diff --git a/extmod/btstack/btstack.mk b/extmod/btstack/btstack.mk
index 3084601b85..7e5d2f646d 100644
--- a/extmod/btstack/btstack.mk
+++ b/extmod/btstack/btstack.mk
@@ -30,10 +30,18 @@ SRC_BTSTACK = \
 	$(addprefix lib/btstack/src/ble/, $(filter-out %_tlv.c, $(SRC_BLE_FILES))) \
 	lib/btstack/platform/embedded/btstack_run_loop_embedded.c
 
+ifeq ($(MICROPY_BLUETOOTH_BTSTACK_USB),1)
+ifeq ($(MICROPY_BLUETOOTH_BTSTACK_H4),1)
+	$(error Cannot specifiy both MICROPY_BLUETOOTH_BTSTACK_USB and MICROPY_BLUETOOTH_BTSTACK_H4)
+endif
+endif
+
 ifeq ($(MICROPY_BLUETOOTH_BTSTACK_USB),1)
 SRC_BTSTACK += \
 	lib/btstack/platform/libusb/hci_transport_h2_libusb.c
 
+CFLAGS_MOD += -DMICROPY_BLUETOOTH_BTSTACK_USB=1
+
 CFLAGS  += $(shell pkg-config libusb-1.0 --cflags)
 LDFLAGS += $(shell pkg-config libusb-1.0 --libs)
 endif
diff --git a/ports/unix/Makefile b/ports/unix/Makefile
index 090b58d8ec..ff5f355022 100644
--- a/ports/unix/Makefile
+++ b/ports/unix/Makefile
@@ -134,24 +134,57 @@ CFLAGS_MOD += -DMICROPY_PY_THREAD=1 -DMICROPY_PY_THREAD_GIL=0
 LDFLAGS_MOD += $(LIBPTHREAD)
 endif
 
-# If the variant enables it and we have libusb, enable BTStack support for USB adaptors.
+# If the variant enables it, enable modbluetooth.
 ifeq ($(MICROPY_PY_BLUETOOTH),1)
 
 HAVE_LIBUSB := $(shell (which pkg-config > /dev/null && pkg-config --exists libusb-1.0) 2>/dev/null && echo '1')
-ifeq ($(HAVE_LIBUSB),1)
+
+# Only one stack can be enabled.
+ifeq ($(MICROPY_BLUETOOTH_NIMBLE),1)
+ifeq ($(MICROPY_BLUETOOTH_BTSTACK),1)
+$(error Cannot enable both NimBLE and BTstack at the same time)
+endif
+endif
+
+# Default to btstack, but a variant (or make command line) can set NimBLE
+# explicitly (which is always via H4 UART).
+ifneq ($(MICROPY_BLUETOOTH_NIMBLE),1)
+ifneq ($(MICROPY_BLUETOOTH_BTSTACK),1)
+MICROPY_BLUETOOTH_BTSTACK ?= 1
+endif
+endif
 
 CFLAGS_MOD += -DMICROPY_PY_BLUETOOTH=1
 CFLAGS_MOD += -DMICROPY_PY_BLUETOOTH_ENABLE_CENTRAL_MODE=1
 # Runs in a thread, cannot make calls into the VM.
 CFLAGS_MOD += -DMICROPY_PY_BLUETOOTH_GATTS_ON_READ_CALLBACK=0
 
-MICROPY_BLUETOOTH_BTSTACK ?= 1
-MICROPY_BLUETOOTH_BTSTACK_USB ?= 1
-
 ifeq ($(MICROPY_BLUETOOTH_BTSTACK),1)
+
+# Figure out which BTstack transport to use.
+ifeq ($(MICROPY_BLUETOOTH_BTSTACK_H4),1)
+ifeq ($(MICROPY_BLUETOOTH_BTSTACK_USB),1)
+$(error Cannot enable BTstack support for USB and H4 UART at the same time)
+endif
+else
+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
+endif
+endif
+
+# BTstack is enabled.
 GIT_SUBMODULES += lib/btstack
 include $(TOP)/extmod/btstack/btstack.mk
-endif
+
+else
+
+# NimBLE is enabled.
+GIT_SUBMODULES += lib/mynewt-nimble
+include $(TOP)/extmod/nimble/nimble.mk
 
 endif
 
@@ -201,7 +234,9 @@ SRC_C = \
 	alloc.c \
 	coverage.c \
 	fatfs_port.c \
+	mpbthciport.c \
 	mpbtstackport_common.c \
+	mpbtstackport_h4.c \
 	mpbtstackport_usb.c \
 	mpnimbleport.c \
 	$(SRC_MOD) \
diff --git a/ports/unix/mpbthciport.c b/ports/unix/mpbthciport.c
new file mode 100644
index 0000000000..5a5c1d4a4e
--- /dev/null
+++ b/ports/unix/mpbthciport.c
@@ -0,0 +1,219 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2020 Jim Mussared
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "py/runtime.h"
+#include "py/mperrno.h"
+#include "py/mphal.h"
+
+#if MICROPY_PY_BLUETOOTH && (MICROPY_BLUETOOTH_NIMBLE || (MICROPY_BLUETOOTH_BTSTACK && MICROPY_BLUETOOTH_BTSTACK_H4))
+
+#if !MICROPY_PY_THREAD
+#error Unix HCI UART requires MICROPY_PY_THREAD
+#endif
+
+#include "extmod/modbluetooth.h"
+#include "extmod/mpbthci.h"
+
+#include <pthread.h>
+#include <unistd.h>
+
+#include <termios.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define DEBUG_printf(...) // printf(__VA_ARGS__)
+#define DEBUG_HCI_DUMP (0)
+
+uint8_t mp_bluetooth_hci_cmd_buf[4 + 256];
+
+// Must be provided by the stack bindings (e.g. mpnimbleport.c or mpbtstackport.c).
+extern bool mp_bluetooth_hci_poll(void);
+
+STATIC const useconds_t UART_POLL_INTERVAL_US = 1000;
+
+STATIC int uart_fd = -1;
+STATIC pthread_t hci_poll_thread_id;
+
+STATIC void *hci_poll_thread(void *arg) {
+    (void)arg;
+
+    // This will return false when the stack is shutdown.
+    while (mp_bluetooth_hci_poll()) {
+        usleep(UART_POLL_INTERVAL_US);
+    }
+
+    return NULL;
+}
+
+STATIC int configure_uart(void) {
+    struct termios toptions;
+
+    // Get existing config.
+    if (tcgetattr(uart_fd, &toptions) < 0) {
+        DEBUG_printf("Couldn't get term attributes");
+        return -1;
+    }
+
+    // Raw mode (disable all processing).
+    cfmakeraw(&toptions);
+
+    // 8N1, no parity.
+    toptions.c_cflag &= ~CSTOPB;
+    toptions.c_cflag |= CS8;
+    toptions.c_cflag &= ~PARENB;
+
+    // Enable receiver, ignore modem control lines
+    toptions.c_cflag |= CREAD | CLOCAL;
+
+    // Blocking, single-byte reads.
+    toptions.c_cc[VMIN] = 1;
+    toptions.c_cc[VTIME] = 0;
+
+    // Enable HW RTS/CTS flow control.
+    toptions.c_iflag &= ~(IXON | IXOFF | IXANY);
+    toptions.c_cflag |= CRTSCTS;
+
+    // 1Mbit (TODO: make this configurable).
+    speed_t brate = B1000000;
+    cfsetospeed(&toptions, brate);
+    cfsetispeed(&toptions, brate);
+
+    // Apply immediately.
+    if (tcsetattr(uart_fd, TCSANOW, &toptions) < 0) {
+        DEBUG_printf("Couldn't set term attributes");
+        return -1;
+    }
+
+    return 0;
+}
+
+// HCI UART bindings.
+int mp_bluetooth_hci_uart_init(uint32_t port, uint32_t baudrate) {
+    (void)port;
+    (void)baudrate;
+
+    DEBUG_printf("mp_bluetooth_hci_uart_init (unix)\n");
+
+    char uart_device_name[256] = "/dev/ttyUSB0";
+
+    char *path = getenv("MICROPYBTUART");
+    if (path != NULL) {
+        strcpy(uart_device_name, path);
+    }
+    DEBUG_printf("Using HCI UART: %s\n", uart_device_name);
+
+    int flags = O_RDWR | O_NOCTTY | O_NONBLOCK;
+    uart_fd = open(uart_device_name, flags);
+    if (uart_fd == -1) {
+        DEBUG_printf("Unable to open port %s", uart_device_name);
+        return -1;
+    }
+
+    if (configure_uart()) {
+        return -1;
+    }
+
+    // Create a thread to run the polling loop.
+    pthread_attr_t attr;
+    pthread_attr_init(&attr);
+    pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
+    pthread_create(&hci_poll_thread_id, &attr, &hci_poll_thread, NULL);
+
+    return 0;
+}
+
+int mp_bluetooth_hci_uart_deinit(void) {
+    DEBUG_printf("mp_bluetooth_hci_uart_deinit\n");
+
+    // Wait for the poll loop to terminate when the state is set to OFF.
+    pthread_join(hci_poll_thread_id, NULL);
+
+    // Close the UART.
+    close(uart_fd);
+    uart_fd = -1;
+
+    return 0;
+}
+
+int mp_bluetooth_hci_uart_set_baudrate(uint32_t baudrate) {
+    (void)baudrate;
+    DEBUG_printf("mp_bluetooth_hci_uart_set_baudrate\n");
+    return 0;
+}
+
+int mp_bluetooth_hci_uart_readchar(void) {
+    // DEBUG_printf("mp_bluetooth_hci_uart_readchar\n");
+
+    uint8_t c;
+    ssize_t bytes_read = read(uart_fd, &c, 1);
+
+    if (bytes_read == 1) {
+        #if DEBUG_HCI_DUMP
+        printf("[% 8ld] RX: %02x\n", mp_hal_ticks_ms(), c);
+        #endif
+        return c;
+    } else {
+        return -1;
+    }
+}
+
+int mp_bluetooth_hci_uart_write(const uint8_t *buf, size_t len) {
+    // DEBUG_printf("mp_bluetooth_hci_uart_write\n");
+
+    #if DEBUG_HCI_DUMP
+    printf("[% 8ld] TX: %02x", mp_hal_ticks_ms(), buf[0]);
+    for (size_t i = 1; i < len; ++i) {
+        printf(":%02x", buf[i]);
+    }
+    printf("\n");
+    #endif
+
+    return write(uart_fd, buf, len);
+}
+
+// No-op implementations of HCI controller interface.
+int mp_bluetooth_hci_controller_init(void) {
+    return 0;
+}
+
+int mp_bluetooth_hci_controller_deinit(void) {
+    return 0;
+}
+
+int mp_bluetooth_hci_controller_sleep_maybe(void) {
+    return 0;
+}
+
+bool mp_bluetooth_hci_controller_woken(void) {
+    return true;
+}
+
+int mp_bluetooth_hci_controller_wakeup(void) {
+    return 0;
+}
+
+#endif // MICROPY_PY_BLUETOOTH && (MICROPY_BLUETOOTH_NIMBLE || (MICROPY_BLUETOOTH_BTSTACK && MICROPY_BLUETOOTH_BTSTACK_H4))
diff --git a/ports/unix/mpbtstackport.h b/ports/unix/mpbtstackport.h
index 29433cc7fb..c82e8bd812 100644
--- a/ports/unix/mpbtstackport.h
+++ b/ports/unix/mpbtstackport.h
@@ -32,6 +32,11 @@
 
 bool mp_bluetooth_hci_poll(void);
 
+#if MICROPY_BLUETOOTH_BTSTACK_H4
+void mp_bluetooth_hci_poll_h4(void);
+void mp_bluetooth_btstack_port_init_h4(void);
+#endif
+
 #if MICROPY_BLUETOOTH_BTSTACK_USB
 void mp_bluetooth_btstack_port_init_usb(void);
 #endif
diff --git a/ports/unix/mpbtstackport_common.c b/ports/unix/mpbtstackport_common.c
index 402cf95283..eb1b1c9c80 100644
--- a/ports/unix/mpbtstackport_common.c
+++ b/ports/unix/mpbtstackport_common.c
@@ -45,6 +45,9 @@ 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).
         mp_uint_t atomic_state = MICROPY_BEGIN_ATOMIC_SECTION();
+        #if MICROPY_BLUETOOTH_BTSTACK_H4
+        mp_bluetooth_hci_poll_h4();
+        #endif
         btstack_run_loop_embedded_execute_once();
         MICROPY_END_ATOMIC_SECTION(atomic_state);
 
@@ -81,6 +84,10 @@ void mp_bluetooth_btstack_port_init(void) {
 
     // hci_dump_open(NULL, HCI_DUMP_STDOUT);
 
+    #if MICROPY_BLUETOOTH_BTSTACK_H4
+    mp_bluetooth_btstack_port_init_h4();
+    #endif
+
     #if MICROPY_BLUETOOTH_BTSTACK_USB
     mp_bluetooth_btstack_port_init_usb();
     #endif
diff --git a/ports/unix/mpbtstackport_h4.c b/ports/unix/mpbtstackport_h4.c
new file mode 100644
index 0000000000..4fdc20c22b
--- /dev/null
+++ b/ports/unix/mpbtstackport_h4.c
@@ -0,0 +1,80 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2020 Jim Mussared
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include <pthread.h>
+
+#include "py/runtime.h"
+#include "py/mperrno.h"
+#include "py/mphal.h"
+
+#if MICROPY_PY_BLUETOOTH && MICROPY_BLUETOOTH_BTSTACK && MICROPY_BLUETOOTH_BTSTACK_H4
+
+#include "lib/btstack/chipset/zephyr/btstack_chipset_zephyr.h"
+
+#include "extmod/btstack/btstack_hci_uart.h"
+#include "extmod/btstack/modbluetooth_btstack.h"
+
+#include "mpbtstackport.h"
+
+#define DEBUG_printf(...) // printf(__VA_ARGS__)
+
+STATIC hci_transport_config_uart_t hci_transport_config_uart = {
+    HCI_TRANSPORT_CONFIG_UART,
+    1000000, // initial baudrate
+    0,       // main baudrate
+    1,       // flow control
+    NULL,    // device name
+};
+
+void mp_bluetooth_hci_poll_h4(void) {
+    if (mp_bluetooth_btstack_state == MP_BLUETOOTH_BTSTACK_STATE_STARTING || mp_bluetooth_btstack_state == MP_BLUETOOTH_BTSTACK_STATE_ACTIVE) {
+        mp_bluetooth_btstack_hci_uart_process();
+    }
+}
+
+void mp_bluetooth_btstack_port_init_h4(void) {
+    DEBUG_printf("mp_bluetooth_btstack_port_init_h4\n");
+
+    const hci_transport_t *transport = hci_transport_h4_instance(&mp_bluetooth_btstack_hci_uart_block);
+    hci_init(transport, &hci_transport_config_uart);
+
+    hci_set_chipset(btstack_chipset_zephyr_instance());
+}
+
+void mp_bluetooth_btstack_port_deinit(void) {
+    DEBUG_printf("mp_bluetooth_btstack_port_deinit\n");
+
+    hci_power_control(HCI_POWER_OFF);
+    hci_close();
+}
+
+void mp_bluetooth_btstack_port_start(void) {
+    DEBUG_printf("mp_bluetooth_btstack_port_start\n");
+
+    hci_power_control(HCI_POWER_ON);
+}
+
+#endif // MICROPY_PY_BLUETOOTH && MICROPY_BLUETOOTH_BTSTACK && MICROPY_BLUETOOTH_BTSTACK_H4
diff --git a/ports/unix/mpconfigport.h b/ports/unix/mpconfigport.h
index 9e24ab10cd..c74d2fd84a 100644
--- a/ports/unix/mpconfigport.h
+++ b/ports/unix/mpconfigport.h
@@ -314,6 +314,11 @@ void mp_unix_mark_exec(void);
 struct _mp_bluetooth_btstack_root_pointers_t;
 #define MICROPY_BLUETOOTH_ROOT_POINTERS struct _mp_bluetooth_btstack_root_pointers_t *bluetooth_btstack_root_pointers;
 #endif
+#if MICROPY_BLUETOOTH_NIMBLE
+struct _mp_bluetooth_nimble_root_pointers_t;
+struct _mp_bluetooth_nimble_malloc_t;
+#define MICROPY_BLUETOOTH_ROOT_POINTERS struct _mp_bluetooth_nimble_malloc_t *bluetooth_nimble_memory; struct _mp_bluetooth_nimble_root_pointers_t *bluetooth_nimble_root_pointers;
+#endif
 #else
 #define MICROPY_BLUETOOTH_ROOT_POINTERS
 #endif
@@ -353,7 +358,7 @@ struct _mp_bluetooth_btstack_root_pointers_t;
 #endif
 
 #if MICROPY_PY_THREAD
-#define MICROPY_BEGIN_ATOMIC_SECTION() (mp_thread_unix_begin_atomic_section(), 0)
+#define MICROPY_BEGIN_ATOMIC_SECTION() (mp_thread_unix_begin_atomic_section(), 0xffffffff)
 #define MICROPY_END_ATOMIC_SECTION(x) (void)x; mp_thread_unix_end_atomic_section()
 #endif
 
diff --git a/ports/unix/mpnimbleport.c b/ports/unix/mpnimbleport.c
new file mode 100644
index 0000000000..8961910098
--- /dev/null
+++ b/ports/unix/mpnimbleport.c
@@ -0,0 +1,84 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2020 Jim Mussared
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "py/runtime.h"
+#include "py/mperrno.h"
+#include "py/mphal.h"
+
+#if MICROPY_PY_BLUETOOTH && MICROPY_BLUETOOTH_NIMBLE
+
+#include "nimble/nimble_npl.h"
+
+#include "extmod/nimble/modbluetooth_nimble.h"
+#include "extmod/nimble/hal/hal_uart.h"
+
+#define DEBUG_printf(...) // printf(__VA_ARGS__)
+
+// Called by the UART polling thread in mpbthciport.c.
+bool mp_bluetooth_hci_poll(void) {
+    // DEBUG_printf("mp_bluetooth_hci_poll (unix nimble) %d\n", mp_bluetooth_nimble_ble_state);
+
+    if (mp_bluetooth_nimble_ble_state == MP_BLUETOOTH_NIMBLE_BLE_STATE_OFF) {
+        DEBUG_printf("mp_bluetooth_hci_poll (unix nimble) -- shutdown\n");
+        return false;
+    }
+
+    if (mp_bluetooth_nimble_ble_state >= MP_BLUETOOTH_NIMBLE_BLE_STATE_WAITING_FOR_SYNC) {
+
+        // Pretend like we're running in IRQ context (i.e. other things can't be running at the same time).
+        mp_uint_t atomic_state = MICROPY_BEGIN_ATOMIC_SECTION();
+
+        // Ask NimBLE to process UART data.
+        mp_bluetooth_nimble_hci_uart_process();
+
+        // Run pending background operations and events, but only after HCI sync.
+        mp_bluetooth_nimble_os_callout_process();
+        mp_bluetooth_nimble_os_eventq_run_all();
+
+        MICROPY_END_ATOMIC_SECTION(atomic_state);
+    }
+
+    return true;
+}
+
+// Extra port-specific helpers.
+void mp_bluetooth_nimble_hci_uart_wfi(void) {
+    // DEBUG_printf("mp_bluetooth_nimble_hci_uart_wfi\n");
+    // TODO: this should do a select() on the uart_fd.
+}
+
+uint32_t mp_bluetooth_nimble_hci_uart_enter_critical(void) {
+    // DEBUG_printf("mp_bluetooth_nimble_hci_uart_enter_critical\n");
+    MICROPY_PY_BLUETOOTH_ENTER
+    return atomic_state; // Always 0xffffffff
+}
+
+void mp_bluetooth_nimble_hci_uart_exit_critical(uint32_t atomic_state) {
+    MICROPY_PY_BLUETOOTH_EXIT
+    // DEBUG_printf("mp_bluetooth_nimble_hci_uart_exit_critical\n");
+}
+
+#endif // MICROPY_PY_BLUETOOTH && MICROPY_BLUETOOTH_NIMBLE
diff --git a/ports/unix/mpnimbleport.h b/ports/unix/mpnimbleport.h
new file mode 100644
index 0000000000..a2935e6fdf
--- /dev/null
+++ b/ports/unix/mpnimbleport.h
@@ -0,0 +1,33 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2020 Jim Mussared
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#ifndef MICROPY_INCLUDED_UNIX_NIMBLE_PORT_H
+#define MICROPY_INCLUDED_UNIX_NIMBLE_PORT_H
+
+#define MICROPY_HW_BLE_UART_ID (0)
+#define MICROPY_HW_BLE_UART_BAUDRATE (1000000)
+
+#endif // MICROPY_INCLUDED_UNIX_NIMBLE_PORT_H
diff --git a/ports/unix/variants/coverage/mpconfigvariant.mk b/ports/unix/variants/coverage/mpconfigvariant.mk
index 66e694e0a9..f11d0b0d28 100644
--- a/ports/unix/variants/coverage/mpconfigvariant.mk
+++ b/ports/unix/variants/coverage/mpconfigvariant.mk
@@ -17,4 +17,3 @@ MICROPY_ROM_TEXT_COMPRESSION = 1
 MICROPY_VFS_FAT = 1
 MICROPY_VFS_LFS1 = 1
 MICROPY_VFS_LFS2 = 1
-MICROPY_PY_BLUETOOTH = 1
diff --git a/ports/unix/variants/dev/mpconfigvariant.mk b/ports/unix/variants/dev/mpconfigvariant.mk
index 1f8611b6fc..91bd28da9b 100644
--- a/ports/unix/variants/dev/mpconfigvariant.mk
+++ b/ports/unix/variants/dev/mpconfigvariant.mk
@@ -6,4 +6,5 @@ MICROPY_ROM_TEXT_COMPRESSION = 1
 MICROPY_VFS_FAT = 1
 MICROPY_VFS_LFS1 = 1
 MICROPY_VFS_LFS2 = 1
-MICROPY_PY_BLUETOOTH = 1
+
+MICROPY_PY_BLUETOOTH ?= 1