Connecting Multiple Sensors to BBB

Hi guys,

I’ve just started out with the BBB, and am basically wanting to use it initially, to gather data on temperature and humidity both inside and outside my property (sensor in each room + 1 outside). Obviously there are going to be quite a few sensors, is it possible to get all these up and running at the same time? I know there are lots of GPIO connectors on the BBB, but only a few voltage connectors, how do I go about splitting these?

Also, would it be possible to wire up the sensors using alarm cable? They will be quite far from the controller in some instances.

Regards
Mike

Wiring would be a nightmare. You have maybe a foot on I/O and 3 feet
with bus extenders for I2C. You want wireless sensors of some type.
OR there are X10 modules that do a lot of what you want maybe you can
interface them to a BBB.
Remember you have voltage loss on powering things over long wiring.

Hi,

Yeah indeed. I’ve just purchased a single sensor for starters to have a play with, and see how I go. I looked into wireless sensors to begin with, but there doesn’t seem to be any set standard, as I was all for a Ninja Block using 433mhz, but even they say that no compatibility was guaranteed. I’ll look into the X10 modules.

Regards
Mike

Greetings,
    Look into "1-wire" sensors. Then work over hundreds of feet using telephone wire and simple line drivers/receivers. Many devices available including temperature, humidity, relays, switch closure, etc.

       --- Jay Nugent WB8TKL
           Ypsilanti, Michigan

One thing to worry about is lightning! I have such a system built with VERY OLD technology, which is probably much more resistant to damage, but have had parts of it blown out at times by thunderstorms. i have one sensor just outside the wall of the house for outside temperature. I use the Analog Devices AD590 series, which is a current proportional sensor. The current through the sensor is 1 uA per degree K. Alarm wire is fine, especially with a current sensor, as noise will largely be cancelled out. But, you need a signal conditioner to bias the detector and convert current to voltage. A simple op-amp circuit can do this. I use a pretty fancy humidity sensor that needs signal conditioning by an exotic AD part, but it gives very good results. Calibrating a humidity sensor is a lot harder than a temperature sensor.

Jon