ISP1807 (nRF52840) – Bootloader + Arduino app does not run on custom board, but works when hex is copied from a working board

RE: ISP1807 (nRF52840) – Bootloader + Arduino app does not run on custom board, but works when hex is copied from a working board

Jason — Mon, 02 Feb 2026 12:49:05 GMT

Glad you got it working :)

RE: ISP1807 (nRF52840) – Bootloader + Arduino app does not run on custom board, but works when hex is copied from a working board

being — Mon, 02 Feb 2026 12:08:55 GMT

Thanks for the comment and the link.

You were right that this turned out to be Arduino-environment related rather than a problem with the ISP1807 itself.

In my case, the root cause was that I was not setting the bootloader start address in UICR, so execution never reached my application. Once that was fixed, the module worked as expected, including reset behavior and SWD access.

So the hardware itself was fine, and the issue was in how the Arduino-based setup handled the boot/flash configuration.

Thanks again for the pointer.

RE: ISP1807 (nRF52840) – Bootloader + Arduino app does not run on custom board, but works when hex is copied from a working board

Jason — Fri, 30 Jan 2026 14:12:20 GMT

I used to use the ISP1807 and it works fine.

I never tried to use it with Arduino.

Maybe there's something in the arduino board specification that stops it working

www.insightsip.com/.../isp_ble_DS1807.pdf

RE: ISP1807 (nRF52840) – Bootloader + Arduino app does not run on custom board, but works when hex is copied from a working board

Amanda Hsieh — Fri, 30 Jan 2026 13:29:42 GMT

Hi,

Please seek help on https://forum.arduino.cc/ for Arduino development.

Regards,
Amanda H.