Motorola MSC8101 ADS User's Guide download pdf (Page 53)

MSC8101 User’s Guide 2-1

Chapter 2

Reset Configuration and Boot

This chapter describes the MSC8101 reset and boot process illustrated with examples of

different system configurations. It also describes the device clocking system, as it pertains

to the reset and boot process. The MSC8101 communicates with other devices in a system

either through the PowerPC system bus or the host port (HDI16). The chosen f

communication mode defines the reset configuration and the boot method.

2.1 Reset Configuration and Boot Basics

Reset configuration sets the basic mode of operation for the MSC8101, including the

operating frequency, arbitration, boot port size, memory controller functionality, and bus

behavior. These are the minimal parameters that must be set for correct operation. The

system configuration (memory controller, system protection logic, interrupt controller,

parallel I/O, and clocks) do not change. There are three kinds of reset in the MSC8101

system:

■ Soft reset. Invoked externally by asserting the SRESET signal or internally by

events. The soft reset initializes the core and internal logic, but system

configuration and clocks do not change.

■ Hard reset. Invoked externally by asserting the HRESET signal or internally by

events. The hard reset initializes the core internal logic and system configuration.

The phased-lock loop (PLL) and delay-lock loop (DLL) are not affected.

■ Power-on reset. Invoked only externally by asserting the PORESET signal.

Power-on reset initializes the core internal logic, the system configuration, and the

clocks. Asserting

PORESET input also asserts the HRESET and SRESET signals

internally. During power-on reset, several configuration pins are sampled to set the

boot mode, the source of the reset configuration values, and the basic clocking

mode. The configuration pins are sampled at the rising edge of

PORESET, and then

the reset configuration process starts. During reset configuration, a reset

configuration word that determines basic parameter settings is written to the

MSC8101, and a PLL and DLL locking process starts. The

HRESET and SRESET

pins remain asserted for a time after the PLL and DLL locking.

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Motorola MSC8101 ADS User's Guide Page 53