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Intro LED Number Display Lamp/Relay Driver Motor/Sensor Expansion

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8-Servo Controller Board

8-Servo Controller Board for Handy Cricket
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  • 8 outputs for standard RC servo motors.

  • Servo power may be supplied by Handy Cricket or external 5–6v supply.

  • Red “servo power” LED indicates status of power supply for servos.

  • Green “servo enable” LED indicates when one or more servo outputs is enabled.

  • Built-in Bus Jack allows additional bus devices to be daisy-chained from the board.


Plugging it into the Cricket

The 8-Servo Controller Board is easy to use. Start off by plugging it into your Handy Cricket. You can use either bus port – they're both the same.


Plugging in a Servo Motor

The 8-Servo Controller has pins that mate with standard Futaba-style servo plugs. Plug the servo across a row of three pins. The servo control signal is present on the inner column of pins. Note the labeling whi red bla at the bottom of the connector bank; these correspond to the white (signal), red (power), and black (ground) of the servo wiring.


Controlling Servos

The Board provides 8 servo motors, labeled 0 through 7. There are two main commands used to control the servos: servopos, for servo position, and servooff, to turn a servo output off.

For example, to turn on servo 0 at position 128:

servoon 0 128

The position input's range is from 0 to 255. This normally corresponds to about a quarter-turn of servo rotation.

To turn servo 0 off:

servooff 0

The routines for these two commands are below. These should be cut-and-pasted into your Cricket Procedures window.
to servopos :id :angle
  bsend $115
  bsend :id * 2 + 1
  bsend :angle

to servooff :id
  bsend $115
  bsend :id * 2
  bsend 0

Here is a test program that will make the servo 1 output go back and forth three times:

to testservo
  repeat 3 [servopos 1 0 wait 10 servopos 1 255 wait 10]
  servooff 1


Servo Power Supply

To power servo motors from the Cricket's own batteries, jumper a wire from the pad labeled “CX-PWR” to the screw terminal connector labeled +. The 8-Servo Controller Board is shipped with a wire in this configuration.

The Board should be used with an external power supply when running more then 2 servos, or in any case where preserving the Cricket's batteries is desireable.

Remove the wire from “CX-PWR” and connect an external power supply of 5 to 6 volts (e.g., 4 C or D cells) to the + and - screw terminal pads. Make sure the connection to CX-PWR is disconnected!


Technical Specifications

The 8-Servo Controller Board measures 1.6” by 1.5”. There are four mounting holes at the corners of a 1.4” x 1.3” rectangle.

Last modified: Tuesday, 31-Aug-2004 08:25:36 PDT by fredm