Best posts made by mtiutiu

After a really long time I received the boards. I finished the assembly for one and uploaded some code to it. So far it seems to work but I need to perform some more tests. I attached some pictures of the finished product. .

The silkscreen text is a little bit blurry and it was a little bit too small for the fab to print it so in some places is not right...anyways this is not important but the functionality is.
One note: the board round edges may be a little bit off the limits but that can be corrected by using some abrasive paper to remove the excess material(which I did in the above pictures and then the board fitted perfectly).

@Nca78

Elecrow is a good fab imho and yes they are very generous - I received too my boards today and instead of 5pcs I received 11pcs !!!. And this is not the first time they deliver more than requested. The price - 5$ for boards and 3.5$ shipping(standard mail) - 8.5$ in total. And yes they are the cheapest and pretty good quality pcbs - I'm very pleased about their services so far. They beat all the Chinese fabs including shipping so far(and the quality is pretty good - at least for what I need my pcbs for it's well beyond my expectations).

@NeverDie

Thanks. Well because it was cheaper/smaller than all of the Aliexpress modules found so far and it's shielded also(talking about the PTR5518 module here). So I found it to be perfect for this solution when this project was created(almost 2 months ago). Other than that nrf51 even if it's older or not so powerful than its nrf52 counterpart I found it to be more "mature" when it comes to the software part - just like atmega328p is for the Arduino world. If I remember well it was among the first one supported in sandeepmistry's nrf5 core: https://github.com/sandeepmistry/arduino-nRF5 or any other Arduino core for the nrf5xx modules so I assume its software support should be more richer than nrf52xxx.

@toyman

You can find it in my kicad repo: symbol and footprint

I didn't used it in any design so please double check.

@NeverDie

For me, elecrow is the best. But you can query this online tool which is very good: https://pcbshopper.com

OK...another remake for the classic Livolo 2 channels 1 Way EU switch and THE LAST ONE that I will make(well except for the 1 channel one which I need to work on it after this one) - @shabba I know that you waited for this. This is just the other Livolo hardware project of mine "ported" for the new hw revision that the Chinese manufacturer made. They made the 12V line available on the connector and moved it on the opposite side(the new connector is a 2mm pitch one and SMD - I choose to use the THT variant as it doesn't have any impact from a mechanical point of view and it's easier to solder for all of us the mortals around here).

The good news is that the power board is the same as the old one with some minor modifications(more or less):

1. the big MOSFET is in the same place but with a 45 degrees orientation
2. the power connector is a 2x7 pins one with the 12V line already supplied on one of the pins - less hacks for the board
3. the bistable relays are the same and drived by a ULN2003 IC(current buffer) in a TSSOP package

Thanks to @tonnerre33 for creating the new board outline which I borrowed from his project. The rest of the board is the same as the other one that I made with the dc-dc converter moved on the opposite side and with some rearrangements. Next I need to create the boards AGAIN using some external manufacturer(China of course) and then wait...and patience and... patience again and...wait.

And as always big thanks to the Mysensors community for their great effort and for maintaining this great project.

Oh...and for some reason the boards are not rendered correctly in the browser - I'm referring to the openhardware.io gerber viewer(both 2D and the 3D one) - maybe it has to do with the latest changes from KiCAD regarding the way the gerber are generated or maybe some bug in there? (I'm using the latest nightly version). The Linux gerbview utility displays them correctly.

@d00616

Hi,

This is a such great addition for this project. For long time I wanted something like this: a RF SOC with pretty good and usable software support and low power also(and a Cortex arch - pff..that's too much :simple_smile: ). I just wanted to congratulate you for your work and bringing this in to MySensors project - it's very neat and useful.

I tested it and it works just great so far. I would give you 100 likes on openhardware.io if it would be possible :simple_smile: . Thanks once again for your effort.

@NeverDie

For the swd connector - some simple wires soldered temporarily :simple_smile: and removed afterwards. The project doesn't support OTA - but can be added if desired as a DFU upload service - needs some extra work and research. But once the switches are flashed there's no need to reflash them as all the MySensors stuff is on the linux board node which can be reconfigured very easily through that web interface(the services behind it will restart automatically when the configuration file changes and the new settings are applied automatically also). I will prepare the required documentation about the whole system on my blog and there's a lot to write :simple_smile: .

Ok, so after posting some questions to CDSENET Aliexpress store(in regards to the E73-2G4M04S module):

1. Is the nrf52832 IC DEC1 pin decoupled with a 100nF capacitor as per Nordic datasheet recommendations?
2. Is the nrf52832 IC  DEC2 pin decoupled with a 100pF capacitor as per Nordic datasheet recommendations?
3. Are all the power pins of the nrf52832 IC decoupled as per  Nordic datasheet recommendations?
4. Are the external components already provided so that the internal DC-DC converter can be used?

I received this part of schematic:

The module that I bought is this one: CDSENET E73-2G4M04S

I hope that it helps demystify some things in regards to this module. Maybe @NeverDie can confirm this by checking his module connections as seen in the above schematic. I'm saying this because Chinese support is well..not so user friendly in my experience and I don't know if the above schematic is indeed what they used on their module or they just provided me an example schematic of how to use the NRF52832 IC in general instead.

@MiKa

I bought this switch(non-radio variant): https://www.aliexpress.com/item/Free-Shipping-White-Crystal-Glass-Switch-Panel-EU-Standard-VL-C702-11-Livolo-AC-110-250V/512770913.html?spm=2114.01010208.3.11.JqUULi&ws_ab_test=searchweb0_0,searchweb201602_4_10065_10068_10000009_10084_10083_10080_10082_10081_10060_10062_10056_10055_10037_10054_10033_10059_10032_10099_10078_10079_10077_10000012_10103_10073_10102_10000015_10096_10052_10053_10107_10050_10106_10051-10050,searchweb201603_9,afswitch_5,single_sort_0_total_tranpro_desc&btsid=518f103c-2c52-4311-9b72-2375b87824c5

The power/relays board looks like this:

@monte

Are you suggesting to implement something like esphome has? If that's the case then I would prefer yaml instead of json as it's easier to read and maintain imho.
The idea to have code generated from a configuration file is pretty neat and it simplifies tedious and repeating tasks a lot besides abstraction.
NodeManager should help as it seems to be pretty modular.

Ok some updates to follow:
performed first tests on the switch power supply/relays board and the results are very promising so far as you can see here

1. switch is OFF: the so called 12V line gives us 12.63V
   

2.switch is ON: the so called 12V line gives us 14.3V

1. switch power supply/relays board ONLY(without the front plate): 12.8V
   

2. a closer look at the switch power supply/relays board and wiring for the unregulated 12V input
   

3. switch power supply/relays board with attached dc-dc step down converter for ~3.3V output
   

The above scenarios were tested with and without the front plate and I achieved the same and constant results on the dc-dc step down converter output: a steady 3.25V(as I managed to get by adjusting the on board trimmer). The DC-DC step down regulator is a cheap one bought from aliexpress which does the job pretty well.

Next I will add the arduino board that I prepared for testing(with code). Basically I created a setup based on:

1. Arduino pro mini @ 8MHz/3.3V
2. TTP223 touch sensor based modules
3. RFM69W radio on an nrf24l01 adapter pcb board
4. Breadboard and wires of course :simple_smile:

After attaching the above setup to the real livolo switch I will come back with the next set of results. Stay tuned.

@jirm

You're a genius!!! I forgot about the parallel capacitor which has to be put on the load(light bulb). I picked a 470nF and a 20W fluorescent light bulb and it works like a charm now and with RFM69W too!!!. Thanks so much for reminding me about the capacitors. Now I can continue and finish this project. Will come back later when my PCB's arrive and assemble the final product. Stay tuned.
Big congrats to @jirm, @DJONvl and @Tigroenot and the rest of the community of course which contributed with the knowledge to make this possible. This is really a big step ahead.

Hi all,

So after some time of testing I give you the final revision of this board which is 0.5. The latest files are available on the openhardware.io page but always the most recent are on my github repo of course(I'll try to keep both in sync anyways). By using good tantalum caps where required I got a good stability for the node. It will be kept for testing for one month still starting from this week(testing already started). So far I'm very satisfied with the results.

As a final note for all of you there: when designing hardware always use good components - especially good filtering capacitors because most of the issues and instability happens because of that.

I will try to design the pcb for the one channel variant of the switch too when I'll get my hands on it so stay tuned. I see that some people asked why RFM69 instead of NRF24L01: this is because the RFM69 module is superior in terms of performance/stability/range compared to the latter(trust me it worth the money difference as I tested both along time). And because it works in the sub-GHz band it's also less prone to interference compared to the 2.4GHz band which is used by all Wi-Fi equipment.

@NeverDie

I did it like this guy here: qfn soldering and it worked like a charm. Just be careful not to put too much solder on the pads. But if you use stencils and solder paste it should be much more easier.

I don't have a oven and I don't use stencils.

Received my boards and started to perform some testing. It worked OK when powering front plates loaded with Bluetooth LE software which are drawing only ~500uA. But as soon as I tried to power a Bluetooth mesh node which draws constantly around 5-6mA then the stand-by supply (the one built around LNK364 IC) didn't acted fast enough when performing the switching causing the BLE mesh node to reset. In other words the power supply startup time was pretty slow for this kind of circuit.

After some serious investigations and headaches (around 3-4 days or so) I finally found why. It has to do with the AC-DC converter "capacitive loading". Initially I though that it was because of the output filtering capacitors and which are also used to store energy between cycling the bi stable relay on and off. As you all know capacitors are good for filtering the ripple and storing electric energy...BUT and very important for this project over here - if they're too big they make the power supply to react a little bit slow.

Why? The reason is very simple: if you use too large capacitors then it takes longer to charge (not to mention about high inrush currents) and because of that they slow down things affecting the AC-DC converter feedback loop.

Well, in a normal use of the power supply and when not cycling between on and off power states too fast this won't be noticed and doesn't matter too much. In my case it matters and guess what? - not the output capacitors were the culprit after tinkering a little bit with their values.

The input filtering capacitor was causing issues. Yes, I'm talking about the input filtering stage after the bridge rectifier. But in this case I started to "attack" the AC/DC power supply in a different way and that is: what happens at the input stage when the supply is switched on and off ?

Let's not forget that in this project the stand-by AC/DC converter is in series with the load (light bulb) and it "breathes" and draws power from the mains voltage and the leakage current from the light bulb which can be very small especially when using LED bulbs.

So what happens actually? As you all know the AC/DC converter won't work if the input AC voltage is less than 85V or so as most are rated to work between 85-265Vac right? But what this means after the rectifier/filtering stage where we have a continuous voltage (let's forget about ripple right now)?
Taking the minimum ac voltage value of 85V this translates to: 85 x 1.41 =~120Vdc. So untill the input filtering capacitor won't reach that dc voltage value the LNK364 chip won't work and here I'm referring to it's internal voltage regulator that powers the internal circuitry or it's "start up" circuit. (in reality it may be less than 120Vdc, but still...)

But then you may think: yes, yes but the input filtering capacitor is only 4.7uF - won't it charge fast enough? Well no, and not quite - let's not forget that it's an electrolytic capacitor with higher ESR and not only that - what matters here the most is the fact that the leakage current from the light bulb dictates it's charging rate an that current can be very small !!!

And now you have it - the input capacitor in this case slows down things and affects the power supply start up time. And it doesn't matter that much if you increase the output capacitors and it becomes even worse because then we end up affecting the feedback loop from the converter.

So what I did was to remove completely the input filtering capacitor and now it's damn fast - yes the power supply still works as expected but it's much faster between on and off cycles. And if you look at the original Livolo switch it doesn't have it either but now I understand why.

We have enough filtering at the output stage so it won't affect our powered circuits. It's a little bit noisy at the input but not that much I would say because we have a bridge rectifier. And the load doesn't draw too much current so it should keep up without the input capacitor which also stores energy for the primary inductor. The LNK364 internal MOSFET shouldn't be affected as it's rated to support the peak input values and even more (700Vdc) as the input capacitor was averaging a little bit the rectified voltage waveform (but not that much anyways because it's small value). I will try with a 1uF/2.2uF and see if that slow things again.

So yes..I was almost ready to give up on this project. Now I'm more happy than ever and also because I learned new stuff. And designing/playing with offline AC/DC converters is kinda new for me. There are still many things to learn of course.

I also need to thank @axillent for its "AC-DC at own" post from where I got inspired a little bit.

As promised the final design! This is for one channel which I will use mostly in my house. The backside is 3d printed and it holds the electronics. The front panel and fake button are bought from the local store (Leroy Merlin) and I like it very much (it's part of modular switches design and it's very cheap). I could 3d print the front side plastics..but it I can't get the same look and feel - can't beat the molded plastic with a 3d printer for now ... (well you could use some resin or other stuff to fill the holes and then spray paint but still it's a lot of work and it doesn't worth imho)

Here are some pictures from the design. I will post later the pictures with the real product also.

@scalz
Thanks.

To answer your questions:

• Range is not that "big" if having multiple walls - if more than 1-2 walls things start to degrade but having more nodes in the mesh helps to overcome this. Also one can tune the number of retransmits as shown on my blog and having more relaying nodes will help a lot also. Of course my custom RF design is not perfect or that optimized. Add to that the ceramic antenna which is not that great...
• Power consumption is a plus also indeed as per node I get around 7mA x 3.3V ~ 24mW. Let's add to this the leds and touch capacitive sensor and make it 30mW on average but no more than that. I enabled the internal DC-DC converter of the MCU and add to that the fact that the nodes will stay more in RX mode hence the 6-7mA constant current draw.
• The boards are a little bit different but not much from a RF performance point of view (I'm still learning this part when it comes to PCB layout)
• The hatched ground plane differs around the capacitive pad(s) but that's because the PCB was designed initially using EasyEDA which offers "90 degree" hatches. Then I ported the PCB to KiCAD where I had to do a little trick with some polygons at 45 degree as it doesn't support hatched ground planes (not now at least or in the stable version).

I tested already both designs - the original one and the KiCAD conversion also and both are working as expected.

Yes it was lots of work and especially the power supply PCB design for which the main inspiration was the DER-622 application note from Power Integrations.

But I'm very happy with the overall result. I will update the blog with some real life videos of the whole system in action in the near future also. There will be more blog entries targeting this topic - that's for sure.

Hello,

Did someone saw or know more about these radios: http://www.semtech.com/wireless-rf/rf-transceivers/sx1212/ ? They seem really low power - I never seen such a low RX current(3mA) in active mode(no sleeping) so far on any radio module in the MySensors history :simple_smile: . The radio modules used in this project take around 16mA in RX mode which is pretty much compared to the MCU current consumption(Atmega in most cases - around few milliamps or so).

When used in battery powered nodes this doesn't matter much I know but when used in circuits which should stay active and power requirements must be at a minimum then it matters: for example for the Livolo switch which uses a series power supply that cannot provide more than 5-10mA. This is just a simple thought.

The Semtech site even provides some libraries(written in C of course) as a starting point and some frequency hopping solution for use in a star network configuration based on these modules.

@Nca78

Hi, I'm working on this one too. This Livolo stuff captured my attention a long time ago as I needed an in wall solution for controlling the lights(without using batteries and such). I wanted this to be integrated with the existing infrastructure also(the existing house electrical wiring for lights). I studied the power supply part before the Livolo switches era as I wanted to make one of my own but in the end it seemed not so an easy task because of the series circuit( to take power from the live wire only). Anyways if the power board from the existing Livolo switches will be capable of delivering the required power it will be really awesome(as the non radio switch is really cheap
).
In my case I'm using the rfm69 module(the CW variant as it's more compact) which requires a little bit more current(45 mA or so). I don't want to use the existing 3V line which the Livolo power board has because as I've seen from this thread pictures and schematics it uses a low current voltage regulator(30mA max or so from my investigations). This is fine for the nrf24l01 low power variant but for RFM69 it isn't. So currently I'm working on identifying the 12V line as my design uses a buck converter to get it as low as 3.0-3.3V.

The project and progress is posted here: https://www.openhardware.io/view/306/Livolo-EU-switch-Mysensors-integration. Depending on my free time I will continue to work on it but I don't know when it will be finished.

Keep up the good work and congrats to the Mysensors creators for this wonderful project.

@MiKa

Done. I added AT25DF512C-SSHN-B SPI Flash for OTA too.

AllPCB it's great with DHL shipping. At least for now. It's true that the boards final price includes shipping too but it's still cheaper via DHL. Even if I have to pay VAT it's ok (19%). For the very short time to my door which is 3-4 days that's just WOW compared with 3-4 weeks via regular shipping.

@gohan I tried smart-prototyping in the past and they are pretty ok I can say but not the best compared to PCBWay for example. For cheap services and pretty decent quality I will still opt for Elecrow for example. And for pretty decent quality and very fast shipping - AllPCB - at least for now and if their prices won't go higher in the future.

Oh and AllPCB finishes the boards in 2 days for that price. Compared to EU factories it's still the cheapest - you can't beat China when it comes to that. Here in EU for the same price that AllPCB does I get ONLY 3 boards...wtf..so yeah you get the idea.

@Mike_Lemo

I used the Arduino IDE with sandeepmistry arduino core installed and I managed to program a nrf51822 module with success. I used a cheap st-link programmer from AliExpress. I don't know about nrf52832 as I don't have one. But I don't see why it wouldn't work. You need 4 wires: Vdd(3.3V), GND, SWD and SWCLK.
From Arduino IDE you need to select st-link as programmer.
It uses openocd under the hood to do the work and it worked both on Windows and Linux. On Linux you might need to set udev rules for allowing regular user to use the st-link.

I won't rely on the integrated voltage regulator because usually it's not capable to supply high currents. As I've seen on other USB to serial converter chips the current capability of the integrated voltage regulator is about 50mA or so(maybe some can provide up to 100mA). Anyway if using NRF24l01 radios and small current LEDs then maybe it won't be an issue but I wouldn't count on it on the long term. Radio module + microcontroller + LEDs + other components can reach the 50mA limit especially when using RFM69W or HW variant. Now I know that the TX period may be short and only the average drawn current matters in the end but still I won't take it to the near limits. Just my 2 cents here.

@javizzz

The Livolo power supply is a sensitive topic and it's special by its nature. Being a live wire only design it requires some special design and it cannot deliver high currents - at least not in standby mode when the light is off.

I've struggled with it along with @tonnerre33 and still working on a solution but not without some hacks unfortunately.

But getting back to this topic issue(s): aren't there some low current optocouplers available? The part that draws more current is the LED from it as far as I know. And for strong coupling/better transfer ratio the LED might require more current.

I found this one for example: ACPL-M61L from Avago. They claim that it works at 1mA and even less.

@NeverDie

About 6 hours. I asked them too if the Nordic datasheet recommendations were followed or not and if they can provide an example of how to use the module.

@AWI

I'm rolling my own(with CP2102 usb-serial converter) https://www.openhardware.io/view/316/MySensors-RFM69W-serial-GWATMEGA328P. Oh and I changed several serial GW's all based on Atmega328p of course but with different usb to serial converters like: CH340G, atmega16u2 from Arduino UNO board and I think I used arduino nano at some point in time with FTDI 232 chip.

Results are the same. Not to mention that after 20-25 days the usb to serial connection stops working so bye-bye serial gw and no output from it. That's why I changed and tested so many usb to serial converters and different boards. But that's another issue and story not related to this tread which I'm still investigating.

Good reading for dc-dc converters when designing for low power: http://www.digikey.com/en/articles/techzone/2014/mar/the-advantages-of-pulse-frequency-modulation-for-dc-dc-switching-voltage-converters

L6920 can operate in both modes(PWM/PFM) and it will switch to PFM on light loads. The quiescent current is around 10uA in general for this device as the manufacturer promises. But and there's a big BUT: in reality a dc-dc converter will always have a drawback on battery life to some degree as stated by the other users that replied in this thread so it would be ideal to accomplish things without it. I wanted to test it in real life anyway and that's why I used in my designs. For the CR123 based board it can be bypassed using the provided smd jumpers. On the other design(CR2032) which is more critical I will provide that too in the next hw revision.

For measuring small currents I'm using Texas Instruments EnergyTrace piece of technology and it works pretty well. You just need one of their development boards with energytrace special microcontroller embedded which is very cheap. More infos here: http://43oh.com/2015/09/how-to-measure-an-energia-applications-power-usage-with-energytrace/

It can be used to measure other boards power usage also - you just need to take of some jumpers and plug in your external board.

It gives you real time energy measurements and with plotting too(and battery life estimation is displayed real time too). No need to worry about burden voltage and other external factors which affect the measurements.

@scalz

Thanks. Well yes...I simplified things a little bit. Your board is better designed than mine ofc regarding the antenna and other protections. But most of the time I found that those are not really necessary at least for me and in my current setup. So yes... I need to start thinking for all the worst cases and environment issues that may arise when designing hw which is not so easy btw imho. In the end is fun to experiment and learn more stuff about electronics because this is the main reason I'm doing this btw.

@mr_red

The rfm69w module was made by me in FreeCAD. Some of the 3d models are made by me when I don't find one online. You can find lots of 3d models(step files) here: www.3dcontentcentral.com and www.tracepartsonline.net. Then you need to use FreeCAD to import the kicad footprint and the downloaded 3d step model to align it with the footprint. I use the kicad stepup tools FreeCAD macro for this: https://sourceforge.net/projects/kicadstepup/. Then you can export the scaled wrl file using the macro dialog. It requires some work to get all things done but it works just fine(patience is your friend here or should be).

The big advantage of using the kicad stepup tools FreeCAD macro is that you can have both the step and wrl files in place for exporting the board afterwards for mechanical CAD integration. Because in the end you'll want maybe to do some 3d printed enclosure for the project. For now kicad stepup tools is the best friend in doing electronics to mechanical CAD exports in order to design the plastic enclosure(a big congrats to the authors for making that possible).

@NeverDie

I think they use Altium Designer and that those are files generated with it.

I still don't understand why people are still bothering to use NRF24l01...it's old tech nowadays . Well I get that it's cheaper and bla, bla but when it comes to performance and tuning things up it gets harder imho. Not to forget that you still need another MCU in order to make it work thus increasing BOM and complexity (yes, yes I know why some prefer "decoupled" systems, but still...)

Why not use NRF52832 which is a much more compact solution and let's face it more efficient than the old NRF24L01. Oh and let's not forget that it has a MCU inside also.

I think the list of advantages is obvious:

• More TX power: 4dbm compared to 0dbm.
• Incorporated MCU
• Incorporated DC-DC converter which when enabled will reduce the current consumption in both TX and RX mode (7.5mA in TX mode and 5.4mA in RX mode - this is only for the radio subsystem)

Simplified design when using an already available module like the CDEBYTE or CDSNET from Aliexpress (just search for nrf52832 cdebyte or cdsnet) is also a plus. Those modules are really cheap now - around 3$. Oh and it needs to have those external components (inductors, caps) to be able to use the internal DC-DC converter - the CDEBYTE or CDSNET modules have it.

Now back to this topic main discussion regarding battery powered nodes which need to be pretty responsive no? Well it's not that easy using MySensors to accomplish this - I may be wrong but I tried this for one of my projects and no matter what techniques I used I couldn't achieve the desired results.
Why? Because MySensors it's not designed to create responsive battery powered nodes - please do correct me here @mfalkvidd if I'm wrong. By responsive I mean to make it respond in a time window of <= 1s.

@iancu If designing pretty responsive and battery powered nodes then Bluetooth LE is your best bet. I know that it's not MySensors but only BLE can achieve that as far as I know (NRF52832 supports BLE also which is yet another advantage).

I know that this deviates from MySensors and it's not that have something with this project - it's a really great project but we have to know its limitations (as of now at least).

Another alternative would be LORA modules which this project supports also and which have lower RX current because this is the state you would want to stay in most of the time (NRF52832 has it pretty low with the internal DC-DC enabled). But I'm not familiar with LORA modules and from what I've read the TX time cand get very high depending on the modulation speed which is not ideal also.

So what do we need in the end for MySensors: radio modules with very low RX current and fast TX time. Do they exist? I'm not quite sure to be honest (excluding lots of marketing stuff). Faster TX time means also a faster modulation speed/scheme which is achievable even by NRF24l01 so I don't think this is an issue nowadays.
When it comes to MySensors I think a good start is the NRF52832 based modules at least but it won't guarantee the responsiveness that you're looking for @iancu - for that you need a better software stack and radio protocols also imho.

@Nca78

Indeed it seems that it's not just a simple capacitor inside it. Well the whole purpose of it and also when using a capacitor in parallel with the light bulb is to have more current to pass through the series circuit so that the livolo power supply can provide much more power in the standby mode(when the light is OFF).

Take for example the simple capacitor: we know that when used in AC circuits it has a reactance which is kind of a resistance with a value that depends on the capacity and AC frequency. So if it's mounted in parallel with the load it reduces the overall resistance that the light bulb may impose in the circuit. We know that in a parallel circuit the lowest resistance element wins right? This way if we choose a proper value capacitor we can reduce the overall resistance in the circuit so more current can flow - this is needed in the OFF state as the standby circuit is weaker in this case. In the ON state the load is powered and much more current flows in the series circuit so no problems here. The only drawback in the ON state is to not use a too big capacitor so that it draws more current than necessary (it's in parallel with the load remember?) - in this case the light bulb could not work properly as it's bypassed by the capacitor so to speak. I used a 470nF capacitor with enough voltage rating and it works just fine...I will test with a 100nF capacitor too.

@iancu
Usually it's best to have an uninterruptible power supply when it comes to building actuators because you want it to "act" all the time. Using batteries for such a thing I wouldn't say it's a reliable choice on the long term.
Imagine what would happen if you do this for a light switch and you come home one day and you find yourself in a situation where you cannot turn on the lights...Of course this very much depends on the final application but still in my opinion actuators should be always powered.

@alexsh1

Hi,

I sent the design files for manufacturing last week so it will take about 2-3 weeks to arrive to my door. I know this may be a long time but unfortunately this is out of my control.

Hi,

Today I managed to finish this project: hardware assembly and initial serial gw sketch upload and I get I_GATEWAY_READY from serial console so everything seems to be in order. I need to perform some more tests though with some nodes attached and see the messages coming in and out but so far it seems very promising. I didnt' soldered the LEDs yet but that's not so important for now :simple_smile: .

CP2102 usb to serial converter chip working(first line from usb devices listing):

mtiutiu@mtiutiu-H67MA-USB3-B3 ~/Work/AVR_Playground/sensors_network/project/SerialGateway $ lsusb 
Bus 002 Device 015: ID 10c4:ea60 Cygnal Integrated Products, Inc. CP210x UART Bridge / myAVR mySmartUSB light
Bus 002 Device 002: ID 8087:0024 Intel Corp. Integrated Rate Matching Hub
Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 004 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 001 Device 005: ID 045e:0779 Microsoft Corp. LifeCam HD-3000
Bus 001 Device 004: ID 1bcf:0005 Sunplus Innovation Technology Inc. Optical Mouse
Bus 001 Device 003: ID 046d:c31c Logitech, Inc. Keyboard K120
Bus 001 Device 002: ID 8087:0024 Intel Corp. Integrated Rate Matching Hub
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

Code uploading using arduino serial bootloader POC:

mtiutiu@mtiutiu-H67MA-USB3-B3 ~/Work/AVR_Playground/sensors_network/project/SerialGateway $ platformio run --target upload
[Tue Feb 14 17:48:38 2017] Processing pro16MHzatmega328 (upload_protocol: arduino, build_flags: -I./lib/MySensors, lib_ignore: MySensors, board_f_cpu: 16000000UL, platform: atmelavr, board: pro16MHzatmega328, framework: arduino)
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Verbose mode can be enabled via `-v, --verbose` option
Collected 69 compatible libraries
Looking for dependencies...
Library Dependency Graph
|-- <SPI> v1.0
Looking for upload port...
Auto-detected: /dev/ttyUSB0
Uploading .pioenvs/pro16MHzatmega328/firmware.hex

avrdude: AVR device initialized and ready to accept instructions

Reading | ################################################## | 100% 0.00s

avrdude: Device signature = 0x1e950f (probably m328p)
avrdude: reading input file ".pioenvs/pro16MHzatmega328/firmware.hex"
avrdude: writing flash (13122 bytes):

Writing | ################################################## | 100% 3.96s

avrdude: 13122 bytes of flash written
avrdude: verifying flash memory against .pioenvs/pro16MHzatmega328/firmware.hex:
avrdude: load data flash data from input file .pioenvs/pro16MHzatmega328/firmware.hex:
avrdude: input file .pioenvs/pro16MHzatmega328/firmware.hex contains 13122 bytes
avrdude: reading on-chip flash data:

Reading | ################################################## | 100% 3.00s

avrdude: verifying ...
avrdude: 13122 bytes of flash verified

avrdude: safemode: Fuses OK (E:00, H:00, L:00)

avrdude done.  Thank you

MySController serial gw connection and startup ok message:

@tonnerre33

This one is: https://m.aliexpress.com/item/512770913.html

Please note that the board that I made is for the 2 channels model(VL-C702 series). Now I hope that they didn't changed the inside pcb hw revision meanwhile. The serial number that you mentioned and which I wrote about on openhardware project page is actually their pcb revision from inside the switch. I don't know for sure if that reflects the switch model which they advertise on AliExpress. But the link that I gave you is for the same switch which I bought some time ago because I took it from my orders list from my AliExpress account.

I see now that the price is bigger... it was 13$ when I bought it.

@tonnerre33

No, I didn't tested a 2 way switch so I don't know how it behaves in that case. I don't have and I don't use switches with that setup.

Hi,

I finally received the boards from the manufacturer(big thanks to @Seeed-Fusion). I manage to assemble one board by soldering the components and such and...it WORKS(including OTA)! I will post the instructions on openhardware.io project page.

Well..I was expecting this to happen at some point in time. This is the nasty thing that may happen when you rely on some external board(s) to do your work. It is a good thing that the 12V line is now exposed..but the pcb needs to be recreated.
And who knows in the future when it might change again. So in the end the best solution would be to have all the boards made(including the power/relays one) so that no one needs to rely on the Livolo company. But for the moment I don't have enough knowledge/time - at least not too much regarding power electronics and creating live wire only power supplies(including testing/safety/etc).

@tonnerre33

Hi,

Nice work. I was very curious regarding on how did you made the pcb layout so I took a little time to inspect it and I noticed that you added a ceramic resonator but it's placed a little bit too far from the MCU pins. Now I know why you did that and this is the reason I didn't used a crystal/ceramic resonator in the first place - that's because of the limited space available. When I say limited is because of many reasons:

1. it's not ok to have traces/components under and/or too close the touch pads
2. didn't wanted to place components on the other side of the board because that's where the livolo glass panel comes and it may interfere from a mechanical point of view

That said I gave up on using a crystal/ceramic resonator and in most of the cases the internal 8MHz RC oscillator is more than enough(as far as I know it only matters when you have an environment where temperature variations are pretty significant so the MCU oscillator frequency can drift a lot).

Now getting back to your board and crystal/ceramic resonator placement: it's advisable to have it as close as possible to the MCU pins where it connects to and this is to reduce parasitic inductance/capacitance that long traces can and will create. Remember that 8MHz is pretty high frequency so even short traces matter so you don't want surprises in your circuit.

Other notes:

1. filtering caps for MCU need to be placed also as close as possible to Vdd pins(and for Aref too).
2. the big polarized capacitors(tantalum and/or electrolytic) need to have lower value ceramic capacitors around 100nF placed in parallel in order to reduce their high ESR

Oh and please stop using Eagle in the future :simple_smile: ..I was a former user of Eagle and now I'm really glad I got rid of it trust me. Aside from the limitations that it has and now even more as it was acquired by Autodesk it doesn't have some VERY useful features like KiCAD has now when it comes to pcb routing( one of them is push and shove ). Now I know it's hard to gave up on a tool that you used for a very long time(it was for me too) but with a little effort and small steps it can be done. And I know that KiCAD it's not that stable as Eagle is but it's still very usable(even with nightly builds that I use because of the new and nifty features). It has a little different learning curve and it's a little bit hard in the beginning but after you master it then it's a kids play. Not to mention that you have a 3D viewer for your board(very useful for mechanical integration and inspection) and it supports step models(in the nightly builds for sure).
I'm making all of my designs using KiCAD for a long time now and I didn't had issues with the final PCB even if I use nightly builds. And on top of all of this: it's FREE and no limitations and great community support on https://forum.kicad.info.

I know that you're still working on it so the pcb layout might change but I just wanted to give my first impressions on it. Good luck with your design and keep up the good work.

@tonnerre33
Nice work. I will steal maybe the outline of the board(board frame) :simple_smile: . Did you tested it from a mechanical point of view? I mean will the board fit in the enclosure? And I see that you use the existent voltage regulator from the Livolo power/relays board...I didn't wanted to use that because the voltage drop over it is pretty big(12-14V - 3V =~ 9-11V) and with that in mind considering the TX current of the RFM69 which is around 50mA gives a max power dissipation of: 11V x 50mA = 550mW - pretty high(I didn't added here the MCU, LEDS and other stuff). Now this only happens on TX time which should be pretty short in theory so it should handle that(but better check the voltage regulator datasheet though). Rest of the time it will be around 16mA(RX current of the RFM69W) + a few milliamps for the MCU and other components - around 20mA let's say and this translates to: 11V x 20mA = 220mW(half power dissipation compared to TX mode).

Now depending on how much time you're in TX mode compared to RX mode this will be around 300mW maybe if we take the average(but this is just a rough estimation). The onboard regulator that they use is a Holtek 7130-1 device which can whitstand a 24V input voltage BUT only 30mA output current max and it can dissipate using the SOT89 package around 500mW maximum so it may heat.
I don't know if on the current board they changed it or not but still imho it's not a good idea on the long term to overload it. Indeed if the average power dissipation doesn't reach that value(500mW) it's ok and you should stay below that: usually it's a good idea to dissipate half of the max allowed power only.

And I saw that the 3V voltage regulator powers other stuff on the relays board not only the front plate so we should take that into consideration too.

Given all of the above and thinking on the long term that's the main reason I used a DC-DC step down converter powered from the 12-14V line which is also the voltage used to power the onboard 3V regulator that Livolo uses.

Most of the problems(if not all) come from a bad designed power supply. It seems that most people underestimate this part but what they don't realize is that the power supply is the most important part of every circuit and that it plays a very important role regarding the final performances and stability of the whole circuit that it powers.

@tonnerre33

If you keep the average power dissipation under 250mW(half of the max rated value from the datasheet) it should be ok. Reducing the Tx power helps but will decrease coverage - but that's not a problem if you set your nodes as repeaters too as this will increase coverage(not the battery powered ones of course). So yes there are solutions don't worry.

Oh and I used paper too when I replicated the original board outline, touchpads and main connector placement. Then I scanned it, imported it into Inkscape, a little bit of QCAD...and in the end got the final results. There may be an easier way of doing it but I didn't had any better idea(s) at that time.

@MiKa

That device is rated at 16V max input voltage...I won't use that because the input varies from 12 to 14V approx. So it's like living on the edge. Why are people afraid of including a DC-DC converter into their design when high voltage drops are involved and a little bit more output current is required - actually we can speak in terms of power here as it's more appropriate. So we all know that when it comes to more power a DC-DC converter is more efficient than a classic LDO. Is it because of noise? That can be filtered not a problem and reduced to an acceptable level. In terms of volume - indeed there are more components involved and a little bit more care is needed when designing the PCB but hey we need to make some compromise in the end...and I for example like to stay on the safe side on the long term.

@tonnerre33

Nice work regarding Kicad. You'll see that on the long term it's a real benefit to switch to Kicad and I strongly adhere to it even though some people would say the contrary. It is indeed a little bit hard maybe to start with it and the learning curve is not the easiest one but after you master it then it will be a joy to work with. And more features/bug fixes are made as we speak because it's a very active developed project now. And on top of that that it's FREE - no limitations or whatsoever.

@tonnerre33

It's a logic level voltage converter. The MCU runs at 5V so the logic level voltage that it uses on the SPI port which connects to the RFM69W use 5V too. But the RFM69W module runs at 3.3V and it's not 5V tolerant on its SPI port pins.

The purpose of that IC is to convert voltage levels on the SPI lines forward and backward (from 5V to 3.3V and vice versa) in order to not damage the RFM69W chip.

@tonnerre33
Because at 3.3V the atmega328p mcu can run at max 8MHz as per datasheet. So I wanted it to run at double the speed and for that it needs 5V as per datasheet again. Why at 16MHz? Well because I want the gateway to be more faster in general and to quickly process the incoming messages from the entire radio network.

And...here comes the 1 channel variant for the classic Livolo switch front plate. Work in progress for both projects(1 and 2 channels)...

@tonnerre33

Here: https://forum.mysensors.org/topic/2775/livolo-glass-panel-touch-light-wall-switch-arduino-433mhz/62. I think that @Tigroenot and @jirm know better than me actually. Sorry @Nca78 to involve you on this part. But @tonnerre33 if you wait until next week I'll inspect the new Livolo power board in a little bit more detail and see if I can come up with something.

Good news everyone! I managed to set up a test board in order to verify the new Livolo relays/power board and with the required modifications IT WORKS!!! as the previous one did from my old project. This time only 2 modifications are required on the board instead of 3 because the 12-14V supply is already connected now to the 2x7 connector.

I expected this to work as the power/relays board didn't changed - they placed the same set of components but in some different places and I was able to recognize the base layout.

@tonnerre33 Maybe yo wired something wrong..but for me it worked from the start. I will post here images and test results so stay tuned.

There you have it in action(sorry for my phone camera and delays): MySensors Livolo in action

Power/relays board required modifications(red lines represent wires - you could desolder those components too and just put some solder/wire bridges)

Next as seen in the video I wired a cheap dc-dc step down converter bought from Aliexpress to the 12-14V pin from the connector and ground and used its 3.3V output to power up the arduino pro mini board. The RELAY 1 - S and 1- R pins mean: channel 1(or 2 - it doesn't matter as the channels are identical) Set and Reset(because we have bi-stable relays). Those were wired to some digital outputs on arduino pro mini as seen here:

@tonnerre33

CFL - 15W. No, I wired both bridges.

Here's a quick block diagram for the whole circuit. I hope that I didn't missed anything or wired wrong there.

Well in reality the internal relay contact is not wired like in my diagram but to some extra circuits in order to provide voltage when the switch is closed - this is just a quick and dirty overview of the system.

The test circuit is working now for more than an hour with no problems. Oh..and the old project that I made for Livolo is in production now for more than a month and it works flawlessly.

I tested both CFL and LED bulbs - 5W was the lowest that I tried and it worked perfectly in both cases. The important part here is the parallel capacitor across the light bulb which gives the extra current that the standby circuit needs from the Livolo board in order to power the whole thing. The most sensitive part is the standby circuit because in that case the light bulb is OFF and it cannot provide enough current in this state - this is obvious because the load which is in series is turned off so only a small amount of current is present in the series circuit.

This works for the original board because the touch sensing part draws very little current(under a 1mA I think) and the radio receiver (in the RC variant) which they use draws 5mA or so. This compared with MySensors RFM69W which draws 60mA peak and on average 20-30mA or so.

@shabba @tonnerre33

Ok. I found the issue with pcbs.io service. They don't accept separate files for plated and non plated holes when it comes to gerber files. My default setting when generating gerbers from KiCAD is set to do that.
So here it's a set of gerbers for the boards(1 channel and 2 channel) with PTH and NPTH gerber files merged into one. If you upload these on pcbs.io you'll see that it renders correctly now. And it should be fabricated correctly too if their rendering page corresponds with the real product.

• 1 channel variant:
  0_1496990513816_livolo_1_channel_1way_eu_switch_rev0.1.zip
• 2 channel variant:
  0_1496990268774_livolo_2_channels_1way_eu_switch_rev0.1.zip

@shabba
Oh and the 1 channel board: please don't fabricate it yet because it may not fit from a mechanical point of view - the atmega328p is above the big mosfet from the power/relays board. So I have to see if everything fits there. But anyways don't be so impatient because both projects are marked as Work in progress on openhardware.io. I'm saying this because I don't want you or anyone else to waste money before the boards are tested for real.

@NeverDie
I used flux paste like this one:
http://s.aliexpress.com/f67bIZb2

And I didn't used preheating because I don't have such a tool. I did just like that guy explained in that video. That's how I soldered the mega328p qfn32 package on my serial gw from here: https://www.openhardware.io/view/316/MySensors-RFM69W-serial-GWATMEGA328P

It's not hard trust me.. just a little bit of patience and after that by practicing a little bit you'll gain experience and see that's just a piece of cake.

@gohan

That's because of the issues that I had with the supply from the Livolo switches which is designed for low currents(several milliamps and even less). I had no luck with other solutions because of the high current consumption(more than 20mA) - and yes for the Livolo supply this is high. And because of that the stand-by power supply from Livolo crashed(burned) several times and I had to repair it(thanks to @tonnerre33 for his support on this part).

I know that other users managed to make this work with nrf24l01 radios and MySensors support but for me it didn't worked well and it wasn't stable - and trust me I studied the Livolo supply from outside to inside and I know its limitations and why it was designed the way it was designed.

Hello,

After a long time of development(both hw and sw) I finally managed to get to a final version and a stable one - production ready also. It's a mix of BLE and Mysensors(the switches are running the nordic ble stack wrapped using the sandeepmistry ble peripheral library) and a linux board running the ble central node and Mysensors integration over MQTT.

Now this seems like a complicate setup and extra components added but it's very stable so far and no more failures with the Livolo switches. The linux board has a web interface for configuring mqtt connections details, mysensors node id's, ble mac addresses and some statistics regarding connected nodes over ble and services status, mqtt connection status.

Maximum ble switches or peripherals that the central node can connect to is 5 or 6 - this is a limitation in the ble stack as far as I know but it's enough to cover one room or maybe two if there aren't too many walls or more than 15-20meters in open space. I tested using an Orico BTA-403 usb ble 4.0 dongle and it works very well even through one wall.

Here are some screenshots from the web panel used to configure the central node(linux board with usb ble dongle)

The code from the linux board(a nanopi duo from friendlyelec) runs custom python code made by me to maintain the ble connections and do the MySensors integration - it also provides failure handling and automatic reconnection for both BLE devices and mqtt broker.

Now the web interface is not very refined but it does its job very well(I'm using the great and almighty bootstrap framework for the UI). I also use flask for the python web server, ajax and other goodies to support all this.

Anyway there's a lot to publish and discuss about this project so I will do that on my blog when I have time: https://electronics-adventures.blogspot.ro/

@alexsh1

I'm sorry but I think I'll abandon this one because I don't have any time left to deal with it.

This board uses the same working principle behind the scenes as the Livolo or Sonoff no neutral switches (some use a triac based implementation). But again the idea is the same - we take advantage of the leakage current from the light bulb. So yes it still requires a capacitor across the bulb in some cases. This is because we power everything via the light bulb which is in series with our circuit and in the end it all comes down to physics law.

So no @arden , this one is not so different compared to the one that you already have. I did this because I'm a more of a diy person and I like to customize stuff and of course learn from it.
Another advantage is that you don't depend on external or 3rd party stuff and you can build/customize it whenever you want (of course this means that you know what you're doing considering the fact that you are dealing with the mains here).
As I live in EU I have only the live wire inside walls for light switches so this is another reason why. I know that there are another ways of accomplishing the same result but I don't want battery powered switches nor putting stuff on or inside my ceiling.

Started designing the enclosure for 3d printing ... I will use PET-G as it's pretty strong and not very flammable or so it seems after some tests. I don't know about electrical insulation properties yet ...This all very depends on what other compounds are used when it's manufactured.

@berkseo

50pcs/lot EE10-A1 Switching Power Supply High Frequency Transformer 220V to 5-12V Maximum Output 3W
https://a.aliexpress.com/_sOShjH

It's the same supplier that I used also and the lot seems to be fine...well at least the 2 pieces that I tested so far .

Now the latching relays. I found them on Aliexpress only and I received something else instead (which seems to happen from time to time) but luckily it works OK so far. So instead of Hongfa relays I got Massuse which seem to be equivalent.

Rest of the components can be sourced from LCSC which is a more trusty component supplier compared to various vendors from Aliexpress (which I already knew..but I didn't had other choices).

Oh and the PCB design and everything else was done using EasyEDA for obvious reasons (JLCPCB is very cheap and pretty good quality for a hobbyist, also their SMT service). I really like their ecosystem - you just create the design using their tool and order everything from there - very, very handy and cheap also as I already mentioned.

For those interested I started "documenting" my work and what I achieved so far on my blog (first time I'm "blogging" ).