diff --git a/ports/unix/Makefile b/ports/unix/Makefile
index d5bd6d4098..62d7793663 100644
--- a/ports/unix/Makefile
+++ b/ports/unix/Makefile
@@ -33,6 +33,31 @@ QSTR_GLOBAL_DEPENDENCIES += $(VARIANT_DIR)/mpconfigvariant.h
 # OS name, for simple autoconfig
 UNAME_S := $(shell uname -s)
 
+# If the variant enables it, enable modbluetooth.
+ifeq ($(MICROPY_PY_BLUETOOTH),1)
+ifeq ($(MICROPY_BLUETOOTH_BTSTACK),1)
+HAVE_LIBUSB := $(shell (which pkg-config > /dev/null && pkg-config --exists libusb-1.0) 2>/dev/null && echo '1')
+
+# Figure out which BTstack transport to use.
+ifeq ($(HAVE_LIBUSB),1)
+# Default to btstack-over-usb.
+MICROPY_BLUETOOTH_BTSTACK_USB ?= 1
+MICROPY_BLUETOOTH_BTSTACK_H4 ?= 0
+else
+# Fallback to HCI controller via a H4 UART (e.g. Zephyr on nRF) over a /dev/tty serial port.
+MICROPY_BLUETOOTH_BTSTACK_USB ?= 0
+MICROPY_BLUETOOTH_BTSTACK_H4 ?= 1
+endif
+
+endif
+endif
+
+# Set the file that will be included by "extmod/btstack/btstack_config.h"
+# 
+# The original file "extmod/btstack/btstack_config_common.h"
+# will be included by it. 
+MICROPY_BLUETOOTH_BTSTACK_CONFIG_FILE ?= '"ports/unix/btstack_config.h"'
+
 # include py core make definitions
 include $(TOP)/py/py.mk
 include $(TOP)/extmod/extmod.mk
@@ -144,21 +169,27 @@ ifeq ($(MICROPY_SSL_AXTLS),1)
 endif
 endif
 
-# If the variant enables it, enable modbluetooth.
 ifeq ($(MICROPY_PY_BLUETOOTH),1)
 ifeq ($(MICROPY_BLUETOOTH_BTSTACK),1)
-HAVE_LIBUSB := $(shell (which pkg-config > /dev/null && pkg-config --exists libusb-1.0) 2>/dev/null && echo '1')
 
-# Figure out which BTstack transport to use.
-ifeq ($(HAVE_LIBUSB),1)
-# Default to btstack-over-usb.
-MICROPY_BLUETOOTH_BTSTACK_USB ?= 1
-else
-# Fallback to HCI controller via a H4 UART (e.g. Zephyr on nRF) over a /dev/tty serial port.
-MICROPY_BLUETOOTH_BTSTACK_H4 ?= 1
+ifndef MICROPY_BLUETOOTH_BTSTACK_HCI_DUMP
+MICROPY_BLUETOOTH_BTSTACK_HCI_DUMP ?= 0
 endif
 
+ifeq ($(MICROPY_BLUETOOTH_BTSTACK_USB),0)
 SRC_BTSTACK_C += lib/btstack/platform/embedded/btstack_run_loop_embedded.c
+endif
+
+ifeq ($(MICROPY_BLUETOOTH_BTSTACK_USB),1)
+SRC_BTSTACK_C += lib/btstack/platform/posix/btstack_run_loop_posix.c
+
+ifeq ($(MICROPY_BLUETOOTH_BTSTACK_HCI_DUMP),1)
+CFLAGS += -DMICROPY_BLUETOOTH_BTSTACK_HCI_DUMP=1
+SRC_BTSTACK_C += lib/btstack/platform/posix/hci_dump_posix_fs.c
+endif
+
+endif
+
 endif
 endif
 
diff --git a/ports/unix/btstack_config.h b/ports/unix/btstack_config.h
new file mode 100644
index 0000000000..374acc02e9
--- /dev/null
+++ b/ports/unix/btstack_config.h
@@ -0,0 +1,23 @@
+#ifndef MICROPY_INCLUDED_PORTS_UNIX_BTSTACK_CONFIG_H
+#define MICROPY_INCLUDED_PORTS_UNIX_BTSTACK_CONFIG_H
+
+
+#include "extmod/btstack/btstack_config_common.h"
+
+#ifdef MICROPY_BLUETOOTH_BTSTACK_USB
+#if MICROPY_BLUETOOTH_BTSTACK_USB
+
+// Workaround:
+//
+// If ENABLE_SCO_OVER_HCI is not defined there is a compiler error:
+//
+// ../../lib/btstack/platform/libusb/hci_transport_h2_libusb.c:1354:13:
+// error: ‘signal_sco_can_send_now’ defined but not used
+//
+// Because the problem is in an external code this workaround is done.
+#define ENABLE_SCO_OVER_HCI
+
+#endif
+#endif
+
+#endif // MICROPY_INCLUDED_PORTS_UNIX_BTSTACK_CONFIG_H
diff --git a/ports/unix/mpbtstackport_common.c b/ports/unix/mpbtstackport_common.c
index 36412e96f4..6cf9d6562f 100644
--- a/ports/unix/mpbtstackport_common.c
+++ b/ports/unix/mpbtstackport_common.c
@@ -41,7 +41,7 @@
 
 #include "mpbtstackport.h"
 
-// Called by the UART polling thread in mpbthciport.c, or by the USB polling thread in mpbtstackport_usb.c.
+// Called by the UART polling thread in mpbthciport.c
 bool mp_bluetooth_hci_poll(void) {
     if (mp_bluetooth_btstack_state == MP_BLUETOOTH_BTSTACK_STATE_STARTING || mp_bluetooth_btstack_state == MP_BLUETOOTH_BTSTACK_STATE_ACTIVE || mp_bluetooth_btstack_state == MP_BLUETOOTH_BTSTACK_STATE_HALTING) {
         // Pretend like we're running in IRQ context (i.e. other things can't be running at the same time).
@@ -80,9 +80,11 @@ uint32_t hal_time_ms(void) {
 }
 
 void mp_bluetooth_btstack_port_init(void) {
+    #if !MICROPY_BLUETOOTH_BTSTACK_USB
     btstack_run_loop_init(btstack_run_loop_embedded_get_instance());
 
     // hci_dump_init(hci_dump_embedded_stdout_get_instance());
+    #endif
 
     #if MICROPY_BLUETOOTH_BTSTACK_H4
     mp_bluetooth_btstack_port_init_h4();
diff --git a/ports/unix/mpbtstackport_usb.c b/ports/unix/mpbtstackport_usb.c
index 8b1d1fff21..15e0f7d34e 100644
--- a/ports/unix/mpbtstackport_usb.c
+++ b/ports/unix/mpbtstackport_usb.c
@@ -34,12 +34,12 @@
 #include "py/runtime.h"
 #include "py/mperrno.h"
 #include "py/mphal.h"
+#include "py/stackctrl.h"
 
 #include "lib/btstack/src/btstack.h"
 #include "lib/btstack/src/hci_transport_usb.h"
-#include "lib/btstack/platform/embedded/btstack_run_loop_embedded.h"
-#include "lib/btstack/platform/embedded/hal_cpu.h"
-#include "lib/btstack/platform/embedded/hal_time_ms.h"
+#include "lib/btstack/platform/posix/btstack_run_loop_posix.h"
+#include "lib/btstack/platform/posix/hci_dump_posix_fs.h"
 
 #include "extmod/btstack/modbluetooth_btstack.h"
 
@@ -49,9 +49,21 @@
 #error Unix btstack requires MICROPY_PY_THREAD
 #endif
 
-static const useconds_t USB_POLL_INTERVAL_US = 1000;
+#define DEBUG_printf(...) // printf("mpbtstackport_usb.c: " __VA_ARGS__)
 
 void mp_bluetooth_btstack_port_init_usb(void) {
+
+    #if MICROPY_BLUETOOTH_BTSTACK_HCI_DUMP
+    // log into file using HCI_DUMP_PACKETLOGGER format
+    const char *pklg_path = "/tmp/hci_dump.pklg";
+    hci_dump_posix_fs_open(pklg_path, HCI_DUMP_PACKETLOGGER);
+    const hci_dump_t *hci_dump_impl = hci_dump_posix_fs_get_instance();
+    hci_dump_init(hci_dump_impl);
+    printf("Packet Log: %s\n", pklg_path);
+    #endif
+
+    btstack_run_loop_init(btstack_run_loop_posix_get_instance());
+
     // MICROPYBTUSB can be a ':'' or '-' separated port list.
     char *path = getenv("MICROPYBTUSB");
     if (path != NULL) {
@@ -76,35 +88,77 @@ void mp_bluetooth_btstack_port_init_usb(void) {
 static pthread_t bstack_thread_id;
 
 void mp_bluetooth_btstack_port_deinit(void) {
-    hci_power_control(HCI_POWER_OFF);
+    DEBUG_printf("mp_bluetooth_btstack_port_deinit: begin: mp_bluetooth_btstack_state=%d\n", mp_bluetooth_btstack_state);
 
-    // Wait for the poll loop to terminate when the state is set to OFF.
+    // Workaround:
+    //
+    // Possibly hci_power_control(HCI_POWER_OFF);
+    // crashes with memory fault if state is already MP_BLUETOOTH_BTSTACK_STATE_OFF.
+    if (mp_bluetooth_btstack_state != MP_BLUETOOTH_BTSTACK_STATE_OFF &&
+        mp_bluetooth_btstack_state != MP_BLUETOOTH_BTSTACK_STATE_TIMEOUT) {
+
+        hci_power_control(HCI_POWER_OFF);
+
+        DEBUG_printf("mp_bluetooth_btstack_port_deinit: after HCI_POWER_OFF: mp_bluetooth_btstack_state=%d\n", mp_bluetooth_btstack_state);
+    }
+
+    // btstack_run_loop_trigger_exit() will call btstack_run_loop_t::trigger_exit()
+    // i.e. btstack_run_loop_posix_trigger_exit().
+    // And that will trigger the exit of btstack_run_loop_execute()
+    // i.e. btstack_run_loop_posix_execute().
+    btstack_run_loop_trigger_exit();
+
+    // A call of btstack_run_loop_poll_data_sources_from_irq() is needed
+    // additional to btstack_run_loop_trigger_exit() to exit the posix run loop.
+    //
+    // Otherwise the posix run loop will wait forever for ready File Descriptors.
+    //
+    // Hint:
+    // btstack_run_loop_poll_data_sources_from_irq()
+    // calls btstack_run_loop_posix_poll_data_sources_from_irq()
+    btstack_run_loop_poll_data_sources_from_irq();
+
+    // MicroPython threads are created with PTHREAD_CREATE_DETACHED.
+    //
+    // Nonetheless the thread is created with PTHREAD_CREATE_JOINABLE and
+    // pthread_join() is used.
+
+    DEBUG_printf("mp_bluetooth_btstack_port_deinit: pthread_join()\n");
     pthread_join(bstack_thread_id, NULL);
+
+    #if MICROPY_BLUETOOTH_BTSTACK_HCI_DUMP
+    DEBUG_printf("mp_bluetooth_btstack_port_deinit: hci_dump_posix_fs_close()\n");
+    hci_dump_posix_fs_close();
+    #endif
+
+    DEBUG_printf("mp_bluetooth_btstack_port_deinit: end\n");
 }
 
-
-// Provided by mpbstackport_common.c.
-extern bool mp_bluetooth_hci_poll(void);
-
 static void *btstack_thread(void *arg) {
     (void)arg;
+
+    // This code runs on an non-MicroPython thread.
+    // But some of the code e.g. in "extmod/btstack/modbluetooth_btstack.c"
+    // make calls that needs the state of a MicroPython thread e. g. "m_del()".
+    //
+    // So set up relevant MicroPython state and obtain the GIL,
+    // to synchronised with the rest of the runtime.
+
+    mp_state_thread_t ts;
+    mp_thread_init_state(&ts, 40000 * (sizeof(void *) / 4) - 1024, NULL, NULL);
+    MP_THREAD_GIL_ENTER();
+
+    log_info("btstack_thread: HCI_POWER_ON");
     hci_power_control(HCI_POWER_ON);
 
-    // modbluetooth_btstack.c will have set the state to STARTING before
-    // calling mp_bluetooth_btstack_port_start.
-    // This loop will terminate when the HCI_POWER_OFF above results
-    // in modbluetooth_btstack.c setting the state back to OFF.
-    // Or, if a timeout results in it being set to TIMEOUT.
+    btstack_run_loop_execute();
 
-    while (true) {
-        if (!mp_bluetooth_hci_poll()) {
-            break;
-        }
+    log_info("btstack_thread: end");
+
+    // Give back the GIL and reset the MicroPython state.
+    MP_THREAD_GIL_EXIT();
+    mp_thread_set_state(NULL);
 
-        // The USB transport schedules events to the run loop at 1ms intervals,
-        // and the implementation currently polls rather than selects.
-        usleep(USB_POLL_INTERVAL_US);
-    }
     return NULL;
 }
 
@@ -112,7 +166,8 @@ void mp_bluetooth_btstack_port_start(void) {
     // Create a thread to run the btstack loop.
     pthread_attr_t attr;
     pthread_attr_init(&attr);
-    pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
+
+    // We need a joinable thread for pthread_join() what is the default.
     pthread_create(&bstack_thread_id, &attr, &btstack_thread, NULL);
 }