How to get log of nRF52840 board from 52DK

[always18]

Hi,I made a 52840 board ,it's p0.18 hanging, without connecting a 10k pull-up resistor and a 100nf capacitor to ground. I connected 3v3, GND, SWDIO, and SWDCLK from the 52DK board to this board, and successfully downloaded software from NCS to it. But only when the jlink RTT Viewer of the PC is connected to this board, its software runs. and the rtt viewer doesn't show any log info of  52840.When the RTT viewer disconnected, 52840's software stops.

When I only connect 3.3v and GND to this board, its software doesn't run。What is the reason?

I added this to device-tree:

&uicr{

    /delete-property/ gpio-as-nreset;

};

[helsing]

Hi,

Is the custom board designed with an external inductor in order to use the DCDC? Try disabling the DCDC: 

1. Disable DCDC in your configuration if your hardware does not support it. Add this to your prj.conf:

CONFIG_BOARD_ENABLE_DCDC=n
CONFIG_BOARD_ENABLE_DCDC_HV=n

If it still does not work:

2. Set the LF clock source to internal RC if you do not have an external 32kHz crystal. Add this as well: 
CONFIG_CLOCK_CONTROL_NRF_K32SRC_RC=y
CONFIG_CLOCK_CONTROL_NRF_K32SRC_XTAL=n

Please let us know if you are still having problems. 

Has your custom board been reviewed by anyone at Nordic? You may upload the design if you would like us to take a look at it. Either make this ticket private (unless you would like to share the design), or make a new private ticket and upload a PDF with the schematic.