8-Servo Controller Board for Handy Cricket|
Click for close-up image
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.
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.
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:
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 end to servooff :id bsend $115 bsend :id * 2 bsend 0 end
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 end
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!
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.