boards/nucleo-l376: added and configured rtt

boards/nucleo-l476/Makefile.features

@@ -5,6 +5,7 @@ FEATURES_PROVIDED += periph_hwrng
 FEATURES_PROVIDED += periph_pwm
 FEATURES_PROVIDED += periph_spi
 FEATURES_PROVIDED += periph_timer
+FEATURES_PROVIDED += periph_rtt
 FEATURES_PROVIDED += periph_uart
 
 # load the common Makefile.features for Nucleo boards

boards/nucleo-l476/include/periph_conf.h

@@ -234,6 +234,17 @@ static const spi_conf_t spi_config[] = {
 #define DAC_NUMOF           (0)
 /** @} */
 
+/**
+ * @name    RTT configuration
+ *
+ * On the STM32Lx platforms, we always utilize the LPTIM1.
+ * @{
+ */
+#define RTT_NUMOF           (1)
+#define RTT_FREQUENCY       (1024U)             /* 32768 / 2^n */
+#define RTT_MAX_VALUE       (0x0000ffff)        /* 16-bit timer */
+/** @} */
+
 #ifdef __cplusplus
 }
 #endif