https://devzone.nordicsemi.com/f/nordic-q-a/110726/nrf52840-high-voltage-mode-with-external-jtag-from-52840-dkWhen custom board with nrf52840 uses High Voltage mode DCDC, in default mode, ( no firmware ), the VDD should be 1.8V as default value in REGOUT0, However the Voltage Level from JTAG from a 52840-DK is 3.3V, is it ? As a result, I cannot uses thisen-USTelligent Community 13Mon, 06 May 2024 12:51:45 GMThttps://devzone.nordicsemi.com/thread/482040?ContentTypeID=1Mon, 06 May 2024 12:51:45 GMT137ad170-7792-4731-bb38-c0d22fbe4515:bf1499b0-92e8-424b-a16d-bc0b4c32e804sprhawk<p>Understand.</p> <p>Thanks</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/482008?ContentTypeID=1Mon, 06 May 2024 11:57:24 GMT137ad170-7792-4731-bb38-c0d22fbe4515:9e9713c7-6e53-47df-b9ca-4873c3c7f68emathiaso[quote user="sprhawk"]I think the VDD voltage is set to 1.8V by default when running in High Voltage mode, right ?[/quote] <p>Yes, that is described in the <a href="https://infocenter.nordicsemi.com/topic/ps_nrf52840/uicr.html?cp=5_0_0_3_4_0_7#register.REGOUT0">REGOUT0</a> register description I linked to earlier.</p> <p>In the description of the nRF52840 DK <a href="https://infocenter.nordicsemi.com/topic/ug_nrf52840_dk/UG/dk/hw_debug_out.html?cp=5_0_4_7_9">debug output</a>, which I also linked to earlier, you can see that it is possible to set the VDD voltage in the firmware.<br /><img style="max-height:240px;max-width:320px;" src="https://devzone.nordicsemi.com/resized-image/__size/640x480/__key/communityserver-discussions-components-files/4/5428.pastedimage1714995986653v1.png" alt=" " /></p> <p>An alternative solution, if possible, could be to short the VDDH pin to VDD on your custom board when debugging, and then supply your custom board from the DK.</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/481883?ContentTypeID=1Sun, 05 May 2024 13:56:06 GMT137ad170-7792-4731-bb38-c0d22fbe4515:9efafaa8-143c-465d-8b3d-8f1365c74b75sprhawk<p>That is correct. </p> <p>( I think the VDD voltage is set to 1.8V by default when running in High Voltage mode, right ?)</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/481290?ContentTypeID=1Tue, 30 Apr 2024 12:47:47 GMT137ad170-7792-4731-bb38-c0d22fbe4515:f1163476-2a19-42ae-aa96-93748f82ecbcmathiaso<p>Hi.</p> <p>Just to make sure, you have a custom board in High voltage mode with the default VDD voltage of 1.8V (set in <a href="https://infocenter.nordicsemi.com/topic/ps_nrf52840/uicr.html?cp=5_0_0_3_4_0_7#register.REGOUT0">REGOUT0</a>) and want to program it using the nRF52840 DK, as described <a href="https://infocenter.nordicsemi.com/topic/ug_nrf52840_dk/UG/dk/hw_debug_out.html?cp=5_0_4_7_9">here</a>?</p> <p>Best regards,<br />Mathias</p><div style="clear:both;"></div>