PC87591L datasheet(302/437 Pages) NSC

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Host Controller Interface Modules (Continued)

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Revision 1.07

The block number may be calculated using the following equation:

Core_Block_Number = (CR_Space_Address < 128K) ?

CR_Space_Address[20-0] / 64K : CR_Space_Address[20-0] / 8K

The Shared Memory Core Override Read Protect 0-2 registers and Shared Memory Core Override Write Protect 0-2 regis-

ters provide core access to the read and write protect bits, respectively. Bits in these registers may be set and cleared by

writing to the registers.

Response to a Restricted Access

A restricted access is an access that complies with at least one of the following conditions:

●

The access type (i.e., Read or Write) of the translated host address (i.e., core address) is protected.

●

A reset to the core domain due to a Warm reset event or a ﬂash empty indication is set (Core Boot Block ﬁeld of the

protection word is 11112).

The PC87591x responds to a restricted access by generating an interrupt (if enabled by HERRIEN bit in SMCCST register)

to the core. Two status bits (HWERR and HRERR) indicate whether the restricted access is a read or write access. The

response on the host bus is according to the HERES field.

For restricted write accesses: Data written is ignored; when the HERES field is 102, the read or write transaction is completed

with an error SYNC; otherwise, it is completed with a ready SYNC.

For restricted read accesses: When the HERES field is 002, the read or write transaction drives Long Wait (endlessly, unless the

access becomes unrestricted or the HERES field is changed). When the field is 012, the PC87591x completes the transaction

with a ready SYNC and data of 0016; when the field is 102, it completes the transaction with an error SYNC and data of 0016.

Figure 102. Protection Blocks for Protection Bits and Override Protection Bits

Area Not Accessible

to Host

00 0000

01 0000

02 0000

03 0000

0F 0000

10 0000

11 0000

12 0000

1F 0000

1F FFFF

Address in

Core Address

Space

64K

04 0000

00 E000

64K

Host Block

Index

Core Override

LA 0

LA 1

LA 2

LA 6

LA 8

LA 15

MBTA

Block Number

PC87591L Datasheet(PDF) 302 Page - National Semiconductor (TI)

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