NRF 52840 serial port not showing on bootloading as seed xiao

[Shivam]

I am using seed XIAO for one of my projects having nrf 52840 ic so in order use the nrf chip on my custom pcb i have to bootload the nrf 52840 IC purchased from digikey. I am trying to bootload it but unable to find the serial monitor of nrf 52840.

What can be the reason or how to solve it, i have made a custom pcb like seed xiao and when i am trying to bootload the pcb with nrf 52840 , serial port is not showing up. However when i am bootloading a purchased seed xiao module then the process is correct and i am able to see the port. 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.

[ovrebekk]

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. 

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.

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

[jackpeng]

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?

[Priyanka]

Hi,

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