Epson ARM.POWERED ARM720T - Manual (Page 204)

A: Signal Descriptions
A-4 EPSON ARM720T CORE CPU MANUAL
A.4 Debugger signals
The debugger signal descriptions are shown in Table A-4.
DBGTDO Output Test data out.
JTAG test data out signal.
DBGTMS Input Test mode select.
JTAG test mode select signal.
a. These signals are only active when scan chain 0 is selected.
Table A-4 Debugger signal descriptions
Name Type Description
DBGBREAK Input Breakpoint.
This signal enables external hardware to halt execution of the processor
for debug purposes. When HIGH, this causes the current memory
access to be breakpointed. If memory access is an instruction Fetch, the
core enters debug state if the instruction reaches the Execute stage of
the core pipeline. If the memory access is for data, the core enters the
debug state after the current instruction completes execution. This
enables extension of the internal breakpoints provided by the
EmbeddedICE-RT module.
In most systems, this input is tied LOW.
COMMRX Output Communication receive full.
When HIGH, this signal denotes that the comms channel receive buffer
contains data for the core to read.
COMMTX Output Communication transmit empty.
When HIGH, this signal denotes that the comms channel transmit buffer
is empty.
DBGACK Output Debug acknowledge.
When HIGH, this signal denotes that the ARM is in debug state.
DBGEN Input Debug enable
A static configuration signal that disables the debug features of the
processor when held LOW.
This signal must be HIGH to allow the EmbeddedICE Logic to function.
DBGRQ Input Debug request.
This signal causes the core to enter debug state after executing the
current instruction. This enables external hardware to force the core into
debug state, in addition to the debugging features provided by the
EmbeddedICE-RT Logic.
In most systems, this input is tied LOW.
DBGRQ must be deasserted on the same clock that DBGACK is
asserted.
DBGEXT[1:0] Input External condition.
These signals allow breakpoints and watchpoints to depend on an
external condition.
Table A-3 JTAG and test signal descriptions (continued)
Name Type Description