Smart Home 200m2: I2C Bus Over 40m, P82B715PN, YF-S201, BE280, Cable Choice?

Question

Assumptions: * smart home – area of 200 m2 * all electronics connected by cables – no WiFi * the longest cables will be approx. 40 m long * temperature and humidity measurement at approx. 20 points (2 in each room) * water flow measurement at 10 points (YF-S201) * central unit - Raspberry Pi 3...

ditomek · Accepted Answer

I2C in such a role I have not yet seen. If the basis is to be rPi then I would lay twisted pair cables everywhere but connect the sensors via rs485. Of course, this requires you to actually build a final device based on some microcontroller to which you connect your sensors and flow meter, but it also has its huge advantages: the device can be equipped with a local small OLED display, it can control and work autonomously independently of the rPi. If it fails, basic functionality is still available. When the rPi is online, it takes over control of the entire system. The options really are numerous. However, it is best to build these devices for Ethernet transmission. In my opinion, building 10 units makes it worthwhile to prepare the board and software.

Ronin · Accepted Answer

Do you want to control the whole thing with domoticz? If yes then mysensors gateway on rs485 Link . I have a prototype built with three sensors. It works very well. Mysensors is an arduino, but you can combine systems. I am at a similar stage of implementation myself.

dzambala · Answer

Thank you for your valuable comments. Regarding the flow sensors, of course I have to build a microcontroller and send the data to „control panel”, the sensors are in one place about 4 m to the rPi. On the other hand, when it comes to „environmental sensors” I am looking for a fairly ready-made solution, I2C uses quite a lot of sensors, temperature, humidity, pressure, air cleanliness, etc. I was also considering rs485 but that requires building in both sides of the devices and their software. Obviously this can be done but I'm checking if there are ready-made solutions. Additionally I don't expect any local functionality, one set of sensors will be at the ceiling the other at the floor. There is as much space for electronics as there is in a flush-mounted box. Data is to be collected and processed centrally. Centrally, decisions will be made about control, furnaces, valves on radiators and the air exchange system from below the ceiling towards the floor. The flat is 340 cm high, after one sensor-monitored heating season I will decide whether to mix this air or not;) .

xury · Answer

As for temperature sensors, the DS18B20 is the best for the RPi.Advantages:Native support on raspbian.The 1wire bus is very resistant to conditions. Even when not following the connection topology very strictly. And the length of the cables themselves can be up to several hundred metres. What cannot be said of I2C, for example.As for the BME280 sensor, I have not noticed any significant disadvantages in terms of measurement accuracy. The only 'disadvantage' is that it is not housed in a sealed enclosure like the DS18B20 so there may be environmental problems when using it outdoors.I know you don't want wifi, but I would suggest looking into ESP8266 boards with ESPeasy loaded on them. I have a couple of these and they have been working for a few months now, without complaint. One board can easily handle several sensors or relays. Especially when it comes to I2C sensors, which need to be on short cables to work properly.

jack63 · Answer

. With these several hundred metres, aren't you exaggerating? People have problems with a dozen or so. I myself had problems when monitoring fridge temp with a DS with 12m of twisted pair utp.

dzambala · Answer

I do not want WiFi because: - I want to reduce electro-smog as much as possible . - I have such thick 120 year old brick walls that the router can't reach the room behind the wall, nothing reaches the next room anymore I'm considering an ESP8266 for another project (not for the flat).

tomek1986022 · Answer

It's been a while, so maybe a colleague can tell what he has decided on, I have a similar problem, also don't want to use wi-fi only cables. House under construction, laid out twisted pair 5e cables. I am looking for some solution for domoticz. Can anyone help?

dzambala · Answer

Cables, cables, just cables. Time has passed somewhat but decisions are not quite final . In fact, I returned to the subject of the malinka yesterday. The current work was with the walls and cables. I have several types of cable in the wall: 5e, telephone twisted pair, intercom twisted pair, etc. time will tell what will work. More elaborate sensors: humidity/temperature/pressure/air cleanliness will be I2C + (time will tell what) and this is a February/March topic. Right now I'll be connecting DS18B20's, but that there are quite a few (10 rooms * 4 sensors) and the length of some individual cables is over 35m. On a single GPIO it won't work. I was planning some multiplexers and other ideas, I was even already at the stage of recompiling the malinka kernel. However, it turns out that it is possible to connect a spider with 1-Wire on several GPIO pins simultaneously, we'll see if five independent circuits are enough. I'll let you know in a few days what the effect is.

Anonymous · Answer

I have an extensive system (something over 100 terminal devices). A few life events have given me some thoughts on the matter - well, no one but me can service it. No one in the house or any service technician, even though all the components come from the same manufacturer. Home-made solutions also occur to me - e.g. integration with the gate or intercom. It's fun to mess around with it all - but for me, not for others. It's important to remember that.

dzambala · Answer

95% of devices are measurement and control elements. It is possible to live without this. And when it comes to controlling the radiators there will be an option „manual” and if I am missing …. It will be possible to go back to the existing thermostatic heads in 15 minutes. I'm trying to design it so that without servicing you can continue to live in this tangle of wires. Some of the sensors will work for one season, and decisions will be made based on their readings, e.g. on whether or not to insulate the ceiling. High rooms (340cm), unheated loft above. I'm also going to look at the in and out water temperatures in the radiators to optimise them. I also intend to experiment with shunting air from below the ceiling towards the floor, while filtering dust. Therefore, only measuring points.

Anonymous · Answer

. It sounded different in the first post. This is what the two measurement points look like to me where the yellow line is a measurement on the ground floor at 1.2m height and the pink line is a measurement point at about 1m height but a floor above with the cage open. . The difference is nil. I will do a test with the temperature below the ceiling say 40cm from the ceiling (that ceiling on the first floor in the open staircase) and let you know. [edit] I will first calibrate the 3rd sensor to the other one. I will give the data in an hour.

tomek1986022 · Answer

Mate, as for the sensors I understand, but what about the control? any cable alternatives to sonof? shely? anyone know anything about such solutions?

Anonymous · Answer

. I have mostly radio (868Mhz). I wouldn't push for WiFi. . Viewed from below, the sensors are located at a height of 1) 1,2m 2) 3.6m (0.4m above the floor of the second storey) 3) 5.2m (about 0.3m in front of the ceiling of the second storey) All sensors in open space. I guess the most meaningful difference would be between 3) and 2) which is 0.9°C. Does it make sense to shunt it? What will be the cost of pushing air through? I guess the only advantage would be this air purification (if effective). In my opinion (from experience), more can be saved by lowering the temperature in unused rooms, and if you could still close them off, even with an internal door, the differences in temperature can be considerable. In one such room on the upper floor, I have the temperature set at 16°C. I also regulate the temperature in the bedroom, for example (warmer in the morning and evening, cooler at other times), as well as in other rooms, depending on their purpose. [edit] The reason I have a radio is because I would have to do a general renovation. I'll be pulling cable control (rs485) as I replace the wiring and renovations. Anyway, here I don't have much choice - I have it imposed by the manufacturer. However, I don't think rs485 is a bad option (because of what the protocol represents) but in your case you have to take other aspects into account - such as availability and price of 'proprietary' solutions. [edit] . Do not mix, reduce the volume (suspend the ceiling).

Marcin Paaa · Answer

Hello, Regarding the monitoring of the temperature of the house, I have used the Evohome Honeywell solution at my home the HR92EE starter kit + additional sensors Hr914Ee for rooms such as hallways and vestibule, and HR92EE for rooms. Everything works wirelessly, I have the thermostats on 3 levels, while the control panel is on the middle level. Hollow block walls, ceiling I think plain screed ( 1980s). setup and operation simple. I have taught my son aged 11, so there is someone to replace me in case of problems. If the kids and the wife want it warmer, they simply turn it up in the room of their choice. A super option is control via the android app. So when we go away I can remotely turn on eco mode and when we come back I turn on normal mode. I set the basement and porch to about 10 degrees, so maybe the investment will pay off at some point. The important thing is to hook up most of the appliances to the thermostats and turn the rest down (reduce the flow) then it makes sense. Heating one room causes heating in all unregulated radiators and underfloor heating. Generally recommended. I set it up in about 20 minutes. I had to drill holes in the gas cooker and make cables for the control system. Marcin

tomek1986022 · Answer

Colleagues Marcin Paaa and Erbit this thread is about CABLE solutions not wireless solutions.... If anyone knows of cable solutions then please feel free to comment on the topic.

dzambala · Answer

I like high rooms, that's why I chose such 340cm lowering the ceilings is not an option;) . If there is a need to insulate the ceiling I will do it on the loft side and not on the ceiling side. Added after 3 [minutes]: When I take measurements at my place I'll let you know how it looks to me, I expect more like 2 degrees difference. Running up and down the ladder during the renovation I had the feeling it was a 3 melt difference. Added after 4 [minutes]: . Radiator control most likely based on : T30NC 24V M30 - NC thermoelectric actuator, 24V, M30x1.5 Currently one piece waiting to be tested.

jack63 · Answer

. I suggest the use of so-called three-position actuators. They are a little more expensive than thermoelectric ones but in my opinion more durable and do not require a continuous power supply. As a result, they can be powered wirelessly from batteries. Unfortunately they are a little more difficult to control. For thermal you just need PWM or something equivalent for AC. One controller port. For triple (up - down - off) you need two ports and a suitable program. The best would be an actuator with a stepper motor, helical gearbox and its own motor control logic, but such are the most expensive. Some off-the-shelf controllers have the ability to operate three-position actuators.

dzambala · Answer

But I am interested in only wired solutions as per the subject of the post.

Anonymous · Answer

Fellow jack63 was probably more concerned with the fact that the actuator you indicated closes when de-energised - meaning that it has to be live all the time (and consumes energy) to be open.

jack63 · Answer

. Not dzambala just me that was the point. A few watts per actuator.

dzambala · Answer

T30NC 24V M30 - Working power consumption - 2W - currently acceptable, but I am open to other suggestions at a sensible price

dzambala · Answer

what do you propose instead?

Smart Home 200m2: I2C Bus Over 40m, P82B715PN, YF-S201, BE280, Cable Choice?

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