diff --git a/CMakeLists.txt b/CMakeLists.txt
index 17fddfe..411936a 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -55,9 +55,11 @@ target_sources(app PRIVATE
   src/events/keyboard_hid_report_event.c
   src/events/mode_switch_event.c
   src/events/proto_rx_event.c
+  src/events/proto_transport_state_event.c
   src/events/proto_tx_event.c
   src/events/set_protocol_event.c
   src/events/theme_rgb_update_event.c
   src/events/time_sync_event.c
+  src/events/usb_control_event.c
   src/events/usb_state_event.c
 )
diff --git a/inc/events/proto_common.h b/inc/events/proto_common.h
index 479e851..f04c398 100644
--- a/inc/events/proto_common.h
+++ b/inc/events/proto_common.h
@@ -11,6 +11,11 @@ enum proto_transport {
 	PROTO_TRANSPORT_COUNT,
 };
 
+enum proto_transport_link_state {
+	PROTO_TRANSPORT_LINK_DOWN = 0,
+	PROTO_TRANSPORT_LINK_READY,
+};
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/inc/events/proto_transport_state_event.h b/inc/events/proto_transport_state_event.h
new file mode 100644
index 0000000..587c0fd
--- /dev/null
+++ b/inc/events/proto_transport_state_event.h
@@ -0,0 +1,36 @@
+#ifndef BLINKY_PROTO_TRANSPORT_STATE_EVENT_H_
+#define BLINKY_PROTO_TRANSPORT_STATE_EVENT_H_
+
+#include <app_event_manager.h>
+#include <app_event_manager_profiler_tracer.h>
+
+#include "proto_common.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+struct proto_transport_state_event {
+	struct app_event_header header;
+	enum proto_transport transport;
+	enum proto_transport_link_state state;
+};
+
+APP_EVENT_TYPE_DECLARE(proto_transport_state_event);
+
+static inline void submit_proto_transport_state_event(
+	enum proto_transport transport, enum proto_transport_link_state state)
+{
+	struct proto_transport_state_event *event =
+		new_proto_transport_state_event();
+
+	event->transport = transport;
+	event->state = state;
+	APP_EVENT_SUBMIT(event);
+}
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* BLINKY_PROTO_TRANSPORT_STATE_EVENT_H_ */
diff --git a/inc/events/usb_control_event.h b/inc/events/usb_control_event.h
new file mode 100644
index 0000000..2bd94ed
--- /dev/null
+++ b/inc/events/usb_control_event.h
@@ -0,0 +1,71 @@
+#ifndef BLINKY_USB_CONTROL_EVENT_H_
+#define BLINKY_USB_CONTROL_EVENT_H_
+
+#include <stdbool.h>
+#include <stdint.h>
+
+#include <app_event_manager.h>
+#include <app_event_manager_profiler_tracer.h>
+#include <zephyr/device.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+enum usb_control_event_type {
+	USB_CONTROL_EVENT_CDC_LINE_STATE = 0,
+	USB_CONTROL_EVENT_CDC_LINE_CODING,
+};
+
+struct usb_control_event {
+	struct app_event_header header;
+	enum usb_control_event_type type;
+	const struct device *dev;
+	union {
+		struct {
+			bool dtr;
+		} cdc_line_state;
+		struct {
+			uint32_t baudrate;
+			uint8_t data_bits;
+			uint8_t stop_bits;
+			uint8_t parity;
+			uint8_t flow_ctrl;
+		} cdc_line_coding;
+	} data;
+};
+
+APP_EVENT_TYPE_DECLARE(usb_control_event);
+
+static inline void submit_usb_control_cdc_line_state_event(
+	const struct device *dev, bool dtr)
+{
+	struct usb_control_event *event = new_usb_control_event();
+
+	event->type = USB_CONTROL_EVENT_CDC_LINE_STATE;
+	event->dev = dev;
+	event->data.cdc_line_state.dtr = dtr;
+	APP_EVENT_SUBMIT(event);
+}
+
+static inline void submit_usb_control_cdc_line_coding_event(
+	const struct device *dev, uint32_t baudrate, uint8_t data_bits,
+	uint8_t stop_bits, uint8_t parity, uint8_t flow_ctrl)
+{
+	struct usb_control_event *event = new_usb_control_event();
+
+	event->type = USB_CONTROL_EVENT_CDC_LINE_CODING;
+	event->dev = dev;
+	event->data.cdc_line_coding.baudrate = baudrate;
+	event->data.cdc_line_coding.data_bits = data_bits;
+	event->data.cdc_line_coding.stop_bits = stop_bits;
+	event->data.cdc_line_coding.parity = parity;
+	event->data.cdc_line_coding.flow_ctrl = flow_ctrl;
+	APP_EVENT_SUBMIT(event);
+}
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* BLINKY_USB_CONTROL_EVENT_H_ */
diff --git a/inc/protocol_module.h b/inc/protocol_module.h
index 437acb8..b3134c6 100644
--- a/inc/protocol_module.h
+++ b/inc/protocol_module.h
@@ -18,8 +18,6 @@ int protocol_module_process_message(enum proto_transport transport,
 				    size_t rsp_payload_buf_size,
 				    size_t *rsp_payload_len);
 
-void protocol_module_reset_transport_state(enum proto_transport transport);
-
 #ifdef __cplusplus
 }
 #endif
diff --git a/src/ble_nus_module.c b/src/ble_nus_module.c
index 7972dfd..9256c77 100644
--- a/src/ble_nus_module.c
+++ b/src/ble_nus_module.c
@@ -14,30 +14,122 @@
 #include <zephyr/logging/log.h>
 
 #include "proto_rx_event.h"
+#include "proto_transport_state_event.h"
 #include "proto_tx_event.h"
-#include "protocol_module.h"
 
 LOG_MODULE_REGISTER(MODULE, LOG_LEVEL_INF);
 
-static struct bt_conn *active_conn;
-static bool initialized;
-static bool running;
-static bool ble_ready;
-static bool tx_notify_enabled;
+enum ble_nus_business_state {
+	BLE_NUS_STACK_OFFLINE = 0,
+	BLE_NUS_IDLE,
+	BLE_NUS_WAIT_NOTIFY,
+	BLE_NUS_SESSION_READY,
+};
 
-static void notif_enabled(bool enabled, void *ctx)
+struct ble_nus_ctx {
+	enum module_state lifecycle;
+	enum ble_nus_business_state business;
+	struct bt_conn *active_conn;
+};
+
+static struct ble_nus_ctx ctx = {
+	.lifecycle = MODULE_STATE_OFF,
+	.business = BLE_NUS_STACK_OFFLINE,
+	.active_conn = NULL,
+};
+
+static bool lifecycle_is_ready(void)
 {
-	ARG_UNUSED(ctx);
-
-	tx_notify_enabled = enabled;
-	LOG_INF("BLE NUS TX notify %s", enabled ? "enabled" : "disabled");
+	return ctx.lifecycle == MODULE_STATE_READY;
 }
 
-static void received(struct bt_conn *conn, const void *data, uint16_t len, void *ctx)
+static enum proto_transport_link_state transport_link_state_get(void)
 {
-	ARG_UNUSED(ctx);
+	return (lifecycle_is_ready() &&
+		(ctx.business == BLE_NUS_SESSION_READY)) ?
+		       PROTO_TRANSPORT_LINK_READY :
+		       PROTO_TRANSPORT_LINK_DOWN;
+}
 
-	if (!running || !ble_ready || (conn != active_conn)) {
+static void state_reconcile(enum module_state old_lifecycle,
+			    enum ble_nus_business_state old_business)
+{
+	enum proto_transport_link_state old_link =
+		((old_lifecycle == MODULE_STATE_READY) &&
+		 (old_business == BLE_NUS_SESSION_READY)) ?
+			PROTO_TRANSPORT_LINK_READY :
+			PROTO_TRANSPORT_LINK_DOWN;
+	enum proto_transport_link_state new_link = transport_link_state_get();
+
+	if (old_link != new_link) {
+		submit_proto_transport_state_event(PROTO_TRANSPORT_BLE_NUS,
+						   new_link);
+	}
+}
+
+static void lifecycle_set(enum module_state new_state)
+{
+	enum module_state old_lifecycle = ctx.lifecycle;
+	enum ble_nus_business_state old_business = ctx.business;
+
+	if (ctx.lifecycle == new_state) {
+		return;
+	}
+
+	ctx.lifecycle = new_state;
+	state_reconcile(old_lifecycle, old_business);
+	module_set_state(new_state);
+}
+
+static void business_state_set(enum ble_nus_business_state new_state)
+{
+	enum module_state old_lifecycle = ctx.lifecycle;
+	enum ble_nus_business_state old_business = ctx.business;
+
+	if (ctx.business == new_state) {
+		return;
+	}
+
+	ctx.business = new_state;
+	state_reconcile(old_lifecycle, old_business);
+}
+
+static void business_state_set_stack_ready(void)
+{
+	if (ctx.business == BLE_NUS_STACK_OFFLINE) {
+		business_state_set(BLE_NUS_IDLE);
+	}
+}
+
+static void business_state_set_from_notify(bool enabled)
+{
+	if (ctx.business == BLE_NUS_STACK_OFFLINE) {
+		return;
+	}
+
+	if (ctx.active_conn == NULL) {
+		return;
+	}
+
+	business_state_set(enabled ? BLE_NUS_SESSION_READY :
+				      BLE_NUS_WAIT_NOTIFY);
+}
+
+static void notif_enabled(bool enabled, void *ctx_ptr)
+{
+	ARG_UNUSED(ctx_ptr);
+
+	LOG_INF("BLE NUS TX notify %s", enabled ? "enabled" : "disabled");
+	business_state_set_from_notify(enabled);
+}
+
+static void received(struct bt_conn *conn, const void *data, uint16_t len,
+		     void *ctx_ptr)
+{
+	ARG_UNUSED(ctx_ptr);
+
+	if (!lifecycle_is_ready() || (ctx.business == BLE_NUS_STACK_OFFLINE) ||
+	    (conn != ctx.active_conn)) {
 		return;
 	}
 
@@ -51,9 +143,11 @@ static struct bt_nus_cb nus_listener = {
 
 static void reset_connection_state(void)
 {
-	active_conn = NULL;
-	tx_notify_enabled = false;
-	protocol_module_reset_transport_state(PROTO_TRANSPORT_BLE_NUS);
+	ctx.active_conn = NULL;
+
+	if (ctx.business != BLE_NUS_STACK_OFFLINE) {
+		business_state_set(BLE_NUS_IDLE);
+	}
 }
 
 static int module_init(void)
@@ -66,45 +160,41 @@ static int module_init(void)
 		return err;
 	}
 
-	reset_connection_state();
+	ctx = (struct ble_nus_ctx) {
+		.lifecycle = MODULE_STATE_OFF,
+		.business = BLE_NUS_STACK_OFFLINE,
+		.active_conn = NULL,
+	};
+
 	return 0;
 }
 
-static int module_start(void)
+static void module_start(void)
 {
-	if (running) {
-		return 0;
-	}
-
-	running = true;
-	return 0;
+	lifecycle_set(MODULE_STATE_READY);
 }
 
 static void module_pause(void)
 {
-	if (!running) {
-		return;
-	}
-
-	running = false;
-	tx_notify_enabled = false;
+	lifecycle_set(MODULE_STATE_STANDBY);
 }
 
 static bool handle_ble_peer_event(const struct ble_peer_event *event)
 {
 	switch (event->state) {
 	case PEER_STATE_CONNECTED:
-		if (active_conn != NULL) {
+		if (ctx.active_conn != NULL) {
 			return false;
 		}
 
-		active_conn = event->id;
-		tx_notify_enabled = false;
-		protocol_module_reset_transport_state(PROTO_TRANSPORT_BLE_NUS);
+		ctx.active_conn = event->id;
+		if (ctx.business != BLE_NUS_STACK_OFFLINE) {
+			business_state_set(BLE_NUS_WAIT_NOTIFY);
+		}
 		return false;
 
 	case PEER_STATE_DISCONNECTED:
-		if (active_conn != event->id) {
+		if (ctx.active_conn != event->id) {
 			return false;
 		}
 
@@ -124,11 +214,13 @@ static bool handle_proto_tx_event(const struct proto_tx_event *event)
 		return false;
 	}
 
-	if (!running || !ble_ready || (active_conn == NULL) || !tx_notify_enabled) {
+	if ((transport_link_state_get() != PROTO_TRANSPORT_LINK_READY) ||
+	    (ctx.active_conn == NULL)) {
 		return false;
 	}
 
-	err = bt_nus_send(active_conn, event->dyndata.data, (uint16_t)event->dyndata.size);
+	err = bt_nus_send(ctx.active_conn, event->dyndata.data,
+			 (uint16_t)event->dyndata.size);
 	if (err) {
 		LOG_WRN("bt_nus_send failed (%d)", err);
 	}
@@ -147,32 +239,29 @@ static bool app_event_handler(const struct app_event_header *aeh)
 	}
 
 	if (is_module_state_event(aeh)) {
-		const struct module_state_event *event = cast_module_state_event(aeh);
-		int err;
+		const struct module_state_event *event =
+			cast_module_state_event(aeh);
 
 		if (check_state(event, MODULE_ID(main), MODULE_STATE_READY)) {
-			if (!initialized) {
-				err = module_init();
+			if (ctx.lifecycle == MODULE_STATE_OFF) {
+				int err = module_init();
+
 				if (err) {
-					module_set_state(MODULE_STATE_ERROR);
+					lifecycle_set(MODULE_STATE_ERROR);
 					return false;
 				}
-
-				initialized = true;
 			}
 
-			err = module_start();
-			if (err) {
-				module_set_state(MODULE_STATE_ERROR);
-			}
+			module_start();
 
 			return false;
 		}
 
 		if (check_state(event, MODULE_ID(ble_state), MODULE_STATE_READY)) {
-			ble_ready = true;
-			if (running) {
-				module_set_state(MODULE_STATE_READY);
+			business_state_set_stack_ready();
+
+			if (lifecycle_is_ready()) {
+				lifecycle_set(MODULE_STATE_READY);
 			}
 
 			return false;
@@ -182,23 +271,16 @@ static bool app_event_handler(const struct app_event_header *aeh)
 	}
 
 	if (is_power_down_event(aeh)) {
-		if (initialized) {
+		if (ctx.lifecycle != MODULE_STATE_OFF) {
 			module_pause();
-			module_set_state(MODULE_STATE_STANDBY);
 		}
 
 		return false;
 	}
 
 	if (is_wake_up_event(aeh)) {
-		if (initialized) {
-			int err = module_start();
-
-			if (err) {
-				module_set_state(MODULE_STATE_ERROR);
-			} else if (ble_ready) {
-				module_set_state(MODULE_STATE_READY);
-			}
+		if (ctx.lifecycle != MODULE_STATE_OFF) {
+			module_start();
 		}
 
 		return false;
diff --git a/src/events/proto_transport_state_event.c b/src/events/proto_transport_state_event.c
new file mode 100644
index 0000000..dabaeb2
--- /dev/null
+++ b/src/events/proto_transport_state_event.c
@@ -0,0 +1,56 @@
+#include "proto_transport_state_event.h"
+
+static const char *transport_name(enum proto_transport transport)
+{
+	switch (transport) {
+	case PROTO_TRANSPORT_USB_CDC:
+		return "usb_cdc";
+	case PROTO_TRANSPORT_BLE_NUS:
+		return "ble_nus";
+	default:
+		return "?";
+	}
+}
+
+static const char *state_name(enum proto_transport_link_state state)
+{
+	switch (state) {
+	case PROTO_TRANSPORT_LINK_DOWN:
+		return "down";
+	case PROTO_TRANSPORT_LINK_READY:
+		return "ready";
+	default:
+		return "?";
+	}
+}
+
+static void log_proto_transport_state_event(const struct app_event_header *aeh)
+{
+	const struct proto_transport_state_event *event =
+		cast_proto_transport_state_event(aeh);
+
+	APP_EVENT_MANAGER_LOG(aeh, "transport:%s state:%s",
+			      transport_name(event->transport),
+			      state_name(event->state));
+}
+
+static void profile_proto_transport_state_event(struct log_event_buf *buf,
+						const struct app_event_header *aeh)
+{
+	const struct proto_transport_state_event *event =
+		cast_proto_transport_state_event(aeh);
+
+	nrf_profiler_log_encode_uint8(buf, event->transport);
+	nrf_profiler_log_encode_uint8(buf, event->state);
+}
+
+APP_EVENT_INFO_DEFINE(proto_transport_state_event,
+		      ENCODE(NRF_PROFILER_ARG_U8, NRF_PROFILER_ARG_U8),
+		      ENCODE("transport", "state"),
+		      profile_proto_transport_state_event);
+
+APP_EVENT_TYPE_DEFINE(proto_transport_state_event,
+		      log_proto_transport_state_event,
+		      &proto_transport_state_event_info,
+		      APP_EVENT_FLAGS_CREATE(
+			      APP_EVENT_TYPE_FLAGS_INIT_LOG_ENABLE));
diff --git a/src/events/usb_control_event.c b/src/events/usb_control_event.c
new file mode 100644
index 0000000..2f86d8c
--- /dev/null
+++ b/src/events/usb_control_event.c
@@ -0,0 +1,82 @@
+#include "usb_control_event.h"
+
+static const char *control_event_name(enum usb_control_event_type type)
+{
+	switch (type) {
+	case USB_CONTROL_EVENT_CDC_LINE_STATE:
+		return "cdc_line_state";
+	case USB_CONTROL_EVENT_CDC_LINE_CODING:
+		return "cdc_line_coding";
+	default:
+		return "?";
+	}
+}
+
+static void log_usb_control_event(const struct app_event_header *aeh)
+{
+	const struct usb_control_event *event = cast_usb_control_event(aeh);
+
+	switch (event->type) {
+	case USB_CONTROL_EVENT_CDC_LINE_STATE:
+		APP_EVENT_MANAGER_LOG(aeh, "type:%s dtr:%u",
+				      control_event_name(event->type),
+				      event->data.cdc_line_state.dtr);
+		break;
+
+	case USB_CONTROL_EVENT_CDC_LINE_CODING:
+		APP_EVENT_MANAGER_LOG(aeh,
+				      "type:%s baud:%u data:%u stop:%u parity:%u flow:%u",
+				      control_event_name(event->type),
+				      event->data.cdc_line_coding.baudrate,
+				      event->data.cdc_line_coding.data_bits,
+				      event->data.cdc_line_coding.stop_bits,
+				      event->data.cdc_line_coding.parity,
+				      event->data.cdc_line_coding.flow_ctrl);
+		break;
+
+	default:
+		APP_EVENT_MANAGER_LOG(aeh, "type:%s",
+				      control_event_name(event->type));
+		break;
+	}
+}
+
+static void profile_usb_control_event(struct log_event_buf *buf,
+				      const struct app_event_header *aeh)
+{
+	const struct usb_control_event *event = cast_usb_control_event(aeh);
+
+	nrf_profiler_log_encode_uint8(buf, event->type);
+	switch (event->type) {
+	case USB_CONTROL_EVENT_CDC_LINE_STATE:
+		nrf_profiler_log_encode_uint8(buf, event->data.cdc_line_state.dtr);
+		break;
+
+	case USB_CONTROL_EVENT_CDC_LINE_CODING:
+		nrf_profiler_log_encode_uint32(buf, event->data.cdc_line_coding.baudrate);
+		nrf_profiler_log_encode_uint8(buf, event->data.cdc_line_coding.data_bits);
+		nrf_profiler_log_encode_uint8(buf, event->data.cdc_line_coding.stop_bits);
+		nrf_profiler_log_encode_uint8(buf, event->data.cdc_line_coding.parity);
+		nrf_profiler_log_encode_uint8(buf, event->data.cdc_line_coding.flow_ctrl);
+		break;
+
+	default:
+		break;
+	}
+}
+
+APP_EVENT_INFO_DEFINE(usb_control_event,
+		      ENCODE(NRF_PROFILER_ARG_U8,
+			     NRF_PROFILER_ARG_U32,
+			     NRF_PROFILER_ARG_U8,
+			     NRF_PROFILER_ARG_U8,
+			     NRF_PROFILER_ARG_U8,
+			     NRF_PROFILER_ARG_U8),
+		      ENCODE("type", "baud_or_zero", "arg1", "arg2", "arg3", "arg4"),
+		      profile_usb_control_event);
+
+APP_EVENT_TYPE_DEFINE(usb_control_event,
+		      log_usb_control_event,
+		      &usb_control_event_info,
+		      APP_EVENT_FLAGS_CREATE(
+			      APP_EVENT_TYPE_FLAGS_INIT_LOG_ENABLE));
diff --git a/src/protocol_module.c b/src/protocol_module.c
index d1765fe..1315fdf 100644
--- a/src/protocol_module.c
+++ b/src/protocol_module.c
@@ -22,6 +22,7 @@
 #include "function_bitmap_update_event.h"
 #include "hid_led_event.h"
 #include "proto_rx_event.h"
+#include "proto_transport_state_event.h"
 #include "proto_tx_event.h"
 #include "protocol_module.h"
 #include "theme_rgb_update_event.h"
@@ -39,7 +40,14 @@ LOG_MODULE_REGISTER(MODULE, LOG_LEVEL_INF);
 
 static bool initialized;
 static bool running;
-static bool hello_done[PROTO_TRANSPORT_COUNT];
+
+enum proto_session_state {
+	PROTO_SESSION_DOWN = 0,
+	PROTO_SESSION_WAIT_HELLO,
+	PROTO_SESSION_ACTIVE,
+};
+
+static enum proto_session_state session_state[PROTO_TRANSPORT_COUNT];
 
 static int decode_body(const uint8_t *payload, size_t payload_len,
 		       CdcPacketBody *body)
@@ -151,8 +159,8 @@ static int encode_function_bitmap_state(const uint8_t *bitmap, uint8_t *payload,
 
 static int module_init(void)
 {
-	for (size_t i = 0; i < ARRAY_SIZE(hello_done); i++) {
-		hello_done[i] = false;
+	for (size_t i = 0; i < ARRAY_SIZE(session_state); i++) {
+		session_state[i] = PROTO_SESSION_DOWN;
 	}
 
 	return 0;
@@ -174,22 +182,13 @@ static void module_pause(void)
 		return;
 	}
 
-	for (size_t i = 0; i < ARRAY_SIZE(hello_done); i++) {
-		hello_done[i] = false;
+	for (size_t i = 0; i < ARRAY_SIZE(session_state); i++) {
+		session_state[i] = PROTO_SESSION_DOWN;
 	}
 
 	running = false;
 }
 
-void protocol_module_reset_transport_state(enum proto_transport transport)
-{
-	if (transport >= PROTO_TRANSPORT_COUNT) {
-		return;
-	}
-
-	hello_done[transport] = false;
-}
-
 int protocol_module_process_message(enum proto_transport transport,
 				    const uint8_t *req_payload,
 				    size_t req_payload_len,
@@ -216,6 +215,10 @@ int protocol_module_process_message(enum proto_transport transport,
 
 	switch (body.which_body) {
 	case CdcPacketBody_hello_req_tag:
+		if (session_state[transport] == PROTO_SESSION_DOWN) {
+			return -EAGAIN;
+		}
+
 		LOG_INF("HelloReq transport:%u protocol_version:%u",
 			transport, body.body.hello_req.protocol_version);
 
@@ -224,11 +227,11 @@ int protocol_module_process_message(enum proto_transport transport,
 				body.body.hello_req.protocol_version);
 		}
 
-		hello_done[transport] = true;
+		session_state[transport] = PROTO_SESSION_ACTIVE;
 		return encode_hello_rsp(rsp_payload, rsp_payload_buf_size, rsp_payload_len);
 
 	case CdcPacketBody_bitmap_tag:
-		if (!hello_done[transport]) {
+		if (session_state[transport] != PROTO_SESSION_ACTIVE) {
 			return encode_error(CdcPacketBody_bitmap_tag,
 					    ErrorCode_ERROR_CODE_NOT_READY,
 					    rsp_payload, rsp_payload_buf_size,
@@ -255,7 +258,7 @@ int protocol_module_process_message(enum proto_transport transport,
 				  rsp_payload_buf_size, rsp_payload_len);
 
 	case CdcPacketBody_time_sync_tag:
-		if (!hello_done[transport]) {
+		if (session_state[transport] != PROTO_SESSION_ACTIVE) {
 			return encode_error(CdcPacketBody_time_sync_tag,
 					    ErrorCode_ERROR_CODE_NOT_READY,
 					    rsp_payload, rsp_payload_buf_size,
@@ -278,7 +281,7 @@ int protocol_module_process_message(enum proto_transport transport,
 				  rsp_payload_buf_size, rsp_payload_len);
 
 	case CdcPacketBody_theme_rgb_tag:
-		if (!hello_done[transport]) {
+		if (session_state[transport] != PROTO_SESSION_ACTIVE) {
 			return encode_error(CdcPacketBody_theme_rgb_tag,
 					    ErrorCode_ERROR_CODE_NOT_READY,
 					    rsp_payload, rsp_payload_buf_size,
@@ -340,6 +343,29 @@ static bool handle_proto_rx_event(const struct proto_rx_event *event)
 	return false;
 }
 
+static bool handle_proto_transport_state_event(
+	const struct proto_transport_state_event *event)
+{
+	if (event->transport >= PROTO_TRANSPORT_COUNT) {
+		return false;
+	}
+
+	switch (event->state) {
+	case PROTO_TRANSPORT_LINK_DOWN:
+		session_state[event->transport] = PROTO_SESSION_DOWN;
+		break;
+
+	case PROTO_TRANSPORT_LINK_READY:
+		session_state[event->transport] = PROTO_SESSION_WAIT_HELLO;
+		break;
+
+	default:
+		return false;
+	}
+
+	return false;
+}
+
 static bool handle_function_bitmap_state_event(
 	const struct function_bitmap_state_event *event)
 {
@@ -353,7 +379,7 @@ static bool handle_function_bitmap_state_event(
 
 	for (enum proto_transport transport = 0; transport < PROTO_TRANSPORT_COUNT;
 	     transport++) {
-		if (!hello_done[transport]) {
+		if (session_state[transport] != PROTO_SESSION_ACTIVE) {
 			continue;
 		}
 
@@ -388,7 +414,7 @@ static bool handle_hid_led_event(const struct hid_led_event *event)
 			    PROTO_TRANSPORT_USB_CDC :
 			    PROTO_TRANSPORT_BLE_NUS;
 
-	if (!hello_done[transport]) {
+	if (session_state[transport] != PROTO_SESSION_ACTIVE) {
 		return false;
 	}
 
@@ -412,6 +438,11 @@ static bool app_event_handler(const struct app_event_header *aeh)
 		return handle_proto_rx_event(cast_proto_rx_event(aeh));
 	}
 
+	if (is_proto_transport_state_event(aeh)) {
+		return handle_proto_transport_state_event(
+			cast_proto_transport_state_event(aeh));
+	}
+
 	if (is_function_bitmap_state_event(aeh)) {
 		return handle_function_bitmap_state_event(
 			cast_function_bitmap_state_event(aeh));
@@ -480,5 +511,6 @@ APP_EVENT_SUBSCRIBE(MODULE, function_bitmap_state_event);
 APP_EVENT_SUBSCRIBE(MODULE, hid_led_event);
 APP_EVENT_SUBSCRIBE(MODULE, module_state_event);
 APP_EVENT_SUBSCRIBE(MODULE, proto_rx_event);
+APP_EVENT_SUBSCRIBE(MODULE, proto_transport_state_event);
 APP_EVENT_SUBSCRIBE_EARLY(MODULE, power_down_event);
 APP_EVENT_SUBSCRIBE(MODULE, wake_up_event);
diff --git a/src/usb_cdc_module.c b/src/usb_cdc_module.c
index 378e434..30b4655 100644
--- a/src/usb_cdc_module.c
+++ b/src/usb_cdc_module.c
@@ -17,8 +17,9 @@
 #include <zephyr/sys/util.h>
 
 #include "proto_rx_event.h"
+#include "proto_transport_state_event.h"
 #include "proto_tx_event.h"
-#include "protocol_module.h"
+#include "usb_control_event.h"
 #include "usb_state_event.h"
 
 LOG_MODULE_REGISTER(MODULE, LOG_LEVEL_INF);
@@ -27,10 +28,22 @@ LOG_MODULE_REGISTER(MODULE, LOG_LEVEL_INF);
 #define USB_CDC_TX_RING_BUF_SIZE 256
 #define USB_CDC_RX_CHUNK_SIZE 32
 #define USB_CDC_PROTO_RX_BUF_SIZE 128
-#define USB_CDC_CONTROL_POLL_INTERVAL K_MSEC(100)
 #define USB_CDC_PROTO_RX_FLUSH_DELAY K_MSEC(3)
 #define USB_CDC_EXPECTED_BAUDRATE 115200U
 
+enum usb_cdc_business_state {
+	USB_CDC_BUS_OFFLINE = 0,
+	USB_CDC_WAIT_DTR,
+	USB_CDC_SESSION_READY,
+};
+
+struct usb_cdc_ctx {
+	enum module_state lifecycle;
+	enum usb_cdc_business_state business;
+	bool usb_active;
+	size_t proto_rx_len;
+};
+
 static const struct device *const cdc_dev = DEVICE_DT_GET_ONE(zephyr_cdc_acm_uart);
 
 static uint8_t rx_ring_buffer[USB_CDC_RX_RING_BUF_SIZE];
@@ -38,15 +51,37 @@ static uint8_t tx_ring_buffer[USB_CDC_TX_RING_BUF_SIZE];
 static struct ring_buf rx_ringbuf;
 static struct ring_buf tx_ringbuf;
 static struct k_work rx_work;
-static struct k_work_delayable control_work;
 static struct k_work_delayable rx_flush_work;
-static bool initialized;
-static bool running;
-static bool usb_active;
-static bool dtr_ready;
-static bool rx_enabled;
 static uint8_t proto_rx_buf[USB_CDC_PROTO_RX_BUF_SIZE];
-static size_t proto_rx_len;
+static struct usb_cdc_ctx ctx = {
+	.lifecycle = MODULE_STATE_OFF,
+	.business = USB_CDC_BUS_OFFLINE,
+	.usb_active = false,
+	.proto_rx_len = 0U,
+};
+
+static void validate_line_coding(void);
+
+static bool lifecycle_is_ready(void)
+{
+	return ctx.lifecycle == MODULE_STATE_READY;
+}
+
+static enum proto_transport_link_state transport_link_state_get(void)
+{
+	return (lifecycle_is_ready() &&
+		(ctx.business == USB_CDC_SESSION_READY)) ?
+		       PROTO_TRANSPORT_LINK_READY :
+		       PROTO_TRANSPORT_LINK_DOWN;
+}
+
+static bool control_poll_needed(enum module_state lifecycle,
+				enum usb_cdc_business_state business)
+{
+	ARG_UNUSED(lifecycle);
+	ARG_UNUSED(business);
+	return false;
+}
 
 static void reset_ring_buffers(void)
 {
@@ -62,16 +97,98 @@ static void disable_uart_io(void)
 {
 	uart_irq_rx_disable(cdc_dev);
 	uart_irq_tx_disable(cdc_dev);
-	rx_enabled = false;
-	dtr_ready = false;
-	proto_rx_len = 0U;
+	ctx.proto_rx_len = 0U;
 	k_work_cancel_delayable(&rx_flush_work);
 	reset_ring_buffers();
 }
 
+static void state_reconcile(enum module_state old_lifecycle,
+			    enum usb_cdc_business_state old_business)
+{
+	enum proto_transport_link_state old_link =
+		((old_lifecycle == MODULE_STATE_READY) &&
+		 (old_business == USB_CDC_SESSION_READY)) ?
+			PROTO_TRANSPORT_LINK_READY :
+			PROTO_TRANSPORT_LINK_DOWN;
+	enum proto_transport_link_state new_link = transport_link_state_get();
+
+	if ((old_lifecycle == MODULE_STATE_READY) &&
+	    (old_business == USB_CDC_SESSION_READY) &&
+	    (new_link == PROTO_TRANSPORT_LINK_DOWN)) {
+		disable_uart_io();
+	}
+
+	if ((old_link == PROTO_TRANSPORT_LINK_DOWN) &&
+	    (new_link == PROTO_TRANSPORT_LINK_READY)) {
+		int err;
+
+		validate_line_coding();
+
+		err = uart_line_ctrl_set(cdc_dev, UART_LINE_CTRL_DCD, 1);
+		if (err) {
+			LOG_WRN("Failed to set DCD (%d)", err);
+		}
+
+		err = uart_line_ctrl_set(cdc_dev, UART_LINE_CTRL_DSR, 1);
+		if (err) {
+			LOG_WRN("Failed to set DSR (%d)", err);
+		}
+
+		uart_irq_rx_enable(cdc_dev);
+	}
+
+	if (old_link != new_link) {
+		submit_proto_transport_state_event(PROTO_TRANSPORT_USB_CDC,
+						   new_link);
+	}
+}
+
+static void lifecycle_set(enum module_state new_state)
+{
+	enum module_state old_lifecycle = ctx.lifecycle;
+	enum usb_cdc_business_state old_business = ctx.business;
+
+	if (ctx.lifecycle == new_state) {
+		return;
+	}
+
+	ctx.lifecycle = new_state;
+	state_reconcile(old_lifecycle, old_business);
+	module_set_state(new_state);
+}
+
+static void business_state_set(enum usb_cdc_business_state new_state)
+{
+	enum module_state old_lifecycle = ctx.lifecycle;
+	enum usb_cdc_business_state old_business = ctx.business;
+
+	if (ctx.business == new_state) {
+		return;
+	}
+
+	ctx.business = new_state;
+	state_reconcile(old_lifecycle, old_business);
+}
+
+static void business_state_sync_from_usb(void)
+{
+	if (!ctx.usb_active) {
+		business_state_set(USB_CDC_BUS_OFFLINE);
+		return;
+	}
+
+	if (!lifecycle_is_ready()) {
+		return;
+	}
+
+	if (ctx.business == USB_CDC_BUS_OFFLINE) {
+		business_state_set(USB_CDC_WAIT_DTR);
+	}
+}
+
 static void kick_tx(void)
 {
-	if (!running || !usb_active || !dtr_ready) {
+	if (transport_link_state_get() != PROTO_TRANSPORT_LINK_READY) {
 		return;
 	}
 
@@ -133,15 +250,15 @@ static void rx_work_handler(struct k_work *work)
 			return;
 		}
 
-		if ((proto_rx_len + len) > sizeof(proto_rx_buf)) {
+		if ((ctx.proto_rx_len + len) > sizeof(proto_rx_buf)) {
 			LOG_WRN("Drop oversized CDC protobuf message len:%u",
-				(uint32_t)(proto_rx_len + len));
-			proto_rx_len = 0U;
+				(uint32_t)(ctx.proto_rx_len + len));
+			ctx.proto_rx_len = 0U;
 		}
 
 		if (len > 0U) {
-			memcpy(&proto_rx_buf[proto_rx_len], buffer, len);
-			proto_rx_len += len;
+			memcpy(&proto_rx_buf[ctx.proto_rx_len], buffer, len);
+			ctx.proto_rx_len += len;
 			k_work_reschedule(&rx_flush_work, USB_CDC_PROTO_RX_FLUSH_DELAY);
 		}
 	}
@@ -151,59 +268,14 @@ static void rx_flush_work_handler(struct k_work *work)
 {
 	ARG_UNUSED(work);
 
-	if (!running || !usb_active || !dtr_ready || (proto_rx_len == 0U)) {
+	if ((transport_link_state_get() != PROTO_TRANSPORT_LINK_READY) ||
+	    (ctx.proto_rx_len == 0U)) {
 		return;
 	}
 
-	(void)submit_proto_rx_event(PROTO_TRANSPORT_USB_CDC, proto_rx_buf, proto_rx_len);
-	proto_rx_len = 0U;
-}
-
-static void control_work_handler(struct k_work *work)
-{
-	uint32_t dtr = 0U;
-	int err;
-
-	ARG_UNUSED(work);
-
-	if (!running || !usb_active) {
-		return;
-	}
-
-	err = uart_line_ctrl_get(cdc_dev, UART_LINE_CTRL_DTR, &dtr);
-	if (err) {
-		LOG_WRN("Failed to get CDC DTR (%d)", err);
-		goto reschedule;
-	}
-
-	if (dtr && !dtr_ready) {
-		dtr_ready = true;
-		LOG_INF("CDC DTR set");
-		validate_line_coding();
-
-		err = uart_line_ctrl_set(cdc_dev, UART_LINE_CTRL_DCD, 1);
-		if (err) {
-			LOG_WRN("Failed to set DCD (%d)", err);
-		}
-
-		err = uart_line_ctrl_set(cdc_dev, UART_LINE_CTRL_DSR, 1);
-		if (err) {
-			LOG_WRN("Failed to set DSR (%d)", err);
-		}
-
-		if (!rx_enabled) {
-			uart_irq_rx_enable(cdc_dev);
-			rx_enabled = true;
-		}
-
-		kick_tx();
-	} else if (!dtr && dtr_ready) {
-		LOG_INF("CDC DTR cleared");
-		disable_uart_io();
-	}
-
-reschedule:
-	k_work_reschedule(&control_work, USB_CDC_CONTROL_POLL_INTERVAL);
+	(void)submit_proto_rx_event(PROTO_TRANSPORT_USB_CDC, proto_rx_buf,
+				    ctx.proto_rx_len);
+	ctx.proto_rx_len = 0U;
 }
 
 static void cdc_interrupt_handler(const struct device *dev, void *user_data)
@@ -229,7 +301,8 @@ static void cdc_interrupt_handler(const struct device *dev, void *user_data)
 				irq_unlock(key);
 
 				if (written < (uint32_t)recv_len) {
-					LOG_WRN("Drop %d CDC RX bytes", recv_len - (int)written);
+					LOG_WRN("Drop %d CDC RX bytes",
+						recv_len - (int)written);
 				}
 
 				k_work_submit(&rx_work);
@@ -271,61 +344,97 @@ static int module_init(void)
 
 	reset_ring_buffers();
 	k_work_init(&rx_work, rx_work_handler);
-	k_work_init_delayable(&control_work, control_work_handler);
 	k_work_init_delayable(&rx_flush_work, rx_flush_work_handler);
 	uart_irq_callback_set(cdc_dev, cdc_interrupt_handler);
-	proto_rx_len = 0U;
+	ctx = (struct usb_cdc_ctx) {
+		.lifecycle = MODULE_STATE_OFF,
+		.business = USB_CDC_BUS_OFFLINE,
+		.usb_active = false,
+		.proto_rx_len = 0U,
+	};
+
 	return 0;
 }
 
-static int module_start(void)
+static void module_start(void)
 {
-	if (running) {
-		return 0;
-	}
-
-	running = true;
-	if (usb_active) {
-		k_work_reschedule(&control_work, K_NO_WAIT);
-	}
-
-	return 0;
+	lifecycle_set(MODULE_STATE_READY);
+	business_state_sync_from_usb();
 }
 
 static void module_pause(void)
 {
-	if (!running) {
-		return;
-	}
-
-	k_work_cancel_delayable(&control_work);
-	k_work_cancel_delayable(&rx_flush_work);
-	disable_uart_io();
-	running = false;
+	business_state_set(USB_CDC_BUS_OFFLINE);
+	lifecycle_set(MODULE_STATE_STANDBY);
 }
 
 static bool handle_usb_state_event(const struct usb_state_event *event)
 {
 	bool new_usb_active = (event->state == USB_STATE_ACTIVE);
 
-	if (new_usb_active == usb_active) {
+	if (new_usb_active == ctx.usb_active) {
 		return false;
 	}
 
-	usb_active = new_usb_active;
-
-	if (!usb_active) {
-		k_work_cancel_delayable(&control_work);
-		k_work_cancel_delayable(&rx_flush_work);
-		protocol_module_reset_transport_state(PROTO_TRANSPORT_USB_CDC);
-		disable_uart_io();
-	} else if (running) {
-		k_work_reschedule(&control_work, K_NO_WAIT);
-	}
+	ctx.usb_active = new_usb_active;
+	business_state_sync_from_usb();
 
 	return false;
 }
 
+static bool handle_usb_control_event(const struct usb_control_event *event)
+{
+	if (event->dev != cdc_dev) {
+		return false;
+	}
+
+	switch (event->type) {
+	case USB_CONTROL_EVENT_CDC_LINE_STATE:
+		if (!ctx.usb_active || !lifecycle_is_ready()) {
+			return false;
+		}
+
+		if (event->data.cdc_line_state.dtr) {
+			LOG_INF("CDC DTR set");
+			business_state_set(USB_CDC_SESSION_READY);
+			kick_tx();
+		} else {
+			LOG_INF("CDC DTR cleared");
+			business_state_set(USB_CDC_WAIT_DTR);
+		}
+		return false;
+
+	case USB_CONTROL_EVENT_CDC_LINE_CODING:
+		if (event->data.cdc_line_coding.baudrate != 0U) {
+			LOG_INF("CDC baudrate %u",
+				event->data.cdc_line_coding.baudrate);
+			if (event->data.cdc_line_coding.baudrate !=
+			    USB_CDC_EXPECTED_BAUDRATE) {
+				LOG_WRN("Expected CDC baudrate %u, got %u",
+					USB_CDC_EXPECTED_BAUDRATE,
+					event->data.cdc_line_coding.baudrate);
+			}
+		}
+
+#ifdef CONFIG_UART_USE_RUNTIME_CONFIGURE
+		if ((event->data.cdc_line_coding.data_bits != 0U) ||
+		    (event->data.cdc_line_coding.stop_bits != 0U) ||
+		    (event->data.cdc_line_coding.parity != 0U) ||
+		    (event->data.cdc_line_coding.flow_ctrl != 0U)) {
+			LOG_INF("CDC line coding data:%u stop:%u parity:%u flow:%u",
+				event->data.cdc_line_coding.data_bits,
+				event->data.cdc_line_coding.stop_bits,
+				event->data.cdc_line_coding.parity,
+				event->data.cdc_line_coding.flow_ctrl);
+		}
+#endif
+		return false;
+
+	default:
+		return false;
+	}
+}
+
 static bool handle_proto_tx_event(const struct proto_tx_event *event)
 {
 	uint32_t written;
@@ -335,7 +444,7 @@ static bool handle_proto_tx_event(const struct proto_tx_event *event)
 		return false;
 	}
 
-	if (!running || !usb_active || !dtr_ready) {
+	if (transport_link_state_get() != PROTO_TRANSPORT_LINK_READY) {
 		return false;
 	}
 
@@ -365,51 +474,41 @@ static bool app_event_handler(const struct app_event_header *aeh)
 		return handle_proto_tx_event(cast_proto_tx_event(aeh));
 	}
 
+	if (is_usb_control_event(aeh)) {
+		return handle_usb_control_event(cast_usb_control_event(aeh));
+	}
+
 	if (is_module_state_event(aeh)) {
-		const struct module_state_event *event = cast_module_state_event(aeh);
+		const struct module_state_event *event =
+			cast_module_state_event(aeh);
 
 		if (check_state(event, MODULE_ID(main), MODULE_STATE_READY)) {
-			int err;
+			if (ctx.lifecycle == MODULE_STATE_OFF) {
+				int err = module_init();
 
-			if (!initialized) {
-				err = module_init();
 				if (err) {
-					module_set_state(MODULE_STATE_ERROR);
+					lifecycle_set(MODULE_STATE_ERROR);
 					return false;
 				}
-
-				initialized = true;
 			}
 
-			err = module_start();
-			if (err) {
-				module_set_state(MODULE_STATE_ERROR);
-			} else {
-				module_set_state(MODULE_STATE_READY);
-			}
+			module_start();
 		}
 
 		return false;
 	}
 
 	if (is_power_down_event(aeh)) {
-		if (initialized) {
+		if (ctx.lifecycle != MODULE_STATE_OFF) {
 			module_pause();
-			module_set_state(MODULE_STATE_STANDBY);
 		}
 
 		return false;
 	}
 
 	if (is_wake_up_event(aeh)) {
-		if (initialized) {
-			int err = module_start();
-
-			if (err) {
-				module_set_state(MODULE_STATE_ERROR);
-			} else {
-				module_set_state(MODULE_STATE_READY);
-			}
+		if (ctx.lifecycle != MODULE_STATE_OFF) {
+			module_start();
 		}
 
 		return false;
@@ -421,6 +520,7 @@ static bool app_event_handler(const struct app_event_header *aeh)
 APP_EVENT_LISTENER(MODULE, app_event_handler);
 APP_EVENT_SUBSCRIBE(MODULE, module_state_event);
 APP_EVENT_SUBSCRIBE(MODULE, proto_tx_event);
+APP_EVENT_SUBSCRIBE(MODULE, usb_control_event);
 APP_EVENT_SUBSCRIBE(MODULE, usb_state_event);
 APP_EVENT_SUBSCRIBE_EARLY(MODULE, power_down_event);
 APP_EVENT_SUBSCRIBE(MODULE, wake_up_event);
diff --git a/src/usb_device_module.c b/src/usb_device_module.c
index adbe9a8..83ed9bd 100644
--- a/src/usb_device_module.c
+++ b/src/usb_device_module.c
@@ -9,12 +9,14 @@
 #include <caf/events/module_suspend_event.h>
 #include <caf/events/power_event.h>
 
+#include <zephyr/drivers/uart.h>
 #include <zephyr/logging/log.h>
 #include <zephyr/usb/usbd.h>
 
 #include <caf/events/power_manager_event.h>
 
 #include "usb_function_hook.h"
+#include "usb_control_event.h"
 #include "usb_state_event.h"
 
 LOG_MODULE_REGISTER(MODULE, LOG_LEVEL_INF);
@@ -147,6 +149,54 @@ static void usbd_msg_cb(struct usbd_context *const usbd_ctx,
 {
 	ARG_UNUSED(usbd_ctx);
 
+	if (msg->type == USBD_MSG_CDC_ACM_CONTROL_LINE_STATE) {
+		uint32_t dtr = 0U;
+		int err = uart_line_ctrl_get(msg->dev, UART_LINE_CTRL_DTR, &dtr);
+
+		if (err) {
+			LOG_WRN("Failed to get CDC DTR (%d)", err);
+		} else {
+			submit_usb_control_cdc_line_state_event(msg->dev, dtr != 0U);
+		}
+
+		return;
+	}
+
+	if (msg->type == USBD_MSG_CDC_ACM_LINE_CODING) {
+		uint32_t baudrate = 0U;
+		uint8_t data_bits = 0U;
+		uint8_t stop_bits = 0U;
+		uint8_t parity = 0U;
+		uint8_t flow_ctrl = 0U;
+		int err;
+
+		err = uart_line_ctrl_get(msg->dev, UART_LINE_CTRL_BAUD_RATE, &baudrate);
+		if (err) {
+			LOG_WRN("Failed to get CDC baudrate (%d)", err);
+		}
+
+#ifdef CONFIG_UART_USE_RUNTIME_CONFIGURE
+		{
+			struct uart_config cfg;
+
+			err = uart_config_get(msg->dev, &cfg);
+			if (err) {
+				LOG_WRN("uart_config_get failed (%d)", err);
+			} else {
+				data_bits = (uint8_t)cfg.data_bits;
+				stop_bits = (uint8_t)cfg.stop_bits;
+				parity = (uint8_t)cfg.parity;
+				flow_ctrl = (uint8_t)cfg.flow_ctrl;
+			}
+		}
+#endif
+
+		submit_usb_control_cdc_line_coding_event(msg->dev, baudrate,
+						 data_bits, stop_bits,
+						 parity, flow_ctrl);
+		return;
+	}
+
 	switch (msg->type) {
 	case USBD_MSG_VBUS_READY:
 		update_power_manager_restriction(true);