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Unread 16-02-2012, 17:26
jhersh jhersh is offline
National Instruments
AKA: Joe Hershberger
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Re: Unable to read accelerometer

Quote:
Originally Posted by StephenNutt View Post
I borrowed a Total Phase Beagle I2C analyser from work and have some additional info.

When successfully reading the I2C bus from an Arduino the clock speed is 100kHz. When unsuccessfully using the cRIO the clock speed is 38.4kHz (the Beagle reports the clock as every 26us)
That is the expected clock rate for I2C on the digital side car... 6.5us access period * 4 cycles to make the waveform.

Quote:
Originally Posted by StephenNutt View Post
The accelerometer is not acknowledging with an ack - the SDA line is not going low after after the final bit is sent from the cRIO.
This basically means that no device believes that it is being addressed. Possibly signal integrity, though at that speed I'd be surprised. Are you using the scope to watch the signals at the sensor or at the DSC?

-Joe