nRF52840 DK v1.0.0

Debug input and trace

The Debug in connector (P18) makes it possible to connect external debuggers for debugging when the interface MCU USB cable is not connected or the board is in nRF only mode.

Figure 1. Debug input and trace connectors
Debug input connector (P18) and trace connector (P25) on nRF52840 Development Kit board

For trace, a footprint for a 20-pin connector is available (P25). If trace functionality is required, it is possible to mount a 2×10 pin 1.27 mm pitch surface mount pin header.

Some of the trace pins are by default used for other functionality on the board. By sliding the TRACE switch (SW7) from Def. to Alt., the functionality is moved to other GPIOs. See the following table:

Table 1. Default and Trace GPIOs
GPIO Trace Default use Optional GPIO
P0.07 TRACECLK UART CTS P0.04
P1.00 TRACEDATA[0]    
P0.11 TRACEDATA[1] Button 1 P1.07
P0.12 TRACEDATA[2] Button 2 P1.08
P1.09 TRACEDATA[3]    

The reference voltage for the debug input and trace is by default connected to VDD_nRF'. This can be connected to the VDD by cutting SB60 and soldering SB59.