Datasheet

PmodCON3™ Reference Manual
Copyright Digilent, Inc. All rights reserved.
Other product and company names mentioned may be trademarks of their respective owners.
Page 2 of 2
Header J1
Jumper JP1
Pin
Number
Description
Jumper
Setting
Description
1
Servo P1
VCC
The voltage source for the servos comes from VCC and Ground
2
Servo P2
VE
The voltage source for the servos come from the + and - screw
terminals
3
Servo P3
4
Servo P4
5
Ground
6
VCC
Table 1. Connector J1- Pin Descriptions as labeled on the Pmod.
Standard servo motors use a potentiometer to adjust the angle at which their central shaft rotates to. In order to
adjust the rotation angle, the motor generally needs to receive a “high” voltage pulse that ranges from 1
millisecond to 2 milliseconds, with 1.5 milliseconds as the “neutral” value. These values typically correspond to 0
degrees, 180 degrees, and 90 degrees, respectively, although depending on the manufacturer of the servo motor,
these angles may vary. A signal that is either too narrow or too wide for a servo will cause the servo to try to go
beyond its rotational range and can damage the servo. Always check the manufacturer’s instructions for a servo’s
rotational range.
2.0 ms
Pulse
Width
1.5 ms
Pulse
Width
1.0 ms
Pulse
Width
Pulse
Period
Servo Position
Set by Pulse
Width
Figure 1. Servo control diagram.
Because the pulse length is relatively long, any of the IO pins on a Digilent system board are capable of driving a
servo motor. However, in order to have the servo motor maintain its given angle, a refresh pulse of the same (or
new) angle will need to be provided to the servo motor periodically (20 milliseconds is a safe value). When using
the Servo library available from Digilent, the refresh pulse and the pulse width are automatically taken care of
allowing the user to simply give the desired angle for the servo motor to rotate to.
3 Physical Dimensions
The pins on the pin header are spaced 100 mil apart. The PCB is 1.0 inches long on the sides parallel to the pins on
the pin header and 0.8 inches long on the sides perpendicular to the pin header.