Table 12-5 Jtag Target Response Summary - ARM Cortex-M3 Technical Reference Manual

Previous scan, at Update-DR state
R/W IR ADDR
X X bXX
R DPACC b01
b10
b00 or
b11
W DPACC b01
b10
b00 or
b11
R APACC bXX
W APACC bXX
X APACC bXX
a. The Previous scan is the most recent scan for which the ACK response at the Capture-DR state was OK/FAULT. Updates made
following a WAIT response are discarded.
b. ADDR[3:2] in the DPACC or APACC access.
ARM DDI 0337B
Capture-DR state of the following DPACC or APACC access. Table 12-5 summarizes
the target responses, at the Capture-DR state, for every possible DPACC and APACC
access in the previous scan.
Note
The target responses shown in Table 12-5 are independent of the operation being
performed in the current DPACC or APACC scan. In the table, Read result is the data
shifted out as Data[34:3], and ACK is decoded from the data shifted out as Data[2:0].
a Current scan, at Capture-DR state
b c
Sticky AP state
X Busy
X Not Busy
X Not Busy
No Ready
Error
No Ready
Error
Yes X
Copyright © 2005, 2006 ARM Limited. All rights reserved.

Table 12-5 JTAG target response summary

d
Read result ACK
e WAIT
UNP
CTRL/STAT OK/FAULT
SELECT
0x00000000
e OK/FAULT
UNP
See Notes OK/FAULT
e
UNP
e OK/FAULT
UNP
e
UNP
e OK/FAULT
UNP
Debug Port
Notes
Can cause Sticky Overrun
f
flag to be set.
Returns CTRL/STAT value.
Returns SELECT value.
No readable DP registers at
addresses b00 and b11.
Write to CTRL/STAT.
Write to SELECT.
Write ignored.
g
See footnote .
Sticky Error flag is set.
h
See footnote .
Sticky Error flag is set.
Previous transaction was
discarded.
12-17