MySensors battey board revision 1.0

  • Mod

    @Damme said:

    Me myself was thinging on using li-ion and depending on space charge controller but atleast protection.
    They come in all sizes and dimensions.

    lion is too bad for outdoor usage at least for the places in the world were snow is a normal thing at winter))
    AAA is much more universal because you can choose between alkilene and rechargeable

    with lion you actually fo not need a step-up
    you can use 3.3V version of pro-mini with direct connection between VCC and lion
    radio you can connect to lion using 3.3V LDO or 1-2 1n4148 connected simultaneously to drop voltage from 4.2 (fresh lion) bellow 3.6V (maximum allowed for radio)

  • Hero Member

    @axillent said:

    @bjornhallberg said:

    1. Still wouldn't have minded an AA-battery instead for more than twice the typical mAh. It's only a few mm more. Perhaps this is a moot point, as the more power hungry sensors that I have in mind wouldn't work on battery anyway.

    it is not too late to remove holder from the board. it is an option we need to decide.This will allow to be more flexible with power source. But with the holder you can run out of the box at least with temperature sensor

    As long as you have the option to (easily) connect / solder wires for a separate 1x or 2x AA holder, or solar I'm sure it'll be fine. And the on-board AAA-battery holder doesn't significantly increase price and / or complicate things. Sounds like something that would be hard to do right without breaking off if it doesn't have the support of an enclosure.

    Does it measure and report battery level by any chance?

    $15-22 doesn't sound too bad. I mean, if you add up the cost of components for a simple DIY sensor node, including a prototype board etc, you'd come pretty close to $15. And then you'd still be stuck with a lousy Ebay boost module drawing 1mA.

  • Mod

    @bjornhallberg the holder adds less than half a dollar to the final price.
    You always can use solar connector for any external alternative source
    you even will be able to extend life by connecting external AA, on board AAA will start working as soon as AA will run out

    battery voltage (level) and external source voltage can be measured and reported by radio. The required connections are build in

    Price is still tricky thing because of discussion going on and also because we all are new to such a business. We will need to have also some profit to support project development. I hope all will be withing $15-$22. We are willing to be competitive but not the cheapest. A good level of innovation is an essential idea of the whole project.
    Design is open source and anyone can do it himself.

  • Contest Winner

    @axillent Looks good. But is not the LED symbol reversed in the schematics?
    I am considering making a board as well for personal use (open HW of course), but using through hole components a bit more extensively for ease of customization. And probably a sockeded MCU so I don't have to include programming interfaces. In the future, I (and hopefully all of you) will push new FW to the board OTA so there will not be a need for holes in the case πŸ™‚
    But I might be interested to join in if your are ordering a batch of these as well. Will it be panelized and pick/placed as well?

  • Mod

    @Anticimex thank you for your attention ) yes, led had a wrong orientation, it was fixed.
    I have an DIY experience for making PCB and like you at the beginning willing to use through hole components mostly.
    But through the real practice I came to a conclusion that SMD is easy to use, it is cheaper and need much less space.
    I also used to make zero-hole PCB using SMD only. This type of PCB requires from me 20-30 minutes of time only for the full production circle. There is 0.5mm copper plates, I use office scissors to cut it in a second.

    The programming interface (ISP) is not only for the bootloader programming. It can be used for bootloader upgrade or hardware debugging.
    Even Nano have it.
    The programming interface (FTDI) can be used also for usual Serial.print debugging.
    Both interfaces also can be used for additional I/O.

    Sure, there is no absolute ideal solution. We spend a few months discussing what is a good trade off for this board and you see the result.

    What do you mean by "panelized and pick/placed as well"?

  • Contest Winner

    @axillent By panelization that I mean that you send the board to the fab with a BOM, and some reels, and have them solder the components to the board as well. Most if not all fabs will then require you to panelize the board if also picking&placing (that is, multiply the board on a bigger standard-size board, that is fed to the pick&place machine).
    Example of a PCB panel
    Having a panelized board could also reduce cost for a non pick&placed design, as it allows the manufacturer to make them with less effort (less cutting and less waste).

    For larger batches this is a good way to save a lot of work, and if good decisions are made on layout, design and component selection, it is not overly expensive either.
    I also like SMD, but for "my" board, I was more thinking of having a generic back-bone which can accept a variety of components, so the user can choose what to put on it and use if for various purposes.
    Some "standard" interfaces need to exist of course (socket for MCU, power, RF), but the rest (decoupling, IO, etc) is just left "empty" and for the user to populate with the components they would like.

    And don't get me wrong, ISP/FTDI is really good to have, especially on "in progress" projects. But for the gritty end product, I personally prefer to program and debug the MCU on a breadboard, and then put it in a socket in my optimized board/casing. I even consider using the Arduino "as is".
    But it could be that I cannot get my casing to be as small as I want it, without soldering the "bare" MCU directly on the board, and then of course programming interfaces will be needed πŸ™‚

  • Mod

    @axillent said:

    There is 0.5mm copper plates, I use office scissors to cut it in a second.

    Do you use this thickness for all boards?
    And what thickness is the copper?

  • Hero Member

    Well, needless to say it sounds interesting, when it's been built and tested I'd surely buy a couple of boards. Right now I'm not sure how many actual battery sensors I need and if the sensors I want to run are even viable for battery operation anyway.

    I think that for me anyway, more practical things are an issue, like avoiding Swedish customs charges, and finding a GOOD open source automation software so that I can actually use my sensors and not just build them πŸ˜‰

    If you could also manufacture a separate 3.3V boost circuit based on a modern chip that would be fantastic. I think that is turning out to be a hurdle for most of us that aren't comfortable with SMD/SMT and/or how to nice integrate it into DPI prototyping.

  • Mod


    Do you use this thickness for all boards?
    And what thickness is the copper?

    No, it is only for hole-less fast-processed boards like this:


    It was a weekend one day project to automate lighting of my DIY desk

  • Mod

    @bjornhallberg I'm an experienced z-wave user and 1/3 devices I currently have managed by my smart-home are battery based

    battery based is most easiest way to launch smart-home without big disaster to the home
    I also expect an interest to use this battery as outdoor sensors, while z-wave do not have any alternative to this
    with double power outdoor sensor can lasts from a single battery for year or even years depending on solar power.

    for open source software I personally looking forward to have an integration between mysensors and openhub

    A separate boost development was finished today and I'm expecting quotes from our partner.
    Any preliminary reservations are welcome.
    It will be board 15 x 14.8 mm with a switch between 3.3V (up to 100mA) or 5V output (up to 70mA)
    it can be sourced by 1-3 cells alkaline or 1-4 cell ni-mh or 1 cell lion

    Henrik are build already a boards documentations section on the site πŸ™‚
    We expect to have a good documentation to the boards

  • Hero Member

    @axillent said:

    radio you can connect to lion using 3.3V LDO or 1-2 1n4148 connected simultaneously to drop voltage from 4.2 (fresh lion) bellow 3.6V (maximum allowed for radio)

    It's probably moot, but the diodes may drop substantially less voltage when the current is very low. Of course, there may be no harm done with such low currents - raising the current brings the Vfwd up too. I'm just noting that the "almost constant Vfwd" only applies to larger currents (eg: 10ma not 10 uA).

  • Hero Member

    @Anticimex said:

    In the future, I (and hopefully all of you) will push new FW to the board OTA so there will not be a need for holes in the case πŸ™‚

    For that, it's handy to have some extra flash on board. (Ref Moteino and anarduino)

  • Admin


    Yep, extra flash for OTA would be nice! Great idea for the next revision.

  • Mod

    @hek @Zeph:

    Yep, extra flash for OTA would be nice! Great idea for the next revision.

    Would we need extra hardware for this?
    If so what is your suggestion?

  • Mod

    @marceltrapman said:

    Would we need extra hardware for this?

    The flash downloader + flash code could be stored as a bootloader, but that would drop Arduino bootloader compatibility and it will be a challenge to get a stripped MySensors implementation in the bootloader area.

    Maybe we can add a small i2c or spi eeprom which is used for temporary storage of the new firmware, but then again, how to get the image data from the eeprom into the ATMega's flash?

  • Admin

    @ToSa is working on it.

    Reports of successful OTA flash yesterday. But work still remain to make it safer. An extra eeprom would probably help safing things up a bit.

  • Mod

    @hek that's looking very promising πŸ‘ Thanks for the tip!
    More toys to play with πŸ˜‰

  • Mod

    @hek said:

    Reports of successful OTA flash yesterday.

    Nice πŸ™‚

    But work still remain to make it safer. An extra eeprom would probably help safing things up a bit.

    I have started my own board design so it would be very interesting for me to know where this is heading at. Any idea what would be preferred to use?

  • Contest Winner

    In my opinion, keeping Arduino bootloader compatibility (or rather, supporting the Arduino IDE flash protocol) is a must for a OTA bootloader. Even if it would mean some more flash need to be reserved for the bootloader.
    But that of course makes it even more interesting to have some external memory support. I2C based EEPROMS have been around for quite some time πŸ™‚

  • Hero Member

    I mentioned the Moteino, which has an optional 8 pin 4 Mbit (512KByte) SPI flash chip.

    Felix has a modified Uno class bootloader, the Dual Optiboot which takes up 1KByte (vs 512 Bytes for normal OptiBoot).

    As I understand it, you send the new code OTA where it's written to the external SPI Flash memory. Then when booting, Dual Optiboot looks for a signature in the Flash memory, and if it found, burns the code into application Flash on the ATMega chip (and it obviously removes that signature). If not signature found in SPI flash, it will boot normally as a normal OptiBoot system.

    The Moteino uses the RF12B or RF69 sub-GHz radios. Another cool design. I however like the 2.4GHz nRF24L01+ because it's cheap and very fast, useful in controlling Christmas lights, which take much more bandwidth. I see periodically reporting MySensor style data as another option using the same nRF24L01+ hardware, either instead of the light control function, or in addition to it.

  • Mod

    OTA is a very promising thing
    for the battery board selecting any external chip is also a question of power consumed

    the idea with flash is good because it builds the ability of transactional while you able to safely recover from any situation.
    but from other hand. you can safely recover even without flash if your second party will take care
    look how upload from USB is organized. It do not have a transactional mechanism, it cannot recover by itself
    if upload failed the only way to recover is to upload again
    why we need OTA to be more safe than regular USB update?

    but while you a thinking on this i found an issue in the board schematics. I have to add one diod and one 10k resistor to isolate D0 of the MCU from the parasite power coming from the external FTDI programmer. Otherwise the parasite power can destroy nordic chip

  • Mod

    I have news

    prototype of the board fully tested except radio
    stepup is working fine, power switching is working
    programming using external FTDI is working, schematics corrected to get rid from parasite power
    al I/O is fine
    battery and solar voltage measurement is working
    temperature sensor is excellent
    it was not simple to solder, the package is unbelievably small - 1.7 x 1.2 mm, 6 pins

    next and last is radio, going to solder it today
    Ρ„ΠΎΡ‚ΠΎ 1.JPG

  • Hero Member

    Interesting that you are choosing GROVE connectors. Are they easy to find (other than SEEEDStudio)?

    This makes for an almost drop in alternative to the DevDuino's :

  • Mod


    @Zeph said:

    Interesting that you are choosing GROVE connectors. Are they easy to find (other than SEEEDStudio)?

    GROVE is just a convention on pin assignment. The physical connectors are standard 4 pin 2.0mm pitch (arduino is using 2.54mm)
    Two pins are used for GND + VCC and two pins for data/analogue arduino pins
    I have them purchased from aliexpress

    This makes for an almost drop in alternative to the DevDuino's :
    we are different.

    we have compact, ready to use double power sensor node
    devduino is using an external radio, v1 is using low capacity CR2032, v2 is using two AAA batteries
    we are using radio on board, single AAA battery with step up and a solar connector with automatic switch

    CR2032 is just 80-120mAh
    AAA alkiline is about 800-1000mAh

    two batteries on devduino is 1600-2000mAh but it will work until discharge of a cell to 0.9-1.65V (supplying 1.8-3.3 V) depending on the frequency used
    we can run until discharge to 0.7V regardless frequency used. Single cell reduces space needed and stepup allows to draws a maximum

  • Hero Member

    Sorry, I by "almost a drop in replacement" I meant that somebody using a DevDuino could (almost) unplug it, plug in your board, upload the code, and go, if they use the same radio and connectors. (Or vice versa). That flexibility could be good.

    I didn't mean that your design was the same or had no advantages! Thanks for listing the key differences, tho.

    And - it's "almost" compatible, software wise. I think the data connector has different pin numbers. Not sure about the radio pins (other than dedicated SPI).

    But I think that with a change in pin defs, most code could be moved between them, and with the same connectors, a physical switch could be simple.

  • Mod

    @Zeph if you have developed a sketch for DevDuino you will just need to change a pin assignment to move it to MySensors board
    it is a good practice to use #define for the definition of your hardware pins and move this to abstract level, for example:

    #define RADIO_CE    8
    #define RADIO_CSN   9
    #define PIR_SENSOR  3

    to change this assignment you just need to change this few lines

  • Hero Member

    Yes, that's about what I thought. Thanks.

    Looking forward to your board being available. I had ordered a couple DevDuinos, but now I'm holding off on ordering more since seeing yours - and for me the option of being able to swap out which is used could be handy.

    Looking forward to hearing more about availability and final pricing, when you have it.

    Oh, did you use the same temp sensor?

  • Mod


    @Zeph said:

    Oh, did you use the same temp sensor?

    devduino is using analogue sensor with accuracy Β± 2 Β° C in range -40 Β° C +125 Β° C

    we are using very low consumption digital sensor with accuracy Β± 0.5 Β° C with MCU wake up function on alert
    range -25 Β° C +85 Β° C

  • Hero Member

    I feel like the straight man, feeding you lines πŸ™‚

    Seriously, it's great to have the differences listed for everybody to see.

  • Mod

    @Zeph YAW πŸ™‚

  • Code Contributor

    How's the progress with the radio?

    I was thinking about the small stuff soldering, Me myself don't have that much trouble with the multi-pin chips.
    For QFN (I hate them) I usually pre-solder the pads and use lot of flux and heat gun.
    For TQFP I usually solder just one pin in 2 corners, and then I put a thin strip of solder along the pins and just drag my iron across. and if it's a mess, you used too much solder and to little flux πŸ™‚
    I hate soldering smd resistors and stuff, the smaller the more ass they get.. πŸ˜›

  • Mod

    @Damme I get first success on testing soldered radio, but more tests are needed

    I use similar technique for QFN and TQFP
    goof flux is a must

    And why you hate this little friendly SMD staff?) I like them. 0603 is optimal size, easy to solder, not too little.
    0402 needs much more care

  • Hero Member


    Looks like a very nice board and the ability to also power it using a solar cell and the very efficient step up converter makes it quite interesting to me.

    One question: Would it be possible to use a rechargeable AAA battery and if there is enough (solar) power, recharge the battery?

  • Mod

    @daulagari sure you can use rechargeable AAA as power source

    it is decided not to add charging function
    if you will use dual power (and if your sketch will be optimal from power saving) regular alkaline can lasts for 1-2 years
    at the same time rechargeable AAA because of often charging-recharging circle (every day because of solar) it can last in one year
    number of recharging circles are limited and also Ni-Mh/Cd they last faster in such way because of "memory" effect

  • Hero Member

    @axillent: Still a bit puzzled as the combination of support operation from an external (solar) supply but no charging support seems not logical to me.

    Understood that the number of recharging cycles of rechargeable batteries is limited but batteries still have about 10 times the capacity of supercaps so also if the capacity is reduced to 10% of the initial capacity because of the number of recharging cycles they are still a better choice.

    On Wikipedia I read that charging at C/300 or even C/40 seems to be safe over long time and that can be done using a diode and resistor I think.

    But ... also if there is no charging support, I am interested to buy a few πŸ˜‰

  • Mod

    the logic is that none rechargeable battery can lasts for 1-2 years
    rechargeable battery can lasts for 1-2 years too
    and what is a reason to pay more for rechargeable one?

    it is theory, but it is based on deep thinking. If we will see a practical reasoning for recharging function it will be added to revision 2

  • Hero Member

    Interesting analysis.

    We get into a mindset that solar + battery implies recharging the battery from solar. That is, we think of the solar as the power and the battery as a buffer for dark periods.

    You are using the solar as a battery extender for a primary battery. It can run for very long periods in total darkness (much less cloudy days), but when it does get solar you can go longer between battery changes.

    And your point is that the rechargeable batteries need to be changed every year or two anyway, so if you can get that long with a primary cell (cheaper and bridges longer gaps without solar), why bother?

    Sounds good to me - I await practical experience. Do you yet have one or more test units accumulating data and testing the approach? On cool things about JeeLabs is that with each new design he puts up some long term test units, wirelessly logging the results. Over time he gets years worth of practical results to report and analyze.

  • Mod

    @Zeph thanks for the feedback
    I'm wondering on triple power sources - main is solar, buffer is super capacitor and none rechargeable as back-up
    super-capacitor is a best choice for night time run while charging at daylight time
    super capacitors are not cheap, but while we will have a production experience I think we will manage its price down

    sure it will be good to track performance. May be Henrik can think of adding some statistics logging to MyCloud service and this can be seed from the whole community in the future

  • Hero Member


    the logic is that none rechargeable battery can lasts for 1-2 years
    rechargeable battery can lasts for 1-2 years too

    After the 1-2 years the none rechargeable battery is empty and should be brought to the recycling point but my own experience is that rechargeable batteries are not gone in two years.

    See Nickel–metal hydride battery#Telecommunications, it looks to me NiMH batteries can be designed for 10 year operation. Also normal available batteries claim they retain 65-70% capacity after five years in storage and like written earlier, I think we can do with 10% of the original capacity.

    No problem for me if this has to wait, I can always add something myself, and yes, let logging prove what's right. Only thing I find a pity is that it will take two but probably much more year to prove things πŸ˜‰

  • Hero Member

    @daulagari said:

    After the 1-2 years the none rechargeable battery is empty and should be brought to the recycling point but my own experience is that rechargeable batteries are not gone in two years.

    I've read that NiCD can sometimes do better for solar landscape lights than NiMH, because the type of cycle favors it, but often they say to plan to replace the batteries every couple of years anyway - between the charge cycling and the outdoor temperature cycling (cold and hot).

    Perhaps this is different, being very shallow discharge compared to lighting. Really only testing will let us know for sure, and I'd be glad to see the results of that.

    And yes, it's hard to wait a year or two for results. (It's hard to get most homebrewers to let their products age, too). But the time to start the test is now, and results will start trickling in. It used to be kind of fun when JeeLabs would post something like "Well, unit #1 is at 420 days and unit #2 is at 287 days, and here are the results so far". Sort of like slow gardening.

  • looks very good indeed. Any ETA on production?

  • Admin


    Can't give any ETA yet. We'll start with production of 500 pcs of the step-up module (to test production site). Vacations has delayed things a bit.

  • Interesting!
    I believe your choices are great between size and functionality for a non specific use case.

  • Hero Member

    Also interested.

  • I'm also interested in buying few. Any update to project?

  • @hek Hi there . I am still interested . Can i pre book some pieces?
    I think the 500 lot will vanish πŸ™‚
    Consider approx 10 boards per interested person...

  • Admin

    Why not use Sil7021, for measuring temperature? It's a combined temperature / humidity sensor

    Am thinking about using them in my own setup, to measure both temperature and humidity in each room of the house.

    / Thomas

  • Also interested in buying 10. Any update on production ETA?

  • Just a bump. πŸ˜ƒ

    Any progress on the board? I'm also very interested.

  • Dito. Current setup is "suboptimal" πŸ˜‰


  • any news

  • Has this died?

  • Admin

    The step-up module didn't perform good enough using single AA-cell according to @axillent.

    The Micro board will be the first in line.

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