Hardware

Worked! Many Thanks

I'd use a DCDC Step up converter (there is a 1-5V to V mentioned in the MySensors shop). For a 5V device I'd not connect directly to the batteries, because the voltage might drop below 5V although the batteries are still far away from beeing empty. You don't want your approach with the diodes (or any other linear voltage regulator) because it wastes expensive energy to produce heat (In order to get the higher voltage down). With 3.3V Device I'd (and will in the near future :) ) try to just use two batteries (without regulator). They'll have 3V max. Voltage and Adrduino Pro mini / nrf24l01 work down to 1.9V - so most if not all of the charge from the battery can be used. (rechargeable batteries shouldn't go below 0.8V so this fits quiet nicely (2*0.85 = 1.9). Additionally I think it might be easier to use the 3.3 V Arduino over the 5V, because more lowpower people use it and because the power consumption typically drops if you use less voltage as long as we are talking about some mA. E.g. Modern CPUs are working <1V to keep down the (thermal) losses. As a last sentence: Designing real low power and battery applications is hard work. It is dependet on sofware but also -maybe somewhat more- on hardware. You must design/find a power supply that matches the application very well and have to think of the parts of your sensor/circuit you can / must switch off. Maybe some of them must be switched off in hardware (cut power supply). Then it is part of the software to re-enable them in the correct sequence and with proper startup times to have everything work. However for a start I'd recommend to try the mentioned ste up converter. But I fear it has a relative large quiescent current because it is able to deliver 500mA which is much. Maybe someone else knows some modules that suit better and have a defined quiescent current. Best regards DirkH

Thanks I'll keep that in mind. But You can never have enough toys and are as common as stepper motors are around an everyday home but open up new possibilities. Sure you could build it though, but having a community working as one is progress [image: upload-e686a1bb-bee7-40ab-9001-265fb0b8b34c.jpg] [image: upload-d223980b-d4f3-4d36-80de-6f64eebe0624.jpg]

@epierre as a battery operated solution I use li-fe battery's they have a lower voltage per cell then lion and lipo so there is no need for any type of voltage regulation witch makes it simple. I just need to watch out not to over discharge the battery, but with 3Ah on a temp/hum sensor that will not be much of a problem ;) OT: seems like a very interesting board with lots of function and usefull stuff. But for $25 I would mutch rather throw my own hardware on a breadboard or protoboard or something.

@diamantmatch It was just the optocoupler approach to control 12V dc from arduino that caught my attention. It's enough with a simple transistor driver to control it. And yes, always have a diode in reverse across the relay coil. If it's 12V relays, you probably already use the same 12V supply to power both relays, and the arduino (maybe with a voltage regulator for providing 5V to the arduino from the 12V rail), and then the optocoupler approach is defeated, as they have a common ground.

@gregl I have messed about with them too, but it seems for me they are not-ready-for-primetime, but with some hard-knocking effort you can get it to do some basic things. Smart guys will develop a great library and it will all come together, I am sure. Spark Core is my new favorite. After sitting on the bench from last year's initial shipment, I finally got to play with it. It is amazing with its tremendous out of the box capabilities. The Photon (which ships april) is only US$19, has 1 Mb of FLASH and 128 Kb of RAM, moving at 120Mhz... wow! Way overkill for a motion sensor, but it brings a lot of life to the world of Home Automation for a small price. ($10 for a surface mount version!!!) I'm in the process of moving my Vera auxiliary controller project over to spark... I'll re-post the wireless version as soon as I can get it in a proper box.

@ferpando @rosskinard Has anyone made any headway on this project?

@hek said: @bluman Candidate for the project contest perhaps? If all my parts turn up from China in time then it should be ready to submit for judging!

For the size and cost I think you better chose an AC powered device. Additional to the link posted by @m26872, @petewill just posted full instructions on how to build this on $8 Lamp (Outlet) "Smart Plug" Module

@gregl said: I think the main reason why most door/window switches are usually NC is so that should a burglar gain access to the wires to the sensor and cup/snip them the alarm would be tripped. Of course in this type of use batteries are not a consideration.... Back to mysensors.... i too like the status sent periodically so i know if a sensor is alive or dead. Fair point. When it really comes down to it, I got started thinking about this in relation to a mailbox sensor. I want to put it there and not touch it for a year. It's flippin cold in Tennessee right now.

@tbowmo said: Hmm only 64MB of ram, and 400Mhz cpu. Seems very small, still it could run a limited Linux system it is designed for openWRT

:) Most will be of the DS18B20 kind. But still, a good silicone sealant around the sensor should still make it watertight. /M

Works fine for me at 3.3V and 16Mhz. Have not had any problems whatsoever.

Thnx. Any specific hints how to do that with this hardware; I will try to get this working with a few pro-mini's as relay, I might have missed this on the educational pages here, but I'm wondering how to start the network / do the roll-out. "The first time a new sensor boots up" section tells me something about that it will find it's way home (which is great, must have cost some time to get this programmed I guess), but my challenge at the moment is to find out how to get this done effectively. Should I start with the gateway and see how far I can get with a single node and replace it at that position with a repaeter node, or can I simply place some repeaters and check with a serial monitor that they contact the gateway? Thanks, Boozz

@funky81 See the link near the top of the (edited) original post, to a thread which follows up on this one. For board designs created by the community, that thread going to be more up to date (and it tracks some information about what's available). This thread was earlier, but lists commercial options as well, so it's still of some value. I'm thinking to let the other thread keep up with community designs, but if you know of a good commercial offering for our purposes, please leave a reply and I'll add it to the list here.

I'm thinking of 4 PIR sensors (at each end of the two aisles). And I was thinking of a reed switch at the top of the garage door opening, and one at the door into the house. And the most convenient location for the relays controlling the lights is still a 7th location. I could put 7 wireless nodes into the garage, but then I have to run power to all of them - if 5v we still have the same long wire issues, if 120VAC then I need 7 power supplies. And the local control now involves passing messages between nodes rather than just sensing input pins and controlling output pins on the same uC. The cables supply power to the RF enabled nodes will have the same length (whether DC or AC power) as the cables going to a simple sensor, and follow the same routes. So it would be possible to do that, but at considerable cost in money and time and complexity - compared to just running a three or 4 wire cable from the main node to a $2 PIR located 1o-20 feet away, if that can easily be made to work (perhaps with the addition of a couple of small, cheap passive components. I don't know if I do need to worry about inductance, capacitance, reflections etc - that's why I'm asking. These things aren't usually specified one way or the other - you kind of need some practical experience. If those are indeed killers that cannot be fixed with a couple of passives, then I may go to the "make every sensor a full node with AC power supply and distribute AC to them instead" route. But wouldn't it be nice if I can do a $2 easy fix instead? One data point - in the Do It Yourself Christamas lighting control community, they routinely get away with sending TTL or CMOS signals quite a ways from a control unit to an optoisolator input (which controls a Triac to form a SSR which does PWM dimming of an AC circuit). The signals are just a 120 Hz PWM signal but the edge timing is at 120Hz * 256 PWM divisions. You won't find much about driving a 50' cable from a TTL or CMOS output in the datasheets, but it works in this application! It would not work if you were sending a 1 Mbps signal tho. So I have some hope that a PIR 20 feet down a cable may be able to pass back a quite usable logic signal, since it changes rather rarely. But I was hoping for some advice about the gotchas. Remember the sensors I've mentioned are magnetic reed switches, LDRs, and PIR sensors - only the latter needs power per se separate from the signal.

@daulagari Thanks :) It worked, and I have logos on my next sensor pcb.. ;) Had googled all the things that came to my mind before throwing the question in here, but I haven't seen that page before..