PC87591L datasheet(38/437 Pages) NSC

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1.0 Introduction (Continued)

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The I/O expansion space is mapped to the address space 00 FB0016 to 00 FBFF16. This space is partitioned as follows:

●

Addresses in the range 00 FB0016 to 00 FB2216 are used by GPIO ports PH, PI, PJ, PK, PL and PM (either on-chip

or in their off-chip implementation, while the chip is in DEV environment).

●

Address 00 FBFE16 is used only in DEV environment by the MCFGSH register and must be written after each write

to the MCFG with the same data written to the MCFG.

●

Addresses in the range 00 FBC016 to 00 FBFF16 are reserved for development board use.

●

All other addresses may be used by the application for adding additional I/O elements.

The PC87591x accesses the off-chip I/O expansion using the I/O zone of the BIU. The zone select signal (SELIO), address

lines A0-7 and the RD and WR0 signals are used to interface to the off-chip logic.

1.5.2

Host Address Domain Memory Map

The host address space includes memory space and I/O space.

The I/O space used by the PC87591x is configured through the PC87591x configuration registers. The configuration register

address is defined by strap inputs (BADDR0-1) to be one of two fixed addresses or an address defined by the core using

registers in the MSWC module.

When a Shared BIOS scheme is enabled via the SHBM strap input, the PC87591x is mapped to enable the host to boot from

a shared flash device. The PC87591x supports either memory or FWH transactions for the host memory interface, with au-

tomatic selection between them (see Section 6.1.11 on page 349). Section 5.3 on page 297 discusses the mapping of mem-

ory between the host and core domains and the read and write access protection scheme from the host and core sides.

Following the boot process, the Shared Memory configuration registers (see Section 6.1.11 on page 349) enable setting

memory sharing. The configuration setting includes defining the memory protocol in use (memory or FWH) and the address

range used in the host address space. The configuration registers allow the defaults set by the SHBM strap input to be over-

ridden; this enables using the shared memory for purposes other than system BIOS (e.g., PC87591x firmware update and

secured storage of information).

1.5.3

Core Access to Host Controlled Peripherals

The core may access host domain devices through the Core to Host Controlled Functions access bridge. The bridge em-

ploys an indirect mapping scheme.

There is only a single set of peripheral registers for host and core use. The bus arbitration guarantees that only one of the

two register accesses occurs at any given time, but this does not prevent problems that may be caused by conflicting write

transactions. When such a case is expected, the core lock mechanism may be used to protect access to one or more of the

devices. The lock may also be used to protect from the host from access to devices due to the security reasons.

The core accesses a register by specifying the logical device and the offset of the register within the logical device. Note that

the configuration registers’ index and data registers are also handled as a logical device. The core triggers a read by writing

1 to the read start bit and waits for the bit to clear; it can then read the data from the data register. The core triggers a write

by performing a write operation to the data register.

Section 5.4 on page 313 provides details of the bridge and its operation.

PC87591L Datasheet(PDF) 38 Page - National Semiconductor (TI)

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