MOTOR BLOCK
FEATURES
- Clock generation for external motor controller chip
- Feedback via external signal or servo block (with automatic switching)
- Prescaler for feedback and reference timer
- Timer error saturation
- 2's-complement error value
- Interrupt directly to CPU or through servo controller
SYSTEM OVERVIEW
The spindle and voice coil motors are controlled by an (external) analog chip. Control of this device is performed with a synchronous serial interface, interfacing with the disk controller chip through the Serial Interface Controller block. Both motors are controlled with a control loop implemented in external firmware. The voice coil motor (VCM) feedback path is provided through the Servo block. The spindle motor feedback path is through the Motor block .
MOTOR BLOCK OVERVIEW
The motor block provides the feedback path for spindle motor control. When the head position is not locked to the servo patterns on the disk, feedback is performed using the signal generated in the analog motor driver chip based upon the motor back-EMF. Once locked to the servo patterns on the disk, feedback can be switched to the timing signal generated by the servo controller. Servo controller feedback always provides greater precision of motor speed control.
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