x Degrees of Freedom vs. individual sensors

Hello together!

i have a basic question. there are often those 6, 8, 10, 12 Degrees of Freedom Sensors, which combine e.g. accelerometers, gyros and so on. as i can see there is the advantage of saving some pins on the arduino. but why? why is it possible that you have on one gyro like 6 pins, 3 for power (or so) and then 1 for X, 1 for Y and 1 for Z, but one de DoF board only one for the sensor signals? is it more difficult to work with them? what would you do? buy DoF or not?

thank you!

i have a basic question. there are often those 6, 8, 10, 12 Dimension of Freedom Sensors,

I believe the term is Degrees of Freedom.

which combine e.g. accelerometers, gyros and so on.

as i can see there is the advantage of saving some pins on the arduino. but why? why is it possible that you have on one gyro like 6 pins, 3 for power (or so) and then 1 for X, 1 for Y and 1 for Z, but one de DoF board only one for the sensor signals? is it more difficult to work with them? what would you do? buy DoF or not?

You lost me there. Are you asking about separate analog inputs vs a serial input like SPI or I2C? Since the basic Arduino only has 6 analog inputs it would not be practical to use more then 6 analog channels of input. Serial input provides for many more possibilities.

Well actually i dont know :D

I was looking for the BMA180 and the ITG3200. I found the sensors, but also together on a DoF. So im asking whats better and how comes the DoF uses less pins? :)

and yeah sure, its degrees

GoingForGold: So im asking whats better and how comes the DoF uses less pins? :)

If you have more than one device on a board and together they have fewer pins than the individual devices use it is likely that the devices are sharing a serial interface. For example the current 9 DoF Sensor Stick from sparkfun (http://www.sparkfun.com/products/10724) contains an ADXL345 accelerometer, HMC5883L magnetometer, and ITG-3200 rate gyro. Since all three devices have an I2C (a.k.a. TwoWire) serial interface the boards only needs four connections: Power, Ground, SCK (Serial Clock) and SDA (Serial Data).

If the devices you want to use have a common interface bus (I2C or SPI) you can share pins like that. If they don't share a common interface, for example if you have one SPI device (4 pins + power and ground), one I2C device (2 pins + power and ground), and one 3-channel analog device (3 pins + power and ground), you will need nine pins + power and ground to connect them all. SPI uses D10, D11, D12, and D13. I2C uses A4 and A5. The analog inputs might use A0, A1, and A2.

Which is "better" is up to you. Individual devices might require more pins but might cost less. Some individual devices may be more capable then the ones chosen for a multi-device board. Most devices will be surface-mount so you will either need to design a circuit board or buy them mounted on a breakout board. Think of the n-DoF boards as a multi-device breakout board.

Ok, thank you for this explanation. I'm a bit afraid of complexity, which arises through merging loads of sensors to one.