H48c g forces
mosquito56
Posts: 387
The h48c demo has this info on how to· read the g forces on the accelerometer. This seems to have been copied from the docs on the·parallax site. However there is no docs on what the word "axis" means.· The bs2 program uses it but I can't make sense of the code.
Can anyone translate "g=axis/455" to spin?·I have tried every combination the demo provides.
·The bs2 code uses·vref to calculate g, but in the demo, vref never·changes.
G = ( axis / 4095 ) x ( 3.3 / 0.3663 )
······· or
G = axis x 0.0022
······· or
G = axis / 455
An expected return value from each axis would range between ±1365.
i.e.
·±455 would represent ±1g
·±910 would represent ±2g
±1365 would represent ±3g
Any help would be appreciated
Don
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
·······
······· "What do you mean, it doesn't have any tubes?"
······· "No such thing as a dumb question" unless it's on the internet
········
Can anyone translate "g=axis/455" to spin?·I have tried every combination the demo provides.
·The bs2 code uses·vref to calculate g, but in the demo, vref never·changes.
G = ( axis / 4095 ) x ( 3.3 / 0.3663 )
······· or
G = axis x 0.0022
······· or
G = axis / 455
An expected return value from each axis would range between ±1365.
i.e.
·±455 would represent ±1g
·±910 would represent ±2g
±1365 would represent ±3g
Any help would be appreciated
Don
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
·······
······· "What do you mean, it doesn't have any tubes?"
······· "No such thing as a dumb question" unless it's on the internet
········
Comments
This data originates from the H48C pdf on our product page...
www.parallax.com/Portals/0/Downloads/docs/prod/acc/HitachiH48C3AxisAccelerometer.pdf
Multiplying by 0.0022 is the approximately the same as dividing by 455.
The value for 'axis' is the returned "raw" value from one of the three axis you request in software.
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Beau Schwabe
IC Layout Engineer
Parallax, Inc.
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
·······
······· "What do you mean, it doesn't have any tubes?"
······· "No such thing as a dumb question" unless it's on the internet
········
Just sitting still you have 1g of force exerted on you, as you move that force changes relative to gravity. The sensor is the same way if it is laying flat on the table it should report 1g on the Z axis and close to 0 G on the X and Y axis... if you flip the sensor upside down and let it rest, you should see a -1g on the Z axis. By moving the sensor perpendicular to the flat resting position you can affect the X and Y axis in a similar way.
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Beau Schwabe
IC Layout Engineer
Parallax, Inc.
Thanx much
Don
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
·······
······· "What do you mean, it doesn't have any tubes?"
······· "No such thing as a dumb question" unless it's on the internet
Post Edited (mosquito56) : 6/10/2009 6:49:50 PM GMT