NRF 52840 serial port not showing on bootloading as seed xiao

RE: NRF 52840 serial port not showing on bootloading as seed xiao

Priyanka — Tue, 03 Jun 2025 07:58:38 GMT

Hi,

Please create a new ticket so that experts can take a fresh look at this.

RE: NRF 52840 serial port not showing on bootloading as seed xiao

jackpeng — Tue, 03 Jun 2025 02:39:54 GMT

I have an nrf52840 board. After burning it with adafruit-nrfutil.exe, the board seems to work fine, but the serial port disappears. The serial port only appears when I double-click rst to enter boot burning mode. How can I troubleshoot this problem?

RE: NRF 52840 serial port not showing on bootloading as seed xiao

ovrebekk — Tue, 19 Sep 2023 11:41:46 GMT

Hi Shivam

When you buy an nRF52840 chip only it will not come with any bootloader programmed, the flash is empty.

The only way to flash this device is to flash it through the SWD interface, using a supported programmer.

[quote user=""]In case of my custom pcb with nrf 52840 i am able to upload hex file through swdio and swclk but port is not showing up.[/quote]

Which hex file are you uploading? Have you made sure to build the hex for your custom hardware, taking pin assignments etc into account?

Have you sent your board schematic and layout to us for review, to ensure that the layout looks OK?
If not I would recommend opening a new ticket and sharing your design so that one of our hardware experts can have a look at it.

Best regards
Torbjørn