I have a few BME 280 sensors and I am going to do a project with 6-7 of them in a theatre for a live performance.
I have been in touch with arduino before but only in small scale. This is the first time im playing with more space. I am struggling if I should use cable to have all the sensors sending data to my Arduino, using SPI (as I did some research is it not possible for I2C to communicate over cable >1m.
However, it is a theatre of the relatively small size. Other discussions I have seen online are mostly about 20m+ distance. Considering the cost, I think wireless will be a bit costly but if that's an absolutely better solution I may also go with that.
Can anyone advise me what should I do? Many thanks!!
You are only giving two dimensions of a three dimension space. Just monitor the air temperature at the highest point or at the place where the warm air leaves the space.
It is true that I2C is designed for short distance communications, but it can be made to work over longer distances. I have it working over about 30m without difficulty. I suggest you experiment and see if you can get it working to your satisfaction over the distances you need, or better still, over twice the distance you need. If you can do than then you have something you can use for your project.
I suggest:
2 twisted pairs, so telephone cable or cat 5/6
One pair 0V and SCL
One pair +5V and SDA
0μ1 capacitors across 0V and +5V at each end of the cable.
Only you can decide that. Nobody else knows anything about the environment, and would hardly dare guess why you need 6-7 sensors. An ESP-01 is probably cheaper than a decent cable to to connect to the base Arduino, and is made for this sort of thing, but you still have to power it.
If all you want to measure is temperature, BME280 seems like a waste, because those can also measure pressure and humidity. Plus they are i2c and only 2 can be connected to the same bus, so a bus multiplexer would also be needed.
DS18B20 would seem like a better choice. They only measure temperature and you can connect as many as you like to the same cable (ok, I'm sure there is a limit, but I'm sure it will be many more than 7).
It might be worth saying why you want to do this , in case there is a different solution - what do you do with the readings ?? Display? Control ?? Just data logging ?? , permanent install ?? All effect the viability of the Arduino solution , you should compare options for the job .
You need to specify all this up and work out a budget .
I would go down the DS18B20 and cables route myself .. But I would look at what is commercially available as this aspect is likely to be the most expensive and packaging your own parts can be tricky ( esp in public areas ).
I would have thought radio might suffer from interference in this environment , and it still needs power .