diff --git a/include/libopencm3/efm32/common/letimer_common.h b/include/libopencm3/efm32/common/letimer_common.h
index 40c2f9ff..a7826731 100644
--- a/include/libopencm3/efm32/common/letimer_common.h
+++ b/include/libopencm3/efm32/common/letimer_common.h
@@ -1,3 +1,5 @@
+/** @addtogroup letimer_defines
+ */
 /*
  * This file is part of the libopencm3 project.
  *
@@ -17,12 +19,13 @@
  * along with this library.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-#ifndef LIBOPENCM3_EFM32_LETIMER_H
-#define LIBOPENCM3_EFM32_LETIMER_H
+#pragma once
 
 #include <libopencm3/efm32/memorymap.h>
 #include <libopencm3/cm3/common.h>
 
+/**@{*/
+
 #define LETIMER_CTRL(base)		((base) + 0x000)
 #define LETIMER_CMD(base)		((base) + 0x004)
 #define LETIMER_STATUS(base)		((base) + 0x008)
@@ -161,5 +164,4 @@
 #define LETIMER0_SYNCBUSY		LETIMER_SYNCBUSY(LETIMER0)
 #define LETIMER0_ROUTE			LETIMER_ROUTE(LETIMER0)
 
-#endif
-
+/**@}*/
\ No newline at end of file
diff --git a/include/libopencm3/efm32/ezr32wg/letimer.h b/include/libopencm3/efm32/ezr32wg/letimer.h
index 6fbfbc7f..dc8d4fd3 100644
--- a/include/libopencm3/efm32/ezr32wg/letimer.h
+++ b/include/libopencm3/efm32/ezr32wg/letimer.h
@@ -1,3 +1,11 @@
+/** @defgroup letimer_defines LETIMER Defines
+ *
+ * @brief <b>Defined Constants and Types for the Low Energy Timer</b>
+ *
+ * @ingroup EZR32WG_defines
+ *
+ * LGPL License Terms @ref lgpl_license
+ */
 /*
  * This file is part of the libopencm3 project.
  *
@@ -17,9 +25,6 @@
  * along with this library.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-#ifndef LIBOPENCM3_EFM32_EZR32WG_LETIMER_H
-#define LIBOPENCM3_EFM32_EZR32WG_LETIMER_H
+#pragma once
 
 #include <libopencm3/efm32/common/letimer_common.h>
-
-#endif
diff --git a/include/libopencm3/efm32/lg/letimer.h b/include/libopencm3/efm32/lg/letimer.h
index 40c283f4..9a12151d 100644
--- a/include/libopencm3/efm32/lg/letimer.h
+++ b/include/libopencm3/efm32/lg/letimer.h
@@ -1,3 +1,11 @@
+/** @defgroup letimer_defines LETIMER Defines
+ *
+ * @brief <b>Defined Constants and Types for the Low Energy Timer</b>
+ *
+ * @ingroup EFM32LG_defines
+ *
+ * LGPL License Terms @ref lgpl_license
+ */
 /*
  * This file is part of the libopencm3 project.
  *
@@ -17,9 +25,6 @@
  * along with this library.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-#ifndef LIBOPENCM3_EFM32_LG_LETIMER_H
-#define LIBOPENCM3_EFM32_LG_LETIMER_H
+#pragma once
 
 #include <libopencm3/efm32/common/letimer_common.h>
-
-#endif
diff --git a/include/libopencm3/efm32/wg/letimer.h b/include/libopencm3/efm32/wg/letimer.h
index 674b2fe4..ee7473a3 100644
--- a/include/libopencm3/efm32/wg/letimer.h
+++ b/include/libopencm3/efm32/wg/letimer.h
@@ -1,3 +1,11 @@
+/** @defgroup letimer_defines LETIMER Defines
+ *
+ * @brief <b>Defined Constants and Types for the Low Energy Timer</b>
+ *
+ * @ingroup EFM32WG_defines
+ *
+ * LGPL License Terms @ref lgpl_license
+ */
 /*
  * This file is part of the libopencm3 project.
  *
@@ -17,9 +25,6 @@
  * along with this library.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-#ifndef LIBOPENCM3_EFM32_WG_LETIMER_H
-#define LIBOPENCM3_EFM32_WG_LETIMER_H
+#pragma once
 
 #include <libopencm3/efm32/common/letimer_common.h>
-
-#endif
diff --git a/lib/efm32/common/letimer_common.c b/lib/efm32/common/letimer_common.c
new file mode 100644
index 00000000..7c1ba9cb
--- /dev/null
+++ b/lib/efm32/common/letimer_common.c
@@ -0,0 +1,15 @@
+/** @addtogroup letimer_file LETIMER peripheral API
+ * @ingroup peripheral_apis
+ * @brief Low Energy Timer helper functions.
+ *
+ * <b>NO</b> helper functions exist. Only header definitions are available.
+ * Delete these lines if/when you add actual helper APIs.
+ * @copyright See @ref lgpl_license
+ */
+
+#include <libopencm3/efm32/letimer.h>
+
+/**@{*/
+
+/**@}*/
+
diff --git a/lib/efm32/ezr32wg/Makefile b/lib/efm32/ezr32wg/Makefile
index 3f270dbf..fd50eafc 100644
--- a/lib/efm32/ezr32wg/Makefile
+++ b/lib/efm32/ezr32wg/Makefile
@@ -46,6 +46,7 @@ OBJS += dma_common.o
 OBJS += emu_common.o
 OBJS += gpio_common.o
 OBJS += i2c_common.o
+OBJS += letimer_common.o
 OBJS += prs_common.o
 OBJS += timer_common.o
 
diff --git a/lib/efm32/lg/Makefile b/lib/efm32/lg/Makefile
index 98572eae..07c92dde 100644
--- a/lib/efm32/lg/Makefile
+++ b/lib/efm32/lg/Makefile
@@ -46,6 +46,7 @@ OBJS += dma_common.o
 OBJS += emu_common.o
 OBJS += gpio_common.o
 OBJS += i2c_common.o
+OBJS += letimer_common.o
 OBJS += prs_common.o
 OBJS += timer_common.o
 
diff --git a/lib/efm32/wg/Makefile b/lib/efm32/wg/Makefile
index 207be1cf..8a0d301e 100644
--- a/lib/efm32/wg/Makefile
+++ b/lib/efm32/wg/Makefile
@@ -46,6 +46,7 @@ OBJS += dma_common.o
 OBJS += emu_common.o
 OBJS += gpio_common.o
 OBJS += i2c_common.o
+OBJS += letimer_common.o
 OBJS += prs_common.o
 OBJS += timer_common.o