diff --git a/boards/samr30-xpro/include/periph_conf.h b/boards/samr30-xpro/include/periph_conf.h
index 2cbcadadcb..f2bb4fe7ab 100644
--- a/boards/samr30-xpro/include/periph_conf.h
+++ b/boards/samr30-xpro/include/periph_conf.h
@@ -85,7 +85,7 @@ static const uart_conf_t uart_config[] = {
  * @{
  */
 static const spi_conf_t spi_config[] = {
-    {
+    {    /* Internal AT86RF212B */
         .dev      = &(SERCOM4->SPI),
         .miso_pin = GPIO_PIN(PC, 19),
         .mosi_pin = GPIO_PIN(PB, 30),
@@ -107,7 +107,7 @@ static const spi_conf_t spi_config[] = {
  * @{
  */
 static const i2c_conf_t i2c_config[] = {
-    {
+    {    /* EXT1 & EXT3 Pin Header */
         .dev      = &(SERCOM1->I2CM),
         .speed    = I2C_SPEED_NORMAL,
         .scl_pin  = GPIO_PIN(PA, 17),