Door Window sensor consuming more power when closed

iask

I have a Door/Window/Switch sensor setup with a reed switch and magnet assembly. When open (magnet moved away) the device consumes 0.20mA, however, when closed the device consumes 0.97mA (uA). Is this normal?

I modified the example to include an INTERRUPT.

// Simple binary switch example 
// Connect button or door/window reed switch between 
// digitial I/O pin 3 (BUTTON_PIN below) and GND.

#include <MySensor.h>
#include <SPI.h>
#include <Bounce2.h>

#define CHILD_ID 3
#define BUTTON_PIN 3  // Arduino Digital I/O pin for button/reed switch
#define INTERRUPT BUTTON_PIN-2

MySensor gw;
Bounce debouncer = Bounce(); 
int oldValue=-1;

// Change to V_LIGHT if you use S_LIGHT in presentation below
MyMessage msg(CHILD_ID,V_TRIPPED);

void setup()  
{  
  
  gw.begin();

 // Setup the button
  pinMode(BUTTON_PIN,INPUT);
  // Activate internal pull-up
  digitalWrite(BUTTON_PIN,HIGH);
  
  // After setting up the button, setup debouncer
  debouncer.attach(BUTTON_PIN);
  debouncer.interval(5);
  
  // Register binary input sensor to gw (they will be created as child devices)
  // You can use S_DOOR, S_MOTION or S_LIGHT here depending on your usage. 
  // If S_LIGHT is used, remember to update variable type you send in. See "msg" above.
  gw.present(CHILD_ID, S_DOOR);  
}


//  Check if digital input has changed and send in new value
void loop() 
{
  debouncer.update();
  // Get the update value
  int value = debouncer.read();
 
  if (value != oldValue) {
     // Send in the new value
     gw.send(msg.set(value==HIGH ? 1 : 0));
     oldValue = value;
     
      gw.sleep(INTERRUPT,CHANGE, 0);
  }
 
} ```

AWI

@iask (probable cause) You are using the internal pull-up of the Arduino. This is a resistor of around 20 k ohm link. If this is pulled to ground by the reed contact. I = U/R = 5/20.000 = 250 uA = 0.250 mA..

Also: debouncer combined with sleep is guaranteed to give trouble. Sleep does also sleep the internal clock which is used by the debouncer class/ library.

iask

@AWI thanks for responding. I will look into the internal pull-up. I did had some doubts with the debouncer. For example, putting the line gw.sleep(INTERRUPT,CHANGE, 0); outside of the IF statement caused the sensor to randomly drop messages to the GATEWAY. I did come across a post whereby someone used a delay instead of debouncing

// Short delay to allow buttons to properly settle
 sensor_node.sleep(5);

iask

@AWI You are right about that internal pull-up. It got even worse when I added an external pull-up. I placed a 10k between pin 3 and GND (for the Door, Window example) and disabled the internal pull-up. When the reed contact is open the sensor pulls only 008.5 uA which is great! When the reed is closed it pulls a whopping 00.32 mA.

I don't know what else to try to bring down that 00.32mA whenever the reed is closed (which will be most of the time because the window will be closed).

I will look into hardware debouncing to see if that will be a solution for the reed switch.

// Simple binary switch example 
// Connect button or door/window reed switch between 
// digitial I/O pin 3 (BUTTON_PIN below) and GND.

#include <MySensor.h>
#include <SPI.h>
#include <Bounce2.h>


#define CHILD_ID 3
#define BUTTON_PIN 3  // Arduino Digital I/O pin for button/reed switch
#define INTERRUPT BUTTON_PIN-2

MySensor gw;
Bounce debouncer = Bounce(); 
int oldValue=-1;

// Change to V_LIGHT if you use S_LIGHT in presentation below
MyMessage msg(CHILD_ID,V_TRIPPED);

void setup()  
{  
  gw.begin();

 // Setup the button
  pinMode(BUTTON_PIN,INPUT);
  // deActivate internal pull-up
  digitalWrite(BUTTON_PIN,LOW);
  
  // After setting up the button, setup debouncer
  debouncer.attach(BUTTON_PIN);
  debouncer.interval(5);
  
  // Register binary input sensor to gw (they will be created as child devices)
  // You can use S_DOOR, S_MOTION or S_LIGHT here depending on your usage. 
  // If S_LIGHT is used, remember to update variable type you send in. See "msg" above.
  gw.present(CHILD_ID, S_DOOR);  
}


//  Check if digital input has changed and send in new value
void loop() 
{
  debouncer.update();
  // Get the update value
  int value = debouncer.read();
 
  if (value != oldValue) {
     // Send in the new value
     gw.send(msg.set(value==HIGH ? 1 : 0));
     oldValue = value;
       
     //Sleep until interrupt comes in on motion sensor. Send update every two minute. 
     //gw.sleep(INTERRUPT,CHANGE, SLEEP_TIME);
      gw.sleep(INTERRUPT,CHANGE, 0);
  }
 
}

AWI

@iask try a 1 Mohm pull up and disable the internal. Hardware debounce is the way to go. Add 100nF to ground and 10k in series with the contact.

iask

I tried that with the code below but it doesn't work at all. It registers the first 0 status with the Gateway and then goes silent.

// Simple binary switch example 
// Connect button or door/window reed switch between 
// digitial I/O pin 3 (BUTTON_PIN below) and GND.

#include <MySensor.h>
#include <SPI.h>
//#include <Bounce2.h>


#define CHILD_ID 3
#define BUTTON_PIN 3  // Arduino Digital I/O pin for button/reed switch
#define INTERRUPT BUTTON_PIN-2

//const byte switchPin = 3;
byte oldSwitchState = HIGH;  // assume switch open because of pull-up resistor


MySensor gw;

// Change to V_LIGHT if you use S_LIGHT in presentation below
MyMessage msg(CHILD_ID,V_TRIPPED);

void setup()  
{  
    for (byte i = 0; i <= A5; i++)
    {
    pinMode (i, INPUT);
    digitalWrite (i, LOW);
    }
  
  gw.begin();

 // Setup the button
  pinMode(BUTTON_PIN,INPUT);
  // Activate internal pull-up
  //digitalWrite(BUTTON_PIN,LOW);
  
  // Register binary input sensor to gw (they will be created as child devices)
  // You can use S_DOOR, S_MOTION or S_LIGHT here depending on your usage. 
  // If S_LIGHT is used, remember to update variable type you send in. See "msg" above.
  gw.present(CHILD_ID, S_DOOR);  
}


//  Check if digital input has changed and send in new value
void loop() 
{
  
  
   // see if switch is open or closed
  byte switchState = digitalRead (BUTTON_PIN);
  
   // has it changed since last time?
  if (switchState != oldSwitchState)
    {
     
       oldSwitchState =  switchState;  // remember for next time 
       
       if (switchState == LOW)
          {
           gw.send(msg.set(0));
          } 
       else
          {
          gw.send(msg.set(1));
          }
         
         gw.sleep(INTERRUPT,CHANGE, 0); 
           
       }  
    }

AWI

@iask Are you measuring a transition on the input? You need the external pull-up at minimum.

iask

@AWI right on! I had some time to go at this again. I realized that I had soldered the pullup on the wrong pin. Right after that my fine 898+ station stopped working. It just wont get hot. Going old school for the next few days.

iask

@AWI So here is what I got. When the sensor (Reed Switch) is open, the sensor consumes 8.5uA and when closed it consumes 11.5uA.

I still have the regulator on board
I removed both LEDS
I am using hardware debouncing
Set Analog pins LOW

Were you able to get lower than 11.5uA, with your NRFXXXXX connected, when in sleep mode? I am trying to find a proper benchmark to work with. My sensor is powered with a 3V CR123A battery.

I find that the CR123A is used in sensors by some alarm companies here in the US. See page 10 here (I've seen these things last a long time...3 years in some cases) so I am using this as my battery benchmark for all my sensors. Definitely not the cheepies from China.

AWI

@iask I am not able to measure anything accurate that low. I use the chargeable version of cr123 in many sensors. No long term results yet, but a lot of power

Door Window sensor consuming more power when closed

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