Table 14-2. Nexus port interface checklist.
Signal name Recommended pin connection
Description
TDI
Test data input, sampled on rising TCK
Test mode select, sampled on rising TCK
Test clock, fully asynchronous to system clock frequency
Test data output, driven on falling TCK
Device external reset line
Event input
TMS
TCK
TDO
RESET
EVTI
MDO[0:5]
EVTO
MCK0
MSE[0:1]
Trace data output
Event output
Trace data output clock
Trace frame control
14.3 aWire port interface
aWire is a single-wire debug solution that offers memory access, programming
capabilities, and On-Chip Debug access. aWire can also be used as a UART when it
is not used for debugging.
A full-duplex mode can be used to increase speed, in which case data is transmitted
on a second pin, DATAOUT.
aWire uses the RESET_N pin for data in/data out. When using aWire, the board reset
circuitry must be disconnected. Refer to Figure 14-3 which demonstrates the use of
RESET_N for half-duplex mode, and Figure 14-4, where DATAOUT is added for full-
duplex communication.
Figure 14-3. Disconnecting the reset circuitry to allow aWire use.
aWire DATA
VDDIO
10 kꢀ
RESET_N
100 nF
Figure 14-4. aWire with full-duplex communication.
26
AVR32768
32157A-AVR-12/10
ATMEL [ ATMEL ]
