My Slim 2AA Battery Node

  • Hardware Contributor

    Board releases
    (other colors might be selected when ordering)

    • Version 2.0 (black) [order] Now designed in KiCad. "Final release". I'm not developing it further atm, but I know others have some projects going.
    • Version 1.4 (red) My latest version in Eagle. Known issues are wrong references due to panelization and broken circuit diagram links.
    • Version 1.2 (blue) Some less convienient placed components and the panelized verision has a faulty via.
    • Version 1.0 (green) The one described below in this first post. Working but not panelized and lacks a few features.

    Share stats and info
    The panelized versions 2.0, 1.4 and 1.2 have until today (2019-02-24) been shared 230 (!) times at boardhouse. Together with a few shares of the non-panelized version and my own orders, and the usual 3x10-11 boards/order, it means a lot of boards! Guess very few build nodes with every board, but at least the design should be well proven by now. This also means a few $ to, since 1 $/order will be donated. Great thanks to everyone who has orderd this board! I'll keep this share-info updated for transparency purposes. IMPORTANT: Please understand that is a non-profit community service, with a lot of manual support required. So please be patient and nice to their support in general. A new site is under development. Read more at their support site. EDIT 2017-06-22: Despite the new site it is still a hassle every time to get a reply from them and then the share credits. If anyone have some more info on this, please let me know.

    This project describes a successor Node concept to my first 2AA battery sensor. I have combined a few simple design options to a result that I find rather useful myself and I think should be shared. The application specific sensor/-s of your own choice has to be added to this Node design, nor here any example sketches provided here except from a few links further below. I use this design for all my door and window reed switches, temperature (calibrated internal or thermistor), LDR and similar simple sensor types. But, nothing prevents the use of more sophisticated sensors like Si7021 here as well. A few links to sensor examples based on this node will be presented further down in this post.


    • Simple, in the sense that it consists of a minimum number of components and common available material.
    • Cheap regarding choice of components, assembly work effort, energy storage and power consumption (battery type and life time).
    • Flexible universal design base equipped with various sensors. PCB pads used as port connections or prototyping area for extensions.
    • Small and discrete to fit in confined spaces and to reach WAF level

    And more concrete:

    The uC
    A "bare bones" ATMega328p 28pin PDIP (with or without socket). Bought from here and here. My reasons to not use Arduino Pro Mini here are

    • The APM width is too big.
    • APM has no prototyping/near connection area. There's no spare pads for separate connections unless you accept to use pads connected to softwise inactive ports.
    • Radio module connection has to be manually made to the APM.
    • Low power hacks like removing power led and voltage regulator are needed.
    • Necessary support components (resistors and capacitors) are few and can easily be added to a custom pcb.

    Since I prefer Arduino IDE for programming (flash) and debugging, I need a bootloader. Bootloader instructions are found all over the internet, but here's anyway how I do it. I use this precompiled bootloader from here. It's an Optiboot with 1MHz internal clock and 9600 baud serial communication. Fuse changed to BOD disable. According to this you should use minimal startup time to reduce power in every 8s sleep cycle, but for the moment I don't care and stick to the default 65ms. I use Avrisp mkII avr programmer for fuse and bootloading similar to this procedure. Arduino as ISP, Avr/USBtiny or whatever any other should of course be just as good. Avr Studio 4.19 is a good choice for Avrisp mkII (perhaps for others too) and 4.19 is the last version before the gigantic (and for me useless) IDEs were released.
    I add this new board to my "boards.txt". Fuse settings, don't forget to set the lock bits. If programming a large batch, the ELF production file is handy.
    Here's a great tutorial for those who use Arduino Uno as ISP.
    UPDATE 1: Today (2017) a lot has happen since I wrote about this. Some things has made it easier for us. A very good selection of precompiled bootloaders is now found here at MySensors. And you don't need to (and shouldn't) mess with the boards.txt any more. Instead I recommend the installation of MiniCore to the Arduino IDE.
    UPDATE 2: There have been reported issues with MySensors 2.x freezing on SlimNodes running at 1MHz, which I've confirmed. Recommended solution when using MyS 2.x, is to use 8MHz (internal) instead.

    The Radio
    A standard NRF24L01+ radio module is used. The width align with the AAs and no mods is needed (like with my other one). As always I try to keep the antenna part of the module free from shading metal.
    2020-12-14: On using RFM69 - here's a hint from @joaoabs at this page: I've been troubleshooting this slimnode with RFM69 radios and realized that a shunt between RFM69's DIO0 and Mega328's INT0 is required, otherwise the node will not "hear" the gateway. Even if the nrf2rmf69 board is used this shunt is required. It seems this is a re-current issue

    The Board
    At first I planned the build on a proto board, just to stick to the cheap-and-standard concept. But with today's low prices on custom made PCBs, it wasn't any longer an option. Space, quality and work effort are so much more attractive.
    Latest design files are open and available at the site. Please click on the image-link below to access where all design files such as latest BOM, kicad-files and circuit diagram (pdf) are found.

    Board (v2.0) Top Side:

    Board (v2.0) Bottom Side:

    The Enclosure
    UPDATE: If you dont't like my primitive casing descibed below, in this post the user @buxtronix made a nice 3D-printed case which you can find here.

    An important overall part of this design idea was to align minimum dimensions of the components and get rid of "expensive" parts like battery holder. It turn out (see below) that the enclosure's functionality as battery holder wasn't needed even though it was the initial idea. The cable duct case has been discussed earlier, but rejected by some due to lack of ways to seal the endings. I still haven't the perfect solution, but I've since many years simply used (cheap) white tape. With some care it looks ok, and still does 5-10 years later. There are often proper terminators/endings to buy, but for some reason to unrealistic high prices.
    I used this cable duct with the dimension 17x20mm. Unfortunately it turned out that this particular type I used (Thorsman TMK T20) is now "professional grade" and dimension 17x20 is no longer very commercially available for consumers (here in Sweden at least). Eg. to get it, you have to pay >5$/m from places like this or buy it in bulk (50m) from a professional store (preferably as a professional with discount). The 50m bulk batch will give you 263 sensor nodes of standard length (19cm).
    Standard consumer dimension cable duct is e.g. 15x15mm from what I've seen. It'd be nice to design a 2AAA node in that one. If only there is a thin radio module? (Future project.)
    box1.jpg box2.jpg box3.jpgbox4.jpg

    The Battery pack
    Easy home made 2AA battery pack. Maybe it looks more demanding and time consuming than it is. (Usually its the other way around in my experience.)

    1. Start by taping the two (connecting) batteries together.
    2. Prepare the wires and make a small bun at the battery connecting ends.
    3. Attach the wires with tape.
    4. Tighten the cable ties and carefully note
    • that the wires are pressed to make good contact with the battery poles
    • how the cable tie ends must be placed to not steal lateral space
    • that the wire from the bottom must be routed near the cable tie to not steal space.
    1. Make the pack more rigid by taping one or two times around at the top, bottom and middle.
    2. Trim wires and solder the female connector. If desired, leave at least a small part of one wire naked for current measurements.
      A battery change is done fast when cables a already made (use solid wires that preserves its shape). So why pay for a battery holder when you can remake a pack with fresh batteries in 1-2 min and your low power sensor will live 5-10 years before anything needs to be done?
      bat1.jpg bat2.jpg bat3.jpg

    The Interface/Connections
    Convenient there's the 6 pin standard serial interface exactly like on the Arduino Pro Mini. Perhaps it's mirrored here, but I think everybody double checks Gnd and Vcc before connecting. The Vcc and Gnd pins also serves as a connector for the battery pack. (CTS is connected to GND on the PCB.)
    "Under" the radiomodule are pads for the ICSP pins. The idea was to have a socket for the radiomodule instead of the "expensive" 328p socket and still have easy future access to the SPI/ICSP interface. Perhaps not very useful. But nice to have Gnd and Vcc in this end of the board for general purpose.

    The Sleep Mode Power Consumption
    I measured the sleep mode current draw to be 1.5uA when it's set to interrupt wake up and 5.8uA when it's set to timer wake up.
    power1.JPG power2.jpg

    Sensor Examples and more
    Reed Switch Sensor: post 116
    Humidity Sensor: Slim Node Si7021 sensor example
    Motion Sensor 1: Slim Node as a Mini 2AA Battery PIR Motion Sensor
    Motion Sensor 2: Slim CR123A (2AA) battery node..
    Scene Controller: Slim Node scene controller/ keypad
    (work in progress to collect more examples here)

    Not Sensor exemples, but some nice to see "node variations" from @AWI:
    Here (post 88) and here (post 233). And now there's also @AWI 's My Slim 2AA Battery Node Tools.

    Still not "slim" enough? Check out Very Narrow and Minimal Switch Node ! by @GertSanders

    And also, there's this 5V-slim-node a 5V-slim-node mod by @Soloam

    Feature Requests
    Here's a collection of suggestions and development ideas for future versions of the board (or other parts). If anyone else make their own board where some of this is included, I'd be happy to reference it from here.

    • Pin labels/references also on board top side.
    • Turn the nRF footprint to make the assembly shorter.
    • Make the board suitable for the nRF SMD version.

    More Pictures
    Some photos. First a comparison next to My (old) 2AA battery sensor, one painted and one not. (Note the high WAF of the colour even without the paint.) Then some placement examples. Reed switch nodes for all my doors and windows are my first priority.
    20150901_220448.jpg 20150901_220505.jpg 20150901_220659.jpg 20150901_220847.jpg 20150901_220948.jpg IMG_2065.JPG IMG_2063.JPG IMG_2064.JPG

  • Nice job and give me another tool to use in my tool box. Thanks.

  • Hardware Contributor

    Very nicely done ! Great idea, makes the sensor blend in. Fortunatly in Belgium we do have access to cheap cableducts. I did not think of using them as a case, but given that we have access to various widths, I will check.

    May I ask, which boardhouse made the PCB's for you ?


  • Hardware Contributor

    @GertSanders I ordered from DirtyPCBs. It was 51mm but it didn't complain.

    Hm. I can now see few strange spot in one of the PCB-photos above. I'll look into what that can be...

  • Hero Member

    Thanks for the detailed information about this project! I was/am looking for a similar solution to check whether doors are opened or closed.
    Have you ever considered drilling a hole in the top of the door, and placing the entire node inside this drilled hole like the video below? Similar to this video?
    That was something I planned to do, but your solution seems really nice as well in case drilling a hole in the door doesn't work out as expected.

  • I see u don't use a external 8mhz quarz. Because any technical reasons (=low current?) or for reasons of space?

  • Hero Member

    @m26872 Great design, did you share the design on dirtyPcb's?

  • Hardware Contributor

    @aproxx I've never thought about it, but I think it's an excellent idea for some situations.

  • Hardware Contributor

    @AWI No, but the Eagle files are attached above. I'm new to all this open hw/sw sharing. You're very welcome to tell me how I should do it the right way. PM if you like.

  • Hero Member

    @m26872 When you check out your order you can set the "sharing" options:
    upload-821ec565-96e5-4214-baa4-72564a63c07a and even get a small profit (or a donation to MySensors..)

  • Hardware Contributor

    @m26872: very nice idea 😃
    just a little question, is your cable duct pvc. I think so. Alloy maybe would not be great for radio...
    yoyur idea can be very helpful thx for share.

  • Hardware Contributor

    @scalz Yes, it's pvc.

  • Hardware Contributor

    @Harrdy said:

    I see u don't use a external 8mhz quarz. Because any technical reasons (=low current?) or for reasons of space?

    Low power, low cost, less space, less work. Stability might be an issue at different ambient temperatures etc.

  • Hardware Contributor

    Added a boardhouse link if anyone would like to order the board straight from there (thx @AWI). Couldn't see any cons.
    I think it's enough tested, but personally I'd wait for a tested v2.0 or make suggested improvements myself first.

  • Hardware Contributor


    great job! I think i will use your board to for small window -sensors.
    But one question: i cannot upload sketches via arduino-ide when the 1mhz bootloader is flashed. i checked the wires and everything else and i tested a 8mhz/internal bootloader - works fine. but the 1mhz-bootloader just does not accept uploads?

  • Hardware Contributor

    @ahhk There's also the precompiled bootloader for 4800 baud in the link above. Did you try that one too? I think 9600 baud was maximum serial speed at 1MHz. Lower should be safer.
    Or what do you mean with "does not accept uploads"? Is it locked?
    Double checked boards.txt settings?

  • Hardware Contributor


    i can upload via RX/TX with arduino IDE with the 8mhz/internal bootloader. but if i flash the 1mhz bootloader from the link above (atmega328_1a.hex), i cannot upload the same way...

    TX/RX is connected correctly. I can upload a sketch via "Upload with programmer" and receive and transmit characters with 9600baud. tested with the example-sketch "SerialEvent".

    IT is a brand new 328P - not locked...

    boards.txt shows

    ############################################################## Optiboot internal 1MHz noBOD 9600baud

    i didnt try the 4800baud bootloader until now....i will do now...

  • Hardware Contributor

    @ahhk Reset issue? Maybe try other startup times (low fuse 42h or 52h), other usb2serial or adjust reset R and C.

  • Hardware Contributor

    For info. I've prototyped and ordered a slightly improved version of the pcb. Note that this is UNTESTED and experimental.
    Eagle brd-file and board house link. Use it for inspiration. Don't expect it to be and tested until next month at least.

  • Mod

    Great work @m26872
    Thanks for sharing!

  • Really great idea @m26872 !!
    I'm waiting for the V1.2 test and review before ordering some boards on DirtyPcb.
    One Tip/question : have you thought on panelizing your slimnode, because we could easily fit 3 board on the 5X5 limitation ? I also think that DirtyPCB would even process the break routing to ease board separation.

  • Hardware Contributor

    AAMOF I ordered a panelized version just a few days ago. I'm completely new to all this, so I leave no guarantees...
    Here's the brd-file.

    Edit 3/12: Boardhouse link removed (the panelized version of v1.2 contains a faulty via between D13 and SCK.)

  • I guess if you ordered panelized version, you have tested the V1.2 ? Would you mind sharing the schematics also please ?
    I'm also very new to this, I've never ordered PCB on Dirtypcb, how long does it takes to arrive in Europe ?

  • Hardware Contributor

    Delivery times depend mostly on shipping time. DirtyPCB have their boards made usually within a week after uploading the files. But shipping can take 3-4 weeks to get to Europe.

  • Hardware Contributor

    No I actually ordered before I got the first sample, due to the delivery time. But now (just a day after) I got the first v1.2. Delivery time was 4 weeks (to Sweden). Soon tested...

    I don't think there are any changes to the already published schematics.

  • @GertSanders @m26872
    Thanks guys for the good work I just ordered your boards
    Will definitely let you know how things goes

    GertSanders, did you find a nice box for your board + battery ?

  • Hardware Contributor

    @frenchclem Not yet, the height is indeed the limiting factor. I'm now looking for a small box that can hold the sensor on it's side. SO for the moment the sensors are scattered around the house without a box around them (usually in places where the cat does not go or could find them).

  • @GertSanders thats what I was worried about. What is the height of the sensor + battery ?

  • Hardware Contributor

    I can not measure that now (at work), but I guess around 35mm if batteries are mounted on he bottom. By using the extrnal (JST connector) power option, the height of PCB, processor and radio is around 22mm I think.

    Most boxes have an internal clearance of around 20-25mm.
    Some boxes have 40mm internal clearance and are good in height, but those are usually also to long and wide for my taste.

    @m26872 's board certainly is lower, since batteries are not on the bottom but in the axis of the board. The radio is also directed away from the processor on his board, so it can be mounted lower (directly on PCB instead of on a header). I really like that concept, since it will fit the plastic cableducts made by Legrand:

  • Hardware Contributor

    Just to confirm: 35mm is the height with the small radio.
    Using the larger radio (with PA+LNA) you need 41mm height
    Without battery holders, and the small radio, the height is 22 mm
    Width is 25mm for AAA battery holders mounted, 33mm for AA battery holder, and length is 53mm (AAA batteries) and 58mm (AA batteries)

  • Hardware Contributor

    v1.2 tested and working. But the design of crossing R1 and C2 was a horrible choice - it's impossible to fit both nicely under/inside the uC socket. Perhaps possible with a 1/8W R1, but otherwise R1, C2 or both must be placed on bottom side.

    Good news is that all versions and orders are OK apart from this little inconvenience.

    I'll try to make a better version ASAP.

  • Hero Member

    @m26872 I have assembled 6 boards now and am very happy with the design. I use strips as a socket for the Atmega. This leaves enough room for components under it. Also made one with SPI connector. Works perfect! Thank you for sharing the design and instructions.upload-422d1df5-f52b-46fd-b28c-67493daa9fdc upload-aea4bc1e-e16a-4881-a378-e609a6c2f0c8

  • Hardware Contributor

    @AWI Great idea with the strips! And thanks for verifying (v1.2?).

  • Hardware Contributor

    I've now ordered yet another prototype version (1.4):

    Eagle brd-file.

    Photo here.

  • Hardware Contributor

    I bought a few enclosures... "mini trunking" seems to be the correct term. This time it was ABS and a little more clear white colour and glossy finish. I think I spent around 2hrs cutting them nicely into >200pcs. 50% 23cm and 50% 19cm lengths.

  • You want to make your town mysensors 😂

  • Admin

    200pcs!! What the heck are you up to?

  • Hero Member

    @m26872 I think I used version 1.1? Did you change any of the wiring in the newer versions?

  • Hardware Contributor

    hehe, I had a hunch it'd be spectacular. Let's just say that I aim to have a few single sensor/purpose sleeping nodes, but probably not 200. At least not in a while.

  • Hardware Contributor

    @AWI Ops sorry, I meant v1.0. I see the larger pads in your pics. The routing is a little different to 1.2 and 1.4. Mostly related components under the uC.

  • Very nice design. Any video on installation of bootloader with various settings described in the original post?.

  • Hardware Contributor

    @ar91 Thx. Sorry no. I don't know of any and I'm too shy to do it myself.

  • Great idea using this housing.

    Why didn't you use CR batteries to decrease size ?

  • Mod

    2AA batteries have approximately 2000mAh capacity. CR1220 has 35mAh. So for the same capacity, more than 50 CR1220 would be needed. That wouldn't save space 🙂
    But CR1220 has lower self-discharge so they can be a good alternative for things that are really low-power, or don't need long battery life.

  • Hardware Contributor

    @ahmedadelhosni I've read a few reports from people with radio module issues after some time on CR "coin cell" batteries. The expected battery life time then doesn't match the result. I think you can find references by searching.

  • m26872, I just wanted to say thank you for your work on this project and for sharing it with everybody. 👍
    I've just ordered the ATMEGAs to build 5 nodes.
    How confident are you about the V1.4 PCB ? If you don't see any issue with them at this point I think I'll take the whopping $14 risk 😋

  • I understood the reason. Thanks

  • Hardware Contributor

    @martkrui I'm not confident until I've tested one, but usually errors can be fixed with some ugly mods if necessary. 😉

    BTW I added to the info that any/every DirtyPCB money from this share will be donated to

  • Like the board and ordered it. Can you also post exactly the capacitor types? Keep up the good work.

  • I also ordered the PCBs (at my own risk) and some of "TMK-T20 20mm 17mm"
    I'll try to CNC or 3Dprint some endcaps or something.

  • Hardware Contributor

    @betonishard There aren't any exact values or types, but good start would be

    Near the radio supply: One radial electrolytic >=4.7uF >=10V capacitor together with one ceramic (range 1pF - 1uF. I use different.).

    The rest (C1, C2, C3): 0.1uF ceramic, where the value probably matters most for C2 (the Reset capacitor)

  • @m26872
    Thanks... Maybe it is answered, but I didn't quite catch it. 3v will be fed to the radio, but isn't the 3.3 important instead of 3v? I don't see any stepup. Is your range acceptible?


  • Mod

    The radio can handle as low as 1.9V (source)

  • Hardware Contributor

    I have had a node sending messages as low as 1.65V 🙂

  • @mfalkvidd @GertSanders Thanks for your answers!! How about the range, I know it is depending on the quality of Chinese products, however can you give an estimate regarding your setups?

  • Mod

    Short answer: Expect about the same range as a regular wifi card.
    Long answer: Look at these informative and quite entertaining videos:
    Ultimate nRF24L01 range comparison
    nRF24L01 range test (arduino)
    nRF24L01 range test part 2 (arduino)

  • I was about to order the 1.4v of your board before that i wanted to ask you a basic question, do i need to use any step up regulator to connect any 5v sensors? Have you connected any 5v sensors, if yes could you please post some pictures?

    Thanks again for the great work.

  • Hardware Contributor

    You will indeed need to use a step-up regulator to use 5V sensors, as his board is 2AA battery based (gives maximum 3.2V on fresh batteries). For quite some sensors, you will find 3V3 versions, which can work at even lower voltages. look for sensors which work down to 1.8V-1.9V
    Using 5V sensors in a battery based node is not efficient.

  • @GertSanders Thank you so much. Is there a recommended list of low voltage sensors? The Mysensor store only has 5v sensors i believe. I will other search other forum post as well. If anyone know from top of their head please list it.

    Temperature sensor - ?
    Humidity sensor - ?
    Luminosity sensor - ?
    PIR - ?
    Infrared sensor -?
    Soil Moisture sesnor -?

  • I also was about to order the 1.4 board. But are there any list of components that I need to complete the board?

  • Hardware Contributor

    @Cliff-Karlsson Sorry for late reply. I've not yet a BOM. I'll try o fix it later.

  • Hardware Contributor


    • A "final" version 2.0 redesigned i KiCad (very similar layout), panelized, ordered and tested OK.
    • A faulty via was introduced during panelization of v1.2, so the panelized v1.2 (blue board) needs a small fix to work.

    More info ASAP.

    Edit 4/11: There seems to be no issues with v1.4 (red board) as I thought first. Luckily since it's now been shared a few times.

  • Hero Member

    @m26872 I received the boards yesterday. Can you direct me to the fix needed.?

  • Hardware Contributor

    @AWI It should be easy the see the via with a missing hole. A connecting wire between Arduino D13 and nRF SCK is needed.

  • Hero Member

    @m26872 Tnhx, however my samples seems to be correct...


  • Hardware Contributor

    @AWI Mine too. I didn't see the red v1.4 until I got it today. Looks promising, but I've not tested it yet. Interesting to see that they've done a different panelizing.

  • Hardware Contributor

    I've now tested v1.4 (red board) and it's working good in my MyS-net.

    I can see that it has been shared 12 times at DirtyPCB, but don't know how I can see any money as suggested? As soon as I see any they'll be sent to

    Edit: Seems that I had a missing confirmation of my Paypal account. I'll try to solve this...

  • Hardware Contributor

    I decided to start learning KiCad instead of Eagle and that a tidy redesign of the Slim Node board would be a good start. Now when the red v1.4 board turned out to be quite ok (apart from the references R1,R2, R3, etc, as you can see above), I guess one can choose v1.4 or v2.0 by colour or by documentation. The v1.4 wasn't very well documented since I never really learned Eagle very good. I think that's improved now with v2.0. I've tested all the regular attributes (AVR ISP pins excluded) and it's OK.
    This is my "final" version since I have a full stock of these boards for a while. If someone else want to pick up the design you're welcome.

    Here's all the KiCad files:
    Gerbers only in the panelized version folder.

    Here's a BOM (for v2.0): v2_BOM.txt

    Purchase link to boardhouse (DirtyPCB). $1/order goes to like before.

    This time it's black:


  • Hardware Contributor

    @m26872 Maybe you can add your info to this message (it's pinned):

  • @m26872 There is something that I really can't understand.

    Are the pin headers at the borders not connected to the IC pins ?


  • Hardware Contributor

    @ahmedadelhosni That's an important feature of this board design and one of the major diffenreces from e.g. Arduino Pro Mini. The rows of unconnected pins is like a prototyping area to mount sensors and/or other supporting components. It's easy to just fold the legs at bottom side and solder to the IC pins you want to connect to. I think you can see an example in the photos of a completed node in the first post above.

    I've sized the pads so pin headers can be used there instead if desired, but then you have to connect every pin manually so that's not the primary purpose. The "Slim Node" was not just board project, but I've understood that many people enjoyed the board as a generic one, which is great.

  • @m26872 great idea indeed. You convinced me 🙂

    Did you think of monitoring the voltage as this type of nodes needs this or did you leave it also as an option for us ?

  • Hero Member

    @ahmedadelhosni you don't need additional hardware to monitor the voltage. Look for the "vcc" library. It uses the internal reference.

  • Hardware Contributor

  • @m26872

    I received my panelized boards as well (guess 1.4). They look great!!.

    I do have a question about this. Maybe it was just some silly thinking. I was trying to program the arduino 328p-pu on a regular arduino uno board (default motion sketch). After I did this I hooked it up on to the board.

    However I am not receiving anything on the arduino serial monitor. I connected the arduino uno to your board. v to v, rx to rx, tx to tx, ground to ground and reset to reset. Am I just thinking to simple? Can someone please advise me to get this board up and running? I also soldered d13 additional to the nrf.

    I soldered all caps, however I did not solder the resistor, is that one mandatory?

    Many thanks and keep up the good work.

  • @m26872 @AWI yeah you are right. Thanks a lot.
    I really consider buying the latest version. I think it is verified now to be working correctly.

  • Hardware Contributor

    If you've got red boards it's v1.4 and should not need the D13 fix. And R1 and C2 are mandatory if you want the 6 pin serial Arduino interface to work.

    Did you read about the necessary bootloader and fuse settings in the first post? An Atmega328p setup as standard Arduino wont work, because of Internal clock, BOD, etc. Perhaps Arduino Uno as a bootloader is good for you.

    If you haven't any experience in bootloader and fuse settings, you should know that it can be a mess. A lot of things can go wrong. Nobody can walk you through it here. Look among all the existing toturials on the internet to find what is working for you and of course ask if you have any more specific questions.

  • I know I have many questions 🙂 but how about inverting the nrf position by 180 degree so that it can be on top of the atmega and decrease that length. Would it fit in your design ?
    Can you do such board for those who are interested like me 🙂 ?

  • Hardware Contributor

    I think it's a good idea! And an easy mod, but it's not on priority list atm. Someone else would get a quick start from my already published kicad-files.

    The thought behind present design is that I didn't want anything to cover the antenna in any direction, but I doubt it would matter much in this suggested case. It'll be worse when it comes to the hight. Look at the photos. The nRF becomes too high for my enclosures if I use a socket, and the 328p with its socket is too high to fit under a nRF without its socket. The solution would be to remove the 328p socket and move the R and Cs to bottom side or somewhere else. And without a 328p socket, the 3x2 AVR ISP pins would become more important to keep. Otherwise the board could have been trimmed even more.

  • @m26872 I guess the nrf above the atmega won't cause problems or interference to the atmega due to rf signals. so that's fine.

    I measured the nrf and it will be 13 mm, so I thought it may fit as from the photos, I guess the max height can be 13 or 14. For me increasing the height is not a problem as I am still searching for cheap compact and not so long enclosure with maximum heigh 20 mm to use. I am searching for cheap products which are kept in that size of enclosure which I need but didn't find it yet 🙂

    I didn't use Kicad before and I guess there is no converters to eagle. Youtube time 🙂

    Can you please tell me the total length of the board + nrf ?

  • Hardware Contributor

    It's 74mm with the angled Arduino pins and 69mm without.

  • @m26872 Thanks.

    Hopefully this is my last question 🙂

    Is V1.4 and 2.0 the same ? One is red in Eagle and the other in black in Kicad ?

    If yes, could you please guide me to the eagle's project files ? Thanks.

  • Hardware Contributor

    Yes, v1.4 is Eagle. I'll upload it later today. But it's just a brd-file. And I think I had some broken sch-brd connections even in v1.2. One reason for the KiCad design was to improve this.

  • @m26872 hmm I see. So i will begin learning Kicad today. Thanks for your effort and support

  • Hardware Contributor

    I uploaded the brd in the v1.4 post above just for completness.
    Happy Kicading! Hope you'll enjoy. I liked it a lot better. There were a few nice youtube tutorials.
    You're welcome.

  • Hardware Contributor

    First Slim Node board donation from the DirtyPCB board share now sent. $12 to Thanks to everyone that have ordered.

    Later credit draw will be in probably linger a bit. DirtyPCB seems to be somewhat of a non-profit community with manual attendance to all share credits. I almost got banned in my attempts to get a reply from them. In order to show my appreciation for their great service, I plan to only request further credits in quantities of 50. If the board not's been shared in a year a so, of course I'll make an exception.

  • Admin

    Thanks for the kind donation to the MySensors project. We'll use it to develop new fun things for the community!

  • Hero Member

    I was out of radio's, only a few "smd" types left which I mounted on the board with some patchwork 😉


    Now even more space left in the (small) housing.



  • Could u show a screen for the lockbits too? I have never set them before and need some guidance 😄 thanks


  • Hardware Contributor

    @dakky Done.

  • Is this what you used to burn the bootloader?


  • Hardware Contributor

    I use this. Maybe not so expensive when I bought it 15 months ago, but still. I remember I was mad after I'd failed a lot with avrdude and cheaper tools (uno).

  • Just received my boards from DirtyPCB 😄
    Enough for 10x3=30 sensors... 😱 The boards look nice. I think I can even skip the R&C's if I use the internal VCC measuring method but I'll have to scan the thread for that.

  • Hardware Contributor

    @martkrui R1 and C2 are mandatory if you intend to use the 6 pin FTDI port (I think you do). C3 (ARef - Gnd) is primarily for when you use Adc external ref, but (if I remember correct) it stabilizes the Adc in general. C1 (Vcc - Gnd) is just the "near chip supply input capacitor" and could probably be left out if there are some other caps near the nRF.

  • @dakky said:

    Could u show a screen for the lockbits too? I have never set them before and need some guidance 😄 thanks


    I use ubuntu, and a tiny USB, so after I have flashed my arduino board, I run this avrdude command, that will run until battery is low

    avrdude -c usbtiny -p m328p -U efuse:w:0x07:m

    I have bought usbtiny from this guy:

  • @m26872 Hi again. Just a small update regarding rotating the nrf.

    I decided that in my designs I'll need the straight and rotated version, thus I'll design a small board to map the pin outputs like the image below. It will be above the ICSP pins but I really don't care about re flashing.

    I'll order the board as soon as I finish pcb layout of some other boards and ship all at once.



  • Hardware Contributor

    @ahmedadelhosni You know that the nRF pins are not centered? That means if you rotate it like this it will no longer be straight above the "slim node motherboard".
    What height do you expect it to be?

  • Another "noobish" question:
    When using this bootloader, one cycle takes 8 seconds? What happens, if for example, a switch is pressed between? does this sensor detect this?

  • Hardware Contributor

    @dakky Plz correct me... but I guess you're talking about the Avr sleep cycles? I don't know what that's got to do with the bootloader or this thread. I think it's related to interrupt, timers, mysensors and arduino lowpower library. The sleep cycles shouldn't be something to worry about if you're using the "sleep" function as in MySensors API.

  • @m26872 hmm you're right. maybe this is a too generic question to be discussed here. pardon me.

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