Processing Accelerometer Data

[beakie]

Hi,

I am confusing myself trying to process the data from EZ430 accelerometer.
Here is what I am working with. Where am I going wrong please?

File:
https://www.electro-tech-online.com/attachments/output-txt.51098/

**Constants:**
Gravity = 80 (This is a guesstimate)

**Columns:**
A: RAWX
B: RAWY
C: RAWZ
D: (IIf(A < 128, 0, 256) - A) / Gravity
E: (IIf(B < 128, 0, 256) - B) / Gravity
F: (IIf(C < 128, 0, 256) - C) / Gravity
G: Math.Asin(D)
H: Math.Asin(E)
I: Math.Asin(F)
J: -(Math.Asin(D) / Math.PI * 180)
K: -(Math.Asin(E) / Math.PI * 180)
L: -(Math.Asin(F) / Math.PI * 180)


**Data:**

****BEGIN TAKING SAMPLES OF POSITION 1****
245 198 229 0.138 0.725 0.338 0.138 0.811 0.344 -7.903 -46.469 -19.725
245 198 229 0.138 0.725 0.338 0.138 0.811 0.344 -7.903 -46.469 -19.725
245 198 229 0.138 0.725 0.338 0.138 0.811 0.344 -7.903 -46.469 -19.725
244 198 229 0.15 0.725 0.338 0.151 0.811 0.344 -8.627 -46.469 -19.725
244 198 229 0.15 0.725 0.338 0.151 0.811 0.344 -8.627 -46.469 -19.725
244 197 228 0.15 0.738 0.35 0.151 0.829 0.358 -8.627 -47.519 -20.487
****BEGIN TAKING SAMPLES OF POSITION 2****
246 43 229 0.125 -0.538 0.338 0.125 -0.567 0.344 -7.181 32.514 -19.725
246 43 229 0.125 -0.538 0.338 0.125 -0.567 0.344 -7.181 32.514 -19.725
245 43 228 0.138 -0.538 0.35 0.138 -0.567 0.358 -7.903 32.514 -20.487
245 43 229 0.138 -0.538 0.338 0.138 -0.567 0.344 -7.903 32.514 -19.725
245 43 229 0.138 -0.538 0.338 0.138 -0.567 0.344 -7.903 32.514 -19.725
245 44 229 0.138 -0.55 0.338 0.138 -0.582 0.344 -7.903 33.367 -19.725
****BEGIN TAKING SAMPLES OF POSITION 3****
241 247 177 0.188 0.112 0.988 0.189 0.113 1.413 -10.807 -6.459 -80.931
241 247 177 0.188 0.112 0.988 0.189 0.113 1.413 -10.807 -6.459 -80.931
240 247 176 0.2 0.112 1 0.201 0.113 1.571 -11.537 -6.459 -90
241 247 177 0.188 0.112 0.988 0.189 0.113 1.413 -10.807 -6.459 -80.931
241 247 177 0.188 0.112 0.988 0.189 0.113 1.413 -10.807 -6.459 -80.931
241 247 177 0.188 0.112 0.988 0.189 0.113 1.413 -10.807 -6.459 -80.931
****BEGIN TAKING SAMPLES OF POSITION 4****
203 248 219 0.662 0.1 0.462 0.724 0.1 0.481 -41.491 -5.739 -27.549
203 249 219 0.662 0.088 0.462 0.724 0.088 0.481 -41.491 -5.02 -27.549
203 249 218 0.662 0.088 0.475 0.724 0.088 0.495 -41.491 -5.02 -28.359
203 249 219 0.662 0.088 0.462 0.724 0.088 0.481 -41.491 -5.02 -27.549
203 248 219 0.662 0.1 0.462 0.724 0.1 0.481 -41.491 -5.739 -27.549
204 248 219 0.65 0.1 0.462 0.708 0.1 0.481 -40.542 -5.739 -27.549
****BEGIN TAKING SAMPLES OF POSITION 5****
41 244 201 -0.512 0.15 0.688 -0.538 0.151 0.758 30.83 -8.627 -43.433
41 245 201 -0.512 0.138 0.688 -0.538 0.138 0.758 30.83 -7.903 -43.433
41 245 201 -0.512 0.138 0.688 -0.538 0.138 0.758 30.83 -7.903 -43.433
40 245 202 -0.5 0.138 0.675 -0.524 0.138 0.741 30 -7.903 -42.454
41 244 201 -0.512 0.15 0.688 -0.538 0.151 0.758 30.83 -8.627 -43.433
41 245 201 -0.512 0.138 0.688 -0.538 0.138 0.758 30.83 -7.903 -43.433
****BEGIN TAKING SAMPLES OF POSITION 6****
243 247 177 0.162 0.112 0.988 0.163 0.113 1.413 -9.352 -6.459 -80.931
243 247 176 0.162 0.112 1 0.163 0.113 1.571 -9.352 -6.459 -90
243 247 176 0.162 0.112 1 0.163 0.113 1.571 -9.352 -6.459 -90
243 247 177 0.162 0.112 0.988 0.163 0.113 1.413 -9.352 -6.459 -80.931
243 247 177 0.162 0.112 0.988 0.163 0.113 1.413 -9.352 -6.459 -80.931
243 247 176 0.162 0.112 1 0.163 0.113 1.571 -9.352 -6.459 -90

 

[misterT]

Are you talking about EZ430-Chronos watch. How did you get the data you posted?

 

[beakie]

Are you talking about EZ430-Chronos watch. How did you get the data you posted?

eZ430 Chronos .Net - Browse Files at SourceForge.net

The value for gravity (80) comes from the value on a third axis when the other two are at 0.

This is a surprising value as I expected 64. The device is +-2g therefore 1g should be a quarter of the returned range (0-256), right?

 

[beakie]

Rephrased question here... https://www.electro-tech-online.com/threads/accelerometer.116384/

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