28029 Parallax Inc, 28029 Datasheet - Page 119

• Manufacturer Part Number: 28029
• Description: KIT PARTS SMART SENSORS W/TEXT
• Manufacturer: Parallax Inc

Specifications of 28029

• Accessory Type: Parts Kit
• Product: Microcontroller Accessories
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• For Use With/related Products: BASIC Stamp® or Javelin Modules
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Contains lead / RoHS non-compliant
• Other names: 28029PAR

With the MX2125, a measurement of 1875 is −1 g, and a measurement of 3125 is 1 g. In
Activity #3, we scaled this to a range of −127 to 127. Remember that −127 is the
equivalent of −1 for the
between −127 and 127 is the equivalent of a fraction, and coming from the MX2125, it's
actually sin θ. So, once the MX2125's measurement has been scaled to −127 to 127, all
you have to do is use the
The simplest way to write a tilt program is to start with the previous example program,
TestArcsine.bs2. Then, incorporate the accelerometer measurement and scaling and
offset commands from TestScaleOffset.bs2 and the accelerometer measurements from
VertWheelRotation.bs2. This program's Main Routine boils down to two commands for
measuring the x and y axes, two commands for scaling, and two small routines that call
the
Figure 3-32: Determining Tilt Angle with Arcsine
Arcsine
DO
PULSIN 6, 1, x
PULSIN 7, 1, y
x = (x MIN 1875 MAX 3125) - 1875 ** 13369 - 127
y = (y MIN 1875 MAX 3125) - 1875 ** 13369 - 127
subroutine and display the result.
Arcsine
Arcsine
subroutine to determine the tilt angle (the value of θ).
subroutine, and 127 is the equivalent of 1. Anything
Chapter 3: Tilt with the Memsic Accelerometer · Page 107
A
sin
sin
θ
A
g
X
=
X
−
θ
sin
=
=
1
=
g
(
sin
sin
−
A
sin
1
g
X
θ
⎛
⎜
⎜
⎝
θ
A
θ
)
g
X
=
sin
⎞
⎟
⎟
⎠
−
1
⎛
⎜
⎜
⎝
A
g
X
⎞
⎟
⎟
⎠