๐Ÿ’ฌ Door/Window Sensor




  • Hardware Contributor

    @Takero
    Cool. Glad to see i inspire :)
    So a little advice, if it can help and prevent you for some disappointment ;)

    Looking at your schematic, your choice for power supply not really great...

    I have a circuit around this booster (never had time to release..) but it's a very optimized circuit 1-2uA max depending of app...
    Here, not talking about the efficiency (because it's <80% even if 2V VIN so you wastes more energy vs an ultra efficient), MCP1640 uses at least 19uA for itself, without any circuit load ! And the resistor divider at MCP output also consumes etc...

    So you're greatly reducing battery life!

    • No regul = door sensor should be a very few uA whereas..
    • Basic MCP1640 circuit = 19uA, and there's also the resistor divider which consumes...your node should be something like 20-21uA min, for door contact

    Maths are easy then ;)

    For using a booster, you need to take care of a lot of things if you want efficiency, low power consumption etc..

    just in case you didn't pay attention..
    Keep the good work.


  • Hardware Contributor

    Thanks for review :-)

    Yes 19uA is to mutch!

    Your circuit works with MCP1640 or an other IC? In my experience the NRF24 needs a stable 3.3V Power to work well,
    especially if you use Signing and OTA.

    I look around for another solution. . .


  • Hardware Contributor

    @Takero said:

    Thanks for review :-)

    Yes 19uA is to mutch!

    Your circuit works with MCP1640 or an other IC? In my experience the NRF24 needs a stable 3.3V Power to work well,
    especially if you use Signing and OTA.

    I look around for another solution. . .

    Hello, you can power the nrf24 down to 1.9V. The CR2032 will be nearly dead at 2.4V anyway and that's high enough to transmit with the NRF24. I don't think you should take OTA into consideration for a CR2032 node, long continuous transfer of data will kill the battery in no time. Signing will make the radio transfers a bit longer but it should not be problem for a door sensor.

    I think you should just power from the CR2032 with help from capacitor and enjoy a much smaller board, with a cheaper pcb if you get below 5cm length and faster to solder ;)
    You could even save one reed switch and use only one, if it's in the middle of the board on one side, as your board is rectangular you could just put it upside down if you need the reed swith on the other side ?


  • Hardware Contributor

    I will try it direct on the CR2032.

    You are right, OTA not needed and not possible. The second Reed is for a second Window, i would trace it seperatly.
    It's for a doble Window, the sensor is placed in the middle of booth windows.


  • Hardware Contributor

    Final Version is tested and released. Have fun!



  • Hello @Takero,

    thanks for your nice work!

    How long does the battery hold? is the consumption still at 19uA?


  • Hardware Contributor

    Yes the consumption is still at 19ยตA, but while sending it increase up to 100mA. The Standby Time is depends on the interval of open/close Windows. For me it was not really ennoth (2-3 month), so i redesigned this Project.

    Just look in my Projects -> Door/Windows AAA

    Greetings


  • Hardware Contributor

    But why did you have so much power consumption ? With high value pullup resistors you should be able to go well below 10uA ?


  • Hardware Contributor

    In deep Sleep the cunsumption is below 19ยตA, but i have to send with PA_MAX. On some Windows the open/close frequency is verry high, so the battery is to fast emty.

    The CR2032 is good, but i want more "lifetime"



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