I have used the stm32Nucleo-F411RE as a ST-Link programmer which uses Serial Wire Debug (SWD) as an alternative to JTag programming to burn the a bootloader onto the nRF52840. To configure the STM32Nuclueo as ST-Link I removed the jumpers on CN2.
I installed openocd an alternative to segger j-link programming
software sudo pamac install openocd and then
within a python virtual environment I pip install pyocd - pyocd - a
python interface making use of the openocd
api.
Running pyocd list should auto detect the ST-Link if it’s plugged
into the USB port. I could have set up udev rules but I ran this as
sudo as I’m using a test laptop I’m not too concerned about.
When I ran it I received an error stating I needed upgrade the firmware on the ST-Link…
Updating the ST-Link Firmware
I needed to update the firmware on the ST-Link module of
the Nucleo using STMs st-link firmware
updater.
Because I’m running Linux (manjaro) on my pc I didn’t have a java
runtime installed I had to sudo pamac install jre-opensdk and then
downloaded firmware with sudo java -jar STLinkUpgrade.jar.
Note that the readme in the firmware download instructs Linux users to run make to install the upgrader but looking at this file I can see it does quite a few things including setting up udev rules and also has some kind of binary blobs involved. I don’t see the need for these and didn’t want to risk poisoning my system so I just ran the jar directly.
The Upgrader GUI that loads is possibly the ugliest GUI I’ve ever come across but the functionality is simple enough. It detected the ST-Link plugged into the USB port and I was able to simply follow the buttons and onscreen messages without any issues.
User Access to the USB Device
Lastly I didn’t want to continue accessing the device using sudo so I
created my own rule. The Serial port (on Manjaro/Arch) is owned by
root and is in the group uucp, and my user is also added to the uucp
group. This is usually sufficient for reading and writing to the
serial ports. However, for some reason, running pyocd I’m getting
the error no available debug probes connected.
To fix this I’ve created a udev rule `/etc/udev/rules.d/50-st-link.rules
SUBSYSTEM=="usb", ATTR{idVendor}=="0483", ATTR{idProduct}=="374b", MODE="0666"
(I sourced the vendor and product id from sudo dmesg when I
connected the ST-Link to my pc).
Conclusion
Now running pyocd list returns:
# Probe Unique ID
-------------------------------------------------
0 STM32 STLink 066EFF495056805087175284
Maybe I could have used the .sh scripts from STM32 but with a load of binary data in there that I couldn’t decipher I didn’t feel comfortable, instead I’m happy with this manual process, it’s a one off really - now my STM32 ST-Link firmware is updated I should be able to use it as a programmer using OpenOCD and PyOCD.
Flashing Micropython onto the nRF52840 Dongle as example of how I have used the ST-Link.