diff --git a/firmware/common/hackrf_core.c b/firmware/common/hackrf_core.c
index a562f7c6..1af5e823 100644
--- a/firmware/common/hackrf_core.c
+++ b/firmware/common/hackrf_core.c
@@ -38,13 +38,15 @@
 
 i2c_bus_t i2c0 = {
 	.obj = (void*)I2C0_BASE,
-	.init = i2c_lpc_init,
+	.start = i2c_lpc_start,
+	.stop = i2c_lpc_stop,
 	.transfer = i2c_lpc_transfer,
 };
 
 i2c_bus_t i2c1 = {
 	.obj = (void*)I2C1_BASE,
-	.init = i2c_lpc_init,
+	.start = i2c_lpc_start,
+	.stop = i2c_lpc_stop,
 	.transfer = i2c_lpc_transfer,
 };
 
@@ -290,7 +292,7 @@ void cpu_clock_init(void)
 	/* use IRC as clock source for APB3 */
 	CGU_BASE_APB3_CLK = CGU_BASE_APB3_CLK_CLK_SEL(CGU_SRC_IRC);
 
-	i2c_bus_init(clock_gen.bus, &i2c_config_si5351c_slow_clock);
+	i2c_bus_start(clock_gen.bus, &i2c_config_si5351c_slow_clock);
 
 	si5351c_disable_all_outputs(&clock_gen);
 	si5351c_disable_oeb_pin_control(&clock_gen);
@@ -362,7 +364,7 @@ void cpu_clock_init(void)
 
 	//FIXME disable I2C
 	/* Kick I2C0 down to 400kHz when we switch over to APB1 clock = 204MHz */
-	i2c_bus_init(clock_gen.bus, &i2c_config_si5351c_fast_clock);
+	i2c_bus_start(clock_gen.bus, &i2c_config_si5351c_fast_clock);
 
 	/*
 	 * 12MHz clock is entering LPC XTAL1/OSC input now.  On
diff --git a/firmware/common/i2c_bus.c b/firmware/common/i2c_bus.c
index 6b60455a..7b5497e0 100644
--- a/firmware/common/i2c_bus.c
+++ b/firmware/common/i2c_bus.c
@@ -21,8 +21,12 @@
 
 #include "i2c_bus.h"
 
-void i2c_bus_init(i2c_bus_t* const bus, const void* const config) {
-	bus->init(bus, config);
+void i2c_bus_start(i2c_bus_t* const bus, const void* const config) {
+	bus->start(bus, config);
+}
+
+void i2c_bus_stop(i2c_bus_t* const bus) {
+	bus->stop(bus);
 }
 
 void i2c_bus_transfer(
diff --git a/firmware/common/i2c_bus.h b/firmware/common/i2c_bus.h
index 784fb602..04b83499 100644
--- a/firmware/common/i2c_bus.h
+++ b/firmware/common/i2c_bus.h
@@ -30,7 +30,8 @@ typedef struct i2c_bus_t i2c_bus_t;
 
 struct i2c_bus_t {
 	void* const obj;
-	void (*init)(i2c_bus_t* const bus, const void* const config);
+	void (*start)(i2c_bus_t* const bus, const void* const config);
+	void (*stop)(i2c_bus_t* const bus);
 	void (*transfer)(
 		i2c_bus_t* const bus,
 		const uint_fast8_t slave_address,
@@ -39,7 +40,8 @@ struct i2c_bus_t {
 	);
 };
 
-void i2c_bus_init(i2c_bus_t* const bus, const void* const config);
+void i2c_bus_start(i2c_bus_t* const bus, const void* const config);
+void i2c_bus_stop(i2c_bus_t* const bus);
 void i2c_bus_transfer(
 	i2c_bus_t* const bus,
 	const uint_fast8_t slave_address,
diff --git a/firmware/common/i2c_lpc.c b/firmware/common/i2c_lpc.c
index 73c3e92c..f7bf4393 100644
--- a/firmware/common/i2c_lpc.c
+++ b/firmware/common/i2c_lpc.c
@@ -26,13 +26,18 @@
 
 /* FIXME return i2c0 status from each function */
 
-void i2c_lpc_init(i2c_bus_t* const bus, const void* const _config) {
+void i2c_lpc_start(i2c_bus_t* const bus, const void* const _config) {
 	const i2c_lpc_config_t* const config = _config;
 
 	const uint32_t port = (uint32_t)bus->obj;
 	i2c_init(port, config->duty_cycle_count);
 }
 
+void i2c_lpc_stop(i2c_bus_t* const bus) {
+	const uint32_t port = (uint32_t)bus->obj;
+	i2c_disable(port);
+}
+
 void i2c_lpc_transfer(i2c_bus_t* const bus,
 	const uint_fast8_t slave_address,
 	const uint8_t* const data_tx, const size_t count_tx,
diff --git a/firmware/common/i2c_lpc.h b/firmware/common/i2c_lpc.h
index 16c04a22..32c79fcd 100644
--- a/firmware/common/i2c_lpc.h
+++ b/firmware/common/i2c_lpc.h
@@ -31,7 +31,8 @@ typedef struct i2c_lpc_config_t {
 	const uint16_t duty_cycle_count;
 } i2c_lpc_config_t;
 
-void i2c_lpc_init(i2c_bus_t* const bus, const void* const config);
+void i2c_lpc_start(i2c_bus_t* const bus, const void* const config);
+void i2c_lpc_stop(i2c_bus_t* const bus);
 void i2c_lpc_transfer(i2c_bus_t* const bus,
 	const uint_fast8_t slave_address,
 	const uint8_t* const data_tx, const size_t count_tx,
diff --git a/firmware/libopencm3 b/firmware/libopencm3
index aec04e96..10503c7c 160000
--- a/firmware/libopencm3
+++ b/firmware/libopencm3
@@ -1 +1 @@
-Subproject commit aec04e962c2264877580be30fe1e1178ce3f568c
+Subproject commit 10503c7cc19647393d98cc66c3dbaf20bd634494