SWO on nRF52811 QCAA QFN32

[NichD]

Hi,

On page 420 of the nRF52811 datasheet (v1.0) it states that pin 14 (P0.18) can be either 1) Digital I/O or 2) Single wire output (SWO). The SWO is not mentioned on any of the other package types (i.e. QFAA or QAAA), nor is it mentioned in section 4.8 (Debug). 

Thus, should this pin be routed on the PCB to the J-Link programming header (on the QFN32 QCAA) package, or is this an error in the documentation? 

Secondly, should a 4K7 pull-up resistor be populated on pin 16 if this pin is used as an external RESET pin? The datasheet states that SWDIO and SWDCLK both have internal pull-up/down resistors already populated, and that pin 16 can be configured with an internal pull-up/down resistor if used as GPIO, but doesn't give reference to the external requirements of p 16 when used as dedicated RESET pin.

Thanks,

Nicholas 

[haakonsh]

SWO is an optional debug resource, see https://wiki.segger.com/SWD.  

Thus, should this pin be routed on the PCB to the J-Link programming header (on the QFN32 QCAA) package, or is this an error in the documentation? 

If you want SWO then route it, if not, then don't.

Secondly, should a 4K7 pull-up resistor be populated on pin 16 if this pin is used as an external RESET pin?

 That's not necessary, a 13K pull-up is used internally when configured as the RESET pin.

[NichD]

Perfect, thanks.