I gave some remarks on the code, which were processed.
If there is a feeling that adding the HeatIndex complicates the example, maybe this example should be a separate file, named "DhtHeatIndexSensor"?
@skywatch My apologies for derailing the topic, yep, got two of the boiler feed and return also, and tapped into the trigger wire to notify boiler ON/OFF so Domoticz tracks the run time per day.
12 degrees is recommended across the radiator but it's not quite so simple, it also matters WHEN you get that differential -
That's where the portable node came in. Plastic pipe clips held sensors on the inlet and outlet pipes of the rad, the downstairs 6 all had a 11-12c differential at around 16/17 minutes, but no way would the upstairs 3 get there before the boiler cycle ended (room thermostat), which I put down to longer pipe runs.
I increase the rate on the thermo-valve (pressure agnostic) to get the same heat on the return at ca 18 minutes. Rinse/repeat the remaining 2, eh voila. Balanced, a nice little peak on the return flow temperature at the boiler, reduced gas bills and every room +/- 0.5 of it's set point.
Actual differential of these 3 upstairs radiators will be WAY under 12 for a constant feed, but for a heat cycle of 19-25 minutes depending on outside temperature it's perfectly balanced before the cycle ends.
@mfalkvidd: So you are right, requestEcho is the end-to-end echo parameter but end-to-end means something else what I thought.
Meanwhile I tested the other direction: controller (node-red) ->mqtt -> gateway -> sensor_node message sending with ack turned on in mqtt message. I found that in this direction the sensor node sends back echo automatically to the controller through gateway and through mqtt. So it is real (full) end-to-end echo If the controller sending command to my-sensor node, but it is not that if the node sends data to controller (in that case gateway sends back echo to node). I haven't found a description in documentation about this behavior. Is it planned to add this feature to tell the gateway to enable pass through echo request to controller? So communication in both direction whould be symmetric. Thanks!
OK, now I understand what you meant. And I was talking about immediately building an all-in-one gateway with W5100, RS485, NRF24 and RFM69. That would require 2 SPIs and 2 USARTs. Taking that into account the ATmega324PB would be a perfect match. And, indeed, I wanted to build it step-by-step and only wire the according MCU pins to pinheads to extend it later.
The big downside of the ATmega324PB is the 5V voltage level @ 16MHz and the limited memory. I compiled the sketch from the all-in-one gateway and came up with about 95% flash usage. So there's not much space left for the future. And I think 16MHz would make sense for the gateway and 8MHz could be a bit slow. 12MHz@5V would be in spec, but 12MHz is quite uncommon.