diff --git a/drv/rcc.c b/drv/rcc.c
index 73fe49b..56adbbc 100644
--- a/drv/rcc.c
+++ b/drv/rcc.c
@@ -60,6 +60,16 @@ void rcc_configure(enum RccPreset preset)
 	regs->APB2ENR = apb2_enr;
 }
 
+void rcc_configure_lsi(bool enable)
+{
+	regs->CSR.LSION = enable;
+
+	//ensure LSI is enabled
+	if (enable) {
+		while (regs->CSR.LSIRDY != 0x1);
+	}
+}
+
 void rcc_enable(enum RccAhb ahb_mask, enum RccApb1 apb1_mask,
 		enum RccApb2 apb2_mask)
 {
diff --git a/drv/rcc.h b/drv/rcc.h
index 770b7a0..f26ba01 100644
--- a/drv/rcc.h
+++ b/drv/rcc.h
@@ -112,6 +112,12 @@ struct RccClocks {
  */
 void rcc_configure(enum RccPreset preset);
 
+/**
+ * Configures the Low Speed Internal (LSI) oscillator for low power
+ * applications.
+ */
+void rcc_configure_lsi(bool enable);
+
 /**
  * Enables peripherals on the different buses. The enums values can used as
  * masks to enable multiple peripherals at the same time. Invalid values will be