
1-26
Introduction
Final Rev F
Copyright 1996 by LSI Logic Corporation. All rights reserved.
1.6.6
System
Controller
Interface
An external system controller (microcontroller) is responsible for test, ini-
tialization, and real-time control of the L64005. The interface between the
system controller and the L64005 is 8 bits wide and fully asynchronous.
1.6.6.1 Device Initialization
The system controller denes the operational mode of the L64005
decoder. L64005 operational modes are controlled through a number of
internal state registers, which may be read or written over the interface.
Device initialization parameters include frame size, sync pulse widths,
active image size and position, frame mode, horizontal re-sizing, and
channel buffer size. The programmability of these parameters greatly
increases the exibility of the L64005 for systems with different resolu-
tions and display system characteristics.
1.6.6.2 Operational Monitoring
The behavior of the L64005 video decoder can be monitored over the
system controller interface. Parameters include channel buffer fullness,
detected bitstream errors, and status of video sync signals. The L64005
internally arbitrates access to the frame stores is arbitrated in the
L64005. Frame store accesses from the system controller have a lower
priority than any other access in the system.
1.6.6.3 Interrupts
The L64005 has multiple interrupt sources, which include synchroniza-
tion events, detectable errors, channel status, and display status. Inter-
rupts are signalled to the system controller over a single interrupt pin,
and are selectively maskable through the controller port. Pending inter-
rupts may be read from an internal register. Interrupts make the program
in the system controller more efcient because the interface does not
need to be polled.
1.6.6.4 Test
Frame memories can be tested by randomly reading and writing them
through the interface. An internal address indirection register controls the
addressing of these accesses. The L64005 arbitrates between these
accesses and those of other subsystems internally.