Using nrfutil to program an off-the-shelf XIAO nRF52840 module

Question

System Details: 
 
 Chip: nRF52840, XIAO Module 
 nRF5 SDK: Version 16.0.0 
 mdk version: 8.46.0 
 nrfjprog version: 10.15.4 external 
 nrfutil version: 6.1.3 
 
 JLinkARM.dll version: 7.64d

Hello, 
 I have tested an nRF SDK example application (usbd_generic_hids) on my nRF52840 DK board, and I now would like to try and flash this application onto my off-the-shelf XIAO nRF52840 modules. I have used nrfutil in the past in order to perform DFU, but it has always been for OTA DFU via BLE. I want to know how I can program just the application itself. I believe this usbd_generic_hids example does not require a SoftDevice to be present, and I am not sure if it needs a bootloader (I dont think so). 
 I havent programmed an off-the-shelf module like this before, so I have a few questions: 
 
 I know that the XIAO module comes with a USB bootloader built-in, and I was recommended to leave that bootloader intact for easier programming. However, as I said before, I am familiar with OTA DFU and secure dfu bootloaders on the nRF52840, so I should be able to program this device wirelessly and not have to worry about overwriting the default XIAO bootloader with a nRF-based bootloader. I would personally prefer to use our normal dfu secure bootloader, with softdevice, because this is more consistent with the other versions of this device that I have been developing. Is this possible? Is there anything I should be aware of in this process? 
 I have tried using nrfutil to generate a package of the application code by itself. It compiles and creates the .zip package just fine, but it fails to actually perform the DFU (error message included below). Is it even possible to do what I am trying? I feel like I need the dfu bootloader on-board in order to perform this usb-based dfu process. + nrfutil pkg generate --hw-version 52 --sd-req 0xCA --application-version 1 --application ../nrf-sdk/examples/peripheral/usbd_hid_generic/pca10056/blank/armgcc/_build/nrf52840_xxaa.hex usbd_hid.zip 
 
|===============================================================| 
|## ## ### ######## ## ## #### ## ## ###### | 
|## ## ## ## ## ## ## ### ## ## ### ## ## ## | 
|## ## ## ## ## ## ## #### ## ## #### ## ## | 
|## ## ## ## ## ######## ## ## ## ## ## ## ## ## ####| 
|## ## ## ######### ## ## ## #### ## ## #### ## ## | 
|## ## ## ## ## ## ## ## ### ## ## ### ## ## | 
| ### ### ## ## ## ## ## ## #### ## ## ###### | 
|===============================================================| 
|You are not providing a signature key, which means the DFU | 
|files will not be signed, and are vulnerable to tampering. | 
|This is only compatible with a signature-less bootloader and is| 
|not suitable for production environments. | 
|===============================================================| 
 
Zip created at usbd_hid.zip 
+ nrfutil dfu usb-serial -pkg usbd_hid.zip -p /dev/cu.usbmodem14301 -b 115200 
 [------------------------------------] 0% 
Traceback (most recent call last): 
 File "/usr/local/bin/nrfutil", line 8, in <module> 
 sys.exit(cli()) 
 File "/usr/local/lib/python3.9/site-packages/click/core.py", line 1128, in __call__ 
 return self.main(*args, **kwargs) 
 File "/usr/local/lib/python3.9/site-packages/click/core.py", line 1053, in main 
 rv = self.invoke(ctx) 
 File "/usr/local/lib/python3.9/site-packages/click/core.py", line 1659, in invoke 
 return _process_result(sub_ctx.command.invoke(sub_ctx)) 
 File "/usr/local/lib/python3.9/site-packages/click/core.py", line 1659, in invoke 
 return _process_result(sub_ctx.command.invoke(sub_ctx)) 
 File "/usr/local/lib/python3.9/site-packages/click/core.py", line 1395, in invoke 
 return ctx.invoke(self.callback, **ctx.params) 
 File "/usr/local/lib/python3.9/site-packages/click/core.py", line 754, in invoke 
 return __callback(*args, **kwargs) 
 File "/usr/local/lib/python3.9/site-packages/nordicsemi/__main__.py", line 1022, in usb_serial
 do_serial(package, port, connect_delay, flow_control, packet_receipt_notification, baud_rate, serial_number, False,
 File "/usr/local/lib/python3.9/site-packages/nordicsemi/__main__.py", line 978, in do_serial 
 dfu.dfu_send_images() 
 File "/usr/local/lib/python3.9/site-packages/nordicsemi/dfu/dfu.py", line 127, in dfu_send_images
 self._dfu_send_image(self.manifest.application) 
 File "/usr/local/lib/python3.9/site-packages/nordicsemi/dfu/dfu.py", line 88, in _dfu_send_image 
 self.dfu_transport.open() 
 File "/usr/local/lib/python3.9/site-packages/nordicsemi/dfu/dfu_transport_serial.py", line 217, in open 
 self.__get_mtu() 
 File "/usr/local/lib/python3.9/site-packages/nordicsemi/dfu/dfu_transport_serial.py", line 366, in __get_mtu 
 self.mtu = struct.unpack('<H', bytearray(response))[0] 
TypeError: cannot convert 'NoneType' object to bytearray 
 Any general advice on what resources will help me learn how to do this?

Thank you in advance :)

mytzyiay · Accepted Answer

According to https://wiki.seeedstudio.com/XIAO_BLE/ the manufacturer advises flashing this device through the Arduino GUI. Are you sure their default bootloader implements a serial protocol compatible with nrfutil? 
 cor10 said: However, as I said before, I am familiar with OTA DFU and secure dfu bootloaders on the nRF52840, so I should be able to program this device wirelessly and not have to worry about overwriting the default XIAO bootloader with a nRF-based bootloader 
 FWIW: I started off using nrfutil to program my nRF52840 Dongles through the Open Bootloader that it ships with. This was sufficient for early prototyping and evaluation. But when it came time to support OTA updates I wanted our own public key embedded into the bootloader so that it would only accept properly signed release images. I also wanted to enforce a static partition map that won't change in future builds. So I reflashed the dongles with a homebuilt mcuboot image through the SWD pins (just SWIO, SWCLK, GND).

cor10 · Answer

Hello mytzyiay and Vidar Berg , 
 I am having trouble replying to the most recent comment left by Mytzjay, but I was able to learn a bit more about the device. I found some information on board my XIAO module that mentions the bootloader, as well as some other high level details. Take a look: 
 UF2 Bootloader 0.6.2-12-g459adc9-dirty lib/nrfx (v2.0.0) lib/tinyusb (0.10.1-293-gaf8e5a90) lib/uf2 (remotes/origin/configupdate-9-gadbb8c7)
Model: Seeed XIAO nRF52840
Board-ID: Seeed_XIAO_nRF52840_Sense
Date: Nov 30 2021
SoftDevice: S140 7.3.0
 
 Right off the bat, I notice that my SoftDevice s140 is version 7.0.1, while this XIAO module has s140 version 7.0.3. Could this difference in version be causing these issues? 
 Aside from that, I am not entirely sure how to make sense of the bootloader information. Do these bootloader details give us a better understanding of what is going on? Any help is greatly appreciated. 
 EDIT: I connected a JLINK to the XIAO module by soldering wires to the SWDIO, SWDCLK, RST, GND and 3.3V pins. This method is working for me and I am getting all of my code onto the device as expected. Thank you for working with me to try and help debug using the USB as a means of DFU. If this bootloader information that I shared sheds light on my previous failures, I would still love to learn what is going on...plus I have to program a handful of these boards and it would be easier over USB, though not needed.

Using nrfutil to program an off-the-shelf XIAO nRF52840 module

Top Replies