diff --git a/ble/att.c b/ble/att.c
index 7c1444fc2..8dd5fb4f1 100644
--- a/ble/att.c
+++ b/ble/att.c
@@ -80,15 +80,15 @@ typedef struct att_iterator {
     uint8_t  const * value;
 } att_iterator_t;
 
-void att_iterator_init(att_iterator_t *it){
+static void att_iterator_init(att_iterator_t *it){
     it->att_ptr = att_db;
 }
 
-int att_iterator_has_next(att_iterator_t *it){
+static int att_iterator_has_next(att_iterator_t *it){
     return it->att_ptr != NULL;
 }
 
-void att_iterator_fetch_next(att_iterator_t *it){
+static void att_iterator_fetch_next(att_iterator_t *it){
     it->size   = READ_BT_16(it->att_ptr, 0);
     if (it->size == 0){
         it->flags = 0;
@@ -114,7 +114,7 @@ void att_iterator_fetch_next(att_iterator_t *it){
     it->att_ptr += it->size;
 }
 
-int att_iterator_match_uuid16(att_iterator_t *it, uint16_t uuid){
+static int att_iterator_match_uuid16(att_iterator_t *it, uint16_t uuid){
     if (it->handle == 0) return 0;
     if (it->flags & ATT_PROPERTY_UUID128){
         if (!is_Bluetooth_Base_UUID(it->uuid)) return 0;
@@ -123,7 +123,7 @@ int att_iterator_match_uuid16(att_iterator_t *it, uint16_t uuid){
     return READ_BT_16(it->uuid, 0)  == uuid;
 }
 
-int att_iterator_match_uuid(att_iterator_t *it, uint8_t *uuid, uint16_t uuid_len){
+static int att_iterator_match_uuid(att_iterator_t *it, uint8_t *uuid, uint16_t uuid_len){
     if (it->handle == 0) return 0;
     // input: UUID16
     if (uuid_len == 2) {
@@ -139,7 +139,7 @@ int att_iterator_match_uuid(att_iterator_t *it, uint8_t *uuid, uint16_t uuid_len
 }
 
 
-int att_find_handle(att_iterator_t *it, uint16_t handle){
+static int att_find_handle(att_iterator_t *it, uint16_t handle){
     if (handle == 0) return 0;
     att_iterator_init(it);
     while (att_iterator_has_next(it)){
@@ -650,7 +650,7 @@ static uint16_t handle_read_blob_request2(att_connection_t * att_connection, uin
     return offset;
 }
 
-uint16_t handle_read_blob_request(att_connection_t * att_connection, uint8_t * request_buffer,  uint16_t request_len,
+static uint16_t handle_read_blob_request(att_connection_t * att_connection, uint8_t * request_buffer,  uint16_t request_len,
                                   uint8_t * response_buffer, uint16_t response_buffer_size){
     return handle_read_blob_request2(att_connection, response_buffer, response_buffer_size, READ_BT_16(request_buffer, 1), READ_BT_16(request_buffer, 3));
 }
@@ -715,7 +715,7 @@ static uint16_t handle_read_multiple_request2(att_connection_t * att_connection,
     response_buffer[0] = ATT_READ_MULTIPLE_RESPONSE;
     return offset;
 }
-uint16_t handle_read_multiple_request(att_connection_t * att_connection, uint8_t * request_buffer,  uint16_t request_len,
+static uint16_t handle_read_multiple_request(att_connection_t * att_connection, uint8_t * request_buffer,  uint16_t request_len,
                                       uint8_t * response_buffer, uint16_t response_buffer_size){
     int num_handles = (request_len - 1) >> 1;
     return handle_read_multiple_request2(att_connection, response_buffer, response_buffer_size, num_handles, (uint16_t*) &request_buffer[1]);
@@ -828,7 +828,7 @@ static uint16_t handle_read_by_group_type_request2(att_connection_t * att_connec
     response_buffer[0] = ATT_READ_BY_GROUP_TYPE_RESPONSE;
     return offset;
 }
-uint16_t handle_read_by_group_type_request(att_connection_t * att_connection, uint8_t * request_buffer,  uint16_t request_len,
+static uint16_t handle_read_by_group_type_request(att_connection_t * att_connection, uint8_t * request_buffer,  uint16_t request_len,
                                            uint8_t * response_buffer, uint16_t response_buffer_size){
     int attribute_type_len;
     if (request_len <= 7){
diff --git a/ble/gatt_client.h b/ble/gatt_client.h
index 17f83baaa..0a663c221 100644
--- a/ble/gatt_client.h
+++ b/ble/gatt_client.h
@@ -367,7 +367,7 @@ le_command_status_t gatt_client_cancel_write(uint16_t gatt_client_id, uint16_t c
 /* API_END */
 
 // only used for testing
-void gatt_client_pts_suppress_mtu_exchange();
+void gatt_client_pts_suppress_mtu_exchange(void);
 
 #if defined __cplusplus
 }
diff --git a/ble/le_device_db.h b/ble/le_device_db.h
index 90c93596e..be3ecbf3e 100644
--- a/ble/le_device_db.h
+++ b/ble/le_device_db.h
@@ -176,6 +176,8 @@ void le_device_db_local_counter_set(int index, uint32_t counter);
  */
 void le_device_db_remove(int index);
 
+void le_device_db_dump(void);
+
 /* API_END */
 
 #if defined __cplusplus
diff --git a/example/embedded/ancs_client.c b/example/embedded/ancs_client.c
index bc699501d..4601135a2 100644
--- a/example/embedded/ancs_client.c
+++ b/example/embedded/ancs_client.c
@@ -97,7 +97,7 @@ static void app_packet_handler (uint8_t packet_type, uint16_t channel, uint8_t *
     }
 }
 
-void ancs_callback(ancs_event_t * event){
+static void ancs_callback(ancs_event_t * event){
     const char * attribute_name;
     switch (event->type){
         case ANCS_CLIENT_CONNECTED:
diff --git a/example/embedded/gap_inquiry.c b/example/embedded/gap_inquiry.c
index 514dfbf02..f4cb122fd 100644
--- a/example/embedded/gap_inquiry.c
+++ b/example/embedded/gap_inquiry.c
@@ -83,7 +83,7 @@ enum STATE {INIT, ACTIVE} ;
 enum STATE state = INIT;
 
 
-int getDeviceIndexForAddress( bd_addr_t addr){
+static int getDeviceIndexForAddress( bd_addr_t addr){
     int j;
     for (j=0; j< deviceCount; j++){
         if (BD_ADDR_CMP(addr, devices[j].address) == 0){
@@ -93,12 +93,12 @@ int getDeviceIndexForAddress( bd_addr_t addr){
     return -1;
 }
 
-void start_scan(void){
+static void start_scan(void){
     printf("Starting inquiry scan..\n");
     hci_send_cmd(&hci_inquiry, HCI_INQUIRY_LAP, INQUIRY_INTERVAL, 0);
 }
 
-int has_more_remote_name_requests(void){
+static int has_more_remote_name_requests(void){
     int i;
     for (i=0;i<deviceCount;i++) {
         if (devices[i].state == REMOTE_NAME_REQUEST) return 1;
@@ -106,7 +106,7 @@ int has_more_remote_name_requests(void){
     return 0;
 }
 
-void do_next_remote_name_request(void){
+static void do_next_remote_name_request(void){
     int i;
     for (i=0;i<deviceCount;i++) {
         // remote name request
diff --git a/example/embedded/gap_inquiry_and_bond.c b/example/embedded/gap_inquiry_and_bond.c
index 7d0fcf154..8a15a1ee7 100644
--- a/example/embedded/gap_inquiry_and_bond.c
+++ b/example/embedded/gap_inquiry_and_bond.c
@@ -78,7 +78,7 @@ enum STATE {INIT, W4_INQUIRY_MODE_COMPLETE, ACTIVE} ;
 enum STATE state = INIT;
 
 
-int getDeviceIndexForAddress( bd_addr_t addr){
+static int getDeviceIndexForAddress( bd_addr_t addr){
     int j;
     for (j=0; j< deviceCount; j++){
         if (BD_ADDR_CMP(addr, devices[j].address) == 0){
@@ -88,12 +88,12 @@ int getDeviceIndexForAddress( bd_addr_t addr){
     return -1;
 }
 
-void start_scan(void){
+static void start_scan(void){
     printf("Starting inquiry scan..\n");
     hci_send_cmd(&hci_inquiry, HCI_INQUIRY_LAP, INQUIRY_INTERVAL, 0);
 }
 
-int has_more_bonding_requests(void){
+static int has_more_bonding_requests(void){
     int i;
     for (i=0;i<deviceCount;i++) {
         if (devices[i].state == BONDING_REQUEST) return 1;
@@ -101,7 +101,7 @@ int has_more_bonding_requests(void){
     return 0;
 }
 
-void do_next_bonding_request(void){
+static void do_next_bonding_request(void){
     int i;
     for (i=0;i<deviceCount;i++) {
         // remote name request
diff --git a/example/embedded/gap_le_advertisements.c b/example/embedded/gap_le_advertisements.c
index d798e952e..b34d678bf 100644
--- a/example/embedded/gap_le_advertisements.c
+++ b/example/embedded/gap_le_advertisements.c
@@ -127,7 +127,7 @@ static char * flags[] = {
  */
 
 /* LISTING_START(GAPLEAdvDataParsing): Parsing advertising data */
-void dump_advertisement_data(uint8_t * adv_data, uint8_t adv_size){
+static void dump_advertisement_data(uint8_t * adv_data, uint8_t adv_size){
     ad_context_t context;
     for (ad_iterator_init(&context, adv_size, adv_data) ; ad_iterator_has_more(&context) ; ad_iterator_next(&context)){
         uint8_t data_type = ad_iterator_get_data_type(&context);
diff --git a/example/embedded/gatt_battery_query.c b/example/embedded/gatt_battery_query.c
index a8e6bb265..1e077e209 100644
--- a/example/embedded/gatt_battery_query.c
+++ b/example/embedded/gatt_battery_query.c
@@ -161,7 +161,7 @@ static void extract_characteristic(le_characteristic_t * characteristic, uint8_t
     }
 }
 
-void handle_gatt_client_event(int8_t packet_type, uint8_t *packet, uint16_t size){
+static void handle_gatt_client_event(uint8_t packet_type, uint8_t *packet, uint16_t size){
 
     switch(state){
         case TC_W4_SERVICE_RESULT:
@@ -284,7 +284,7 @@ static void handle_hci_event(void * connection, uint8_t packet_type, uint16_t ch
     }
 }
 
-void usage(const char *name){
+static void usage(const char *name){
 	fprintf(stderr, "\nUsage: %s [-a|--address aa:bb:cc:dd:ee:ff]\n", name);
 	fprintf(stderr, "If no argument is provided, GATT browser will start scanning and connect to the first found device.\nTo connect to a specific device use argument [-a].\n\n");
 }
diff --git a/example/embedded/gatt_browser.c b/example/embedded/gatt_browser.c
index 93f9554b6..b7730ed4b 100644
--- a/example/embedded/gatt_browser.c
+++ b/example/embedded/gatt_browser.c
@@ -300,7 +300,7 @@ void handle_gatt_client_event(uint8_t packet_type, uint8_t *packet, uint16_t siz
 }
 /* LISTING_END */
 
-void usage(const char *name){
+static void usage(const char *name){
 	fprintf(stderr, "\nUsage: %s [-a|--address aa:bb:cc:dd:ee:ff]\n", name);
 	fprintf(stderr, "If no argument is provided, GATT browser will start scanning and connect to the first found device.\nTo connect to a specific device use argument [-a].\n\n");
 }
diff --git a/example/embedded/sdp_bnep_query.c b/example/embedded/sdp_bnep_query.c
index 2437f7dc8..2e2f52cc0 100644
--- a/example/embedded/sdp_bnep_query.c
+++ b/example/embedded/sdp_bnep_query.c
@@ -131,7 +131,7 @@ static void packet_handler (void * connection, uint8_t packet_type, uint16_t cha
 }
 /* LISTING_END */
 
-char * get_string_from_data_element(uint8_t * element){
+static char * get_string_from_data_element(uint8_t * element){
     de_size_t de_size = de_get_size_type(element);
     int pos     = de_get_header_size(element);
     int len = 0;
diff --git a/example/embedded/sdp_rfcomm_query.c b/example/embedded/sdp_rfcomm_query.c
index 38166512b..24a54d515 100644
--- a/example/embedded/sdp_rfcomm_query.c
+++ b/example/embedded/sdp_rfcomm_query.c
@@ -84,7 +84,7 @@ static void packet_handler (void * connection, uint8_t packet_type, uint16_t cha
     }
 }
 
-void store_found_service(uint8_t * name, uint8_t port){
+static void store_found_service(uint8_t * name, uint8_t port){
     printf("APP: Service name: '%s', RFCOMM port %u\n", name, port);
     channel_nr[service_index] = port;
     service_name[service_index] = (char*) malloc(SDP_SERVICE_NAME_LEN+1);
@@ -93,7 +93,7 @@ void store_found_service(uint8_t * name, uint8_t port){
     service_index++;
 }
 
-void report_found_services(void){
+static void report_found_services(void){
     printf("\n *** Client query response done. ");
     if (service_index == 0){
         printf("No service found.\n\n");
@@ -107,7 +107,7 @@ void report_found_services(void){
     printf(" ***\n\n");
 }
 
-void handle_query_rfcomm_event(sdp_query_event_t * event, void * context){
+static void handle_query_rfcomm_event(sdp_query_event_t * event, void * context){
     sdp_query_rfcomm_service_event_t * ve;
     sdp_query_complete_event_t * ce;
             
diff --git a/example/embedded/spp_counter.c b/example/embedded/spp_counter.c
index 2b6569339..f59101478 100644
--- a/example/embedded/spp_counter.c
+++ b/example/embedded/spp_counter.c
@@ -89,7 +89,7 @@ static uint32_t  spp_service_buffer[150/4];  // implicit alignment to 4-byte mem
  */
 
 /* LISTING_START(SPPSetup): SPP service setup */ 
-void spp_service_setup(void){
+static void spp_service_setup(void){
     l2cap_init();
     l2cap_register_packet_handler(packet_handler);
 
diff --git a/example/embedded/spp_streamer.c b/example/embedded/spp_streamer.c
index d41bf9b32..c50ae413d 100644
--- a/example/embedded/spp_streamer.c
+++ b/example/embedded/spp_streamer.c
@@ -150,7 +150,7 @@ static void packet_handler (void * connection, uint8_t packet_type, uint16_t cha
     }
 }
 
-void handle_found_service(char * name, uint8_t port){
+static void handle_found_service(char * name, uint8_t port){
     printf("APP: Service name: '%s', RFCOMM port %u\n", name, port);
 
     if (strncmp(name, spp_service_name_prefix, strlen(spp_service_name_prefix)) != 0) return;
@@ -160,7 +160,7 @@ void handle_found_service(char * name, uint8_t port){
     state = W4_SDP_COMPLETE;
 }
 
-void handle_query_rfcomm_event(sdp_query_event_t * event, void * context){
+static void handle_query_rfcomm_event(sdp_query_event_t * event, void * context){
     sdp_query_rfcomm_service_event_t * ve;
             
     switch (event->type){
diff --git a/platforms/libusb/Makefile b/platforms/libusb/Makefile
index c8cd68f28..b21291b8b 100644
--- a/platforms/libusb/Makefile
+++ b/platforms/libusb/Makefile
@@ -9,7 +9,7 @@ COMMON += hci_transport_h2_libusb.c run_loop_posix.c remote_device_db_fs.c
 include ${BTSTACK_ROOT}/example/embedded/Makefile.inc
 
 # CC = gcc-fsf-4.9
-CFLAGS  += -g -Wall 
+CFLAGS  += -g -Wall -Wmissing-prototypes -Werror
 # CFLAGS += -Werror
 
 CFLAGS += -I${POSIX_ROOT}/src
diff --git a/platforms/posix/src/hci_transport_h2_libusb.c b/platforms/posix/src/hci_transport_h2_libusb.c
index 0dd0f0ddb..2c02391e9 100644
--- a/platforms/posix/src/hci_transport_h2_libusb.c
+++ b/platforms/posix/src/hci_transport_h2_libusb.c
@@ -325,7 +325,7 @@ static int usb_process_ds(struct data_source *ds) {
     return 0;
 }
 
-void usb_process_ts(timer_source_t *timer) {
+static void usb_process_ts(timer_source_t *timer) {
     // log_info("in usb_process_ts");
 
     // timer is deactive, when timer callback gets called
diff --git a/platforms/posix/src/remote_device_db_fs.c b/platforms/posix/src/remote_device_db_fs.c
index c4aaa5a9b..e22c15a36 100644
--- a/platforms/posix/src/remote_device_db_fs.c
+++ b/platforms/posix/src/remote_device_db_fs.c
@@ -51,13 +51,6 @@
 
 static char keypath[sizeof(LINK_KEY_PATH) + sizeof(LINK_KEY_PREFIX) + 17 + sizeof(LINK_KEY_SUFIX) + 1];
 
-static char char_for_nibble(int nibble){
-    if (nibble < 10) return '0' + nibble;
-    nibble -= 10;
-    if (nibble < 6) return 'A' + nibble;
-    return '?';
-}
-
 static char bd_addr_to_dash_str_buffer[6*3];  // 12-45-78-01-34-67\0
 static char * bd_addr_to_dash_str(bd_addr_t addr){
     char * p = bd_addr_to_dash_str_buffer;
diff --git a/platforms/posix/src/stdin_support.c b/platforms/posix/src/stdin_support.c
index 8b55e2627..acf5c16b9 100644
--- a/platforms/posix/src/stdin_support.c
+++ b/platforms/posix/src/stdin_support.c
@@ -88,7 +88,7 @@ void btstack_stdin_reset(void){
 #endif
 }
 
-int getstring(char *line, int size)
+static int getstring(char *line, int size)
 {
     int i = 0;
     while (1){
diff --git a/src/hci.c b/src/hci.c
index 0831e5c03..b42ce8752 100644
--- a/src/hci.c
+++ b/src/hci.c
@@ -355,7 +355,7 @@ uint8_t hci_number_free_acl_slots_for_handle(hci_con_handle_t con_handle){
     }
 }
 
-int hci_number_free_sco_slots_for_handle(hci_con_handle_t handle){
+static int hci_number_free_sco_slots_for_handle(hci_con_handle_t handle){
     int num_sco_packets_sent = 0;
     linked_item_t *it;
     for (it = (linked_item_t *) hci_stack->connections; it ; it = it->next){
@@ -432,7 +432,7 @@ void hci_release_packet_buffer(void){
 }
 
 // assumption: synchronous implementations don't provide can_send_packet_now as they don't keep the buffer after the call
-int hci_transport_synchronous(void){
+static int hci_transport_synchronous(void){
     return hci_stack->hci_transport->can_send_packet_now == NULL;
 }
 
@@ -762,17 +762,17 @@ int hci_non_flushable_packet_boundary_flag_supported(void){
     return (hci_stack->local_supported_features[6] & (1 << 6)) != 0;
 }
 
-int hci_ssp_supported(void){
+static int hci_ssp_supported(void){
     // No. 51, byte 6, bit 3
     return (hci_stack->local_supported_features[6] & (1 << 3)) != 0;
 }
 
-int hci_classic_supported(void){
+static int hci_classic_supported(void){
     // No. 37, byte 4, bit 5, = No BR/EDR Support
     return (hci_stack->local_supported_features[4] & (1 << 5)) == 0;
 }
 
-int hci_le_supported(void){
+static int hci_le_supported(void){
 #ifdef HAVE_BLE
     // No. 37, byte 4, bit 6 = LE Supported (Controller)
     return (hci_stack->local_supported_features[4] & (1 << 6)) != 0;
@@ -792,7 +792,7 @@ void hci_le_advertisement_address(uint8_t * addr_type, bd_addr_t  addr){
 }
 
 #ifdef HAVE_BLE
-void le_handle_advertisement_report(uint8_t *packet, int size){
+static void le_handle_advertisement_report(uint8_t *packet, int size){
     int offset = 3;
     int num_reports = packet[offset];
     offset += 1;
@@ -2729,7 +2729,7 @@ void hci_emit_connection_complete(hci_connection_t *conn, uint8_t status){
     hci_stack->packet_handler(HCI_EVENT_PACKET, event, sizeof(event));
 }
 
-void hci_emit_le_connection_complete(uint8_t address_type, bd_addr_t address, uint16_t conn_handle, uint8_t status){
+static void hci_emit_le_connection_complete(uint8_t address_type, bd_addr_t address, uint16_t conn_handle, uint8_t status){
     uint8_t event[21];
     event[0] = HCI_EVENT_LE_META;
     event[1] = sizeof(event) - 2;
diff --git a/src/l2cap.c b/src/l2cap.c
index 26bea7b05..2390af078 100644
--- a/src/l2cap.c
+++ b/src/l2cap.c
@@ -126,7 +126,7 @@ void l2cap_register_packet_handler(void (*handler)(void * connection, uint8_t pa
 }
 
 //  notify client/protocol handler
-void l2cap_dispatch(l2cap_channel_t *channel, uint8_t type, uint8_t * data, uint16_t size){
+static void l2cap_dispatch(l2cap_channel_t *channel, uint8_t type, uint8_t * data, uint16_t size){
     if (channel->packet_handler) {
         (* (channel->packet_handler))(type, channel->local_cid, data, size);
     } else {
@@ -179,7 +179,7 @@ void l2cap_emit_connection_request(l2cap_channel_t *channel) {
     l2cap_dispatch(channel, HCI_EVENT_PACKET, event, sizeof(event));
 }
 
-void l2cap_emit_connection_parameter_update_response(uint16_t handle, uint16_t result){
+static void l2cap_emit_connection_parameter_update_response(uint16_t handle, uint16_t result){
     uint8_t event[6];
     event[0] = L2CAP_EVENT_CONNECTION_PARAMETER_UPDATE_RESPONSE;
     event[1] = 4;
@@ -200,7 +200,7 @@ static void l2cap_emit_service_registered(void *connection, uint8_t status, uint
     (*packet_handler)(connection, HCI_EVENT_PACKET, 0, event, sizeof(event));
 }
 
-void l2cap_emit_credits(l2cap_channel_t *channel, uint8_t credits) {
+static void l2cap_emit_credits(l2cap_channel_t *channel, uint8_t credits) {
     
     log_info("L2CAP_EVENT_CREDITS local_cid 0x%x credits %u", channel->local_cid, credits);
     // track credits
@@ -219,7 +219,7 @@ void l2cap_block_new_credits(uint8_t blocked){
     new_credits_blocked = blocked;
 }
 
-void l2cap_hand_out_credits(void){
+static void l2cap_hand_out_credits(void){
 
     if (new_credits_blocked) return;    // we're told not to. used by daemon
 
@@ -235,7 +235,7 @@ void l2cap_hand_out_credits(void){
     }
 }
 
-l2cap_channel_t * l2cap_get_channel_for_local_cid(uint16_t local_cid){
+static l2cap_channel_t * l2cap_get_channel_for_local_cid(uint16_t local_cid){
     linked_list_iterator_t it;    
     linked_list_iterator_init(&it, &l2cap_channels);
     while (linked_list_iterator_has_next(&it)){
@@ -330,7 +330,7 @@ static int l2cap_security_level_0_allowed_for_PSM(uint16_t psm){
     return (psm == PSM_SDP) && (!require_security_level2_for_outgoing_sdp);
 }
 
-int l2cap_send_signaling_packet(hci_con_handle_t handle, L2CAP_SIGNALING_COMMANDS cmd, uint8_t identifier, ...){
+static int l2cap_send_signaling_packet(hci_con_handle_t handle, L2CAP_SIGNALING_COMMANDS cmd, uint8_t identifier, ...){
 
     if (!hci_can_send_acl_packet_now(handle)){
         log_info("l2cap_send_signaling_packet, cannot send");
@@ -349,7 +349,7 @@ int l2cap_send_signaling_packet(hci_con_handle_t handle, L2CAP_SIGNALING_COMMAND
 }
 
 #ifdef HAVE_BLE
-int l2cap_send_le_signaling_packet(hci_con_handle_t handle, L2CAP_SIGNALING_COMMANDS cmd, uint8_t identifier, ...){
+static int l2cap_send_le_signaling_packet(hci_con_handle_t handle, L2CAP_SIGNALING_COMMANDS cmd, uint8_t identifier, ...){
 
     if (!hci_can_send_acl_packet_now(handle)){
         log_info("l2cap_send_signaling_packet, cannot send");
@@ -520,7 +520,7 @@ static inline void channelStateVarClearFlag(l2cap_channel_t *channel, L2CAP_CHAN
 
 // MARK: L2CAP_RUN
 // process outstanding signaling tasks
-void l2cap_run(void){
+static void l2cap_run(void){
     
     // log_info("l2cap_run: entered");
 
@@ -872,7 +872,7 @@ static void l2cap_handle_connection_success_for_addr(bd_addr_t address, hci_con_
     l2cap_run();
 }
 
-void l2cap_event_handler(uint8_t *packet, uint16_t size){
+static void l2cap_event_handler(uint8_t *packet, uint16_t size){
     
     bd_addr_t address;
     hci_con_handle_t handle;
@@ -1133,7 +1133,7 @@ void l2cap_decline_connection_internal(uint16_t local_cid, uint8_t reason){
     l2cap_run();
 }
 
-void l2cap_signaling_handle_configure_request(l2cap_channel_t *channel, uint8_t *command){
+static void l2cap_signaling_handle_configure_request(l2cap_channel_t *channel, uint8_t *command){
 
     channel->remote_sig_id = command[L2CAP_SIGNALING_COMMAND_SIGID_OFFSET];
 
@@ -1180,7 +1180,7 @@ static int l2cap_channel_ready_for_open(l2cap_channel_t *channel){
 }
 
 
-void l2cap_signaling_handler_channel(l2cap_channel_t *channel, uint8_t *command){
+static void l2cap_signaling_handler_channel(l2cap_channel_t *channel, uint8_t *command){
 
     uint8_t  code       = command[L2CAP_SIGNALING_COMMAND_CODE_OFFSET];
     uint8_t  identifier = command[L2CAP_SIGNALING_COMMAND_SIGID_OFFSET];
@@ -1310,7 +1310,7 @@ void l2cap_signaling_handler_channel(l2cap_channel_t *channel, uint8_t *command)
 }
 
 
-void l2cap_signaling_handler_dispatch( hci_con_handle_t handle, uint8_t * command){
+static void l2cap_signaling_handler_dispatch( hci_con_handle_t handle, uint8_t * command){
     
     // get code, signalind identifier and command len
     uint8_t code   = command[L2CAP_SIGNALING_COMMAND_CODE_OFFSET];
@@ -1372,7 +1372,7 @@ void l2cap_signaling_handler_dispatch( hci_con_handle_t handle, uint8_t * comman
     }
 }
 
-void l2cap_acl_handler( uint8_t *packet, uint16_t size ){
+static void l2cap_acl_handler( uint8_t *packet, uint16_t size ){
         
     // Get Channel ID
     uint16_t channel_id = READ_L2CAP_CHANNEL_ID(packet); 
@@ -1596,10 +1596,11 @@ void l2cap_register_fixed_channel(btstack_packet_handler_t packet_handler, uint1
 
 #ifdef HAVE_BLE
 
+
+#if 0
 static inline l2cap_service_t * l2cap_le_get_service(uint16_t psm){
     return l2cap_get_service_internal(&l2cap_le_services, psm);
 }
-
 /**
  * @brief Regster L2CAP LE Credit Based Flow Control Mode service
  * @param
@@ -1652,3 +1653,4 @@ void l2cap_le_unregister_service_internal(void * connection, uint16_t psm) {
     btstack_memory_l2cap_service_free(service);
 }
 #endif
+#endif
diff --git a/src/l2cap_signaling.c b/src/l2cap_signaling.c
index 85301f59c..222d12ee4 100644
--- a/src/l2cap_signaling.c
+++ b/src/l2cap_signaling.c
@@ -85,7 +85,7 @@ uint16_t l2cap_next_local_cid(void){
     return source_cid++;
 }
 
-uint16_t l2cap_create_signaling_internal(uint8_t * acl_buffer, hci_con_handle_t handle, uint16_t cid, L2CAP_SIGNALING_COMMANDS cmd, uint8_t identifier, va_list argptr){
+static uint16_t l2cap_create_signaling_internal(uint8_t * acl_buffer, hci_con_handle_t handle, uint16_t cid, L2CAP_SIGNALING_COMMANDS cmd, uint8_t identifier, va_list argptr){
     
     int pb = hci_non_flushable_packet_boundary_flag_supported() ? 0x00 : 0x02;
 
diff --git a/src/pan.c b/src/pan.c
index 33ab7d123..5f28557ea 100644
--- a/src/pan.c
+++ b/src/pan.c
@@ -58,7 +58,7 @@ static const char default_nap_service_desc[] = "Personal Ad-hoc Network Service
 static const char default_gn_service_name[] = "Group Ad-hoc Network Service";
 static const char default_gn_service_desc[] = "Personal Group Ad-hoc Network Service";
 
-void pan_create_service(uint8_t *service, uint32_t service_uuid, uint16_t * network_packet_types, const char *name, const char *descriptor,
+static void pan_create_service(uint8_t *service, uint32_t service_uuid, uint16_t * network_packet_types, const char *name, const char *descriptor,
 	 security_description_t security_desc, net_access_type_t net_access_type, uint32_t max_net_access_rate,
 	 const char *IPv4Subnet, const char *IPv6Subnet){
 
diff --git a/src/remote_device_db.h b/src/remote_device_db.h
index a1fb64d8b..6ba5e5104 100644
--- a/src/remote_device_db.h
+++ b/src/remote_device_db.h
@@ -87,6 +87,8 @@ extern const remote_device_db_t remote_device_db_memory;
  */
 extern const remote_device_db_t remote_device_db_fs;
 
+const remote_device_db_t * remote_device_db_fs_instance(void);
+
 /* API_END */
 
 // MARK: non-persistent implementation
diff --git a/src/rfcomm.c b/src/rfcomm.c
index 9858b0cb5..2a0efac43 100644
--- a/src/rfcomm.c
+++ b/src/rfcomm.c
@@ -228,8 +228,7 @@ static void rfcomm_emit_service_registered(void *connection, uint8_t status, uin
 	(*app_packet_handler)(connection, HCI_EVENT_PACKET, 0, (uint8_t *) event, sizeof(event));
 }
 
-// static
-void rfcomm_emit_remote_line_status(rfcomm_channel_t *channel, uint8_t line_status){
+static void rfcomm_emit_remote_line_status(rfcomm_channel_t *channel, uint8_t line_status){
     log_info("RFCOMM_EVENT_REMOTE_LINE_STATUS cid 0x%02x c, line status 0x%x", channel->rfcomm_cid, line_status);
     uint8_t event[5];
     event[0] = RFCOMM_EVENT_REMOTE_LINE_STATUS;
@@ -240,7 +239,7 @@ void rfcomm_emit_remote_line_status(rfcomm_channel_t *channel, uint8_t line_stat
     (*app_packet_handler)(channel->connection, HCI_EVENT_PACKET, 0, (uint8_t *) event, sizeof(event));
 }
 
-void rfcomm_emit_port_configuration(rfcomm_channel_t *channel){
+static void rfcomm_emit_port_configuration(rfcomm_channel_t *channel){
     // notify client about new settings
     uint8_t event[2+sizeof(rfcomm_rpn_data_t)];
     event[0] = RFCOMM_EVENT_PORT_CONFIGURATION;
@@ -1406,7 +1405,7 @@ static void rfcomm_channel_state_machine_2(rfcomm_multiplexer_t * multiplexer, u
     rfcomm_channel_state_machine(channel, event);
 }
 
-void rfcomm_channel_packet_handler(rfcomm_multiplexer_t * multiplexer,  uint8_t *packet, uint16_t size){
+static void rfcomm_channel_packet_handler(rfcomm_multiplexer_t * multiplexer,  uint8_t *packet, uint16_t size){
     
     // rfcomm: (0) addr [76543 server channel] [2 direction: initiator uses 1] [1 C/R: CMD by initiator = 1] [0 EA=1]
     const uint8_t frame_dlci = packet[0] >> 2;
@@ -2183,7 +2182,7 @@ int rfcomm_query_port_configuration(uint16_t rfcomm_cid){
 }
 
 
-void rfcomm_create_channel2(void * connection, bd_addr_t addr, uint8_t server_channel, uint8_t incoming_flow_control, uint8_t initial_credits){
+static void rfcomm_create_channel2(void * connection, bd_addr_t addr, uint8_t server_channel, uint8_t incoming_flow_control, uint8_t initial_credits){
     log_info("RFCOMM_CREATE_CHANNEL addr %s channel #%u flow control %u init credits %u",  bd_addr_to_str(addr), server_channel,
              incoming_flow_control, initial_credits);
     
@@ -2245,7 +2244,7 @@ void rfcomm_disconnect_internal(uint16_t rfcomm_cid){
 }
 
 
-void rfcomm_register_service2(void * connection, uint8_t channel, uint16_t max_frame_size, uint8_t incoming_flow_control, uint8_t initial_credits){
+static void rfcomm_register_service2(void * connection, uint8_t channel, uint16_t max_frame_size, uint8_t incoming_flow_control, uint8_t initial_credits){
     log_info("RFCOMM_REGISTER_SERVICE channel #%u mtu %u flow_control %u credits %u",
              channel, max_frame_size, incoming_flow_control, initial_credits);
     // check if already registered
diff --git a/src/sdp.c b/src/sdp.c
index d797245f4..c7e9525b7 100644
--- a/src/sdp.c
+++ b/src/sdp.c
@@ -85,7 +85,7 @@ void sdp_register_packet_handler(void (*handler)(void * connection, uint8_t pack
     l2cap_cid = 0;
 }
 
-uint32_t sdp_get_service_record_handle(uint8_t * record){
+static uint32_t sdp_get_service_record_handle(uint8_t * record){
     uint8_t * serviceRecordHandleAttribute = sdp_get_attribute_value_for_attribute_id(record, SDP_ServiceRecordHandle);
     if (!serviceRecordHandleAttribute) return 0;
     if (de_get_element_type(serviceRecordHandleAttribute) != DE_UINT) return 0;
@@ -105,7 +105,7 @@ static void sdp_emit_service_registered(void *connection, uint32_t handle, uint8
 	(*app_packet_handler)(connection, HCI_EVENT_PACKET, 0, (uint8_t *) event, sizeof(event));
 }
 
-service_record_item_t * sdp_get_record_for_handle(uint32_t handle){
+static service_record_item_t * sdp_get_record_for_handle(uint32_t handle){
     linked_item_t *it;
     for (it = (linked_item_t *) sdp_service_records; it ; it = it->next){
         service_record_item_t * item = (service_record_item_t *) it;
@@ -117,7 +117,7 @@ service_record_item_t * sdp_get_record_for_handle(uint32_t handle){
 }
 
 // get next free, unregistered service record handle
-uint32_t sdp_create_service_record_handle(void){
+static uint32_t sdp_create_service_record_handle(void){
     uint32_t handle = 0;
     do {
         handle = sdp_next_service_record_handle++;
@@ -264,7 +264,7 @@ void sdp_unregister_service_internal(void *connection, uint32_t service_record_h
 // PDU
 // PDU ID (1), Transaction ID (2), Param Length (2), Param 1, Param 2, ..
 
-int sdp_create_error_response(uint16_t transaction_id, uint16_t error_code){
+static int sdp_create_error_response(uint16_t transaction_id, uint16_t error_code){
     sdp_response_buffer[0] = SDP_ErrorResponse;
     net_store_16(sdp_response_buffer, 1, transaction_id);
     net_store_16(sdp_response_buffer, 3, 2);
diff --git a/src/sdp_client.c b/src/sdp_client.c
index 49a8f4e9a..c58f247e4 100644
--- a/src/sdp_client.c
+++ b/src/sdp_client.c
@@ -78,7 +78,7 @@ static sdp_client_state_t sdp_client_state = INIT;
 static SDP_PDU_ID_t PDU_ID = SDP_Invalid;
 
 // TODO: inline if not needed (des(des))
-void parse_attribute_lists(uint8_t* packet, uint16_t length){
+static void parse_attribute_lists(uint8_t* packet, uint16_t length){
     sdp_parser_handle_chunk(packet, length);
 }
 
diff --git a/src/sdp_parser.c b/src/sdp_parser.c
index 4de7c1d56..5164fc725 100644
--- a/src/sdp_parser.c
+++ b/src/sdp_parser.c
@@ -107,7 +107,7 @@ int de_state_size(uint8_t eventByte, de_state_t *de_state){
     return 1;
 }
 
-void dummy_notify(sdp_query_event_t* event){}
+static void dummy_notify(sdp_query_event_t* event){}
 
 void sdp_parser_register_callback(void (*sdp_callback)(sdp_query_event_t* event)){
     sdp_query_callback = dummy_notify;
@@ -116,7 +116,7 @@ void sdp_parser_register_callback(void (*sdp_callback)(sdp_query_event_t* event)
     } 
 }
 
-void parse(uint8_t eventByte){
+static void parse(uint8_t eventByte){
     // count all bytes
     list_offset++;
     record_offset++;
diff --git a/src/sdp_query_rfcomm.c b/src/sdp_query_rfcomm.c
index b8a76b710..8bbe4b581 100644
--- a/src/sdp_query_rfcomm.c
+++ b/src/sdp_query_rfcomm.c
@@ -107,7 +107,7 @@ void sdp_query_rfcomm_register_callback(void (*sdp_callback)(sdp_query_event_t*
     sdp_app_context = context;
 }
 
-void handleProtocolDescriptorListData(uint32_t attribute_value_length, uint32_t data_offset, uint8_t data){
+static void handleProtocolDescriptorListData(uint32_t attribute_value_length, uint32_t data_offset, uint8_t data){
     // init state on first byte
     if (data_offset == 0){
         pdl_state = GET_PROTOCOL_LIST_LENGTH;
@@ -206,7 +206,7 @@ void handleProtocolDescriptorListData(uint32_t attribute_value_length, uint32_t
     }
 }
 
-void handleServiceNameData(uint32_t attribute_value_length, uint32_t data_offset, uint8_t data){
+static void handleServiceNameData(uint32_t attribute_value_length, uint32_t data_offset, uint8_t data){
 
     // Get Header Len
     if (data_offset == 0){
@@ -289,7 +289,7 @@ static void handle_sdp_parser_event(sdp_query_event_t * event){
     // insert higher level code HERE
 }
 
-void sdp_query_rfcomm_init(void){
+static void sdp_query_rfcomm_init(void){
     // init
     de_state_init(&de_header_state);
     de_state_init(&sn_de_header_state);
diff --git a/src/sdp_query_util.c b/src/sdp_query_util.c
index 62806b362..cff066d51 100644
--- a/src/sdp_query_util.c
+++ b/src/sdp_query_util.c
@@ -40,7 +40,8 @@
  */
 #include "sdp_parser.h"
 #include "sdp_client.h"
-
+#include "sdp_query_util.h"
+ 
 static uint8_t des_attributeIDList[]    = { 0x35, 0x05, 0x0A, 0x00, 0x01, 0xff, 0xff};  // Attribute: 0x0001 - 0x0100
 static uint8_t des_serviceSearchPattern[] = {0x35, 0x03, 0x19, 0x00, 0x00};
 static uint8_t des_serviceSearchPatternUUID128[] = {
@@ -48,7 +49,7 @@ static uint8_t des_serviceSearchPatternUUID128[] = {
 	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
 	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00};
 
-uint8_t* create_service_search_pattern_for_uuid128(uint8_t* uuid){
+static uint8_t* create_service_search_pattern_for_uuid128(uint8_t* uuid){
 	memcpy(&des_serviceSearchPatternUUID128[3], uuid, 16);
 	return (uint8_t*)des_serviceSearchPatternUUID128;
 }
diff --git a/src/sdp_query_util.h b/src/sdp_query_util.h
index 3c7d06998..2f5ca3a36 100644
--- a/src/sdp_query_util.h
+++ b/src/sdp_query_util.h
@@ -57,12 +57,12 @@ uint8_t* create_service_search_pattern_for_uuid(uint16_t uuid);
 /*
  * @brief Searches SDP records on a remote device for all services with a given UUID.
  */
-void sdp_general_query_for_uuid(bd_addr_t remote, uint16_t uuid);
+void sdp_general_query_for_uuid(bd_addr_t remote, uint16_t uuid16);
 
 /*
  * @brief
  */
-void sdp_general_query_for_uuid128(bd_addr_t remote, uint8_t* uuid);
+void sdp_general_query_for_uuid128(bd_addr_t remote, uint8_t* uuid128);
 
 /* API_END */
 
diff --git a/src/sdp_util.c b/src/sdp_util.c
index b3be7d294..38821a723 100644
--- a/src/sdp_util.c
+++ b/src/sdp_util.c
@@ -289,9 +289,6 @@ void des_iterator_next(des_iterator_t * it){
     it->pos += element_len;
 }
 
-void sdp_add_attribute(uint8_t *seq, uint16_t attributeID, uint8_t attributeValue){
-}
-
 // MARK: DataElementSequence traversal
 typedef int (*de_traversal_callback_t)(uint8_t * element, de_type_t type, de_size_t size, void *context);
 static void de_traverse_sequence(uint8_t * element, de_traversal_callback_t handler, void *context){
@@ -359,6 +356,7 @@ static int sdp_traversal_attributeID_search(uint8_t * element, de_type_t type, d
     }
     return 0;
 }
+
 int sdp_attribute_list_constains_id(uint8_t *attributeIDList, uint16_t attributeID){
     struct sdp_context_attributeID_search attributeID_search;
     attributeID_search.result = 0;
@@ -607,6 +605,7 @@ struct sdp_context_match_pattern {
     uint8_t * record;
     int result;
 };
+
 int sdp_traversal_match_pattern(uint8_t * element, de_type_t attributeType, de_size_t size, void *my_context){
     struct sdp_context_match_pattern * context = (struct sdp_context_match_pattern *) my_context;
     uint8_t normalizedUUID[16];
diff --git a/src/sdp_util.h b/src/sdp_util.h
index b1b847bb3..d66c46461 100644
--- a/src/sdp_util.h
+++ b/src/sdp_util.h
@@ -169,6 +169,8 @@ uint8_t   sdp_set_attribute_value_for_attribute_id(uint8_t * record, uint16_t at
 int       sdp_record_matches_service_search_pattern(uint8_t *record, uint8_t *serviceSearchPattern);
 int       spd_get_filtered_size(uint8_t *record, uint8_t *attributeIDList);
 int       sdp_filter_attributes_in_attributeIDList(uint8_t *record, uint8_t *attributeIDList, uint16_t startOffset, uint16_t maxBytes, uint16_t *usedBytes, uint8_t *buffer);  
+int       sdp_attribute_list_constains_id(uint8_t *attributeIDList, uint16_t attributeID);
+int       sdp_traversal_match_pattern(uint8_t * element, de_type_t attributeType, de_size_t size, void *my_context);
 
 void      sdp_create_spp_service(uint8_t *service, int service_id, const char *name);
 void      sdp_normalize_uuid(uint8_t *uuid, uint32_t shortUUID);
diff --git a/src/utils.c b/src/utils.c
index 0e1882e21..57601ea5a 100644
--- a/src/utils.c
+++ b/src/utils.c
@@ -311,7 +311,7 @@ static const uint8_t crc8table[256] = {    /* reversed, 8-bit, poly=0x07 */
 #define CRC8_INIT  0xFF          // Initial FCS value 
 #define CRC8_OK    0xCF          // Good final FCS value 
 /*-----------------------------------------------------------------------------------*/
-uint8_t crc8(uint8_t *data, uint16_t len)
+static uint8_t crc8(uint8_t *data, uint16_t len)
 {
     uint16_t count;
     uint8_t crc = CRC8_INIT;
diff --git a/src/utils.h b/src/utils.h
index ef959e565..0c570df76 100644
--- a/src/utils.h
+++ b/src/utils.h
@@ -142,6 +142,8 @@ void swap56(const uint8_t  src[7],  uint8_t dst[7]);
 void swap64(const uint8_t  src[8],  uint8_t dst[8]);
 void swap128(const uint8_t src[16], uint8_t dst[16]);
 
+char char_for_nibble(int nibble);
+
 void printf_hexdump(const void *data, int size);
 void hexdump(const void *data, int size);
 void hexdumpf(const void *data, int size);