Chapter 8

System Control Module (SCM)

This section details the functionality of the System Control Module (SCM) which provides the programming model for the System Access Control Unit (SACU), the system bus arbiter, a 32-bit core watchdog timer (CWT), and the system control registers and logic. Specifically, the system control includes the internal peripheral system (IPS) base address register (IPSBAR), the processor’s dual-port RAM base address register (RAMBAR), and system control registers that include the core watchdog timer control.

8.1Overview

The SCM provides the control and status for a variety of functions including base addressing and address space masking for both the IPS peripherals and resources (IPSBAR) and the ColdFire core memory spaces (RAMBAR). The MCF5282 CPU core supports two memory banks, one for the internal SRAM and the other for the internal Flash.

The SACU provides the mechanism needed to implement secure bus transactions to the system address space.

The programming model for the system bus arbitration resides in the SCM. The SCM sources the necessary control signals to the arbiter for bus master management.

The CWT provides a means of preventing system lockup due to uncontrolled software loops via a special software service sequence. If periodic software servicing action does not occur, the CWT times out with a programmed response (system reset or interrupt) to allow recovery or corrective action to be taken.

8.2Features

The SCM includes these distinctive features:

IPS base address register (IPSBAR)

Base address location for 1-Gbyte peripheral space

User control bits

Processor-local memory base address register (RAMBAR)

System control registers

MOTOROLA

Chapter 8. System Control Module (SCM)

8-1

Page 187
Image 187
Motorola MCF5281, MCF5282 user manual Overview, Features