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10: ETM Interface
ARM720T CORE CPU MANUAL EPSON 10-3
10.4 Clocks and resets
The ARM720T processor uses a single clock, HCLK, as both the main system clock and the
JTAG clock. You must connect the processor clock to both HCLK and TCK on the ETM. You
can then use TCKEN to control the JTAG interface.
To trace through a warm reset of the ARM720T processor, use the TAP reset (connect nTRST
to DBGnTRST) to reset the ETM7 state.
For more information about ETM7 clocks and resets, see the
ETM7 Technical Reference
Manual
.
10.5 Debug request wiring
It is recommended that you connect together the DBGRQ output of the ETM7 to the DBGRQ
input of the ARM720T processor. If this input is already in use, you can OR the DBGRQ inputs
together. See the
ETM7 Technical Reference Manual
for more details.
10.6 TAP interface wiring
The ARM720T processor does not provide a scan chain expansion input. ARM Limited
recommends that you connect the ARM720T processor and the ETM7 TAP controllers in
parallel. For more details, see the
ETM7 (Rev 1) Technical Reference Manual
.
TDI DBGTDI
TDO
e
DBGTDO
TMS DBGTMS
WDATA[31:0] ETMWDATA[31:0]
INSTRVALID ETMINSTRVALID
a. See
Clocks and resets
on page 10-3.
b. See
Debug request wiring
on page 10-3.
c. See
Enabling and disabling the ETM7 interface
on page 10-1.
d. Leave this pin unconnected.
e. See
TAP interface wiring
on page 10-3.
Table 10-1 Connections between the ETM7 macrocell and the ARM720T processor (continued)
ETM7 macrocell signal name ARM720T processor signal name