Seeed Studio XIAO nRF52840 Problem

Dear all,

it is me again. I got already some help, some month ago:

Thanks for that.
And the project mentioned above works fine for some month. Last day I tried to pair the Seeed with a new device and now it is not working anymore.
As you can read above, I have absolutely no idea - I’m even surprised that I managed to get the thing running at all.
The current status is, when I power the Motorbuttons I have sometimes one and sometimes two LED on, but there is no Bluetooth where I can connect.
I can upload the Arduino Code via Arduino IDE, the board is seen. Upload works, but after this nothing (then above) happen. In windows words, I would say it will noct boot.
In normal mode both LED will blink until a Bluetooth device is paired.
So how can I start failure search?
Can I totally reset the board?

make sure to put it in boot mode and restart after new program… sometimes it acts like it updated but it really did not… also you can try wipe it clean by uploading blink sketch

Hi there,
Where are the buttons connected to?
D0 , D1?
You’ll need to press reset after this also.
GL :slight_smile: PJ

You have a BLE dongle, use nrf connect for desktop and get a nordic $9 dongle , great for troubleshooting BLE issue.

Please excuse my lack of knowledge. How to get in boot mode?
I managed to get the blink sketch working.
A good sign that the board is OK.

Please excuse my lack of knowledge

Yes, two pins of the joystick are connected to D0 and D1 among others.

“You’ll need to press reset after this also” Reset button on the board? And after what?

I will try to upload the right sketch again and will comment this.


Q1: My Arduino IDE is stuck when uploading code to the board

You can first try to reset the board by clicking the “Reset Button” once. If that does not work, rapidly click it twice to enter bootloader mode. If that also doesn’t work, disconnect the board from the PC, and connect the board again.

Q2: My board is not showing up as a serial device on Arduino IDE

You can first try to reset the board by clicking the “Reset Button” once. If that does not work, rapidly click it twice to enter bootloader mode.

Press reset button… and if that doesnt work… double click the reset button

… press reset button after uploading sketch… because sometimes it will automaticly reset… but sometimes it does not so after upload it is good idea to press reset button or power cycle

Morning, I managed to load the sketch again. The board is sometimes working, sometimes not. It looks like a boot problem, I believe the board is the problem.
I will monitor this and in the worst case change the board.

Thanks for the help!

Hi there,
Does the Xiao show up as a Drive? (BL mode) if so, Grab the Uf2 file for the RGB LED test in the
“Drag & Drop” test file thread. There’s a zip. DRAG the uf2 file to it , it will reset after it reloads anf cycle thru the RGB colors thus reloading the BootLoader image and code that is verified good. Looks to me the BootLoader is corrupted. or you code hit a memory boundary and messed it up.
GL :slight_smile: PJ

Yes it does (sometimes if you double click the on board reset button and only then you can uplaod sketch)

Ok, I will copy the uf2 file onto this board.

The sketch (code) is only 28KB big.

Thanky you

Hi there,
Yes, If it only lets you upload in Bootloader mode, Then something got wacked in the flash, luckily “Size” doesn’t matter…LOL of the code. any lib or io miss code parameter can write to a location and only slightly mess it up. Even small programs that have too fast, or very tight loops will prevent enough time for it to see the upload signal from the com port. That requires a double press then.
You should be able to upload regardless of mode it’s in on a Normal Xiao situation. (note the com port will change however) in some cases.
BL mode is required to drag and drop the Uf2 files.
GL :slight_smile: PJ