@gonzalonal
Yes I am.
But I have got a lot of other works, so It's going slowly.
The problem is, that CAN can transfer only 29 bits ID ( 3 bytes + 5 bits ) and max. 8 bytes of data.
MySensors message has got max. 32 bytes ( 7 bytes header and 25 bytes of data ).
I must either send MySensors message like 3 packets of CAN messages or limit properties of MySensors protocol.
Now I am working on second variant.
I am able code to one CAN message:
6 bits - destination
6 bis - sender
(gateway, broadcast, 62 nodes - it is enough for me for one bus. I plane three buses and gateway can " translate " or "expand" nodes ID from and to controller )
1 bit - RACK
1 bit - IS ACK
3 bits - command
6 bits - type ( MY sensors has 56 types max. now )
6 bits - sensor id ( only 64 sensors per node ... )
3 bits - payload type ( int, uint, long .... )

The sum of these is not 29, but 32 so I am using a little "hacking" data length field in CAN frame to obtain additional 3 bits.
For data I have got 8 bytes.
It is enough for conventional data types from char to floating point.
Only text messages are limited to 8 bytes. But for us, old boys, who remember old DOS file names, it is enough.

In this time, I am able send and receive packets in that format between nodes and now I am working on transfer RS485 library to CAN library.
The problem is, that RS485 library sends destination address, node id, length of message and then MySensors message, witch "surprisingly" contain again destination and sender bytes. A little bit redundant for me.
So I must remove some fields from MySensors message, put it to CAN ID and send only payload in CAN data fields.
When I receive CAN message, I must again assemble correct MySensors message format and put it to MySensors system.
But unfortunately only documentation is library code itself :o(

I try a "stress test" like here:
https://forum.mysensors.org/topic/5051/rs485-stress-test

I send 10 000 messages from two nodes to "gateway" ( 22kbps ).
Result - zero messages lost.
But it is expectable with CAN.

Why sleep?
Switch it completely off.
Use button with two pairs of contacts.
One pair on each button connect battery + pole with processor power pin.
Second pairs to different inputs pins.
You push button, processor will start execute program, immediately read inputs status,
then send command and when you release button, it will be switched off.
If you need longer processing time and do not want hold button all this time, then processor can hold power itself by logical output with connected transistor. When work will be done, then switch itself off.
Your car remote key works the same way.

@stevanov
It seems, that both of you use MySensors in "outofbox" state.
You do not write which radio module are using.
If RFM69 - change netwotk ID, with NRF24 change channel or network ID
Somewhere in config files.

MyConfig.h

#define MY_RF24_CHANNEL (76)
/**
 * @def MY_RF24_BASE_RADIO_ID
 * @brief RF24 radio network identifier.
 *
 * This acts as base value for sensor nodeId addresses. Change this (or channel) if you have more
 * than one sensor network.
 */
#ifndef MY_RF24_BASE_RADIO_ID
#define MY_RF24_BASE_RADIO_ID 0x00,0xFC,0xE1,0xA8,0xA8
#endif

/**
 * @def MY_RFM69_NETWORKID
 * @brief RFM69 Network ID. Use the same for all nodes that will talk to each other.
 */
#ifndef MY_RFM69_NETWORKID
#define MY_RFM69_NETWORKID (100)
#endif

Of course you must reprogram all nodes and gateway :o(

Or talk with your neighbours and ask them using different network ID if they only starting building their network and have got smaller number of sensors.

Some Sonoff switching devices has got power metering.
Upload ESPeasy or Tasmota firmware and connect with HA....

Why "plus" 7805.
Nano has got voltage regulator on board.
Original Arduinos 7805 I think, clones LM1117 usually.

@Sixkillers
You can wake up every hour, but hold wifi modem off, increment "wake up counter" and go to deep sleep.
Running time between deep sleeps will be very short
And connect to wifi one per day for example.
And make some tweaks for wifi connection:
For inspiration from Step 6 here:

https://www.instructables.com/ESP8266-Pro-Tips/

And final tweak here:

https://www.bakke.online/index.php/2017/06/24/esp8266-wifi-power-reduction-avoiding-network-scan/

@bluezr1
Do you see "MockMySensors" example sketch which comes with MySensors library?
There are all sensors in one sketch together.
Presentation, sending its values, receiving ....

@bjacobse said in Nano minimum voltage:

Datasheet: The device operates between 1.8-5.5 volts.
and this means to bypass/remove the voltage regulator on the Nano board

But it do NOT means with 16Mhz crystal on Arduino Nano ...

@gbuico
tmr.now() is LUA function
NodeMCU LUA is firmware, which you load to your NodeMCU ( or other ESP2866 ) and then write your programs in LUA scripts, which stores in ESP2866.

MySensors is writen In Ardfuino language ( C++ ), so Arduino IDE compile your program and load it to ESP2866. And there is not tmr.now(). Use millis() instead off.

ESPeasy is firemware to load to ESP2866.
It runs on ESP2866 and you can create sensors and write simple "program" when connected to ESP webpage.
There are any timeouts, you can send message one per day or month, no problem.
You do not need compile ESPeasy itself. Use compiled file and download it to your ESP2866.

First you create your sensors in Domoticz as "Dummy" devices and remembers their "idx".
Then connect with browser to your sensor with ESPeasy running and through its webpage you can define different sensors ( sensor type, GPIO where connected, its domoticz idx , sending interval, etc )
For example, for DS18b20 you select pin for 1-wire bus, then you can see all sensors on this bus and select which you need. Temperature is automatically send to Domoticz.
Different sensor - no problem, select for example pins for i2c bus, discover this bus and then select sensor.
Display - select i2c address and it is done.
But what I really love on ESPeasy is its communication model.
If you cannot send some info through ESPeasy autmatically, you can write json command and send to Domotic whateverelse.
Need send data from Domoticz to your ESPeasy - no problem.
You can send commands from Domoticz with parameters and receive it in ESPeasy.
You can transfer everything this way.
No compilation, only write in your browser and hit "Apply" button.

I like MySensors very much, but for wi-fi connected single sensors exists easier ways.

But my dream is feature for MySensor ethernet gateway, when I can send to gateway something like this:
http://gatewayip/control?cmd=23;5;24.5
which means = to_node, sensor_id, value.

Or opposite way, send from sensor to gateway command with domoticz sensor idx, type of domoticz value (svalue or nvalue ) and value itself and gateway will send to domoticz appropriate json command.

@pihome
very power hungry (Quiescent current 13uA) ?
And do you know, that with AAA (1000 mAh) it is 8 years in standby?
Maybe self discharge is greater.
Alternetively use 3xAAA with low quiescent current 3.3V LDO.

@3nibble

Diode is bad.
You can shorting it.
But then you can power this Arduino only from USB or from +5V in the same time!!!
Not both !!! This can damage your USB port.

@Olaf-Jacobs said in Temperature serial sketch:

First I had 4x DS18B20 temperature sensors hooked up to gpio4 on the pi without the resistor, this worked fine for some time till this gave some issues

Can you write what issues.
Why you connect DS18B20s to RPi without resistor ?
Is it some experiment?

@Sixkillers
You can wake up every hour, but hold wifi modem off, increment "wake up counter" and go to deep sleep.
Running time between deep sleeps will be very short
And connect to wifi one per day for example.
And make some tweaks for wifi connection:
For inspiration from Step 6 here:

https://www.instructables.com/ESP8266-Pro-Tips/

And final tweak here:

https://www.bakke.online/index.php/2017/06/24/esp8266-wifi-power-reduction-avoiding-network-scan/

@openhardware-io
I think this is not too useful concept.
In circuit diagram, there is no connection GPIO16 to RESET - so no deep sleep mode.
It seems, your node only connect to server when water leaks.
But what after two years, you do not know if battery are still good and your detector alive.
Better way use deep sleep, after some number deep sleep cycles ( one per day? ),
connect to wifi and send battery voltage for example.
If this message is missed, your controller can send you battery replacement message.

wake up circuit

@fdlou147
Ethernet ( with POE ) is very very expensive way to connect your sensors.
Look for prices 24port switches with POE for example.
And 24 nodes is not enough....

Super...
You add software for relay, switch or new temperature sensor through FOTA...
And then go to your node, remove it and connect this devices to it in fact.
No, you really do not need FOTA for this.
But for repairing some bugs in your program yes.
Other case is for example node ID, mqtt topic, some calibrations, offsets, Domoticz sensor IDX etc.

@PedroHernandez
If you build sensor with ethernet connectivity, simply send your data to Domoticz via http call using Domoticz JSON API.

Domoticz globally or only with MySensors ?
My Domoticz is the same version like yours.
Temperatures from ESPeasy are with two decimals on Temperature sensors page, but on devices page only one decimal.
Exactly the opposite like you wrote.

https://github.com/MajenkoLibraries/ICSC

Examples are there too.

( MySensors uses this code for 485 transport layer too )

Or another very simple example:

https://circuitdigest.com/microcontroller-projects/rs485-serial-communication-between-arduino-uno-and-arduino-nano

I would simply endured.
Once clean clothes go away and they will go out of the house dirty, smelly or naked...
Then they empty basket sure.