Accelorometer - robot balance -- Lab View examples

[mbone206]

Hi...

i wasn't sure if this should be LabView or Sensor forum, i decided to try sensor first..

I am helping my team and they ask me to look into using the Accelerometer to give feed back if robot is balanced on board.

First queston: I do not have any experience with this (not much experience in Robotics as a whole), has anyone used the accelerometer in past for a similar task to what my team wants to accomplish? Will accelerometer be accurate enpough and/or do you expect too much noise in measurements?

I did searches on other links and noticed some people recommend filtering, but wasn't in Lab View. Also, in my research, one link indicated need to send code to turn on accelerometer, but that person used IC2 set up. Does SPI need same type of software intialization, did not see it in LabView
examples?

I reviewed all of the LabVIew examples and found 4. IC2 and SPI are the first two. From what I read, it appears there are two ways to communicate with board, does anyone have experience with the two options, any preference by experience? my team has wired up for SPI because they indicated it was easier to wire, they never wired/used the IC2 connections.

So it looks like I will be starting with SPI (J4 wire connection)
I found ADCL345 data sheet and tried to make some sense of it, a lot of info. Page 15 indicates SPI has 3 or 4 wire conenction, reference figure 34 & 35. figure 34, 35 is on same page, but shows different signal names in figure than what is in Lab View example.

SPI Example,can someone explain this more, uses for MOSI channels?

Other two example are alarm and angle. I am assuming the angle example is the one I should get familar with (ie... when angle at X +/- 2 degrees, robot will be balanced???)

Tha Labview Angle example shows y-axis (Y-5-G) and X-Axis (X-5-G), I do not know how to correlate that to the SPI wiring my team did or with SPI Lab View example.

I am using Lab View, since I am not a programmmer and this team needs help programming (LabView easier and quicker to learn and work with students)

I would greatly appreciate support in right direction since I already spent a lot of time on this and still feel like I made minimal progress (working on this part time at nights after regular job to help team). I will be working on Robot tomorrow night again and hope to have some input before I get there.

thank you
Mark

[NeatNit]

The SPI and I²C examples are for the ADXL345 digital accelerometer. They also show you how to wire it up when you open each example. They're two different ways to connect it, choose whichever you like.

Personally I could not get either one working, but if you do - great for you.

The other two examples are not designed for the ADXL345 - they're designed for analog accelerometers, that work with 0-5 v, and so will not work with the ADXL345. You could change them using code from the SPI/I²C examples to make them work, if you want.


I could not understand from your post what you're seeking assistance with, so I'm guessing the accelerometer doesn't work for you. It doesn't for me either. I'll let you know if I make any progress, but it looks like a lost cause
I'm just about to give up on the ADXL345 and buy an analog accelerometer.

[Joe Ross]

Originally Posted by NeatNit

Personally I could not get either one working, but if you do - great for you.

The SPI example has a bug, which is fixed here: http://firstforge.wpi.edu/sf/go/artf1432

[NeatNit]

I've tried that one already, didn't work either. I2C works though, using the fixed flat db-37 cable from the kit instead of the older round one!


Still no clue why SPI doesn't work, but honestly I don't care