To:6.270
cc:
Subject:Servo motor code
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Hello all,

Thanks to the efforts of P.K. and Anne Wright, the code to operate the
kit servo motor is now fully functional and ready to use.

Please note the following documentation CHANGES and ADDITIONS from the
description in the course notes:

The servo motor must be turned on with the function

	int servo_on(int dummy);

The "servo_on" function takes a dummy integer variable and returns a
dummy integer variable.

To turn the servo motor off, use the function

	int servo_off(int dummy);

The servo motor in the kit operates over about 180 degrees of turn.
To set the angle, modify the integer variable "servo_pulse_wavetime".
Setting this variable between values of 600 and 5000 control the full
range of movement.  The default value is 2000.

Note:  If the servo is on, and the "servo_pulse_wavetime" is set
outside of the range just mentioned, the servo motor will continuously
drive into its physical stops, trying to achieve the out-of-bound
setting.  Obviously, this is not good for the motor.

The program "servotst.c" is a good test program to run to put your
servo through its paces.  If you're confused about how to use the
servo functions, just take a look at this program (in
/mit/6.270/lib/ic).

Enjoy!!

	- Fred

P.S.  This message will be copied into /mit/6.270/doc92 for ease of
reference.