pc87591l National Semiconductor Corporation, pc87591l Datasheet - Page 25

• Manufacturer Part Number: pc87591l
• Description: Lpc Mobile Embedded Controllers
• Manufacturer: National Semiconductor Corporation

Revision 1.07
1.0 Introduction
The Keyboard Controller and the EC functions (core and associated peripherals) are powered by V
as long as the system has a power source (e.g., main battery or outlet). Using V
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:
1.2.3
The PC87591x can operate in one of the following four environments:
1.3
The PC87591x consists of several main components divided into three groups:
The descriptions below detail the functions of the various blocks shown in Figure 2.
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 - V
state of some memory and configuration elements.
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.
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
INTERNAL ARCHITECTURE
Operating Environments
CC
is absent and only backup battery is available to supply the Real Time Clock (RTC) and retain the
(Continued)
25
CC
, the core may be programed to monitor
CC
, which remains active
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