System Integration Module; Module Operation; Mc68328 Processor System Configuration; System Control Register Functions - Motorola DragonBall MC68328 User Manual

SECTION 2

SYSTEM INTEGRATION MODULE

The MC68328 processor system integration module (SIM28) consists of several functions
that control the system startup, initialization, configuration, and the external bus with mini-
mum glue logic. The SIM28 contains the following functions:
• System configuration
• Chip-selects and wait states
• External bus interfaces
• Interrupt configuration / response
• PCMCIA V1.0 memory card support

2.1 MODULE OPERATION

The various SIM28 internal function blocks and their operation are described here along with
methods and recommendations to program the various register locations that allow users to
configure the MC68328 processor for their target systems.

2.1.1 MC68328 Processor System Configuration

The MC68328 processor system configuration logic consists of a system control register
(SCR) that lets users configure operation of the following functions:
• Access permission of internal peripheral registers
• Address space of internal peripheral registers
• Bus timeout control and status (bus-error generator)
The on-chip peripherals occupy a reserved 4096-byte block of address space for their
registers. This block is located at $FFFFF000 and $FFF000 from reset. There is a double-
map control bit in the SCR to disable this double-mapping feature. If the bit is cleared, the
on-chip peripheral registers appear at the top 4K of the 4 Gbyte address range starting from
$FFFFF000. The on-chip peripherals address-decode logic block diagram is shown in
Figure 2-1.
2.1.1.1 SYSTEM CONTROL REGISTER FUNCTIONS. The
settings that influence system operation, such as power-down and oscillator control logic,
bus interface, and hardware watchdog protection. It also includes status bits that allow
exception-handler code to monitor the cause of exceptions and resets.
While most of the functions controlled by these register bits are described in detail else-
where, they include those listed below.
MOTOROLA MC68328 DRAGONBALL PROCESSOR USER'S MANUAL
SCR allows for various
2-1