https://devzone.nordicsemi.com/f/nordic-q-a/93921/nrf-52840dk-pca10056-versions-1-0-0-versus-3-0-0---debug-outHi, we have 10 nRF52840 DK&#39;s 8 are version 1.0.0 and 2 are version 3.0.0(purchased this week). The older version 1.0.0(made in Norway) work perfect with our 3V boards we develop but new version 3.0.0(made in Poland) do not successfuly GND Detect ouren-USTelligent Community 13Wed, 16 Nov 2022 14:11:00 GMThttps://devzone.nordicsemi.com/thread/396010?ContentTypeID=1Wed, 16 Nov 2022 14:11:00 GMT137ad170-7792-4731-bb38-c0d22fbe4515:5f2d9cd0-88c0-443c-9f62-5877e24e259eBendik Heiskel<p>Hi Dosa,</p> <p>The debugger chip was changed in v3.0.0, this changed the way external boards is detected. The earlier versions used voltage on EXT_VDD(pin 1) to detect external boards, but v3.0.0 uses ground on SWD0_SEL(pin 3) to detect the external board.</p> <p>Your custom board must tie this pin to ground, or you can make a adapter cable that connects pin 3 and 5 together.</p> <p>&nbsp;</p> <p>Best regards,</p> <p>Bendik</p><div style="clear:both;"></div>