28125 Parallax Inc, 28125 Datasheet - Page 129

• Manufacturer Part Number: 28125
• Description: TEXT ROBOTICS
• Manufacturer: Parallax Inc

Specifications of 28125

• Title: Robotics with the Boe-Bot
• Product: Microcontroller Accessories
• Lead Free Status / RoHS Status: Not applicable / Not applicable

be 650. If you enter a pulse width of 700,
examples. They will all add up to 1500.
A
pulseWidthComp
direction.
Your Turn – Advanced Topic: Graphing Pulse Width vs. Rotational Velocity
Figure 3-20 shows an example of a transfer curve for a continuous rotation servo. The
horizontal axis shows the pulse width in ms, and the vertical axis shows the rotational
velocity in RPM. In this graph, clockwise is negative and counterclockwise is positive.
This particular servo’s transfer curve ranges from about -48 RPM to 48 RPM over the
range of test pulse widths that range from 1.3 ms to 1.7 ms.
FOR…NEXT
-20
-40
-60
60
40
20
0
1.300
pulseWidthComp = 1500 - pulseWidth
FOR counter = 1 TO 244
NEXT
PULSOUT 12, pulseWidth
PULSOUT 13, pulseWidthComp
PAUSE 20
loop that runs for 6 seconds sends pulses to the right (P12) servo. The
1.350
value is sent to the left (P13) servo, making it turn in the opposite
Rotational Velocity vs. Pulse Width for Servo
1.400
1.450
Pulse Width, m s
Right Servo
1.500
1.550
pulseWidthComp
1.600
1.650
will be 800. Try a few other
1.700
Figure 3-20
Transfer Curve
Example for
Parallax Servo