ADP315PC87570 National Semiconductor, ADP315PC87570 Datasheet - Page 48

• Manufacturer Part Number: ADP315PC87570
• Description: Keyboard and Power Management Controller
• Manufacturer: National Semiconductor

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5.0 Host Bus Interface (HBI)
The HBI facilitates the various data transfers required be-
tween the different modules of the system. It also arbitrates
between host and CompactRISC CR16A accesses to
shared resources: the memory device and the RTC/APC.
Figure 5-1 shows a schematic diagram of the possible bus-
to-bus bridging options.
The host bus is an 8-bit wide ISA-compatible bus. The
PC87570 is accessed from the host bus as:
The HBI allows the host and CR16A core to share the same
Flash memory. In this way, only one memory device is
needed for both the host system BIOS, and for the
PC87570 code. Memories other than Flash may be used.
Both the host and the CR16A can access the three legacy
I/O devices:
Data transfers to/from host or CR16A core can be imple-
mented using polling or interrupt driven schemes. This en-
hances system performance and flexibility. The on-chip
hardware is designed to allow a race-free interface for both
these access paths.
a memory device when using the HMEMR, HMEMW
and HMEMCS signals, (to interface the external mem-
ory device, BIOS Flash).
an I/O device when using the HIOW, HIOR and HAEN
signals, (to interface on-chip resident I/O devices)
The KBC, used for keyboard control, mouse and an
auxiliary pointing device, at default host addresses
0060h and 0064h
The Power Management (PM) device, at default host
addresses 0062h and 0066h
The RTC and APC (referred to in this chapter as the
RTC/APC), at default host addresses 0070h and 0071h.
Memory
Access
Shared
Host
External
Memory
(Flash)
to
HMEMW
HMEMR
HMEMCS
ROM
BIU
Figure 5-1. Host Bus Interface Schematic Diagram
Host Bus
Core Bus
Host Bus Interface (HBI)
Core Bus to
ISA Bus
Bridge
CR16A CORE
48
Host Interface
5.1 FEATURES
Memory device sharing between the host (BIOS) and
the PC87570 firmware, for both read and write
Direct support for an 8-bit ISA bus (host)
PnP support
— Host Device Enable (HDEN) strap input pin selects
— First enable using PnP escape sequence
— Relocatable chip-configuration-base-address
— Default legacy addresses for each module, relocat-
— Configuration lock bits for the chip-configuration-
— programmable IRQ polarity and output buffer type
Three Host Interface channels, typically used for KBC,
PM, and RTC/APC, as follows:
— KBC
— PM, (Power Management channel); interrupt IRQ11
— RTC/APC, accessible from both the host and
Core and
Arbitrator
if the modules are disabled (default) or enabled after
reset; software programmable enable/disable bits
for each module
(Index/Data registers)
able by software
base-address and for each module
— 8042-compatible KBC standard interface
— Intel 8051SL compatible host interface
— Standard IRQ1 (keyboard) and IRQ12 (mouse)
— Fast gate A20 and fast reset via firmware
— Reset signal to the host on dedicated HRSTO
CR16A
Host
may be operated by either hardware or firmware
pin; both hardware and software control
HIOR
HIOW
HAEN
CR16A Access
to RTC
Host Access to
Peripherals
PC87570
Resident
Device
Bus