nrf52840 SWDIO Internal Pullup and SWDCLK Internal Pulldown Values

[Angelo]

Hi,

The datasheet for the nRF52840 says that the SWDIO and SWDCLK lines have internal pullup and pulldown resistors already, and thus, does not need external ones.

Two questions:

1. Is it really ok to use the internal resistors as is, or should we connect external ones as well? I remember having programming issues not placing external resistors for the SWD lines in the past... anyone who has a custom PCB using no external resistors can attest to this?

2. What are the internal pullup/pulldown values for these lines. The datasheet says 13kΩ typical, but I am measuring something in the 300kΩ+ on a bare chip -- and its a steady-state reading (definitely not Hi-Z).

Thanks in advance!

Cheers,
Angelo


EDIT:

Solved -- production PCB did not use external pullups. Thanks!

[FormerMember]

1. No, on the nRF52840, there is no need for external pull-up/pull-down resistors on SWDCLK and SWDIO for programming the chip.
2. 300 kΩ+ sounds like too much. How did you do the measurements?