pc87591l National Semiconductor Corporation, pc87591l Datasheet - Page 28

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

1.0 Introduction
(Continued)
The ACB Interface is a two-wire serial interface compatible with the ACCESS.bus physical layer. It is also compatible with
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Intel’s SMBus and Philips’ I
C. This module can serve as a bus master or slave and performs both transmit or receive op-
erations. As a slave, it can respond to two assigned addresses, a global call address and an SMBus ARP address.
The PC87591x includes two ACB Interface modules to allow operation on two isolated buses in the system.
The USART (Universal Synchronous Asynchronous Receiver Transmitter) gives full-duplex support for a wide range of
software programmable baud rates and data formats. It handles automatic parity generation and several error detection
schemes. It also supports DMA transfers to allow for fast processor-independent receive and transmit. It implements flow
control logic to provide the capability for hardware handshaking.
The MFT16 (Multi-Function 16-Bit Timer) contains two 16-bit timers with a range of operation modes. These timers can op-
erate, using several clock sources, in PWM, Capture or Counter mode to satisfy a wide range of application requirements.
The PC87591x includes two MFT16 modules, each of which may be assigned to functions and configured independently.
The TWD (Timer and WATCHDOG) module has a 16-bit periodic interrupt timer that can be programed to generate inter-
rupts at pre-defined intervals and an 8-bit WATCHDOG timer that can reset the PC87591x whenever the software loses
control of the processor.
The periodic timer is typically used as a system tick timer. This timer is fed by the 32.768 KHz clock. Thus its counting is not
impacted by the setting of the HFCG, and it may continue to operate even in Idle mode. This enables it to serve as a periodic
wake-up source during Idle mode.
The PWM (Pulse Width Modulator) module provides eight modulated outputs. The output signals have the same program-
mable frequency and individually-controlled duty cycles.
The ADC (Analog to Digital Converter) provides the PC87591x with an accurate means for measuring slow changing volt-
ages and temperature. The ADC module can measure up to ten external and four internal voltages with 10-bit resolution
over a voltage range of 0 to 2.97V. It can measure temperature using thermistors or perform diode-based temperature mea-
surement. Special circuits are provided to allow accurate measurement of temperature, based on the voltage drop on the
diode junction. This technique is tuned for measuring the temperature of processors with an internal diode.
The DAC (Digital to Analog Converter) has four channels of voltage output. Each of the four DAC channels has an 8-bit res-
olution with a full output range from AGND to AV
. The DAC provides a settling time of about 1 s on a 50 pF load.
CC
The Debugger Interface module provides a JTAG-based interface to a remote, host-based debugger. This interface en-
ables device debugging while in OBD environment (i.e., in the final production board) or in DEV environment once in the
development system. The Debugger Interface module uses the JTAG interface to enable programing of the on-chip flash in
both these environments.
1.3.5
Host-Controller Interface Modules
Chapter 5 on page 277 describes a set of modules that resides in the boundary between the host-controlled functions and
the core-controlled functions. These modules are used for message communication, data exchange, memory access and
generating power management events to the host. Chapter 5 also discusses the mechanism that enables the core to access
the host-controlled peripherals.
The Keyboard Controller, Power Management module has three channels that are available for keyboard and power
management (EC)-related host-controller communication.
The keyboard and mouse data channel (i.e., host legacy I/O addresses 60
and 64
) is compatible with the legacy inter-
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face of keyboard controllers. It may be used with polling or interrupts. For use with interrupts, the module can generate the
two legacy IRQ signals: IRQ1 and IRQ12. In addition, the PC87591x generates the gate A20 control signal (GA20 pin) and
a soft reset signal (KBRST pin) to the host. Optionally, this KBRST reset signal can be used to prevent the host from ac-
cessing the shared flash when the PC87591x cannot perform the shared memory access during PC87591x boot-up. See
“GA20 Pin Functionality” on page 322 and “Host Keyboard Fast Reset” on page 322 for details).
The PC87591x supports three Power Management channels, compliant with ACPI requirements for Embedded Controller
(EC) interface. This enables the PC87591x to implement an EC interface that operates in either shared or private modes.
The number of Power Management channels in use and the addresses they respond to (i.e., legacy host I/O addresses 62
16
and 66
) are configured in the Host Controlled Functions configuration space. These channels may generate IRQ, SMI or
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SCI events to the host. The Power Management channels include a PC87570-compatible mode and an enhanced scheme
that enables more efficient control by the core.
Shared Memory and Security is supported between the host and the core. This sharing may be used for the support of a
shared BIOS scheme, secured information storage and/or for the PC87591x firmware update by the host. The base memory
of the PC87591x and, if needed, the expansion memory can be used as shared memory. The use of the Expansion memory
is optional. The Shared Memory module provides means for the host to access the shared memory. It can also secure ac-
cess to portions of the shared memory for read and/or write operations to allow reliable and tamper-protected storage and
secured update. In addition (PC87591S only), this module includes a random number generator (RNG) that provides hard-
ware-generated random numbers to the core.
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Revision 1.07