encountering an issue while trying to program the Fanstel BT840F module using the nRF52840 DK

RE: encountering an issue while trying to program the Fanstel BT840F module using the nRF52840 DK

Kenneth — Thu, 03 Apr 2025 12:46:38 GMT

Define fluctuate? Have you modified the DK in any way?

Kenneth

RE: encountering an issue while trying to program the Fanstel BT840F module using the nRF52840 DK

Clarity — Thu, 03 Apr 2025 11:56:49 GMT

I’m noticing that the Vdd supply fluctuates when I power up the DK board using the MCU USB connection, without involving the FANSTEL board. Could this be a sign of a problem with the buck converter?

RE: encountering an issue while trying to program the Fanstel BT840F module using the nRF52840 DK

Kenneth — Thu, 03 Apr 2025 11:47:48 GMT

If the Fanstel module is self powered, then you can disconnect the VDD pin. Only make sure the voltage level is about the same (~3V).

Kenneth

RE: encountering an issue while trying to program the Fanstel BT840F module using the nRF52840 DK

Clarity — Thu, 03 Apr 2025 11:36:06 GMT

when connecting the SWD0_SELECT pin to ground on the external board and connecting the Debug connector to the Debug out. When these connections are made, the Vdd supply on the DK board starts fluctuating.

RE: encountering an issue while trying to program the Fanstel BT840F module using the nRF52840 DK

Kenneth — Thu, 03 Apr 2025 11:12:25 GMT

Hello,

If you want to program an external module, you should use the debug out (P19) from the DK to the external board. You also need to connect pin #3 (SWD0_SELECT) to ground on the external board, as described here:
RE: nrf52840 DK description and schematic do not agree for external debug port P19

Kenneth