diff --git a/boards/ikea-tradfri/include/periph_conf.h b/boards/ikea-tradfri/include/periph_conf.h
index 7b3dc0b9e6c0c2bd28168bbbf35c7eff352dae9e..fbb133e4fa84c2791b951ed20c61622ba7717aeb 100644
--- a/boards/ikea-tradfri/include/periph_conf.h
+++ b/boards/ikea-tradfri/include/periph_conf.h
@@ -126,6 +126,9 @@ static const uart_conf_t uart_config[] = {
         .tx_pin = GPIO_PIN(PB, 14),
         .loc = USART_ROUTELOC0_RXLOC_LOC9 |
                USART_ROUTELOC0_TXLOC_LOC9,
+#if EFM32_UART_MODES
+        .mode = UART_MODE_8N1,
+#endif
         .cmu = cmuClock_USART0,
         .irq = USART0_RX_IRQn
     }
diff --git a/boards/slstk3401a/include/periph_conf.h b/boards/slstk3401a/include/periph_conf.h
index 6dfc97597ee25a24e16528da4fd23e3d40333e98..e2f394fe65744113b38a89e8661d36f04cac70fe 100644
--- a/boards/slstk3401a/include/periph_conf.h
+++ b/boards/slstk3401a/include/periph_conf.h
@@ -175,6 +175,9 @@ static const uart_conf_t uart_config[] = {
         .tx_pin = GPIO_PIN(PA, 0),
         .loc = USART_ROUTELOC0_RXLOC_LOC0 |
                USART_ROUTELOC0_TXLOC_LOC0,
+#if EFM32_UART_MODES
+        .mode = UART_MODE_8N1,
+#endif
         .cmu = cmuClock_USART0,
         .irq = USART0_RX_IRQn
     },
@@ -184,6 +187,9 @@ static const uart_conf_t uart_config[] = {
         .tx_pin = GPIO_PIN(PC, 6),
         .loc = USART_ROUTELOC0_RXLOC_LOC11 |
                USART_ROUTELOC0_TXLOC_LOC11,
+#if EFM32_UART_MODES
+        .mode = UART_MODE_8N1,
+#endif
         .cmu = cmuClock_USART1,
         .irq = USART1_RX_IRQn
     },
@@ -193,6 +199,9 @@ static const uart_conf_t uart_config[] = {
         .tx_pin = GPIO_PIN(PD, 10),
         .loc = LEUART_ROUTELOC0_RXLOC_LOC18 |
                LEUART_ROUTELOC0_TXLOC_LOC18,
+#if EFM32_UART_MODES
+        .mode = UART_MODE_8N1,
+#endif
         .cmu = cmuClock_LEUART0,
         .irq = LEUART0_IRQn
     }
diff --git a/boards/sltb001a/include/periph_conf.h b/boards/sltb001a/include/periph_conf.h
index 552a78641807a6d37e87d66685f3fc385bad5e84..4ab11bcdeaddec7df715cbe105f987500dd2ea14 100644
--- a/boards/sltb001a/include/periph_conf.h
+++ b/boards/sltb001a/include/periph_conf.h
@@ -176,6 +176,9 @@ static const uart_conf_t uart_config[] = {
         .tx_pin = GPIO_PIN(PA, 0),
         .loc = USART_ROUTELOC0_RXLOC_LOC0 |
                USART_ROUTELOC0_TXLOC_LOC0,
+#if EFM32_UART_MODES
+        .mode = UART_MODE_8N1,
+#endif
         .cmu = cmuClock_USART0,
         .irq = USART0_RX_IRQn
     },
@@ -185,6 +188,9 @@ static const uart_conf_t uart_config[] = {
         .tx_pin = GPIO_PIN(PC, 7),
         .loc = USART_ROUTELOC0_RXLOC_LOC11 |
                USART_ROUTELOC0_TXLOC_LOC11,
+#if EFM32_UART_MODES
+        .mode = UART_MODE_8N1,
+#endif
         .cmu = cmuClock_USART1,
         .irq = USART1_RX_IRQn
     },
@@ -194,6 +200,9 @@ static const uart_conf_t uart_config[] = {
         .tx_pin = GPIO_PIN(PD, 10),
         .loc = LEUART_ROUTELOC0_RXLOC_LOC18 |
                LEUART_ROUTELOC0_TXLOC_LOC18,
+#if EFM32_UART_MODES
+        .mode = UART_MODE_8N1,
+#endif
         .cmu = cmuClock_LEUART0,
         .irq = LEUART0_IRQn
     }
diff --git a/boards/slwstk6000b/include/periph_conf.h b/boards/slwstk6000b/include/periph_conf.h
index feabf04891b6a3facaa18d562c552620d3337daa..f53a9cf3b74baf022db3479f9d76cd4820ee7fb3 100644
--- a/boards/slwstk6000b/include/periph_conf.h
+++ b/boards/slwstk6000b/include/periph_conf.h
@@ -177,6 +177,9 @@ static const uart_conf_t uart_config[] = {
         .tx_pin = MODULE_PIN_F6,
         .loc = USART_ROUTELOC0_RXLOC_LOC0 |
                USART_ROUTELOC0_TXLOC_LOC0,
+#if EFM32_UART_MODES
+        .mode = UART_MODE_8N1,
+#endif
         .cmu = cmuClock_USART0,
         .irq = USART0_RX_IRQn
     }
diff --git a/boards/stk3600/include/periph_conf.h b/boards/stk3600/include/periph_conf.h
index 344903b0d392b396de10e5af3a354a79a1662c69..505bd85c79a54b505305bd80f77cd57f604316bd 100644
--- a/boards/stk3600/include/periph_conf.h
+++ b/boards/stk3600/include/periph_conf.h
@@ -237,6 +237,9 @@ static const uart_conf_t uart_config[] = {
         .rx_pin = GPIO_PIN(PE, 1),
         .tx_pin = GPIO_PIN(PE, 0),
         .loc = UART_ROUTE_LOCATION_LOC1,
+#if EFM32_UART_MODES
+        .mode = UART_MODE_8N1,
+#endif
         .cmu = cmuClock_UART0,
         .irq = UART0_RX_IRQn
     },
@@ -245,6 +248,9 @@ static const uart_conf_t uart_config[] = {
         .rx_pin = GPIO_PIN(PD, 1),
         .tx_pin = GPIO_PIN(PD, 0),
         .loc = USART_ROUTE_LOCATION_LOC1,
+#if EFM32_UART_MODES
+        .mode = UART_MODE_8N1,
+#endif
         .cmu = cmuClock_USART1,
         .irq = USART1_RX_IRQn
     },
@@ -253,6 +259,9 @@ static const uart_conf_t uart_config[] = {
         .rx_pin = GPIO_PIN(PD, 5),
         .tx_pin = GPIO_PIN(PD, 4),
         .loc = LEUART_ROUTE_LOCATION_LOC0,
+#if EFM32_UART_MODES
+        .mode = UART_MODE_8N1,
+#endif
         .cmu = cmuClock_LEUART0,
         .irq = LEUART0_IRQn
     }
diff --git a/boards/stk3700/include/periph_conf.h b/boards/stk3700/include/periph_conf.h
index c75de87848178d6a68b7c8ae235859b29934a319..11ec369011917cdd9f820f52a94a7c6475e3d3c6 100644
--- a/boards/stk3700/include/periph_conf.h
+++ b/boards/stk3700/include/periph_conf.h
@@ -237,6 +237,9 @@ static const uart_conf_t uart_config[] = {
         .rx_pin = GPIO_PIN(PE, 1),
         .tx_pin = GPIO_PIN(PE, 0),
         .loc = UART_ROUTE_LOCATION_LOC1,
+#if EFM32_UART_MODES
+        .mode = UART_MODE_8N1,
+#endif
         .cmu = cmuClock_UART0,
         .irq = UART0_RX_IRQn
     },
@@ -245,6 +248,9 @@ static const uart_conf_t uart_config[] = {
         .rx_pin = GPIO_PIN(PD, 1),
         .tx_pin = GPIO_PIN(PD, 0),
         .loc = USART_ROUTE_LOCATION_LOC1,
+#if EFM32_UART_MODES
+        .mode = UART_MODE_8N1,
+#endif
         .cmu = cmuClock_USART1,
         .irq = USART1_RX_IRQn
     },
@@ -253,6 +259,9 @@ static const uart_conf_t uart_config[] = {
         .rx_pin = GPIO_PIN(PD, 5),
         .tx_pin = GPIO_PIN(PD, 4),
         .loc = LEUART_ROUTE_LOCATION_LOC0,
+#if EFM32_UART_MODES
+        .mode = UART_MODE_8N1,
+#endif
         .cmu = cmuClock_LEUART0,
         .irq = LEUART0_IRQn
     }