AN4035 datasheet(29/42 Pages) STMICROELECTRONICS

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AN4035

Nexus Read/Write access block

Doc ID 022669 Rev 2

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Table 6 details the status bit encodings.

RWD is shown in Figure 20.

29–27

[2:0]

Word size.

0008-bit (byte)

0016-bit (half-word)

01032-bit (word)

01164-bit (double-word - only in burst mode)

100–111 Reserved (default to word)

26–24

MAP

[2:0]

MAP select.

000Primary memory map

001-111 Reserved

23–22

[1:0]

Read/write access priority.

00Lowest access priority

01Reserved (default to lowest priority)

10Reserved (default to lowest priority)

11Highest access priority

BST

BST Burst control.

0 Module accesses are single bus cycle at a time.

1 Module accesses are performed as burst operation.

20–16

—

Reserved.

15–2

CNT

[13:0]

Access control count. Number of accesses of word size SZ.

ERR

Read/write access error. See Table 4-2.

Read/write access data valid. See Table 4-2.

Table 6.

Read/Write access status bit encoding

Read action

Write action

ERR

Read access has not

completed

Write access completed

without error

Read access error has

occurred

Write access error has

occurred

Read access

completed without error

Write access has not

completed

Not allowed

Table 5.

RWCS field description (continued)

Bits

Name

Description

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