πŸ’¬ MySensors Low-power Multi-function node on CR2032




  • Hardware Contributor

    Looks great! I notised one small thing you might want to check. It looks like you are going to use a low profile battery holder and the battery directly on the board? The ISCP header might short the battery since the battery is all metal. I would not solder pinheaders to this as your 3d view shows, because that will short the battery. You can use pogo-pins and electrical tape for isolation.

    0_1553588101475_4f32944e-3e78-4158-a257-feb2c8671434-image.png



  • Hi,
    Thanks a lot for your feedback. My plan is to avoid any soldered header pin, to keep the design small and I use pogo pins for FTDI and ICSP. . This is my very first design. I received the PCB and began to solder. Thus, I found more critical issues :

    • ATmega328pb is not fully pin compatible with atmega328p !! but it does not seem to hurt here
    • the battery holder foot print is wrong : GND is not in the center but one of the side pads
    • the AT25DF pads 5-8 are reversed
    • the antenna schematic and routing is completely false
    • I met issues with the node sketch running at 1Mhz
    • My FTDI and my ICSP send 5V on the power rails, too much for NRF and AT25DF, I should take care of that
      Next iteration should have a better design and be able to work, but this one is clearly not functional. πŸ˜‰


  • Hi @sundberg84 , Just in case, I redesigned the whole thing to fix some issues. This is still a work in progress, but it is very close to the final design.



  • @Fanfan
    what is battery life like running uC at 1Mhz?



  • @pihome I don't know yet, I'm still waiting for the PCB. I should receive them this week. From the mysensors site, 1Mhz vs 8Mhz does not make a huge difference. I'll try them both. What I can say is that 1Mhz as other constraints (I had to compile my own bootloader, then it is difficult to have reliable serial communication faster than 9600bauds, including for uploading sketches, meaning an update in the boards.txt file). Anyway, for sure, I'll build the board and make tests very soon. In the worst scenario, I may switch to CR123 batteries or LS14250.



  • @fanfan
    I been using temperature sensors with 8Mhz without any custom bootloader or any other modifications on 18650 battery for over 2 years, sensor read temperature once every minute and go to sleep, haven’t done any battery consumption calculations, i m switching from 18650 battery to AAA or AA batteries hence need for power saving



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