28029 Parallax Inc, 28029 Datasheet - Page 110

• 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

Page 98 · Smart Sensors and Applications
To reverse the angle of rotation the that program displays, all you have to do is use −Ay
instead of A
counterclockwise, A
arctangent of −A
Figure 3-25: Reversing Direction of Rotation with -Ay
This change is easy to make in the program. Simply insert a negative sign before the y in
angle = x ATN y
ACTIVITY #6: MEASURE TILT FROM THE HORIZONTAL
This activity measures how far the Board of Education is tilted from the horizontal.
Figure 3-26 shows the Board of Education with the Memsic Accelerometer on the
breadboard. The accelerometer's acceleration-sensing axes (x
top and left of the Board of Education. This activity develops a program that displays the
tilt angle for each axis. When the board is held level, the tilt angle is 0° for both the x
an y
tilt angle for the y-axis. If you tilt it so that y
angle. The same applies for x
tilt angle. If you tilt the board towards one of its corners, the program will report tilt for
both the x
tan
tan
√
√
√
−
−
m
1
1
⎛ −
⎜
⎜
⎝
⎛ −
⎜ ⎜
⎝
axes. If you tilt the board so that y
Save VertWheelRotation.bs2 as VertWheelRotationCounterclockwise.bs2
Change
Run the program and verify that the rotation angle now increases as you rotate
the board counterclockwise.
A
Ax
A
Ay
m
X
Y
and y
⎞
⎟ ⎟
⎠
⎞
⎟
⎟
⎠
y
=
=
.
tan
tan
angle = x ATN y
y
m
/A
Take a look at Figure 3-25.
.
axes.
x
−
−
y
, the result is 30°.
1
1
⎛
⎜
⎜
⎜
⎜ ⎜
⎝
⎛
⎜
⎜
⎜
⎜ ⎜
⎝
is −1/2, and the arctangent turns out to be 330°. By taking the
2
2
2
1
1
3
3
2
⎞
⎟
⎟
⎟
⎟ ⎟
⎠
⎞
⎟
⎟
⎟
⎟ ⎟
⎠
=
=
m
330
30
; point it up for a positive tilt angle or down for a negative
°
°
to
angle = x ATN −y
m
points up, the program will report a positive
m
points down, it will report a negative tilt
If you rotate the accelerometer
.
m
and y
m
) point toward the
m