PC87591L datasheet(25/437 Pages) NSC

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1.0 Introduction (Continued)

Revision 1.07

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The Keyboard Controller and the EC functions (core and associated peripherals) are powered by VCC, which remains active

as long as the system has a power source (e.g., main battery or outlet). Using VCC, the core may be programed to monitor

and control the system even when the host processor is turned off. To support this, the PC87591x is equipped with advanced

means to control its power consumption: software controlled clock frequency throttling, the ability to disable modules, and

four power modes. These power modes include:

●

Active Mode - Full functionality

●

Active Mode Executing WAIT Instruction - Core execution and associated operations (such as memory access) are suspended

●

Idle - Main clock is stopped, but the device can be woken up by internal or external events. The system tick timer is

still operational and can be used to periodically wake up the device.

●

Power Off - VCC is absent and only backup battery is available to supply the Real Time Clock (RTC) and retain the

state of some memory and conﬁguration elements.

1.2.3

Operating Environments

The PC87591x can operate in one of the following four environments:

●

Internal ROM Enabled (IRE). Used while the PC87591x operates in the production system and executes the appli-

cation. The on-chip ﬂash or ROM is the main source of code for the device.

●

On-Board Development (OBD). Used to debug the PC87591x code while it is mounted on its ﬁnal production board.

All pins have their IRE functionality. Interface to a debugger (running on the host) is through the JTAG-based debug-

ger interface. OBD environment is binary and cycle-by-cycle compatible with IRE environment.

●

Development (DEV). Used in Application Development Boards (ADB) or In System Emulators (ISE). In this environ-

ment, the on-chip ﬂash or ROM is replaced with off-chip SRAM memory to allow ﬂexible and fast development of ap-

plication code. Some pins are allocated to development system use, and the GPIO functions associated with them

are replicated using off-chip logic as part of the ADB system. DEV environment is binary and cycle-by-cycle compat-

ible with OBD and IRE environments.

●

Programing (PROG). Used to program the on-chip ﬂash in parallel programers. No other operation is possible in this

environment.

1.3

INTERNAL ARCHITECTURE

The PC87591x consists of several main components divided into three groups:

●

Core Domain

— CR16B core processing unit

— Bus Interface Unit and Memory Controller (BIU)

— RAM and ﬂash memory

— Core peripherals

●

Host Domain

— Host-Controlled functions

— Host Interface

●

Host-Controller Interface

The descriptions below detail the functions of the various blocks shown in Figure 2.

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