Cirrus Logic CS485xx - Manual (Page 19)

2-1 Copyright 2009 Cirrus Logic, Inc. DS734UM7
Introduction
CS485xxr Hardware User’s Manual
Chapter 2
Operational Modes
2.1 Introduction
The CS485xx has several operational modes that can be used to conform to many system configurations.
The operational modes for the CS485xx specify both the communication mode and boot mode. This chapter
discusses the selection of operational modes, booting procedures and process of performing a soft reset.
The CS485xx can be either a slave device or a master device for the boot procedure. In Master Boot Mode,
the CS485xx is the master boot device and can automatically boot the application code from external serial
ROM (the slave boot device). In Slave Boot Mode, the CS485xx is the slave boot device and requires the
system host controller (the master boot device) to load the application code. Please see
Figure 2-1 .
Thus, there are two boot modes for the CS485xx:
• Master Boot (From serial SPI or I
2
C FLASH/EEPROM)
• Slave Boot (Using SPI or I
2
C)
When the CS485xx is configured for an operational mode where it is the slave boot device, one of the below
communication modes must be specified by the host controller (i.e. the master boot device). These
communication modes are described in detail in
Chapter 3, "Serial Control Port" . Please see this section for
block diagrams and flowcharts depicting each of the Slave and Master boot modes.
Figure 2-1. Operation Mode Block Diagrams
Slave Boot
System Host
Controller
(Master)
CS4953xx
(Slave)
Control Bus
CS4953xx
(Master)
External ROM
(Slave)
External
Memory Bus
Master Boot