Table 15-1: ARM JTAG-AP Signal Use in the Scan Manager
The following table describes how the ARM JTAG-AP signals are connected in the scan manager. These signals are
internal to the scan manager, are provided here for reference only, and are not shown in the preceding figure. The
signal, register, and field names listed in the table match the names used in the
ARM Debug Interface v5 Architecture
Specification
.
Implementation
Direction
Signal
Tied to 0. The read-only
SRSTCONNECTED
field in the
CSW
register always reads as 0.
Input
SRSTCONNECTED[7:0]
Tied to 0x8F, which connects only
ports 0-3 and 7. The read-only
PORTCONNECTED
field in the
CSW
register reads as 1 when the
PORTSEL
register is written with
a value that enables one of the
connected ports, and reads as 0,
otherwise.
Input
PORTCONNECTED[7:0]
Tied to 0x8F, so all connected
ports are always considered
powered on. The
PSTA
register
does not contain a useful value, so
there is no reason for software to
access it. Software does not need
to monitor the status of ports 0-3
because they are always on. For
port 7, software can read the
mode
field of the
stat
register
in the FPGA manager to
determine the FPGA power status.
Input
PORTENABLED[7:0]
Not connected. Writing to the
SRST_OUT
field of the
CSW
register has no effect.
Output
nSRSTOUT[7:0]
nTRST*[7]
is connected to the
FPGA JTAG TAP controller and
nTRST*[6:0]
are not
connected. Writing to the
TRST_
OUT
field of the
CSW
register (the
trst
bit of the
stat
register in
the scan manager) has an effect
only when port 7 is enabled by
software. For details, refer to
Communicating with the JTAG
TAP Controller section.
Output
nTRST*[7:0]
Altera Corporation
Scan Manager
15-3
Scan Manager Block Diagram and System Integration
cv_54015
2013.12.30