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#1
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Interfacing 3.3 Volt Logic sensors with CRIO
We have bought a sensor board that includes a 3 axis: Acceleration, Gyroscope, and Magnetometer. It is interfaced via the i2c bus using 3.3 volt logic. We have spent alot of time trying to use our logic level converter ic to translate the logic levels however nothing has worked. We are now trying to just run the 5 volt logic directly to the sensors and this is not working. Does anybody have any ideas of how we should best proceed?
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#2
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Re: Interfacing 3.3 Volt Logic sensors with CRIO
Without having more details, the best I can suggest is that you go back to the logic level converter and do some more troubleshooting.
A few questions that will help us help you: - What IC are you using? - Does the conversion from 5V to 3.3V work if you just hook up a 5V signal and the appropriate power supply? - What about from 3.3V to 5V? - How fast is the I2C bus running, and can your chip handle it? You're going to need an oscilloscope if you don't have one, and maybe a function generator. If you don't have access to these, seek out some mentors from a local university or technology company that might. This Sparkfun board might work, but unless you know what your current problem is, don't expect to plug it in and have everything "just work". |
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#3
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Re: Interfacing 3.3 Volt Logic sensors with CRIO
We are using the Sparkfun 3 sensor board found at the followinghttp://www.sparkfun.com/products/10724
We soldered our logic bus analyzer a TXB0104 to a breakout board. We are 100% sure we have it wired correctly however we could never pass any single through it. The bus is running at the default digital sidecar frequency which I believe is 400Khz? We are thinking the 3.3v logic may not be able to trigger the CRIO high level. |
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#4
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Re: Interfacing 3.3 Volt Logic sensors with CRIO
The Pololu version includes logic level conversion. Different chips. Source code for arduino. http://www.pololu.com/catalog/product/1265
Played with it some this fall. Conclusion that an average FRC bot has to much magnetic interference to calibrate out. Did get a accelerometer and gyro to give heading. Not easy for precision. |
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#5
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Re: Interfacing 3.3 Volt Logic sensors with CRIO
Yes, you're correct that the 3.3V output won't trigger a 5V input.
Simple things which you've probably checked already:
Hmm, nevermind. There's this little note on page 11 of the datasheet: Quote:
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#6
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Re: Interfacing 3.3 Volt Logic sensors with CRIO
Yeah sorry about that I think I may have changed what I was typing mid sentence. That's what I mean't I hooked up the bus pirate. The double regulated 5v supply is looking to be the culprit as I didn't even see the built in regulator on the schematic. Thanks for the second look at things.
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#7
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Re: Interfacing 3.3 Volt Logic sensors with CRIO
Are you saying that you were able to simply resolve your problem by connecting the sensor to the 5 volts rather than the 3.3 volts?
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