pc87591l National Semiconductor Corporation, pc87591l Datasheet - Page 271

• Manufacturer Part Number: pc87591l
• Description: Lpc Mobile Embedded Controllers
• Manufacturer: National Semiconductor Corporation

Revision 1.07
Embedded Controller Modules
Debug ISE Source Registers A (DBGISESRCA)
DBGISESRCA is a word-wide read/write register that indicates the ISE sources. The register is cleared on reset. Writing 1
to a bit in this register clears it. Writing 0 to a bit does not change its value. The DBGISESRCA register format is shown
below.
Location: 00 FDEA
Type: R/W S
4.19.10 Usage Hints
JTAG Performance
For best performance, the PC87591x should be the only device in the scan path. Since the Debugger interface is used in
the development phase of the product, this should not be a problem. Keep the scan path as short as possible.
JTAG Clock Rate
For reliable communication over the JTAG serial bus, the error probability should be extremely low. This can be achieved
by connecting the TAP to the JTAG bus controller card, paying attention to the TCK frequency, signal timing, this cable type
and cable length (for long cables, transceivers may be required).
Communication Lockout
Some erroneous operations by the host may cause a lockout of the communication hardware. Examples of such cases are:
A reset instruction is guaranteed to recover from all of these locked cases, but it resets the entire PC87591x.
Bit
Name
Reset
Bit
Name
Reset
Bit
7-2
Performing a data scan when the JTAG instruction is SCAN_RX with a PID value of ‘1111’
Performing a data scan with a JTAG instruction with a PID value that is not in the system (i.e., PID > 0)
Performing a SCAN_TX when the PID value is ‘1111’
0
1
RX_i. The ISE source is the Rx data link. Turn on with ISE assertion. Turn off by writing a byte to DBGISESRC
containing 1 in the RX_i bit location.
0: Not an ISE source
1: The ISE source is the Rx data link
ABORT_i. The ISE source is an ABORT request by the debugger or one of the processors. This bit is set by
either an abort command from the debugger (SCAN_RX with PID=‘1111’) or by a write of a 1 to the processor’s
respective bit in DBGISECA register.
0: Not an ISE source
1: The ISE source is an ABORT event
Reserved. These bits are reserved for future expansion.
Reserved
16
15
0
7
0
Reserved
14
0
6
0
Reserved
(Continued)
13
0
5
0
Reserved
Reserved
Description
271
12
0
4
0
Reserved
11
0
3
0
Reserved
10
0
2
0
ABORT_0
Reserved
9
0
1
0
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Reserved
RX_0
8
0
0
0