Strange behaviour with DC 3.3v step-up booster



  • Hello,
    my "mysensors" nodes are based upon a modified version of Easy/Newbie PCB (https://www.mysensors.org/hardware/newbie-pcb).
    The nodes work fine with battery supply but without the step-up booster,
    when I use a 3,3v DC step-up booster, the transmission with the gateway fails:

    Starting sensor (RNNNA-, 2.0.0)
    TSM:INIT
    TSM:RADIO:OK
    TSM:FPAR
    TSP:MSG:SEND 255-255-255-255 s=255,c=3,t=7,pt=0,l=0,sg=0,ft=0,st=bc:
    TSM:FPAR
    TSP:MSG:SEND 255-255-255-255 s=255,c=3,t=7,pt=0,l=0,sg=0,ft=0,st=bc:
    TSM:FPAR
    TSP:MSG:SEND 255-255-255-255 s=255,c=3,t=7,pt=0,l=0,sg=0,ft=0,st=bc:
    TSM:FPAR
    TSP:MSG:SEND 255-255-255-255 s=255,c=3,t=7,pt=0,l=0,sg=0,ft=0,st=bc:
    !TSM:FPAR:FAIL
    !TSM:FAILURE
    

    Other info:

    • 47uF capacitor beetween VCC and GND
    • mysensors version is 2.0

    Do you have any idea to solve the problem?
    Thank you for your help!


  • Hero Member

    @jumping step ups tend to make a lot of noise on the power lines (switching frequency) . Combined with the sensitive radio there is every reason to get into trouble.
    A few possible remedies : a better quality step up. ; filter the power lines with a coil/capacitor or (better) include an LDO regulator ; get rid of the step up and use a lithium 3v battery. ;-)
    I'm sure there is a lot of experience with the setup of this @sundberg84 board.


  • Hardware Contributor

    @jumping - I cant say it better than @AWI.

    I have experienced this in a few nodes - and it was due to bad booster quality. I have had some success using a 0,1uF ceramic capacitor on the booster between out and gnd but sometimes its just not possible to get the noice away.
    When i have ordered batches of 10 booster - its about 8 which is good and the other crap for different reasons (noice is one).

    And just to confirm - you have only added the jumper on "BAT". If you have any other jumpers/connections that means the radio are getting its power from the booster which it should not. The radio should be feed directly from the battery for this reason.



  • Thanks for your answers!
    I will try with a 0.1uF ceramic capacitor.

    @sundberg84 yes, I only have added the jumper on "BAT" :-)



  • Hello,
    yesterday I added a 0,1uF capacitor between 3,3V and GND pins and I tried 8 different step-up booster without success!

    In the next days I will try different configurations to understand what is happening!


  • Hero Member

    @jumping Not to get you completely demotivated :smirk: but there is some good (educated) reading in this article about noise suppression and why a simple capacitor doesn't work.

    My personal (open to suggestions) preference is in using a 3v lithium cell (i.e. CR123, around €1 on aliexpress) which keeps a high voltage utill it's bitter end..

    0_1474449026870_upload-c8acdd59-bbdc-4a8f-a70e-55c043614fd2



  • Hello @AWI thanks for you reply, I will read the document!

    With other sensors I use LiOn Nokia/Samsung battery, and it's ok!
    But I want to solve this little issue :smiley:


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