boards/slstk3301a: add support by basilfx · Pull Request #22069 · RIOT-OS/RIOT

basilfx · 2026-02-10T08:30:09Z

Contribution description

This PR adds support for the SLSTK3301A starter kit. It is based on the EFM32TG11 Series 1 microcontroller, which is a Cortex M0+. It has about 128 KiB of flash and 32 KiB of memory, rich amount of peripheral and quite some more advanced features such as HWRNG and CAN.

In terms of capabilities I would put it between the SLSTK3400A and the SLSTK3401A. And for the line-up I think it is a relevant board. The STK3200 and and SLSTK3400A have a Cortex M0+ too, but for Series 0. They often lack flash and/or memory to run more-advanced applications. This board is more capable.

I have this board for quite some time, but never bothered to add it before. I am considering this family of microcontrollers for a next project, and with #22040, adding support was easier. Although the kit is a bit older, you can still buy this starter kit (it is not not-recommended for new designs).

Testing procedure

This board makes use of the drivers already working for other EFM32-based boards, so it should be straight forward to run some applications and see how they work.

I tested a few of the peripheral tests, and some basic interaction with examples/default/basic.

Screenshots of test applications

Just a few screenshots of the test I ran (not all of them).

examples/default/basic

tests/periph/uart

tests/periph/uart_mode

tests/periph/hwrng

tests/periph/wdt

Issues/PRs references

~~Depends on #22040.~~

crasbe

There is a static error and some copyright headers might have to be adjusted.

crasbe · 2026-02-10T10:39:28Z

boards/slstk3301a/include/board.h

+#endif
+
+/**
+ * @name    Xtimer configuration


Is that still relevant? xtimer is deprecated and the compat layer uses ztimer in the backend 🤔

All the other EFM32-based boards still have the same defines, so I would presume it is still relevant.

For example: https://github.com/RIOT-OS/RIOT/blob/master/boards/slstk3401a/include/board.h#L36

The xtimer defines are used as fallback for ztimer apparently:

RIOT/sys/include/ztimer/config.h

Lines 36 to 54 in 8b0ceb9

/* for ZTIMER_USEC, use xtimer configuration if available and no ztimer

* specific configuration is set. */

#if CONFIG_ZTIMER_USEC_TYPE_PERIPH_TIMER

# ifndef CONFIG_ZTIMER_USEC_DEV

# ifdef XTIMER_DEV

# define CONFIG_ZTIMER_USEC_DEV XTIMER_DEV

# endif

# endif

# ifndef CONFIG_ZTIMER_USEC_BASE_FREQ

# ifdef XTIMER_HZ

# define CONFIG_ZTIMER_USEC_BASE_FREQ XTIMER_HZ

# endif

# endif

# ifndef CONFIG_ZTIMER_USEC_WIDTH

# ifdef XTIMER_WIDTH

# define CONFIG_ZTIMER_USEC_WIDTH XTIMER_WIDTH

# endif

# endif

#endif

Although with #21960 on the horizon, it might be better to just use the respective ztimer defines. One thing less to (eventually) migrate.

Good point! I will adapt and provide a PR for the other boards later.

crasbe · 2026-02-10T10:39:57Z

boards/slstk3301a/include/periph_conf.h

+ * @{
+ */
+#ifndef CLOCK_HF
+#define CLOCK_HF            cmuSelect_HFXO


Suggested change

#define CLOCK_HF cmuSelect_HFXO

# define CLOCK_HF cmuSelect_HFXO

Same for many other locations, this is just an example.

crasbe · 2026-02-10T10:42:09Z

boards/slstk3301a/doc.md

+
+### Pinout
+This is the pinout of the expansion header on the right side of the board.
+PIN 1 is the bottom-left contact when the header faces you horizontally.


This is a bit confusing IMO, especially since the table has pin 1 in the bottom right position 🤔

~~This was an auto-generated document, and it turns out that this is not the case for this board (it is actually top-left).~~

~~This will probably be the case for other EFM32-boards (starting with SLSTK*).~~

On second thought: it is correct. The table reflects the documentation and the silk screen.

crasbe · 2026-02-10T10:43:33Z

boards/slstk3301a/doc.md

+the speeds above, ensure to pass `EFM32_HFXO_FREQ=freq_in_hz` and
+`EFM32_LFXO_FREQ=freq_in_hz` to your compiler.


Is this a CFLAG or an environment variable?

Changes this into 'compiler defines'.

boards/slstk3301a/doc.md

crasbe · 2026-02-10T10:45:41Z

boards/slstk3301a/doc.md

+## License information
+Silicon Labs' EMLIB: zlib-style license (permits distribution of source).


Is that for this README or for the Toolchain?

It is to mention that emlib (used by this board and CPU) permits distribution of source.

This is also added to the other EFM32 boards.

Yes, but the headline is at the same level as the other headlines, it's not on a sub-level for emlib.

Suggested change

## License information

Silicon Labs' EMLIB: zlib-style license (permits distribution of source).

### License information

Silicon Labs' EMLIB: zlib-style license (permits distribution of source).

Ah now I understand. I'll address this and provide a PR for the other board (with probably the same mistake) too (will also check for other inconsistencies).

I moved this below the emlib section as an additional sentence to that section.

crasbe · 2026-02-10T10:47:13Z

cpu/efm32/families/efm32tg11b/Makefile

@@ -0,0 +1,9 @@
+MODULE = cpu_efm32tg11b
+
+# (file triggers compiler bug. see #5775)


Is that still the case? #5775 got fixed with #14422 🤔

This is still in-place for many more CPUs (als non-EFM32), so the honest answer is: I don't know.

This is still in-place for many more CPUs (als non-EFM32)

That doesn't have to mean much, it is not unlikely that these remarks were not removed when the bug was fixed.

Ping @maribu 👀

Well, let's drop and check if something breaks when compiling with LTO=1

I'm unable to build with LTO=1, even without dropping this line.

There are many errors, but most are related to undefined reference to '__wrap_puts' and undefined reference to '__wrap_printf'.

basilfx · 2026-02-10T10:51:11Z

I did not alter the copyright headers, because they have been copy-pasted from the original board back in the days. This board was already generated a long time ago ;-)

boards/slstk3301a/doc.md

basilfx · 2026-02-11T22:39:11Z

#22040 is now merged, so no more dependencies.

riot-ci · 2026-02-12T03:50:29Z

Murdock results

✔️ PASSED

1a8067c fixup! boards/slstk3301a: add support

Success	Failures	Total	Runtime
11004	0	11005	08m:52s

Artifacts

Documentation preview

basilfx requested review from MrKevinWeiss, jia200x and leandrolanzieri as code owners February 10, 2026 08:30

github-actions bot added Platform: ARM Platform: This PR/issue effects ARM-based platforms Area: doc Area: Documentation Area: build system Area: Build system Area: boards Area: Board ports Area: cpu Area: CPU/MCU ports Area: Kconfig Area: Kconfig integration labels Feb 10, 2026

basilfx force-pushed the feature/add_slstk3301a branch 2 times, most recently from f6f58d5 to b8d422c Compare February 10, 2026 10:04

crasbe added the State: waiting for other PR State: The PR requires another PR to be merged first label Feb 10, 2026

crasbe reviewed Feb 10, 2026

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kfessel reviewed Feb 11, 2026

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basilfx force-pushed the feature/add_slstk3301a branch from 6f936f3 to 5545621 Compare February 11, 2026 22:37

github-actions bot added the Area: tools Area: Supplementary tools label Feb 11, 2026

basilfx removed the State: waiting for other PR State: The PR requires another PR to be merged first label Feb 11, 2026

basilfx added the CI: ready for build If set, CI server will compile all applications for all available boards for the labeled PR label Feb 11, 2026

basilfx added 7 commits February 15, 2026 14:57

cpu/efm32: add support for efm32tg11b

765b0de

boards/slstk3301a: add support

081c44f

dist/tools/doccheck: add SI7210_EN_PIN to exclude_simple

31173a7

fixup! boards/slstk3301a: add support

1ac5330

fixup! boards/slstk3301a: add support

77c77e0

fixup! boards/slstk3301a: add support

42f71c5

fixup! boards/slstk3301a: add support

1a8067c

basilfx force-pushed the feature/add_slstk3301a branch from 5545621 to 1a8067c Compare February 15, 2026 13:57

	/* for ZTIMER_USEC, use xtimer configuration if available and no ztimer
	* specific configuration is set. */
	#if CONFIG_ZTIMER_USEC_TYPE_PERIPH_TIMER
	# ifndef CONFIG_ZTIMER_USEC_DEV
	# ifdef XTIMER_DEV
	# define CONFIG_ZTIMER_USEC_DEV XTIMER_DEV
	# endif
	# endif
	# ifndef CONFIG_ZTIMER_USEC_BASE_FREQ
	# ifdef XTIMER_HZ
	# define CONFIG_ZTIMER_USEC_BASE_FREQ XTIMER_HZ
	# endif
	# endif
	# ifndef CONFIG_ZTIMER_USEC_WIDTH
	# ifdef XTIMER_WIDTH
	# define CONFIG_ZTIMER_USEC_WIDTH XTIMER_WIDTH
	# endif
	# endif
	#endif

	#define CLOCK_HF cmuSelect_HFXO
	# define CLOCK_HF cmuSelect_HFXO

		the speeds above, ensure to pass `EFM32_HFXO_FREQ=freq_in_hz` and
		`EFM32_LFXO_FREQ=freq_in_hz` to your compiler.

		## License information
		Silicon Labs' EMLIB: zlib-style license (permits distribution of source).

		@@ -0,0 +1,9 @@
		MODULE = cpu_efm32tg11b

		# (file triggers compiler bug. see #5775)

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Contribution description

Testing procedure

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