Design of 1-axis angular rate sensor (gyro) on I2C bus using MSP430

[peppecol]

Hi everybody, I need some help.
I'm working on a project of 1-axis angular rate sensor (gyroscope) able to sense an angular velocity of 10rpm...communicating with a microcontroller MSP430 on I2C bus. This sensor would be assembled aboard a small satellite, used for the attitude control subsystem.

I'm looking on web for a single axis gyro that uses the I2C interface. The only "I2C gyro" I found was the STMicro LY530AL, the others are all SPI.
Does anyone have any suggestions?

If I use an analog output gyro as ADXRS620, what can I do?
Can I use an appropriate ADC with I2C output to interface the analog output of the sensor with the microcontroller, or what else?

Does someone have some useful advices for my work, links on projects or schematic design whom I can look at?

Thank you all for your time
Joe

 

[VEBill]

Is it going to be one of those cubic-foot microsats? Is this a school project? Site rules prevent us from helping students with their projects. Excuse me for asking, but it needs to be asked.

If it's a microsat (with all that implies about how it is ejected into orbit), then how do you know that it'll be neatly spinning around one predefined axis? Combined with the availability of tiny MEMS 3-axis gyros (hint: iPhone 4), wouldn't it be safer and no additional mass to go with three axis?

 

[itsmoked]

I would go with three axis too as it covers all your contingencies. That might get you an I²C version. Or the A2D method is also valid. Why are you stuck on I²C? I hate it myself. You can always bit-bang SPI very easily.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[IRstuff]

ST doesn't spec their gyro drift, but most such gyros can have pretty ferocious drifts. Therefore, in addition to the suggestion of using a 3-axis gyro, you might consider something that includes a 3-axis compass as well, since you can use the compass to determine whether the gyro is lying or not. Something like this:

http://www.sparkfun.com/products/10125

might be useful. It also includes a 3-axis accelerometer.

TTFN

FAQ731-376
Chinese prisoner wins Nobel Peace Prize

 

[AustinMatt]

What is wrong with using SPI instead? Are you extremely limited in pin count or board space? I haven't worked with gyros, but I have used both SPI and I2C on the MSP430. I've also used both the USI and USCI to do this. None are especially difficult to implement.

It definitely doesn't make sense to me to use a separate ADC module just so you get I2C.