AN4035 datasheet(28/42 Pages) STMICROELECTRONICS

28 / 42 page

Nexus Read/Write access block

AN4035

28/41

Doc ID 022669 Rev 2

Nexus Read/Write access block

The Nexus module provided on the cores of the SPC56x family of devices offers the

capability for program trace, data trace, ownership trace, watchpoint messaging and trigger,

and read/write (R/W) access to memory mapped regions. This section covers R/W access

using the Nexus R/W access block. The other features of the Nexus module are out of the

scope of this document and is not covered.

Unlike the OnCE method of memory access, the Nexus R/W access block provides the

ability to read and write memory without having to stop code execution by entering debug

mode. The Nexus R/W access method provides faster memory access over the OnCE

method due to fewer JTAG scans, and it doesn’t require loading and single stepping over

any instructions. The Nexus R/W access block is independent of the CPU.

The R/W access block is controlled by three Nexus registers. These registers are the

Read/Write Access Control/Status register (RWCS), Read/Write Access Data register

(RWD), and Read/Write Access Address register (RWA). Access to the Nexus registers is

covered inSection 4.1. RWCS is shown in Figure 19 and Figure 5 gives the field

descriptions.

Figure 19.

Read/Write Access Control/Status Register (RWCS)

MAP

BST

00000

Reset

00000

Nexus

Reg

0x7

8765

43210

CNT

ERR

Reset

00000

0000

00000

Nexus

Reg

0x7

Table 5.

RWCS field description

Bits

Name

Description

Access control.

0 End access

1 Start access

Read/write select.

0 Read access

1 Write access

AN4035 датащи(PDF) 28 Page - STMicroelectronics

AN4035 датащи(HTML) 28 Page - STMicroelectronics

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42

датащи скачать

ссылки URL