ADXL345 I2C Accelerometer NOT WORKING

[saquib]

ive been having some trouble coding for the accelerometer and i am very confused as to how i can use the i2c bus to actually read from the accelerometer
it would be very helpful if i could get some some sample code or a basic outline of what i need to do

[jhersh]

Originally Posted by saquib

ive been having some trouble coding for the accelerometer and i am very confused as to how i can use the i2c bus to actually read from the accelerometer
it would be very helpful if i could get some some sample code or a basic outline of what i need to do

There is a class for the sensor that only has a few functions and they are documented. What exactly are you having trouble with? You can look at the LabVIEW example for the ADXL345 to see a wiring diagram.

-Joe

[brian3795]

Originally Posted by jhersh

There is a class for the sensor that only has a few functions and they are documented. What exactly are you having trouble with? You can look at the LabVIEW example for the ADXL345 to see a wiring diagram.

-Joe

Either we have a borked ADXL345, or the LabVIEW code isn't working. The example code just returns a "sensor not responding" error code. It's wired correctly, with the "correct" address of 0x3A.

[jhersh]

Originally Posted by brian3795

Either we have a borked ADXL345, or the LabVIEW code isn't working. The example code just returns a "sensor not responding" error code. It's wired correctly, with the "correct" address of 0x3A.

Do you have any equipment (oscilloscope or logic analyzer) you can debug this with? Can you look at the I2C bus to determine if the traffic looks good or not?

-Joe

[brian3795]

Originally Posted by jhersh

Do you have any equipment (oscilloscope or logic analyzer) you can debug this with? Can you look at the I2C bus to determine if the traffic looks good or not?

We have access to a scope...have any references for us as to what "good traffic" will look like?

[jhersh]

Originally Posted by brian3795

We have access to a scope...have any references for us as to what "good traffic" will look like?

Just look at the data sheet for the ADXL345... it should have some waveforms in it.

[brian3795]

Yep, see them...will give the scope a try and see what's up.

[brian3795]

Well, we ended up getting it to work in SPI mode (we did have to shorten the loop time from 100ms to 10ms). So we'll just live with that unless we run out of DIO ports. Thanks!

[Trevin]

I have been trying to hook up my accelerometer and have had similar problems. I am writing in Java and have tried using the ADXL345_I2C class to interface with the accelerometer, but to no end. Every time I try to get the acceleration all I get back is 0, no matter how much I shake it.

I have also tried using I2C directly and still got nothing.

I would like to try SPI, but I don't know how I would get the data back in the code, the DigitalInput class only returns boolean values, not doubles.

If someone could tell me how to use SPI in Java or what I'm doing wrong with the I2C I would really appreciate it!!! Thanks.

[jhersh]

Originally Posted by Trevin

I have been trying to hook up my accelerometer and have had similar problems. I am writing in Java and have tried using the ADXL345_I2C class to interface with the accelerometer, but to no end. Every time I try to get the acceleration all I get back is 0, no matter how much I shake it.

I have also tried using I2C directly and still got nothing.

I would like to try SPI, but I don't know how I would get the data back in the code, the DigitalInput class only returns boolean values, not doubles.

If someone could tell me how to use SPI in Java or what I'm doing wrong with the I2C I would really appreciate it!!! Thanks.

There is not currently an easy-to-use API in java for accessing SPI so I recommend against that (unless you are savvy C++ to Java porters and would like to contribute an implementation). I2C should work (works on the sensor I have) but check for errors on the console.

Joe

[Bob649]

(Bump on an old thread and hope someone sees it!)

Hello all,
I am having the same problem. We are using Java. Can someone post the wiring diagram from LabView or a screenshot of it? I can not find one though I looked. I did put a scope on the clock and data and they show traffic, but I don't have a protocol analyzer to tell if the traffic is correct.
Also can anyone who has it working confirm if we need to put out own pullup resistor on the CS pin to get into i2c mode? It doesn't look like it, but it could just be the cRIO telling the senor to wake up over and over again.
The code seems so simple I can't imagine it is the code, but if anyone knows any non-obvious points, that would also be appreciated.
Thank you in advance!

Bob
PS My first CD post!