How many sensors will work at a time in an Arduino for Home automation?

Question

As I am thinking to do a Home automation using Arduino, using Light sensor, temperature control , motion sensor , gas leakage sensor , fire detection sensor , hall effect sensor for Light on/off , fan on/off and fan speed control , motion detection , alarm for gas / fire detection , door open/close respectively. But my question is how many sensors will work at a time in at an Arduino board?
And is it possible to control Arduino by using PIC or i.MX6 Dual Lite/Solo?

Answer 1

If the sensors use I2C then the limit is 128 devices on the bus, but they each have to have a unique address which are sometimes "hard-coded" on the device by the manufacturer. The Arduino Wired library is used to read/write I2C and it only takes two pins. I2C is also sometimes called TWI (Two Wire Interface). The PIC can do I2C, not so sure about the i.MX6 but I've controlled an Arduino over I2C using a Raspberry Pi.

Answer 2

For the Arduino Uno go here to find the specifications of the open source design:

http://arduino.cc/en/Main/arduinoBoardUno

There you will read that the Arduino Uno has 14 digital and 6 analog I/O pins.

Note, you are not limited to the number of sensors based on the number of I/O pins.

Example:

Any processor has a limited number of I/O pins. You can add hardware to multiplex external signals before they get to these I/O pins. For example, say the processor has 4 I/O pins. You can devote 3 to control a multiplexer selecting 1 of 8 signals to route to the 4th processor I/O pin. Thereby doubling the number of inputs you can sample.

Answer 3

You can use many number of sensors as you wish. But your board need to have that much I/O pins. Try to get mega Arduino board. Arduino Mega 2560 has 54 pins totally. So in the mega board you can connect many sensors.

You can also control the board by PIC, Arduino sketch and so on.