn from this.

  • Contest Winner

    Hmmm.. Node stalls after 45 minutes or so. Switched 800 mA to 1A power supply. If that doesn't work I'll give up on the idea of combining the doorbell with a pir sensor.

  • Hero Member

    @TheoL It sounds like the problem which often occur with relay's (inductive loads). From my experience the radio is sensitive to electromagnetic fiels or at least the power issues coming from driving an inductive load. I stopped using relays in the vincinity of the radio oand arduino. Time to switch to an SSD/ MP3 doorbell? 😄

  • Contest Winner

    @AWI I think you're right. But I don't use a relay. I use a low power doorbell Chime IC.

    Okay. The node is now stable for more than 12 hours. I hooked up the radio to an LD33V. And also changed the interrupt based switch and motion detection to Debounced reading. Both are necessary. Even thought I kept the interrupt handlers really small, they conflicts with - I presume - one of the libraries. I'm pretty confident this problem is solved. But I'm monitoring the node for a but longer.

    Next step is the power the doorbell IC from the LD33V as well.

  • Contest Winner

    So tonight I tried to pinpoint the exact problem with the PIR sensor. It has nothing to do with MySensors but all with the motion sensor. It's internal circuit is really sensitive. I've added an optocoupler between the arduino and the doorbell circuit (that is a much better solution than controlling the circuit through a transistor imo). powered the pir motion sensor from the arduino 5V and hooked an Led to the output pin (no connection to the arduino). Still the same problem. Pir triggers motion whenever the doorbell chime is being controlled from the arduino.

    Happy with the opto coupler, so I'm keeping that one. Since the doorbell circuit is it the moment also powered from the same Arduino Nano, the next thing is to power it from a buck converter and see if that will stabilize the PIR.

    If that doesn't work as well I have the following options left.
    1 Power the pir sensor from another power adapter and hook it up to a opto coupler as well
    2 try an the MP3 player that someone suggested.
    3 Power the doorbell circuit with batteries to see if this solves the problem
    3 Give this one up 😉

    My conclusion so far is, that the pir sensor works great as long as the doorbell circuit doesn't play a sound through the speaker.

    Keep you guys informed.

    Updated: Powering the doorbell circuit and the receiving side of the opto coupler with 2 AA batteries works like a charm. Triggering the doorbell doesn't cause a reset of the PIR motion detection so no motion is being detected when the doorbell chime is playing the melody. Happy with that. It has one disadvantage though. I have to replace the batteries every couple of years, which I probably will forget ;-). But since the circuit is not draining a lot of power I think the batteries will last for a long time.

    One step closer! Next step replace the batteries with a buck converter connected to a power adapter that also powers the Arduino and the motion sensor. I'm still trying to power this all from one connector. I know, I'm stubborn.

  • Contest Winner

    Solved it. I think it was just a beginners mistake. But here's the circuit that causes the problem.


    Basicly when you press the switch it'll activate the led in the optocoupler. But for some reason it unstabilizes the PIR sensor. No this was a good start for trying to solve it, because I had a reproducable wrong state. Instead of connecting the output of the pir to an Arduino I hooked it up to an LED. And finally found the solution for this problem.


    Basicly the circuits are now completely separated and the circuits are both stable. Next thing to do, is hookup an NRF24L01+ and let it run for a couple of days. Just to see if the PIR isn't detecting motion when everyone is in bed or everyone is away from home. Or when the doorbell is being pressed.

    I've connected the door chime to the 3.3V of the Arduino, but the volume went down. So I've added a buck converter to power adapter, just the same as I did on the last fritzing - so on the upper right breadboard. And know everything works like a charm.

    I'll post the outcome of the MySensors test within a week. But I'm pretty confident that it's stable now.

  • Hardware Contributor

    @TheoL said:

    The question is, why is the LD33V stabilizing the circuit. I'd like to know why, so that I can learn from this.

    A little late and OT, but I think this makes sense. I'm often in favour of wasting some power as a simple way to gain some PSRR.