Even though there is an on-board debugger, external debuggers can be connected directly to ATtiny1607 Curiosity Nano to program/debug the ATtiny1607. The on-board debugger keeps all the pins connected to the ATtiny1607 and board edge in tri-state when not actively used. Therefore, the on-board debugger will not interfere with any external debug tools.
Figure 1. Connecting the MPLAB PICkit™ 4 In-Circuit Debugger/Programmer to ATtiny1607 Curiosity Nano
Figure 2. Connecting the Atmel-ICE to ATtiny1607 Curiosity Nano
CAUTION: To avoid contention
between the external debugger and the on-board debugger, do not start any
programming/debug operation with the on-board debugger through Atmel Studio/Microchip MPLAB® X or mass storage programming while
the external tool is active.