I currently have a functioning fuel level sensor for my fuel tank built with an ultrasonic hc-sr04 device and it works pretty ok.
Before installing that on the top of the tank (hot-glued to the cap actually) all my tests were done on a water tank, so I know beforehand that this works well with water.

There some things you'll want to consider though:

• This does NOT work well on moist environments, you'll have wrong readings, I recommend the "water proof" version for that (it's not waterproof, it simply works better with higher humidity levels)
• If the water is moving you'll have different readings (as with ALL water level meters) I've modified the sketch to read the distance several times at random intervals (for example 6 times with intervals at 1 sec, 3, 5.5, 6,7, 9.2 secs) and then give the average distance, this flattens false readings and gives a more realistic value.

Hope that it works for you.

Regards.

Remove PROGMEM from line 72 at the file PubSubClient.h

Works for me, but I really don't know why, I remember to read it somewhere.... not sure if it is "safe" to do, but at least I can compile it and test it, and BTW, works fine with my mosquitto instance on my NAS, still have to do more tests.

Regards.

EDIT: The solution is on this thread XD

Hi.

I recommend you to check the relay example, the sketch includes support for multiple relays and you'll understand what do do in that scenario, but answering you initial question, no, I'm afraid you can't do gw.present(CHILD_ID, S_DISTANCE1, S_DISTANCE2, XXXX); but you can do gw.present(CHILD_ID1, S_DISTANCE); and gw.present(CHILD_ID2, S_DISTANCE); after that one... and... so on, you'll see better reading the relay sketch.

Regards.

Hi.

That's the same problem I'm facing at my house, multiple levels, also the radios don't have enough coverage to reach the far end of the same floor (PA's radios do, but I only use them on the GW and MQTT GWs, can't use them on battery powered sensors for obvious reasons), so the multiple gw distribution system should be an ideal solution for me and people living in "castles" or "Faraday cages" XD

Currently I have moved from a serial gw to Ethernet and MQTT gws (one Ethernet and one or two MQTTs), I find the Ethernet GW to be more stable than the MQTT ones (Client or Broker, same DIY PCB, I just pop out one nano and place the other) , your scenario 1, also some messages get mixed from time to time, even using different channels. Some times the GWs stop looping and I need to restart them, funny thing is that connecting to them in order to debug if they are running seem to jump-start the loop again.

So my vote goes for scenario 2 also, plus, it should be interesting for the Ethernet GWs to act also like MQTT Clients and/or Brokers, because the IOT community is clearly taking that approach in their effort to "standardize" all the chaos that exists today. I think we should keep things as simple as possible, I've read this post:

http://forum.mysensors.org/topic/887/future-network-topology-for-discussion

And I think it's a superb idea, clustering the whole network into more easy to manage subnetworks, each one with a different topology connecting to a Network (TCP) controller through their GWs, all the complicated stuff should be done by the "Controller" the subnetworks should be as dumb as possible, leaving the heavy duty processing to the controller.

I know this isn't much, I wish I knew more about all of this, but I hope my experience will be useful.

Regards.

Hi.

Just wanted to let you know that I've tested this with an Arduino Leonardo, with the RF24 library bundled with "My Sensors" (from GIT), MISO MOSI and SCK connected to ICSP as stated on the offcial Wiki:

http://arduino.cc/en/Reference/SPI

also works for the MEGA 2560, but you have to connect to the ICSP or use the 50-52 pins (if using it for the Ethernet gateway for example)

Regards.

Hi.

I've tried to do exactly the same thing with the remotes for my roller blinds, I also started with relays (as they are the most obvious solution), but I found something that works just fine, no noise and low power:

http://www.ti.com/lit/ds/symlink/cd4066b.pdf

Just power it with 5V (I think it works from 3 to 18 V) and you have 4 "switches" using pairs from the IC and send a "high" state using a control Output from the arduino to the control pin on the IC, it doesn't really "connect" the two contacts, there is still an small resistance between them (about 500 ohms) but it works just fine with my remotes, they think the button has been pressed.
And, as a bonus, they only are about 1.50 euros for 10 PCs, that is 40 switches for 1.50... try to do that with conventional relays and you are looking at about 45 euros at least.

Regards.

PS: Also, they work with the Relay example from the libraries, just changing the default value from #define RELAY_ON 0 and #define RELAY_OFF 1 to make they active HIGH, (#define RELAY_ON 1 #define RELAY_OFF 0)