Cannot program nrf52840 over SWD on custom board. Potential hardware issue. "init mode failed (unable to connect to the target)"

RE: Cannot program nrf52840 over SWD on custom board. Potential hardware issue. "init mode failed (unable to connect to the target)"

DragonLord64 — Fri, 01 Dec 2023 22:55:55 GMT

Thank you for the help. I have ordered an nrf52840-DK.

I have tried with several other non-supported programmers, all unsuccessful in communicating with the MCU.

Soldering has been difficult to verify with the QIAA package. I currently suspect the chip is damaged.

I will update when I have attempted with the supported programmer.

RE: Cannot program nrf52840 over SWD on custom board. Potential hardware issue. "init mode failed (unable to connect to the target)"

ketiljo — Thu, 30 Nov 2023 11:15:18 GMT

Neither openOCD or ST-link is supported. Get a proper Segger debugger/programmer or a nRF52-DK. On nRF52840 QIAA-F, the approtect bit is set by default.

You can leave VDDH floating and power the device wih 3 V on VDD, that will solve the voltage issue. The schematic looks correct so check for solder problems.

RE: Cannot program nrf52840 over SWD on custom board. Potential hardware issue. "init mode failed (unable to connect to the target)"

Frank Viganske — Wed, 29 Nov 2023 11:45:59 GMT

[quote userid="130159" url="~/f/nordic-q-a/106155/cannot-program-nrf52840-over-swd-on-custom-board-potential-hardware-issue-init-mode-failed-unable-to-connect-to-the-target"]External bench power supplies 3V directly to VDD pin. VDDH pin is left floating[/quote]

Hi,

when you supply the chip over VDD in low voltage mode, you need to connect VDD and VDDH. You shouldn't leave it floating. See for example this Link: https://infocenter.nordicsemi.com/topic/ps_nrf52840/power.html?cp=5_0_0_4_2_0_3#unique_1591758884

I don't know if this will solve your problem though.

Best regards

Frank