Memsic2125 theta question

MacGeek117

I've been trying to Spin without a Prop and have moved on to the Memsic 2125 driver, but my project needs the theta values for forward, back, left, and right. Could someone please post the values for those directions?
RoboGeek

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Beau Schwabe

RoboGeek,

I am not exactly sure what you are asking?

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Beau Schwabe

IC Layout Engineer
Parallax, Inc.

MacGeek117

In the NV column, "No more coffee spills", the brad measurements for 0 degreees, 90, 180, and 270 degrees. I would like to have the same for the raw theta values.
RoboGeek

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"I reject your reality and subsitute my own!"

Adam Savage, Mythbusters
www.parallax.com
www.goldmine-elec.com
www.expresspcb.com
www.startrek.com
·

Beau Schwabe

RoboGeek,


BRADS are "Byte radians" ... Simply a way to represent 0-360 deg within a BYTE value ranging from 0-255

BRAD = (DEG / 360) * 255

..or for integer math...

BRAD = DEG * 255····· <--- For the Propeller (360 * 255) would not be an overflow problem
BRAD = BRAD / 360


Applying the above formula...

  0 Deg = 0 Brads 
 90 Deg = 63 Brads 
180 Deg = 127 Brads 
270 Deg = 191 Brads

The RAW theta values in the object I posted are returned as a 32-bit value but need to be shifted right 19 places
to create a valid 13-bit value that ranges from 0 to 8192 ($0-$1FFF)

deg := acc.theta >>19

Brads := deg * 255 / $1FFF

13-bit degree    0 =   0 Brads    '  0 Deg 
13-bit degree 2047 =  63 Brads    ' 90 Deg
13-bit degree 4095 = 127 Brads    '180 Deg
13-bit degree 6143 = 191 Brads    '270 Deg

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Beau Schwabe

IC Layout Engineer
Parallax, Inc.

MacGeek117

Thanks, Beau!
RoboGeek

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
"I reject your reality and subsitute my own!"

Adam Savage, Mythbusters
www.parallax.com
www.goldmine-elec.com
www.expresspcb.com
www.startrek.com
·