PDA

View Full Version : BS2SX + A/D + Accelerometer advice needed



OAV
08-15-2008, 06:18 AM
Hi guys

I need some advice please.



I have a BS2SX and have recently purchased a 3D Accelerometer (http://www.dimensionengineering.com/DE-ACCM3D.htm). Obviously without reading up enough since it is an analog device and interfacing to BS2 was going to be difficult if not impossible.

So after reading one of Tracy's articles on using the TLC2543 (http://www.emesystems.com/OL2tlc2543.htm#TLC2543)·A/D converter with a stamp, I thought that that would do the trick.

Now I am approaching this from a programmer's perspective and my electronics knowledge is a bit limited, but basically I need to know if I am wasting my time with this or if you guys recon I will be able to make it work.

The aim of the project is to use the accelerometer to sense orientation and then use 2 servo's to keep a platform level.

Ok, so this is what i've done:
I used the BS2SX's 5v out as power and reference for the ADC. I used Tracy's article to get the ADC working. It is basically interfacing the TLC2543 with the stamp, reading the 11 channel values and displaying them. When I run the test application (code as per Tracy's article), I get numbers on all 11 open channels. They range from 300-400 (that is in a 0-4096 range for the 12bit conversion) but nothing stable. I thought that they would probly drift a lot because they are all open, so I went ahead and added the Accelerometer. Using the same +5v off the BS2SX. I connected one of the axis output to channel 1 of the ADC.
It gave me a different range of values, but jumping all over the place. Moving the accelerometer around did not visabily change the numbers, but I tested it independantly and I got values in the +1.9v to 2.6v·range by moving it about, so it seems to work.

Ok, so that was my uneducated, hope its easy and will just work approach, but obviously I need some direction and help.

Any help and advice appreciated.

OAV
08-26-2008, 07:03 PM
^^
any advice welcome!!

stamptrol
08-26-2008, 08:06 PM
OAV,

Quite likely, you'll have to filter the analog voltages with a bit of capacitance to give the a/d a stable value.

The link you gave contains several sample projects, the last of which is pretty close to what you're trying to do.

I'd probably ground any unused channels on the a/d.

Cheers,

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Tom Sisk

http://www.siskconsult.com
·