diff --git a/src/hci_transport_h4_dma.c b/src/hci_transport_h4_dma.c
index 61b9dea34..76f91015d 100644
--- a/src/hci_transport_h4_dma.c
+++ b/src/hci_transport_h4_dma.c
@@ -81,6 +81,10 @@ static const char * h4_get_transport_name();
 static int h4_set_baudrate(uint32_t baudrate);
 static int h4_can_send_packet_now(uint8_t packet_type);
 
+// externa prototyps, support for foo
+void foo_handle(uint8_t action);
+void foo_prepare_for_send(void);
+
 // packet reader state machine
 static  H4_STATE h4_state;
 static int read_pos;
@@ -160,10 +164,14 @@ static void h4_block_received(void){
                     h4_state = H4_W4_EVENT_HEADER;
                     bytes_to_read = HCI_EVENT_HEADER_SIZE;
                     break;
+
                 default:
+#ifdef HAVE_FOO:
+                    foo_handle(hci_packet[0]);
+#else
                     log_error("h4_process: invalid packet type 0x%02x\r\n", hci_packet[0]);
+#endif
                     read_pos = 0;
-                    h4_state = H4_W4_PACKET_TYPE;
                     bytes_to_read = 1;
                     break;
             }
@@ -226,7 +234,7 @@ static void h4_register_packet_handler(void (*handler)(uint8_t packet_type, uint
     packet_handler = handler;
 }
 
-// #define DUMP
+#define DUMP
 
 #ifdef DUMP
 static void dump(uint8_t *data, uint16_t len){
@@ -275,6 +283,10 @@ static int h4_send_packet(uint8_t packet_type, uint8_t *packet, int size){
     printf("TX: %02x ", packet_type);
     dump(packet, size);
 #endif
+
+#ifdef HAVE_FOO:
+    foo_prepare_for_send();
+#endif
     
     tx_data = packet;
     tx_len  = size;