8. JTAG and Boundary Scan > Configuration Register Access (Revision C)
CPS-1848 User Manual
190
June 2, 2014
Formal Status
This document is confidential and is subject to an NDA.
Integrated Device Technology
8.7.2
Configuration Register Access – Writes
The timing of a typical JTAG register access Write command is shown in
. Note that the status of the Write command
is obtained while shifting in the next command. If the Write is the last functional command, a NOP command can be shifted in
while the Write status is shifted out.
Figure 45: JTAG Register Access – Write Timing Diagram
8.7.3
Configuration Register Access – Reads
The timing of a typical JTAG register access Read command is shown in
. Note that the status of the Read command,
including the read data, is obtained while shifting in the next command. If the Read is the last functional command, a NOP
command can be shifted in while the Read status and data are shifted out.
Figure 46: JTAG Register Access – Read Timing Diagram
U
pdat
e-D
R
R
u
n
-T
e
st/Id
le
Exi
t1-D
R
Sel
e
c
t-DR
C
a
pture-D
R
Shift-D
R
Time
R
u
n
-T
e
st/Id
le
U
pdat
e-D
R
Exi
t1-D
R
Shift-D
R
Sel
e
c
t-DR
C
a
pture-D
R
Shift out status of previous
cmd on TDO
Shift in next cmd on TDI,
R
u
n
-T
e
st/Id
le
TAP
State
Write cmd
Write cmd starts
Write cmd finishes
Status of Write cmd captured
Inter-command
delay allows Write
cmd to complete
Shift out status of Write
cmd on TDO (including
READY and ERROR)
Shift in Write cmd on TDI
(including Write data)
Up
dat
e-DR
R
un-T
e
st/Idl
e
Exit
1-
DR
Select-
D
R
C
aptur
e-DR
Shif
t-
DR
R
un-T
e
st/Idl
e
Up
dat
e-DR
Exit
1-
DR
Shif
t-
DR
Select-
D
R
C
aptur
e-DR
R
un-T
e
st/Idl
e
TAP
State
Read cmd
Time
Shift out status of previous
cmd on TDO
Shift in next cmd on TDI,
Read cmd starts
Read cmd finishes
Inter-command
delay allows Read
cmd to complete
Read data and status of
Read cmd captured
Shift in Read cmd on TDI
Shift out status of Read cmd
on TDO (including READY,
ERROR, and Read data)
