Posts made by Moebius Lutching

Using voltage divider still might be necessary if you don't have battery directly connected to the MCU VCC, for example using step-up/down regulator to power the MCU. In this case you still can use a voltage divider and have a P+N Mosfet to control the current going through the voltage divider, so no leak to ground.

In practical terms you basically use another GPIO to enable or disable it the Mosfet when needed. I saw that on the Whisper Node board I'm using and seems to be effective (reference: https://bitbucket.org/talk2/whisper-node-avr#markdown-header-voltage-monitor)... In any case using high value resistors (over 100K) will reduce any current draw. Finally a small capacitor can be used to stabilize the voltage.

Hi jfeger, sorry I can't find the sketches anymore... if I end-up finding it I post here.

So, I decided to use bare Arduino with the RadioHead RFM69 lib and parts of the Talk2 library. I just didn't feel the need for the whole framework and doing this I was able to customize a bit more the low-power usage and easily integrate with other third-party libraries which weren't playing nice together with MySensor.

In terms of messages, protocol I just follow the Talk2 example and I'm using their "Message" format. I just assigned the "id" to a kind of message by convention and use the 8 bytes payload for the data... I normally use only 1 to 4 bytes actually.

@jfeger hey... I don't have it in this computer, I sort of moved away from it and I'm using my own "protocol" and code. but i'll try to find the working mysensor sketches on the company's laptop and post here. From the top of my head I don't remember changing anything apart from the RFM69 config parameters documented for the "mysensors".

@gohan it worth for me... I thought the same initially, but after lots of time spending building my own nodes, which were never 100% and some quick maths I believe it's a good board for low power nodes.

RFM69: $4; Arduino Mini Pro: $2.5 - $3; Step-up Regulator: $3.5; 4Mbit Flash: $2 - $3; SMA 2dBi Whip Antenna: $5 - $8; SMA Connector + LEDs + Buttons: $3 - $4; PCB Headers + Passives: $1.5... Total $21.5+?!

That's what the board comes with (I assume). I must say that I would never build my node with all of the components, for me I prefer to focus on my project instead of build nodes from a Mini Pro, soldering the step-up and the RFM69 and testing everything... plus the whole thing look like a Frankenstein

There is a TI paper about adding a big capacitor in series with the coin-cell battery to minimize the voltage drop during high-current peaks: http://www.ti.com/lit/wp/swra349/swra349.pdf, also another interesting article related to low-power and CR2032: http://www.low-powerdesign.com/121312-article-extending-battery-life.htm

Just found this post https://www.hackster.io/Talk2/temp-and-humidity-sensor-with-a-cr2032-for-over-1-year-580114 showing some details about using a CR2032 to power a sensor node. By my calculations, if the author removed the LED at all the solution would last for over 2 years!

I'm building my home automation with a few Whisper Nodes (https://talk2.wisen.com.au/product-talk2-whisper-node-avr/) and I just got them working with the MySensor code. I'm running most of my projects with two AA but I just setup one with a CR2032 transmitting my attic temperature every 5 minutes to see how it goes. One thing I discovered is that the board comes two "built-in" resistor divider to monitor the battery and power supply voltage, which is pretty handy... also they have added a Mosfet on the battery voltage divider, I guess to eliminate the constant current leak consumed by the voltage divider, am I right?! (https://bitbucket.org/talk2/whisper-node-avr/overview#markdown-header-voltage-monitor)

Thanks for that scalz. With the provided details I already got things working fine with the additional RFM69 settings. I'll move on to create some customized nodes and message types and try to integrate with Domoticz.

Hello,

I tried to post similar question at the Domoticz forum but I think it's a bit quiet over there, so I trying to post over here.

I just downloaded the Domoticz and I'm trying to configure my Whisper Node (https://talk2.wisen.com.au/product-talk2-whisper-node-avr/) as a Node and serial Gateway connected to my Rasbperry PI. I can see a "define" to change the module from NRF24 to RFM69 on the example (https://www.mysensors.org/build/serial_gateway), but where I define details for the RFM69 driver like frequency, power, encryption, etc?

Also, I'm trying to find details about the protocol between a MySensor node and the Gateway as well, so I can try to write my own Remote Node for non-standard uses, as well to optimize for very low-power consumption. My plan is to run few nodes using two AA batteries and others using CR2032 coin-cell. At the moment I only found documentation about the Serial protocol (https://www.mysensors.org/download/serial_api_20).

Meanwhile I'll keep digging into the code, still getting familiar with the libraries. Any help is appreciated, thanks.