diff --git a/.vscode/c_cpp_properties.json b/.vscode/c_cpp_properties.json
index 1a8639a..1b6ca9a 100644
--- a/.vscode/c_cpp_properties.json
+++ b/.vscode/c_cpp_properties.json
@@ -19,8 +19,13 @@
                 "ENABLED_REGIONS=\"AS923 AU915 CN470 CN779 EU433 EU868 IN865 KR920 RU864 US915\"",
                 "DEFAULT_ACTIVE_REGION=\"EU868\"",
                 "DEFAULT_UART_BAUDRATE=19200",
-                "DEBUG_PORT=1",
-                "TCXO_PIN=1"
+                "FACTORY_RESET_PIN=1",
+                "RESTORE_CHMASK_AFTER_JOIN=0",
+                "TCXO_PIN=1",
+                "DETACHABLE_LPUART=1",
+                "DEBUG_LOG=1",
+                "ENABLE_SWD=1",
+                "DEBUG_MCU=1"
             ],
             "includePath": [
                 "${workspaceFolder}/**",
@@ -47,7 +52,13 @@
                  "ENABLED_REGIONS=\"AS923 AU915 CN470 CN779 EU433 EU868 IN865 KR920 RU864 US915\"",
                  "DEFAULT_ACTIVE_REGION=\"EU868\"",
                  "DEFAULT_UART_BAUDRATE=19200",
-                 "TCXO_PIN=1"
+                 "FACTORY_RESET_PIN=1",
+                 "RESTORE_CHMASK_AFTER_JOIN=0",
+                 "TCXO_PIN=1",
+                 "DETACHABLE_LPUART=1",
+                 "DEBUG_LOG=0",
+                 "ENABLE_SWD=0",
+                 "DEBUG_MCU=0"
             ],
              "includePath": [
                  "${workspaceFolder}/**",
diff --git a/Makefile b/Makefile
index 63384d2..0846044 100644
--- a/Makefile
+++ b/Makefile
@@ -15,19 +15,6 @@ ENABLED_REGIONS ?= AS923 AU915 EU868 KR920 IN865 US915 RU864
 # application.
 DEFAULT_ACTIVE_REGION ?= EU868
 
-# Uncomment the following line to configure pin 14 (GPIOB15/SPI2_MOSI) as a
-# factory reset pin. During normal operation, the pin should be pulled up or
-# left floating. When continuously pulled down for more than five seconds and
-# then pulled up, the modem resets itself to factory defaults.
-#
-# This functionality is only available in release builds. In debug builds, the
-# same pin is used by the SWD debugging interface.
-#
-# Since the modem can also be reset through the AT command interface, this
-# functionality is disabled by default to save a little bit of power.
-#
-# ENABLE_FACTORY_RESET_PIN = 1
-
 # The default channel plan for the AS923 region. One of:
 #  - CHANNEL_PLAN_GROUP_AS923_1
 #  - CHANNEL_PLAN_GROUP_AS923_2
@@ -59,17 +46,24 @@ VERSION_COMPAT ?= 1.1.06
 # build date of Murata Modem in version configured through VERSION_COMPAT.
 BUILD_DATE_COMPAT ?= Aug 24 2020 16:11:57
 
+# Set the following variable to 1 configure pin 14 (GPIOB15/SPI2_MOSI) as a
+# factory reset pin. During normal operation, the pin should be pulled up or
+# left floating. When continuously pulled down for more than five seconds and
+# then pulled up, the modem resets itself to factory defaults.
+#
+# Since the modem can also be reset through the AT command interface, this
+# functionality is disabled by default to save a little bit of power.
+#
+# Used GPIOs: PB15
+FACTORY_RESET_PIN ?= 0
+
 # The LoRaWAN network server may reconfigure the node's channel mask in the Join
 # Accept message. If you want to prevent that from happening, e.g., if you work
-# with an incorrectly configured LoRaWAN network server, uncomment the following
-# variable. Use with caution. This feature is designed as a work-around for
+# with an incorrectly-configured LoRaWAN network server, set the following
+# variable to 1. Use with caution. This feature is designed as a work-around for
 # incorrectly configured LoRa networks. If you are unsure, leave the variable
-# commented out.
-# RESTORE_CHMASK_AFTER_JOIN = 1
-
-# Select the USART port number which will receive debug messages when the
-# firmware is built in debugging mode. You can select 1 or 2 here.
-DEBUG_PORT ?= 1
+# set to 0.
+RESTORE_CHMASK_AFTER_JOIN ?= 0
 
 # Select the GPIO pin connected to VDD_TCXO (pin 48). The modem will use this
 # pin to control power to the TCXO IC. The TCXO IC generates clock for the
@@ -83,8 +77,62 @@ DEBUG_PORT ?= 1
 #       also the default value. Hardwario LoRa devices use this pin.
 #
 #   2 - PB6 (pin 39). Arduino MKRWAN1310 boards use this pin.
+#
+# Used GPIOs: PA12 (1), PB6 (2)
 TCXO_PIN ?= 1
 
+# Arduino MKRWAN boards share some lines between the TypeABZ module's LPUART
+# interface (the AT command interface) and SPI. On MKRWAN1310 boards, the SPI
+# interface is also used to communicate with the on-board SPI flash. As a
+# consequence, the host cannot access the flash while the TypeABZ AT command
+# interface is active. This is a design flaw of the Arduino MKRWAN1310 board.
+#
+# The Arduino documentation recommends that the host MCU keeps the TypeABZ modem
+# in a reset state while it accesses the on-board flash. Resetting the TypeABZ
+# modem could result in the loss of some internal LoRaWAN state maintained by
+# the modem and is not recommended unless absolutely necessary.
+#
+# When the following option is set to 1, the host can request to detach LPUART
+# GPIO pins with the AT command AT$DETACH. The GPIO PB12 must be set to 1 at
+# that time. While detached, the host can use SPI to communicate with the
+# on-board flash. To reattach LPUART GPIO pins, the host pulls PB12 GPIO down.
+# The modem emits "+EVENT=0,9" to indicate that the LPUART port has been
+# attached and the AT command interface is available again.
+#
+# Used GPIOs: PA2, PA3 (LPUART1), PB12 (attach LPUART1 signal)
+DETACHABLE_LPUART ?= 0
+
+# Select the target for the debugging logger. The target can be one of:
+#   0 - No target, disable the debugging logger
+#   1 - Send debugging messages to USART1
+#   2 - Send debugging messages to USART2
+#   3 - Send debugging messages to Segger RTT
+#
+# By default, the variable is set to 0 in release mode and to 1 in debug mode.
+#
+# Used GPIOs: PA9 (USART1), PA2 (USART2)
+#DEBUG_LOG =
+
+# Enable (1) or disable (0) the SWD debugging interface. This is most useful
+# when the firmware is being built in debugging mode. When set to 0, the SWD
+# interface will be disabled at startup. The interface should be disabled when
+# the firmware is being built in release mode.
+#
+# By default, the variable is set to 0 in release mode and to 1 in debug mode.
+#
+# Used GPIOs: PA13, PA14
+#DEBUG_SWD =
+
+# Enable (1) or disable (0) the MCU debugging interface. Consider enabling the
+# interface when compiling the firmware in debugging mode. You may need to
+# disable other features that use the same ports when you enable the MCU
+# debugging interface.
+#
+# By default, the variable is set to 0 in release mode and to 1 in debug mode.
+#
+# Used GPIOs: PB12, PB13, PB14, PB15
+#DEBUG_MCU =
+
 ################################################################################
 # You shouldn't need to edit the text below under normal circumstances.        #
 ################################################################################
@@ -97,7 +145,7 @@ OUT_DIR ?= out
 
 # The current compilation type (either debug or release). Passed recursively
 # across make invocations.
-TYPE ?= debug
+TYPE ?= release
 
 ELF ?= $(OUT_DIR)/$(TYPE)/$(BASENAME).elf
 MAP ?= $(OUT_DIR)/$(TYPE)/$(BASENAME).map
@@ -110,7 +158,10 @@ HEX ?= $(OUT_DIR)/$(TYPE)/$(BASENAME).hex
 
 # Add all the application files to the list of directories to scan.
 SRC_DIRS = $(SRC_DIR)
-SRC_DIRS_DEBUG = $(SRC_DIR)/debug
+
+ifneq ($(DEBUG_LOG),0)
+SRC_DIRS += $(SRC_DIR)/debug
+endif
 
 # Include only the following selected sources from the STM HAL and everything
 # from stm/src
@@ -134,17 +185,23 @@ stm_hal = \
 	stm32l0xx_hal_uart_ex.c \
 	stm32l0xx_ll_dma.c
 
-stm_hal_debug = \
+ifneq ($(DEBUG_LOG),0)
+stm_hal += \
 	stm32l0xx_ll_usart.c \
 	stm32l0xx_ll_rcc.c
+endif
 
 SRC_FILES += $(patsubst %.c,$(LIB_DIR)/stm/STM32L0xx_HAL_Driver/Src/%.c,$(stm_hal))
-SRC_FILES_DEBUG = $(patsubst %.c,$(LIB_DIR)/stm/STM32L0xx_HAL_Driver/Src/%.c,$(stm_hal_debug))
 
 SRC_DIRS += $(LIB_DIR)/stm/src
 
-# Include all source code from rtt and LoRaWAN lib subdirectories
-SRC_DIRS_DEBUG += $(LIB_DIR)/rtt
+# If we log to Segger RTT, include the source code from the rtt lib
+# subdirectory.
+ifeq ($(DEBUG_LOG),3)
+SRC_DIRS += $(LIB_DIR)/rtt
+endif
+
+# Include all source code from LoRaWAN lib subdirectories
 SRC_DIRS += $(LIB_DIR)/LoRaWAN/Utilities
 
 # Include the core LoRa MAC stack with only the base regional files
@@ -310,8 +367,6 @@ CFLAGS += -DUSE_FULL_LL_DRIVER
 
 CFLAGS += -DDEFAULT_UART_BAUDRATE=$(DEFAULT_UART_BAUDRATE)
 
-CFLAGS += -DTCXO_PIN=$(TCXO_PIN)
-
 # Extra flags to be only applied when we compile the souce files from the lib
 # subdirectory. Since that sub-directory contains third-party code, disable some
 # of the warnings.
@@ -322,7 +377,6 @@ CFLAGS_LIBS += -Wno-int-conversion
 CFLAGS_DEBUG += -g3
 CFLAGS_DEBUG += -Og
 CFLAGS_DEBUG += -DDEBUG
-CFLAGS_DEBUG += -DDEBUG_PORT=$(DEBUG_PORT)
 
 CFLAGS_RELEASE += -Os
 CFLAGS_RELEASE += -DRELEASE
@@ -336,18 +390,18 @@ CFLAGS += -DDEFAULT_ACTIVE_REGION='"$(DEFAULT_ACTIVE_REGION)"'
 CFLAGS += -DREGION_AS923_DEFAULT_CHANNEL_PLAN=$(AS923_DEFAULT_CHANNEL_PLAN)
 CFLAGS += -DREGION_CN470_DEFAULT_CHANNEL_PLAN=$(CN470_DEFAULT_CHANNEL_PLAN)
 
-
-ifdef ENABLE_FACTORY_RESET_PIN
-CFLAGS += -DENABLE_FACTORY_RESET_PIN
-endif
-
 ifneq (,$(LORAMAC_ABP_VERSION))
 CFLAGS += -DLORAMAC_ABP_VERSION=$(LORAMAC_ABP_VERSION)
 endif
 
-ifdef RESTORE_CHMASK_AFTER_JOIN
-CFLAGS += -DRESTORE_CHMASK_AFTER_JOIN
-endif
+CFLAGS += -DFACTORY_RESET_PIN=$(FACTORY_RESET_PIN)
+CFLAGS += -DRESTORE_CHMASK_AFTER_JOIN=$(RESTORE_CHMASK_AFTER_JOIN)
+CFLAGS += -DTCXO_PIN=$(TCXO_PIN)
+CFLAGS += -DDETACHABLE_LPUART=$(DETACHABLE_LPUART)
+
+CFLAGS += -DDEBUG_LOG=$(DEBUG_LOG)
+CFLAGS += -DDEBUG_SWD=$(DEBUG_SWD)
+CFLAGS += -DDEBUG_MCU=$(DEBUG_MCU)
 
 ################################################################################
 # Compiler flags for .s files                                                  #
@@ -386,7 +440,6 @@ LDFLAGS += --specs=nosys.specs
 ################################################################################
 
 SRC_FILES += $(foreach dir,$(SRC_DIRS),$(wildcard $(dir)/*.c))
-SRC_FILES_DEBUG += $(foreach dir,$(SRC_DIRS_DEBUG),$(wildcard $(dir)/*.c))
 
 OBJ_C = $(SRC_FILES:%.c=$(OBJ_DIR)/$(TYPE)/%.o)
 OBJ_S = $(ASM_SOURCES:%.s=$(OBJ_DIR)/$(TYPE)/%.o)
@@ -397,21 +450,26 @@ DEP = $(OBJ:%.o=%.d)
 # Build targets                                                                #
 ################################################################################
 
-.PHONY: debug
-debug: export TYPE=debug
-debug: export CFLAGS=$(CFLAGS_DEBUG)
-debug: export ASFLAGS=$(ASFLAGS_DEBUG)
-debug: export SRC_FILES=$(SRC_FILES_DEBUG)
-debug:
-	$(Q)$(MAKE) install
-
 .PHONY: release
 release: export TYPE=release
+release: export DEBUG_LOG ?= 0
+release: export DEBUG_SWD ?= 0
+release: export DEBUG_MCU ?= 0
 release: export CFLAGS=$(CFLAGS_RELEASE)
 release: export ASFLAGS=$(ASFLAGS_RELEASE)
 release:
 	$(Q)$(MAKE) install
 
+.PHONY: debug
+debug: export TYPE=debug
+debug: export DEBUG_LOG ?= 1
+debug: export DEBUG_SWD ?= 1
+debug: export DEBUG_MCU ?= 1
+debug: export CFLAGS=$(CFLAGS_DEBUG)
+debug: export ASFLAGS=$(ASFLAGS_DEBUG)
+debug:
+	$(Q)$(MAKE) install
+
 .PHONY: install
 install: $(BIN) $(HEX) $(MAKEFILE_LIST)
 	$(Q)$(ECHO) "Copying $(BIN) to ./$(BASENAME).bin..."
diff --git a/src/cmd.c b/src/cmd.c
index 6400326..edb83dd 100644
--- a/src/cmd.c
+++ b/src/cmd.c
@@ -43,7 +43,8 @@ typedef enum cmd_errno {
     ERR_DUTYCYCLE     = -18,  // Cannot transmit due to duty cycling
     ERR_NO_CHANNEL    = -19,  // Channel unavailable due to LBT or error
     ERR_TOO_MANY      = -20,  // Too many link check requests
-    ERR_ACCESS_DENIED = -50   // Read access to security keys is denied
+    ERR_ACCESS_DENIED = -50,  // Read access to security keys is denied
+    ERR_DETACH_DENIED = -51   // The re-attach GPIO is active
 } cmd_errno_t;
 
 
@@ -53,6 +54,14 @@ static TimerEvent_t payload_timer;
 
 bool schedule_reset = false;
 
+#if DETACHABLE_LPUART == 1
+
+static Gpio_t attach_pin = {
+    .port     = GPIOB,
+    .pinIndex = GPIO_PIN_12
+};
+
+#endif
 
 #define abort(num) do {                     \
     atci_printf("+ERR=%d" ATCI_EOL, (num)); \
@@ -1655,7 +1664,7 @@ static void set_netid(atci_param_t *param)
 }
 
 
-#if defined(DEBUG)
+#if DEBUG_LOG != 0
 static void dbg(atci_param_t *param)
 {
     (void)param;
@@ -1977,7 +1986,7 @@ static void set_rfpower(atci_param_t *param)
     OK_();
 }
 
-#if defined(DEBUG)
+#if DEBUG_LOG != 0
 static void get_loglevel(void)
 {
     OK("%d", log_get_level());
@@ -2107,78 +2116,155 @@ static void lock_keys(atci_param_t *param)
 }
 
 
+#if DETACHABLE_LPUART == 1
+
+#if FACTORY_RESET_PIN != 0
+#  error DETACHABLE_LPUART and FACTORY_RESET_PIN cannot be enabled at the same time.
+#endif
+
+#if DEBUG_MCU != 0
+#  error DETACHABLE_LPUART and DEBUG_MCU cannot be enabled at the same time.
+#endif
+
+static void detach_lpuart(atci_param_t *param)
+{
+    (void)param;
+
+    // First check if the LPUART wake-up GPIO pin is low. If it is, the host
+    // indicates that it wants to reattach the port. If that's the case, we
+    // return an error.
+    int v = gpio_read(attach_pin.port, attach_pin.pinIndex);
+    if (v == 0) abort(ERR_DETACH_DENIED);
+
+    // The SPI lines are connected to PB12, PB13, PB14, and PB15. We use PB12 as
+    // the wake-up signal. The remaining pins are configured in analog mode with
+    // no pull-up unless the factory reset pin or the debug MCU features are
+    // enabled. Hence the error reported above if either of those features is
+    // enabled with this feature. We would need to reconfigure those pins in
+    // input mode and will not be able to put them back into the original
+    // configuration when the modem is reattached.
+
+    // Send an OK and wait for the OK to be also transmitted to the remote peer.
+    OK_();
+    atci_flush();
+
+    // Finally, detach the LPUART port from its GPIOs. This operation stops DMA
+    // and reconfigures LPUART GPIOs in analog input mode.
+    lpuart_detach();
+
+    // From this moment on, the modem cannot be woken up with ATCI activity. The
+    // host has to pull lpuart_attach_pin down to wake the modem up and make it
+    // reattach LPUART. Any incoming LoRaWAN downlinks will be buffered until
+    // the ATCI port is attached again.
+}
+
+
+static void attach_isr(void *ctx)
+{
+    (void)ctx;
+    lpuart_attach();
+}
+
+
+void cmd_init_attach_pin(void)
+{
+    // Note: This function is mutually exclusive with init_dbgmcu (PB12 conflict).
+
+    GPIO_InitTypeDef gpio = {
+        .Mode  = GPIO_MODE_IT_FALLING,
+        .Pull  = GPIO_PULLUP,
+        .Speed = GPIO_SPEED_HIGH,
+    };
+
+    if (attach_pin.port == GPIOA)      __GPIOA_CLK_ENABLE();
+    else if (attach_pin.port == GPIOB) __GPIOB_CLK_ENABLE();
+    else if (attach_pin.port == GPIOC) __GPIOC_CLK_ENABLE();
+    else if (attach_pin.port == GPIOD) __GPIOD_CLK_ENABLE();
+    else if (attach_pin.port == GPIOE) __GPIOE_CLK_ENABLE();
+    else if (attach_pin.port == GPIOH) __GPIOH_CLK_ENABLE();
+
+    gpio_init(attach_pin.port, attach_pin.pinIndex, &gpio);
+    gpio_set_irq(attach_pin.port, attach_pin.pinIndex, 0, attach_isr);
+}
+
+#endif
+
+
 static const atci_command_t cmds[] = {
-    {"+UART",        NULL,         set_uart,         get_uart,         NULL, "Configure UART interface"},
-    {"+VER",         NULL,         NULL,             get_version_comp, NULL, "Firmware version and build time"},
-    {"+DEV",         NULL,         NULL,             get_model,        NULL, "Device model"},
-    {"+REBOOT",      reboot,       NULL,             NULL,             NULL, "Reboot the modem"},
-    {"+FACNEW",      facnew,       NULL,             NULL,             NULL, "Restore modem to factory defaults"},
-    {"+BAND",        NULL,         set_band,         get_band,         NULL, "Configure radio band (region)"},
-    {"+CLASS",       NULL,         set_class,        get_class,        NULL, "Configure LoRaWAN class"},
-    {"+MODE",        NULL,         set_mode,         get_mode,         NULL, "Configure activation mode (1:OTTA 0:ABP)"},
-    {"+DEVADDR",     NULL,         set_devaddr,      get_devaddr,      NULL, "Configure DevAddr"},
-    {"+DEVEUI",      NULL,         set_deveui,       get_deveui,       NULL, "Configure DevEUI"},
-    {"+APPEUI",      NULL,         set_joineui,      get_joineui,      NULL, "Configure AppEUI (JoinEUI)"},
-    {"+NWKSKEY",     NULL,         set_nwkskey,      get_nwkskey,      NULL, "Configure NwkSKey (LoRaWAN 1.0)"},
-    {"+APPSKEY",     NULL,         set_appskey,      get_appskey,      NULL, "Configure AppSKey"},
-    {"+APPKEY",      NULL,         set_appkey_10,    get_appkey,       NULL, "Configure AppKey (LoRaWAN 1.0)"},
-    {"+JOIN",        join,         NULL,             NULL,             NULL, "Send OTAA Join packet"},
-    {"+JOINDC",      NULL,         set_joindc,       get_joindc,       NULL, "Configure OTAA Join duty cycling"},
-    {"+LNCHECK",     lncheck,      lncheck,          NULL,             NULL, "Perform link check"},
-    {"+RFPARAM",     NULL,         set_rfparam,      get_rfparam,      NULL, "Configure RF channel parameters"},
-    {"+RFPOWER",     NULL,         set_rfpower_comp, get_rfpower_comp, NULL, "Configure RF power"},
-    {"+NWK",         NULL,         set_nwk,          get_nwk,          NULL, "Configure public/private LoRa network setting"},
-    {"+ADR",         NULL,         set_adr,          get_adr,          NULL, "Configure adaptive data rate (ADR)"},
-    {"+DR",          NULL,         set_dr_comp,      get_dr_comp,      NULL, "Configure data rate (DR)"},
-    {"+DELAY",       NULL,         set_delay,        get_delay,        NULL, "Configure receive window offsets"},
-    {"+ADRACK",      NULL,         set_adrack,       get_adrack,       NULL, "Configure ADR ACK parameters"},
-    {"+RX2",         NULL,         set_rx2_comp,     get_rx2_comp,     NULL, "Configure RX2 window frequency and data rate"},
-    {"+DUTYCYCLE",   NULL,         set_dutycycle,    get_dutycycle,    NULL, "Configure duty cycling in EU868"},
-    {"+SLEEP",       NULL,         set_sleep,        get_sleep,        NULL, "Configure low power (sleep) mode"},
-    {"+PORT",        NULL,         set_port,         get_port,         NULL, "Configure default port number for uplink messages <1,223>"},
-    {"+REP",         NULL,         set_rep,          get_rep,          NULL, "Unconfirmed message repeats [1..15]"},
-    {"+DFORMAT",     NULL,         set_dformat,      get_dformat,      NULL, "Configure payload format used by the modem"},
-    {"+TO",          NULL,         set_to,           get_to,           NULL, "Configure UART port timeout"},
-    {"+UTX",         utx,          NULL,             NULL,             NULL, "Send unconfirmed uplink message"},
-    {"+CTX",         ctx,          NULL,             NULL,             NULL, "Send confirmed uplink message"},
-    {"+MCAST",       NULL,         set_mcast,        get_mcast,        NULL, "Configure multicast addresses and keys"},
-    {"+PUTX",        putx,         NULL,             NULL,             NULL, "Send unconfirmed uplink message to port"},
-    {"+PCTX",        pctx,         NULL,             NULL,             NULL, "Send confirmed uplink message to port"},
-    {"+FRMCNT",      NULL,         NULL,             get_frmcnt,       NULL, "Return current values for uplink and downlink counters"},
-    {"+MSIZE",       NULL,         NULL,             get_msize,        NULL, "Return maximum payload size for current data rate"},
-    {"+RFQ",         NULL,         NULL,             get_rfq,          NULL, "Return RSSI and SNR of the last received message"},
-    {"+DWELL",       NULL,         set_dwell,        get_dwell,        NULL, "Configure dwell setting for AS923"},
-    {"+MAXEIRP",     NULL,         set_maxeirp,      get_maxeirp,      NULL, "Configure maximum EIRP"},
-    {"+RSSITH",      NULL,         set_rssith,       get_rssith,       NULL, "Configure RSSI threshold for LBT"},
-    {"+CST",         NULL,         set_cst,          get_cst,          NULL, "Configure carrier sensor time (CST) for LBT"},
-    {"+BACKOFF",     NULL,         NULL,             get_backoff,      NULL, "Return duty cycle backoff time for EU868"},
-    {"+CHMASK",      NULL,         set_chmask_comp,  get_chmask_comp,  NULL, "Configure channel mask"},
-    {"+RTYNUM",      NULL,         set_rtynum,       get_rtynum,       NULL, "Configure number of confirmed uplink message retries"},
-    {"+NETID",       NULL,         set_netid,        get_netid,        NULL, "Configure LoRaWAN network identifier"},
-    {"$VER",         NULL,         NULL,             get_version,      NULL, "Firmware version and build time"},
-#if defined(DEBUG)
-    {"$DBG",         dbg,          NULL,             NULL,             NULL, ""},
+    {"+UART",        NULL,          set_uart,         get_uart,         NULL, "Configure UART interface"},
+    {"+VER",         NULL,          NULL,             get_version_comp, NULL, "Firmware version and build time"},
+    {"+DEV",         NULL,          NULL,             get_model,        NULL, "Device model"},
+    {"+REBOOT",      reboot,        NULL,             NULL,             NULL, "Reboot the modem"},
+    {"+FACNEW",      facnew,        NULL,             NULL,             NULL, "Restore modem to factory defaults"},
+    {"+BAND",        NULL,          set_band,         get_band,         NULL, "Configure radio band (region)"},
+    {"+CLASS",       NULL,          set_class,        get_class,        NULL, "Configure LoRaWAN class"},
+    {"+MODE",        NULL,          set_mode,         get_mode,         NULL, "Configure activation mode (1:OTTA 0:ABP)"},
+    {"+DEVADDR",     NULL,          set_devaddr,      get_devaddr,      NULL, "Configure DevAddr"},
+    {"+DEVEUI",      NULL,          set_deveui,       get_deveui,       NULL, "Configure DevEUI"},
+    {"+APPEUI",      NULL,          set_joineui,      get_joineui,      NULL, "Configure AppEUI (JoinEUI)"},
+    {"+NWKSKEY",     NULL,          set_nwkskey,      get_nwkskey,      NULL, "Configure NwkSKey (LoRaWAN 1.0)"},
+    {"+APPSKEY",     NULL,          set_appskey,      get_appskey,      NULL, "Configure AppSKey"},
+    {"+APPKEY",      NULL,          set_appkey_10,    get_appkey,       NULL, "Configure AppKey (LoRaWAN 1.0)"},
+    {"+JOIN",        join,          NULL,             NULL,             NULL, "Send OTAA Join packet"},
+    {"+JOINDC",      NULL,          set_joindc,       get_joindc,       NULL, "Configure OTAA Join duty cycling"},
+    {"+LNCHECK",     lncheck,       lncheck,          NULL,             NULL, "Perform link check"},
+    {"+RFPARAM",     NULL,          set_rfparam,      get_rfparam,      NULL, "Configure RF channel parameters"},
+    {"+RFPOWER",     NULL,          set_rfpower_comp, get_rfpower_comp, NULL, "Configure RF power"},
+    {"+NWK",         NULL,          set_nwk,          get_nwk,          NULL, "Configure public/private LoRa network setting"},
+    {"+ADR",         NULL,          set_adr,          get_adr,          NULL, "Configure adaptive data rate (ADR)"},
+    {"+DR",          NULL,          set_dr_comp,      get_dr_comp,      NULL, "Configure data rate (DR)"},
+    {"+DELAY",       NULL,          set_delay,        get_delay,        NULL, "Configure receive window offsets"},
+    {"+ADRACK",      NULL,          set_adrack,       get_adrack,       NULL, "Configure ADR ACK parameters"},
+    {"+RX2",         NULL,          set_rx2_comp,     get_rx2_comp,     NULL, "Configure RX2 window frequency and data rate"},
+    {"+DUTYCYCLE",   NULL,          set_dutycycle,    get_dutycycle,    NULL, "Configure duty cycling in EU868"},
+    {"+SLEEP",       NULL,          set_sleep,        get_sleep,        NULL, "Configure low power (sleep) mode"},
+    {"+PORT",        NULL,          set_port,         get_port,         NULL, "Configure default port number for uplink messages <1,223>"},
+    {"+REP",         NULL,          set_rep,          get_rep,          NULL, "Unconfirmed message repeats [1..15]"},
+    {"+DFORMAT",     NULL,          set_dformat,      get_dformat,      NULL, "Configure payload format used by the modem"},
+    {"+TO",          NULL,          set_to,           get_to,           NULL, "Configure UART port timeout"},
+    {"+UTX",         utx,           NULL,             NULL,             NULL, "Send unconfirmed uplink message"},
+    {"+CTX",         ctx,           NULL,             NULL,             NULL, "Send confirmed uplink message"},
+    {"+MCAST",       NULL,          set_mcast,        get_mcast,        NULL, "Configure multicast addresses and keys"},
+    {"+PUTX",        putx,          NULL,             NULL,             NULL, "Send unconfirmed uplink message to port"},
+    {"+PCTX",        pctx,          NULL,             NULL,             NULL, "Send confirmed uplink message to port"},
+    {"+FRMCNT",      NULL,          NULL,             get_frmcnt,       NULL, "Return current values for uplink and downlink counters"},
+    {"+MSIZE",       NULL,          NULL,             get_msize,        NULL, "Return maximum payload size for current data rate"},
+    {"+RFQ",         NULL,          NULL,             get_rfq,          NULL, "Return RSSI and SNR of the last received message"},
+    {"+DWELL",       NULL,          set_dwell,        get_dwell,        NULL, "Configure dwell setting for AS923"},
+    {"+MAXEIRP",     NULL,          set_maxeirp,      get_maxeirp,      NULL, "Configure maximum EIRP"},
+    {"+RSSITH",      NULL,          set_rssith,       get_rssith,       NULL, "Configure RSSI threshold for LBT"},
+    {"+CST",         NULL,          set_cst,          get_cst,          NULL, "Configure carrier sensor time (CST) for LBT"},
+    {"+BACKOFF",     NULL,          NULL,             get_backoff,      NULL, "Return duty cycle backoff time for EU868"},
+    {"+CHMASK",      NULL,          set_chmask_comp,  get_chmask_comp,  NULL, "Configure channel mask"},
+    {"+RTYNUM",      NULL,          set_rtynum,       get_rtynum,       NULL, "Configure number of confirmed uplink message retries"},
+    {"+NETID",       NULL,          set_netid,        get_netid,        NULL, "Configure LoRaWAN network identifier"},
+    {"$VER",         NULL,          NULL,             get_version,      NULL, "Firmware version and build time"},
+#if DEBUG_LOG != 0
+    {"$DBG",         dbg,           NULL,             NULL,             NULL, ""},
 #endif
-    {"$HALT",        do_halt,      NULL,             NULL,             NULL, "Halt the modem"},
-    {"$JOINEUI",     NULL,         set_joineui,      get_joineui,      NULL, "Configure JoinEUI"},
-    {"$NWKKEY",      NULL,         set_nwkkey,       get_nwkkey,       NULL, "Configure NwkKey (LoRaWAN 1.1)"},
-    {"$APPKEY",      NULL,         set_appkey_11,    get_appkey,       NULL, "Configure AppKey (LoRaWAN 1.1)"},
-    {"$FNWKSINTKEY", NULL,         set_fnwksintkey,  get_fnwksintkey,  NULL, "Configure FNwkSIntKey (LoRaWAN 1.1)"},
-    {"$SNWKSINTKEY", NULL,         set_snwksintkey,  get_snwksintkey,  NULL, "Configure SNwkSIntKey (LoRaWAN 1.1)"},
-    {"$NWKSENCKEY",  NULL,         set_nwksenckey,   get_nwksenckey,   NULL, "Configure NwkSEncKey (LoRaWAN 1.1)"},
-    {"$CHMASK",      NULL,         set_chmask,       get_chmask,       NULL, "Configure channel mask"},
-    {"$RX2",         NULL,         set_rx2,          get_rx2,          NULL, "Configure RX2 window frequency and data rate"},
-    {"$DR",          NULL,         set_dr,           get_dr,           NULL, "Configure data rate (DR)"},
-    {"$RFPOWER",     NULL,         set_rfpower,      get_rfpower,      NULL, "Configure RF power"},
-#if defined(DEBUG)
-    {"$LOGLEVEL",    NULL,         set_loglevel,     get_loglevel,     NULL, "Configure logging on USART port"},
+    {"$HALT",        do_halt,       NULL,             NULL,             NULL, "Halt the modem"},
+    {"$JOINEUI",     NULL,          set_joineui,      get_joineui,      NULL, "Configure JoinEUI"},
+    {"$NWKKEY",      NULL,          set_nwkkey,       get_nwkkey,       NULL, "Configure NwkKey (LoRaWAN 1.1)"},
+    {"$APPKEY",      NULL,          set_appkey_11,    get_appkey,       NULL, "Configure AppKey (LoRaWAN 1.1)"},
+    {"$FNWKSINTKEY", NULL,          set_fnwksintkey,  get_fnwksintkey,  NULL, "Configure FNwkSIntKey (LoRaWAN 1.1)"},
+    {"$SNWKSINTKEY", NULL,          set_snwksintkey,  get_snwksintkey,  NULL, "Configure SNwkSIntKey (LoRaWAN 1.1)"},
+    {"$NWKSENCKEY",  NULL,          set_nwksenckey,   get_nwksenckey,   NULL, "Configure NwkSEncKey (LoRaWAN 1.1)"},
+    {"$CHMASK",      NULL,          set_chmask,       get_chmask,       NULL, "Configure channel mask"},
+    {"$RX2",         NULL,          set_rx2,          get_rx2,          NULL, "Configure RX2 window frequency and data rate"},
+    {"$DR",          NULL,          set_dr,           get_dr,           NULL, "Configure data rate (DR)"},
+    {"$RFPOWER",     NULL,          set_rfpower,      get_rfpower,      NULL, "Configure RF power"},
+#if DEBUG_LOG != 0
+    {"$LOGLEVEL",    NULL,          set_loglevel,     get_loglevel,     NULL, "Configure logging on USART port"},
+#endif
+    {"$CERT",        NULL,          set_cert,         get_cert,         NULL, "Enable or disable LoRaWAN certification port"},
+    {"$SESSION",     NULL,          NULL,             get_session,      NULL, "Get network session information"},
+    {"$CW",          cw,            NULL,             NULL,             NULL, "Start continuous carrier wave transmission"},
+    {"$CM",          cm,            NULL,             NULL,             NULL, "Start continuous modulated FSK transmission"},
+    {"$NVM",         nvm_userdata,  NULL,             NULL,             NULL, "Manage data in NVM user registers"},
+    {"$LOCKKEYS",    lock_keys,     NULL,             NULL,             NULL, "Prevent read access to security keys from ATCI"},
+#if DETACHABLE_LPUART == 1
+    {"$DETACH",      detach_lpuart, NULL,             NULL,             NULL, "Disconnect LPUART (ATCI) GPIOs"},
 #endif
-    {"$CERT",        NULL,         set_cert,         get_cert,         NULL, "Enable or disable LoRaWAN certification port"},
-    {"$SESSION",     NULL,         NULL,             get_session,      NULL, "Get network session information"},
-    {"$CW",          cw,           NULL,             NULL,             NULL, "Start continuous carrier wave transmission"},
-    {"$CM",          cm,           NULL,             NULL,             NULL, "Start continuous modulated FSK transmission"},
-    {"$NVM",         nvm_userdata, NULL,             NULL,             NULL, "Manage data in NVM user registers"},
-    {"$LOCKKEYS",    lock_keys,    NULL,             NULL,             NULL, "Prevent read access to security keys from ATCI"},
     ATCI_COMMAND_CLAC,
     ATCI_COMMAND_HELP};
 
diff --git a/src/cmd.h b/src/cmd.h
index fb0a514..d560861 100644
--- a/src/cmd.h
+++ b/src/cmd.h
@@ -47,6 +47,10 @@ void cmd_event(unsigned int type, unsigned subtype);
 
 void cmd_ans(unsigned int margin, unsigned int gwcnt);
 
+#if DETACHABLE_LPUART == 1
+void cmd_init_attach_pin(void);
+#endif
+
 #define cmd_process atci_process
 #define cmd_print atci_print
 #define cmd_printf atci_printf
diff --git a/src/debug/log.c b/src/debug/log.c
index c11327c..8f0d300 100644
--- a/src/debug/log.c
+++ b/src/debug/log.c
@@ -39,11 +39,9 @@ void _log_init(log_level_t level, log_timestamp_t timestamp)
     _log.initialized = true;
     _log.state = LOG_STATE_SIMPLE_MSG;
 
-#if LOG_TO_USART != 0
+#if DEBUG_LOG != 3
     usart_init();
-#endif
-
-#if LOG_TO_RTT != 0
+#else
     SEGGER_RTT_Init();
 #endif
 }
@@ -63,11 +61,9 @@ void _log_set_level(log_level_t level)
 
 static void _write(const char *buf, size_t len)
 {
-#if LOG_TO_USART != 0
+#if DEBUG_LOG != 3
     usart_write(buf, len);
-#endif
-
-#if LOG_TO_RTT != 0
+#else
     SEGGER_RTT_Write(0, buf, len);
 #endif
 }
@@ -75,7 +71,7 @@ static void _write(const char *buf, size_t len)
 
 static void _write_message(log_level_t level, char id, const char *format, va_list ap)
 {
-#if LOG_TO_USART == 0 && LOG_TO_RTT == 0
+#if DEBUG_LOG == 0
     return;
 #endif
 
@@ -131,7 +127,7 @@ void _log_dump(const void *buffer, size_t length, const char *format, ...)
     uint32_t line_size;
     uint32_t i;
 
-#if LOG_TO_USART == 0 && LOG_TO_RTT == 0
+#if DEBUG_LOG == 0
     return;
 #endif
 
diff --git a/src/debug/log.h b/src/debug/log.h
index 85a37ef..16728cb 100644
--- a/src/debug/log.h
+++ b/src/debug/log.h
@@ -7,14 +7,6 @@
 #define LOG_BUFFER_SIZE 256
 #endif
 
-#ifndef LOG_TO_USART
-#define LOG_TO_USART 1
-#endif
-
-#ifndef LOG_TO_RTT
-#define LOG_TO_RTT 0
-#endif
-
 #define LOG_DUMP_WIDTH 8
 
 //! @brief Log level
@@ -60,7 +52,7 @@ typedef enum
 //! @param[in] level Minimum required message level for propagation
 //! @param[in] timestamp Timestamp logging setting
 
-#if defined(DEBUG)
+#if DEBUG_LOG != 0
 
 void _log_init(log_level_t level, log_timestamp_t timestamp);
 
diff --git a/src/debug/usart.c b/src/debug/usart.c
index c8ed8a8..b372f34 100644
--- a/src/debug/usart.c
+++ b/src/debug/usart.c
@@ -6,25 +6,22 @@
 #include "system.h"
 #include "halt.h"
 
+#if DEBUG_LOG != 3
 
-#if !defined(DEBUG_PORT)
-#  error DEBUG_PORT is not defined
-#endif
-
-#if DEBUG_PORT == 1
+#if DEBUG_LOG == 1
 #  define PORT       USART1
 #  define IRQn       USART1_IRQn
 #  define CLK_ENABLE __USART1_CLK_ENABLE
 #  define PIN        GPIO_PIN_9
 #  define ALTERNATE  GPIO_AF4_USART1
-#elif DEBUG_PORT == 2
+#elif DEBUG_LOG == 2
 #  define PORT       USART2
 #  define IRQn       USART2_IRQn
 #  define CLK_ENABLE __USART2_CLK_ENABLE
 #  define PIN        GPIO_PIN_2
 #  define ALTERNATE  GPIO_AF4_USART2
 #else
-#  error Unsupported DEBUG_PORT value
+#  error Unsupported DEBUG_LOG value
 #endif
 
 
@@ -113,12 +110,12 @@ size_t usart_write(const char *buffer, size_t length)
 }
 
 
-#if DEBUG_PORT == 1
+#if DEBUG_LOG == 1
 void USART1_IRQHandler(void)
-#elif DEBUG_PORT == 2
+#elif DEBUG_LOG == 2
 void USART2_IRQHandler(void)
 #else
-#error Unsupport DEBUG_PORT
+#error Unsupport DEBUG_LOG
 #endif
 {
     uint8_t c;
@@ -136,3 +133,5 @@ void USART2_IRQHandler(void)
         system_stop_lock &= ~SYSTEM_MODULE_USART;
     }
 }
+
+#endif
\ No newline at end of file
diff --git a/src/debug/usart.h b/src/debug/usart.h
index b99204c..dbef7bb 100644
--- a/src/debug/usart.h
+++ b/src/debug/usart.h
@@ -1,5 +1,6 @@
 #ifndef __USART_H__
 #define __USART_H__
+#if DEBUG_LOG != 3
 
 #include <stddef.h>
 
@@ -14,4 +15,5 @@ void usart_init(void);
 
 size_t usart_write(const char *buffer, size_t length);
 
+#endif
 #endif /* __USART_H__ */
diff --git a/src/halt.c b/src/halt.c
index 8144389..c83d98e 100644
--- a/src/halt.c
+++ b/src/halt.c
@@ -9,7 +9,7 @@
 
 __attribute__((noreturn)) void halt(const char *msg)
 {
-#if defined(DEBUG)
+#if DEBUG_LOG != 0
     const char prefix[] = "Halted";
 #endif
     cmd_event(CMD_EVENT_MODULE, CMD_MODULE_HALT);
diff --git a/src/lpuart.c b/src/lpuart.c
index 8ceb335..7ad5e55 100644
--- a/src/lpuart.c
+++ b/src/lpuart.c
@@ -8,7 +8,7 @@
 #include "log.h"
 #include "irq.h"
 #include "system.h"
-
+#include "cmd.h"
 
 #ifndef LPUART_BUFFER_SIZE
 #define LPUART_BUFFER_SIZE 512
@@ -31,6 +31,13 @@ static unsigned char rx_buffer[LPUART_BUFFER_SIZE];
 volatile cbuf_t lpuart_rx_fifo;
 
 
+#if DETACHABLE_LPUART == 1
+
+static bool volatile attached;
+
+#endif // DETACHABLE_LPUART
+
+
 // This function is invoked from the IRQ handler context
 static void enqueue(unsigned char *data, size_t len)
 {
@@ -64,6 +71,9 @@ void lpuart_init(unsigned int baudrate)
     cbuf_init(&lpuart_tx_fifo, tx_buffer, sizeof(tx_buffer));
     cbuf_init(&lpuart_rx_fifo, rx_buffer, sizeof(rx_buffer));
     tx_idle = 1;
+#if DETACHABLE_LPUART == 1
+    attached = true;
+#endif
 
     uint32_t masked = disable_irq();
 
@@ -133,6 +143,7 @@ static void init_gpio(void)
 {
     GPIO_InitTypeDef gpio = {
         .Mode = GPIO_MODE_AF_PP,
+        .Alternate = GPIO_AF6_LPUART1,
         .Speed = GPIO_SPEED_HIGH
     };
 
@@ -140,12 +151,10 @@ static void init_gpio(void)
     __HAL_RCC_GPIOA_CLK_ENABLE();
 
     gpio.Pin = GPIO_PIN_2;
-    gpio.Alternate = GPIO_AF6_LPUART1;
     gpio.Pull = GPIO_NOPULL;
     HAL_GPIO_Init(GPIOA, &gpio);
 
     gpio.Pin = GPIO_PIN_3;
-    gpio.Alternate = GPIO_AF6_LPUART1;
     gpio.Pull = GPIO_PULLUP;
     HAL_GPIO_Init(GPIOA, &gpio);
 }
@@ -158,6 +167,7 @@ static void deinit_gpio(void)
         .Pull = GPIO_NOPULL
     };
 
+    __HAL_RCC_GPIOA_CLK_ENABLE();
     __HAL_RCC_GPIOA_CLK_ENABLE();
 
     gpio.Pin = GPIO_PIN_2;
@@ -255,6 +265,31 @@ void HAL_UART_MspDeInit(UART_HandleTypeDef *port)
 }
 
 
+static void flush_tx_fifo(void)
+{
+    cbuf_view_t v;
+
+    if (lpuart_tx_fifo.length > 0) {
+        // We need to reacreate the sleep lock here even when tx_idle is false
+        // in case this function is invoked after reattaching the port.
+        system_stop_lock |= SYSTEM_MODULE_LPUART_TX;
+
+        if (tx_idle) {
+            tx_idle = 0;
+
+            cbuf_head(&lpuart_tx_fifo, &v);
+            if (v.len[0]) {
+                HAL_UART_Transmit_DMA(&port, (unsigned char *)v.ptr[0], v.len[0]);
+                tx_len = v.len[0];
+            } else {
+                HAL_UART_Transmit_DMA(&port, (unsigned char *)v.ptr[1], v.len[1]);
+                tx_len = v.len[1];
+            }
+        }
+    }
+}
+
+
 size_t lpuart_write(const char *buffer, size_t length)
 {
     uint32_t masked = disable_irq();
@@ -268,20 +303,10 @@ size_t lpuart_write(const char *buffer, size_t length)
     masked = disable_irq();
     cbuf_produce(&lpuart_tx_fifo, written);
 
-    if (tx_idle && lpuart_tx_fifo.length > 0) {
-        tx_idle = 0;
-        system_stop_lock |= SYSTEM_MODULE_LPUART_TX;
-
-        cbuf_head(&lpuart_tx_fifo, &v);
-        if (v.len[0]) {
-            HAL_UART_Transmit_DMA(&port, (unsigned char *)v.ptr[0], v.len[0]);
-            tx_len = v.len[0];
-        } else {
-            HAL_UART_Transmit_DMA(&port, (unsigned char *)v.ptr[1], v.len[1]);
-            tx_len = v.len[1];
-        }
-    }
-
+#if DETACHABLE_LPUART == 1
+    if (attached)
+#endif
+        flush_tx_fifo();
     reenable_irq(masked);
     return written;
 }
@@ -302,7 +327,7 @@ void lpuart_write_blocking(const char *buffer, size_t length)
                 // If the TX FIFO is at full capacity, we invoke system_idle to
                 // put the MCU to sleep until there is some space in the output
                 // FIFO which will be signalled by the ISR when the DMA transfer
-                // finishes. Since transmission happens via DMA, system_idle
+                // finishes. Since the transmission happens via DMA, system_idle
                 // used below must not enter the Stop mode. That is, however,
                 // guaranteed, since the function luart_write above creates a
                 // stop mode wake lock which will still be in place when the
@@ -320,21 +345,31 @@ void HAL_UART_TxCpltCallback(UART_HandleTypeDef *port)
 {
     cbuf_view_t v;
 
-    if (tx_len) cbuf_consume(&lpuart_tx_fifo, tx_len);
+    if (tx_len) {
+        cbuf_consume(&lpuart_tx_fifo, tx_len);
+        tx_len = 0;
+    }
 
-    if (lpuart_tx_fifo.length) {
-        cbuf_head(&lpuart_tx_fifo, &v);
-        if (v.len[0]) {
-            HAL_UART_Transmit_DMA(port, (unsigned char *)v.ptr[0], v.len[0]);
-            tx_len = v.len[0];
-        } else {
-            HAL_UART_Transmit_DMA(port, (unsigned char *)v.ptr[1], v.len[1]);
-            tx_len = v.len[1];
-        }
-    } else {
+    if (!lpuart_tx_fifo.length) {
         system_stop_lock &= ~SYSTEM_MODULE_LPUART_TX;
-        tx_len = 0;
         tx_idle = 1;
+        return;
+    }
+
+#if DETACHABLE_LPUART == 1
+    if (!attached) {
+        system_stop_lock &= ~SYSTEM_MODULE_LPUART_TX;
+        return;
+    }
+#endif
+
+    cbuf_head(&lpuart_tx_fifo, &v);
+    if (v.len[0]) {
+        HAL_UART_Transmit_DMA(port, (unsigned char *)v.ptr[0], v.len[0]);
+        tx_len = v.len[0];
+    } else {
+        HAL_UART_Transmit_DMA(port, (unsigned char *)v.ptr[1], v.len[1]);
+        tx_len = v.len[1];
     }
 }
 
@@ -402,22 +437,73 @@ void DMA1_Channel4_5_6_7_IRQHandler(void)
 }
 
 
+static void pause_rx_dma(void)
+{
+    if ((HAL_IS_BIT_SET(port.Instance->CR3, USART_CR3_DMAR)) &&
+        (port.RxState == HAL_UART_STATE_BUSY_RX)) {
+        CLEAR_BIT(port.Instance->CR3, USART_CR3_DMAR);
+    }
+}
+
+
+static void pause_tx_dma(void)
+{
+    if ((HAL_IS_BIT_SET(port.Instance->CR3, USART_CR3_DMAT)) &&
+        (port.gState == HAL_UART_STATE_BUSY_TX)) {
+        CLEAR_BIT(port.Instance->CR3, USART_CR3_DMAT);
+    }
+}
+
+
+static void pause_dma(void)
+{
+    pause_rx_dma();
+    pause_tx_dma();
+}
+
+
 void lpuart_before_stop(void)
 {
+    pause_dma();
     HAL_UART_DMAPause(&port);
     LL_LPUART_EnableIT_WKUP(port.Instance);
 }
 
 
+static void resume_tx_dma(void)
+{
+    if (port.gState == HAL_UART_STATE_BUSY_TX) {
+        SET_BIT(port.Instance->CR3, USART_CR3_DMAT);
+    }
+}
+
+
+static void resume_rx_dma(void)
+{
+    if (port.RxState == HAL_UART_STATE_BUSY_RX) {
+        /* Clear the Overrun flag before resuming the Rx transfer */
+        __HAL_UART_CLEAR_FLAG(&port, UART_CLEAR_OREF);
+
+        /* Enable the UART DMA Rx request */
+        SET_BIT(port.Instance->CR3, USART_CR3_DMAR);
+    }
+}
+
+
 void lpuart_after_stop(void)
 {
     LL_LPUART_DisableIT_WKUP(port.Instance);
-    HAL_UART_DMAResume(&port);
 
-    // Resuming DMA re-enables the LPUART1 error interrupt, so we need to
-    // disable it here again. We ignore all errors on LPUART1 and let upper
-    // layers (ATCI) deal with it.
-    LL_LPUART_DisableIT_ERROR(port.Instance);
+    // We cannot use HAL_UART_DMAResume provided by the STM HAL here. That
+    // function resumes both RX and TX DMA transfers and additionally re-enables
+    // error interrupts. We need to resume the TX DMA here if and only if the
+    // port is attached. Resuming a TX DMA while the port is detached from GPIO
+    // would result in lost data.
+    resume_rx_dma();
+#if DETACHABLE_LPUART == 1
+    if (attached)
+#endif
+        resume_tx_dma();
 }
 
 
@@ -458,4 +544,31 @@ void HAL_UART_ErrorCallback(UART_HandleTypeDef *port)
 {
     (void)port;
     log_error("LPUART1 error: %ld", port->ErrorCode);
-}
\ No newline at end of file
+}
+
+
+#if DETACHABLE_LPUART == 1
+
+void lpuart_detach(void)
+{
+    if (!attached) return;
+    pause_tx_dma();
+    deinit_gpio();
+    attached = false;
+}
+
+
+void lpuart_attach(void)
+{
+
+    if (attached) return;
+    init_gpio();
+    resume_tx_dma();
+
+    uint32_t masked = disable_irq();
+    flush_tx_fifo();
+    reenable_irq(masked);
+    attached = true;
+}
+
+#endif // DETACHABLE_LPUART
diff --git a/src/lpuart.h b/src/lpuart.h
index 53c89ea..b1a5f33 100644
--- a/src/lpuart.h
+++ b/src/lpuart.h
@@ -2,13 +2,42 @@
 #define __LPUART_H__
 
 #include <stddef.h>
+#include <stdbool.h>
 #include "cbuf.h"
+#include "gpio.h"
 
 
 extern volatile cbuf_t lpuart_tx_fifo;
 extern volatile cbuf_t lpuart_rx_fifo;
 
+#if DETACHABLE_LPUART == 1
 
+/*! @brief Detach from the ATCI LPUART port
+ *
+ * Detach (disconnect) from the LPUART port used by the AT command interface.
+ * Detaching pauses active DMA transfer (if any) and reconfigures the GPIO ports
+ * used by the LPUART port in analog mode.
+ *
+ * This function is intended for use on boards that share the LPUART lines with
+ * some other peripheral. This is the case, e.g., on MKRWAN boards. Forcing the
+ * modem to detach allows the host to temporarily use the lines to communicate
+ * with the other peripheral.
+ */
+void lpuart_detach(void);
+
+/*! @brief Attach the ATCI LPUART port
+ *
+ * Attach to the LPUART port used by the AT command interface. Calling this
+ * function reconfigures the GPIO ports used by LPUART1 and if there is an
+ * active DMA transfer, it is resumed.
+ *
+ * This function is intended to restore ATCI functionality after the modem has
+ * detached from LPUART1 (used by the ATCI). The function should be invoked
+ * after an interrupt on a preconfigured GPIO pin or timeout.
+ */
+void lpuart_attach(void);
+
+#endif
 
 /*! @brief Initialize LPUART1
  *
@@ -96,5 +125,4 @@ void lpuart_before_stop(void);
  */
 void lpuart_after_stop(void);
 
-
 #endif /* __LPUART_H__ */
diff --git a/src/lrw.c b/src/lrw.c
index 4a279cb..b3256bb 100644
--- a/src/lrw.c
+++ b/src/lrw.c
@@ -59,7 +59,7 @@ static struct {
 };
 
 
-#ifdef RESTORE_CHMASK_AFTER_JOIN
+#if RESTORE_CHMASK_AFTER_JOIN == 1
 static uint16_t saved_chmask[REGION_NVM_CHANNELS_MASK_SIZE];
 #endif
 
@@ -73,7 +73,7 @@ static int region2id(const char *name)
     return -2;
 }
 
-#if defined(DEBUG)
+#if DEBUG_LOG != 0
 static const char *region2str(int id)
 {
     for (unsigned int i = 0; i < sizeof(region_map) / sizeof(region_map[0]); i++)
@@ -396,7 +396,7 @@ static int set_abp_mac_version(void)
 #endif
 
 
-#ifdef RESTORE_CHMASK_AFTER_JOIN
+#if RESTORE_CHMASK_AFTER_JOIN == 1
 static void save_chmask(void)
 {
     MibRequestConfirm_t r = { .Type = MIB_CHANNELS_DEFAULT_MASK };
@@ -466,7 +466,7 @@ static void stop_join(unsigned int status)
     // sysconf.device_class here.
     sync_device_class();
 
-#ifdef RESTORE_CHMASK_AFTER_JOIN
+#if  RESTORE_CHMASK_AFTER_JOIN == 1
     MibRequestConfirm_t r = { .Type = MIB_NETWORK_ACTIVATION };
     LoRaMacMibGetRequestConfirm(&r);
 
@@ -929,7 +929,7 @@ int lrw_join(uint8_t datarate, uint8_t tries)
 
         join_datarate = datarate;
 
-#ifdef RESTORE_CHMASK_AFTER_JOIN
+#if RESTORE_CHMASK_AFTER_JOIN == 1
         save_chmask();
 #endif
         LoRaMacStatus_t rc = send_join();
diff --git a/src/radio.c b/src/radio.c
index 844707c..102d8d4 100644
--- a/src/radio.c
+++ b/src/radio.c
@@ -10,7 +10,7 @@ int8_t radio_snr;
 // The original callback (the one from LoRaMac-node) is kept here.
 static void (*OrigRxDone)(uint8_t *payload, uint16_t size, int16_t rssi, int8_t snr);
 
-#if defined (DEBUG)
+#if DEBUG_LOG != 0
 
 static const char *modem2str(RadioModems_t modem)
 {
@@ -81,7 +81,7 @@ static void SetTxConfig(RadioModems_t modem, int8_t power, uint32_t fdev,
     uint16_t preambleLen, bool fixLen, bool crcOn, bool freqHopOn,
     uint8_t hopPeriod, bool iqInverted, uint32_t timeout)
 {
-#if defined (DEBUG)
+#if DEBUG_LOG != 0
     log_compose();
     log_debug("SX1276SetTxConfig: %d dBm", power);
     log_debug(" %s", modem2str(modem));
@@ -116,7 +116,7 @@ static void SetRxConfig(RadioModems_t modem, uint32_t bandwidth, uint32_t datara
     uint16_t symbTimeout, bool fixLen, uint8_t payloadLen, bool crcOn,
     bool freqHopOn, uint8_t hopPeriod, bool iqInverted, bool rxContinuous)
 {
-#if defined (DEBUG)
+#if DEBUG_LOG != 0
     log_compose();
     log_debug("SX1276SetRxConfig: %s", modem2str(modem));
 
diff --git a/src/system.c b/src/system.c
index 8d3aa73..9798397 100644
--- a/src/system.c
+++ b/src/system.c
@@ -8,6 +8,7 @@
 #include "gpio.h"
 #include "nvm.h"
 #include "lrw.h"
+#include "cmd.h"
 
 
 // Unique Devices IDs register set ( STM32L0xxx )
@@ -158,21 +159,23 @@ static void init_gpio(void)
 }
 
 
-#if defined(DEBUG)
+#if DEBUG_MCU == 1
+
 static void init_dbgmcu(void)
 {
-    // Note: This function is mutually-exclusive with init_facnew_gpio (they
-    // share the same GPIO pin).
+    // Note: This function is mutually exclusive with the factory reset pin
+    // feature (conflict on PB15) and with the detachable LPUART1 feature
+    // (conflict on PB12).
 
     // Enable the GPIO B clock
     __GPIOB_CLK_ENABLE();
 
     // Configure debugging GPIO pins
     GPIO_InitTypeDef gpio = {
-        .Mode = GPIO_MODE_OUTPUT_PP,
-        .Pull = GPIO_PULLUP,
+        .Mode  = GPIO_MODE_OUTPUT_PP,
+        .Pull  = GPIO_PULLUP,
         .Speed = GPIO_SPEED_HIGH,
-        .Pin = GPIO_PIN_12 | GPIO_PIN_13 | GPIO_PIN_14 | GPIO_PIN_15
+        .Pin   = GPIO_PIN_12 | GPIO_PIN_13 | GPIO_PIN_14 | GPIO_PIN_15
     };
     HAL_GPIO_Init(GPIOB, &gpio);
 
@@ -187,16 +190,14 @@ static void init_dbgmcu(void)
     HAL_DBGMCU_EnableDBGStopMode();
     HAL_DBGMCU_EnableDBGStandbyMode();
 }
-#endif
 
+#endif // DEBUG_MCU
+
+
+#if DEBUG_SWD == 0
 
-#if defined(RELEASE)
 static void disable_swd(void)
 {
-    // init_gpio called before this function does not touch GPIO A 13 & 14 (SWD)
-    // to keep the SWD port operational. In release mode, we re-configure the
-    // two pins in analog mode to minimize power consumption.
-
     GPIO_InitTypeDef gpio = {
         .Mode = GPIO_MODE_ANALOG,
         .Pull = GPIO_NOPULL,
@@ -214,8 +215,10 @@ static void disable_swd(void)
     __DBGMCU_CLK_DISABLE();
 }
 
+#endif // DEBUG_SWD
+
+#if FACTORY_RESET_PIN == 1
 
-#if defined(ENABLE_FACTORY_RESET_PIN)
 static Gpio_t facnew_pin = {
     .port     = GPIOB,
     .pinIndex = GPIO_PIN_15
@@ -249,10 +252,9 @@ static void facnew_isr(void *ctx)
 
 static void init_facnew_gpio(void)
 {
-    // Note: This function is mutually-exclusive with init_dbgmcu (they share
-    // the same GPIO pin).
+    // Note: This function is mutually exclusive with init_dbgmcu (PB15 conflict).
 
-    __GPIOA_CLK_ENABLE();
+    __GPIOB_CLK_ENABLE();
     GPIO_InitTypeDef gpio = {
         .Mode  = GPIO_MODE_IT_RISING_FALLING,
         .Pull  = GPIO_PULLUP,
@@ -261,8 +263,8 @@ static void init_facnew_gpio(void)
     gpio_init(facnew_pin.port, facnew_pin.pinIndex, &gpio);
     gpio_set_irq(facnew_pin.port, facnew_pin.pinIndex, 0, facnew_isr);
 }
-#endif // ENABLE_FACTORY_RESET_PIN
-#endif // RELEASE
+
+#endif // FACTORY_RESET_PIN
 
 
 static void init_clock(void)
@@ -325,13 +327,19 @@ void system_init(void)
     HAL_Init();
     init_flash();
     init_gpio();
-#if defined(RELEASE)
+#if DEBUG_SWD == 0
+    // init_gpio does not touch PA13 & PA14 (SWD) to keep the SWD port
+    // operational. If the SWD feature is disabled (e.g., in release mode),
+    // reconfigure the pins in analog mode to minimize power consumption.
     disable_swd();
-#if defined(ENABLE_FACTORY_RESET_PIN)
+#endif
+#if FACTORY_RESET_PIN == 1
     init_facnew_gpio();
 #endif
+#if DETACHABLE_LPUART == 1
+    cmd_init_attach_pin();
 #endif
-#if defined(DEBUG)
+#if DEBUG_MCU == 1
     init_dbgmcu();
 #endif
     init_clock();
diff --git a/tools/release.sh b/tools/release.sh
index 5aaef43..82b7535 100755
--- a/tools/release.sh
+++ b/tools/release.sh
@@ -113,10 +113,11 @@ $tar --exclude .editorconfig   \
 echo "done."
 
 # Build both release and debug versions of the firmware binary. This is the
-# default build variant that uses PA12 (as recommended in the datasheet) to
-# control TCXO_VDD. Debug builds have a debugging logger on USART1.
-make TCXO_PIN=1 release
-make TCXO_PIN=1 DEBUG_PORT=1 debug
+# default build variant for the Hardwario LoRa modem that uses PA12 (as
+# recommended in the datasheet) to control TCXO_VDD, has the factory reset
+# pin disabled, and does not support LPUART1 detaching.
+make FACTORY_RESET_PIN=0 TCXO_PIN=1 DETACHABLE_LPUART=0 release
+make FACTORY_RESET_PIN=0 TCXO_PIN=1 DETACHABLE_LPUART=0 debug
 
 # And copy the resulting binary files into the firmware release directory.
 cp -f out/release/firmware.bin "$firmware_dir/$name.bin"
@@ -126,10 +127,12 @@ cp -f out/debug/firmware.hex   "$firmware_dir/$name.debug.hex"
 cp -f out/debug/firmware.map   "$firmware_dir/$name.debug.map"
 
 # Now build the variants for Arduino MKRWAN boards. These build variants use PB6
-# to control TCXO power. Debug builds start the debugging logger on USART2.
+# to control TCXO power. We also enable support for detaching the ATCI UART port
+# so that the host MCU can access the on-board SPI flash. Debug builds start the
+# debugging logger on USART2.
 make clean
-make TCXO_PIN=2 release
-make TCXO_PIN=2 DEBUG_PORT=2 debug
+make FACTORY_RESET_PIN=0 TCXO_PIN=2 DETACHABLE_LPUART=1 release
+make FACTORY_RESET_PIN=0 TCXO_PIN=2 DETACHABLE_LPUART=1 DEBUG_LOG=2 DEBUG_MCU=0 debug
 
 # And copy the resulting binary files to the firmware release directory.
 cp -f out/release/firmware.bin "$firmware_dir/$name.mkrwan.bin"