boards: add STM32C0116-DK and STM32C0316-DK [new PR]

[crasbe]

Contribution description

Unfortunately the PR #20939 that added several new STM32C0 based boards went stale, so I took the liberty to take it over.

The fixup commit changes the copyright notice to the new SPDX format and the headerguards to #pragma once as well as fixing a typo in the KConfig file. The flashing information now points to the guide merged in #21767 (following the scheme from #21337).

This PR is the second part #21775 because I don't have the hardware yet. After #21775 is merged, the DELETEME commit will be removed. Hardware arrive, PR is merged.

TODO: Apply the comments of benpicco's review from the other PR.

Testing procedure

tbd as soon as I have the hardware.

Issues/PRs references

This is continued from #20939 (and will close it).
Tracking Issue #19264.

[riot-ci]

Murdock results

✔️ PASSED

7caafd0 tests: update Makefile.ci with stm32c0116-dk & stm32c0316-dk

Success	Failures	Total	Runtime
3103	0	3103	06m:11s

Artifacts

• Documentation preview

[crasbe]

I currently can not get the boards running right. The STM32C0116-DK can be flashed, but it appears that some clock configuration is wrong. The blinky example blinks way too fast even though ztimer is used. This probably also messes up the baudrate which is why no communication with the ST-Link is possibly even though I changed the pin and interrupt etc assignments.

The STM32C0316-DK cannot be flashed currently (neither with Linux nor WSL), I get this error. That board doesn't have a built-in ST-Link but ships with an ST-Link Mini V3.
Most likely it'll have similar issues as the C0116-DK as well.

### Flashing Target ###
Open On-Chip Debugger 0.12.0+dev-02241-g3fd975941-dirty (2025-10-14-09:55)
Licensed under GNU GPL v2
For bug reports, read
        http://openocd.org/doc/doxygen/bugs.html
Warn : Transport "swd" was already selected
DEPRECATED! use 'tcl port' not 'tcl_port'
DEPRECATED! use 'telnet port', not 'telnet_port'
DEPRECATED! use 'gdb port', not 'gdb_port'
Error: libusb_open() failed with LIBUSB_ERROR_ACCESS
Error: open failed

[crasbe]

The STM32C0316-DK cannot be flashed currently (neither with Linux nor WSL), I get this error. That board doesn't have a built-in ST-Link but ships with an ST-Link Mini V3.

Okay two issues: First of all OpenOCD does not update the udev rules when installing, so it did not know about the ST-Link V3 yet.
Secondly my STM32C0316-DK is broken. The 3.3V regulator does not output any voltage at all...

[crasbe]

The STM32C0116-DK can be flashed, but it appears that some clock configuration is wrong. The blinky example blinks way too fast even though ztimer is used.

Now this is interesting. When using ztimer_usec (which is the default) for the blinky, it blinks with ~25Hz. When using ztimer_msec, it blinks somewhat erratic suggesting an overflow of some sort?
ztimer_sec does not work at all.
This is odd though because the Nucleo-C071RB uses the same timer configuration and it works there. The Nucleo-C071RB has crystals for HSE and LSE though, the C011 has neither. Setting CONFIG_BOARD_HAS_LSE and CONFIG_BOARD_HAS_HSE to zero didn't change anything.

This is what I mean with "erratic":

document_5436140939770890711.mp4

[crasbe]

Now this is interesting. When using ztimer_usec (which is the default) for the blinky, it blinks with ~25Hz. When using ztimer_msec, it blinks somewhat erratic suggesting an overflow of some sort?
ztimer_sec does not work at all.

This is fixed thanks to a hint from Kaspar. The culprit was a missing TIMER_0_MAX_VALUE. The STM32C011 only has 16-bit timers and ztimer assumed 32-bits, which is why odd things happened.

[AnnsAnns]

I found nothing to really complain about. As with the other PR, I will simply trust you that it works since this is a quasi second round review PR and your work in itself is already a review of the old code. (And once again thank you for working on this and ty to the original author for the OG code) [and I also don't have the hardware 🙈]

[crasbe]

I still have to test the addition with the STM32C0316-DK, once Digikey replies with how we proceed with the broken board.
Of course I can add a new 3.3V regulator, but if they want me to send it back it would be... inconvenient... to have modified it 😅

[AnnsAnns]

I still have to test the addition with the STM32C0316-DK, once Digikey replies with how we proceed with the broken board. Of course I can add a new 3.3V regulator, but if they want me to send it back it would be... inconvenient... to have modified it 😅

Lets wait for the Digikey overlords to decide this PRs fate then 😛

[crasbe]

The Digikey overloads said that I can keep the broken board, so anyway I started blast...soldering :D

Well what can I say, it works:

cbuec@W11nMate:~/RIOTstuff/riot-guides/RIOT$ BOARD=stm32c0316-dk make -C examples/basic/hello-world/ flash t
erm -j
Building application "hello-world" for "stm32c0316-dk" with CPU "stm32".

"make" -C /home/cbuec/RIOTstuff/riot-guides/RIOT/pkg/cmsis/
...
"make" -C /home/cbuec/RIOTstuff/riot-guides/RIOT/cpu/cortexm_common/periph
   text    data     bss     dec     hex filename
   6816       8    2292    9116    239c /home/cbuec/RIOTstuff/riot-guides/RIOT/examples/basic/hello-world/bin/stm32c0316-dk/hello-world.elf
/home/cbuec/RIOTstuff/riot-guides/RIOT/dist/tools/openocd/openocd.sh flash /home/cbuec/RIOTstuff/riot-guides/RIOT/examples/basic/hello-world/bin/stm32c0316-dk/hello-world.elf
### Flashing Target ###
Open On-Chip Debugger 0.12.0+dev-02241-g3fd975941-dirty (2025-10-14-09:55)
Licensed under GNU GPL v2
For bug reports, read
        http://openocd.org/doc/doxygen/bugs.html
Warn : DEPRECATED: auto-selecting transport "swd (dapdirect)". Use 'transport select swd' to suppress this message.
swd (dapdirect)
swd (dapdirect)
DEPRECATED! use 'tcl port' not 'tcl_port'
DEPRECATED! use 'telnet port', not 'telnet_port'
DEPRECATED! use 'gdb port', not 'gdb_port'
Info : STLINK V3J16M8 (API v3) VID:PID 0483:3754
Info : Target voltage: 3.285562
Info : Unable to match requested speed 2000 kHz, using 1000 kHz
Info : Unable to match requested speed 2000 kHz, using 1000 kHz
Info : clock speed 1000 kHz
Info : SWD DPIDR 0x0bc11477
Info : [stm32c0x.cpu] Cortex-M0+ r0p1 processor detected
Info : [stm32c0x.cpu] target has 4 breakpoints, 2 watchpoints
Info : [stm32c0x.cpu] Examination succeed
Info : [stm32c0x.cpu] starting gdb server on 0
Info : Listening on port 39163 for gdb connections
    TargetName         Type       Endian TapName            State
--  ------------------ ---------- ------ ------------------ ------------
 0* stm32c0x.cpu       cortex_m   little stm32c0x.cpu       unknown
[stm32c0x.cpu] halted due to debug-request, current mode: Thread
xPSR: 0xf1000000 pc: 0x08000818 msp: 0x20000200
Info : device idcode = 0x10006453 (STM32C03xx - Rev A : 0x1000)
Info : RDP level 0 (0xAA)
Info : flash size = 32 KiB
Info : flash mode : single-bank
Warn : Adding extra erase range, 0x08001aa8 .. 0x08001fff
auto erase enabled
wrote 6824 bytes from file /home/cbuec/RIOTstuff/riot-guides/RIOT/examples/basic/hello-world/bin/stm32c0316-dk/hello-world.elf in 0.338695s (19.676 KiB/s)
verified 6824 bytes in 0.135212s (49.286 KiB/s)
shutdown command invoked
Done flashing
/home/cbuec/RIOTstuff/riot-guides/RIOT/dist/tools/pyterm/pyterm -p "/dev/ttyACM0" -b "115200" -ln "/tmp/pyterm-cbuec" -rn "2025-10-20_14.38.40-hello-world-stm32c0316-dk"
2025-10-20 14:38:40,616 # Connect to serial port /dev/ttyACM0
Welcome to pyterm!
Type '/exit' to exit.
2025-10-20 14:38:46,476 # main(): This is RIOT! (Version: 2025.10-devel-455-ga35ba66-pr/stm32c0-dk_new)
2025-10-20 14:38:46,477 # Hello World!
2025-10-20 14:38:46,481 # You are running RIOT on a(n) stm32c0316-dk board.
2025-10-20 14:38:46,486 # This board features a(n) stm32 CPU.

[AnnsAnns]

Hooray

[crasbe]

Thanks for the review :)