3.5.3 Configuration and Test Points

Special Considerations for the NEXUS pins

On the Atmel AVR UC3 C series, the NEXUS pins are multiplexed with I/O lines. While using these multiplexed NEXUS lines all normal peripheral activity on these lines are disabled. The user must make sure that no external peripheral is blocking the NEXUS lines while debugging.

Table 3-16 highlights the components of the Atmel AT32UC3C-EK that might interfere with the multiplexed NEXUS pins. These components must not be used while debugging with the NEXUS interface.

Table 3-16. Conflicts Conditions over the NEXUS Debugging Pins
QFP144 pinGPIOConflict conditions
18PB15Nexus pin in conflict with Wireless (WLESS) CTS Signal
17PB14Nexus pin in conflict with Wireless (WLESS) RTS Signal
64PB25Nexus pin in conflict with Wireless (WLESS) CS Signal

To summarize, debugging on NEXUS will not work if:

  • The WLESS connector is used

Test Points

A few test points covering the Programming and Debugging Interface block have been placed on the AT32UC3C-EK for the verification of important signals.

Table 3-17. Programming and Debugging Interface Block Test Points
DesignationFeature
TP57JTAG.TCK
TP58JTAG.TDO
TP59JTAG.TMS
TP60JTAG.TDI
TP61GND
TP62VCC3
TP63RESET_N

Using the aWire

The Atmel AVR ONE! and JTAGICE mkII tools can interface with the Atmel AVR UC3 C series using the single-wire aWire interface available on J24. Check the documentation of these tools to find out the recommended pinout to connect to an aWire target.