Page 168 - Mechatronic Systems Modelling and Simulation with HDLs

7.5 DEMONSTRATOR 4: DISK DRIVE 157

Pre- Motion- HDC, e-DRAM,
(1)
amp control e-channel

Pre- Motion- HDC,
(2) amp control e-channel DRAM

Pre- Motion- HDC,
(3) Channel
amp control e-DRAM

Pre- Motion-
(4) HDC Channel DRAM
amp control

Figure 7.15 Several alternatives for the mapping of circuits to chips

7.5.4 The virtual disk drive

The design of circuits for disk drives has to take into account analogue–digital,
hardware–software and electronics–mechanics interfaces at the same time. The
Virtual Disk Drive was created to cope with that. It provides simulation models
for all the parts of a disk drive and is meant to support an electronics product for
a disk drive throughout its entire life-cycle.

• In the concept phase, high-level models form an executable specification which
can be validated by simulation. This model also serves as a framework for
design space exploration and even allows for early firmware development.

• In the design phase, the virtual prototype creates a general test bench. In this
high-level system model, it is possible to ‘zoom’ into the components being
designed, replacing high-level component models by their implementations.
This may be done for any part of the system, whereas the system modelling
has to be carried out just once. Moreover, this reveals information on the real-
life system behaviour rather than more or less synthetic data on signals at a
component’s interface. For a disk drive the focus may, for instance, be on
spin-up, track-following or seeking.

• The development of a high-level (sub)system model is also indispensable for the
virtual testing of the analogue circuitry. The test program development may be
carried out much earlier in combination with a model of the testing equipment.