diff --git a/examples/natmod/esp-counter/Makefile b/examples/natmod/esp-counter/Makefile
new file mode 100644
index 0000000000000..19cf46b919316
--- /dev/null
+++ b/examples/natmod/esp-counter/Makefile
@@ -0,0 +1,35 @@
+# Location of top-level MicroPython directory
+MPY_DIR = ../../..
+
+# Espressif ESP-IDF path
+IDF_PATH := /home/src/esp32/esp-idf-micropython
+# Board to get correct ESP-IDF config
+BOARD := GENERIC
+# xtensa toolchain bin dir
+PATH := $(IDF_PATH)/xtensa-esp32-elf/bin:$(PATH)
+
+# Name of module
+MOD = espidf
+
+# Source files (.c or .py)
+SRC = modespidf.c
+
+# Architecture to build for (x86, x64, armv7m, xtensa, xtensawin)
+ARCH = xtensawin
+
+# Include to get the rules for compiling and linking the module
+include dyn_esp32.mk
+include $(MPY_DIR)/py/dynruntime.mk
+CFLAGS += -std=gnu99 # override -std=c99 in dynruntime.mk
+CFLAGS += -DMPY_DYN_MODULE=1
+
+modespidf.c: $(MPY_DIR)/ports/esp32/plat_relo.py build/sdkconfig.h
+	$(ECHO) "GEN $@"
+	$(Q)mkdir -p build
+	$(Q)$< --module >$@
+
+build/sdkconfig.h: $(BOARD_BUILD)/sdkconfig.h build
+	$(Q)cp $< $@
+
+build:
+	$(Q)mkdir -p $@
diff --git a/examples/natmod/esp-counter/counter.py b/examples/natmod/esp-counter/counter.py
new file mode 100644
index 0000000000000..02278feeb656f
--- /dev/null
+++ b/examples/natmod/esp-counter/counter.py
@@ -0,0 +1,101 @@
+import struct, espidf
+
+# Directions (PCNT_COUNT_* in components/driver/include/driver/pcnt.h)
+UP=1
+DOWN=2
+
+# Edges
+RISING=1
+FALLING=2
+
+# Private constants
+_COUNT_DIS = 0
+_COUNT_INC = 1
+_COUNT_DEC = 2
+_MODE_KEEP = 0
+_MODE_REVERSE = 1
+_MODE_DISABLE = 2
+
+def _err_raise(err):
+    if err == 0: return
+    raise ValueError(espidf.esp_err_to_name(err))
+
+class Counter:
+    def __init__(self, unit, pin, direction=UP, edge=RISING, limit=0, reset=True):
+        # check unit number
+        if unit < 0 or unit >= 8:
+            raise ValueError("unit must be in range 0..7")
+        self.unit = unit
+        # init obj
+        self.pin = pin
+        # init unit
+        self.init(direction, edge, limit, reset)
+
+    def init(self, direction=UP, edge=RISING, limit=0, reset=True):
+        # init config elements
+        channel = 0
+        pulse_gpio_num = self.pin
+        ctrl_gpio_num = -1 # not yet supported
+        counter_h_lim = 0
+        counter_l_lim = 0
+        pos_mode = _COUNT_DIS
+        neg_mode = _COUNT_DIS
+        lctrl_mode = _MODE_KEEP
+        hctrl_mode = _MODE_KEEP
+        #
+        self.dir_up = direction == UP
+        self.edges = edge
+        if self.dir_up: mode = _COUNT_INC
+        else:           mode = _COUNT_DEC
+        # tweak config according to parameters
+        if edge & RISING: pos_mode = mode
+        if edge & FALLING: neg_mode = mode
+        self.limit = limit
+        if self.limit == 0: limit = 0x7ffff
+        if self.dir_up:
+            counter_h_lim = self.limit
+        else:
+            counter_l_lim = -self.limit
+        # convert pcnt_config to C struct
+        print('IIIIIIhhII', pulse_gpio_num, ctrl_gpio_num,
+                lctrl_mode, hctrl_mode, pos_mode, neg_mode, counter_h_lim, counter_l_lim,
+                self.unit, channel)
+        pcnt_config_struct = bytearray(struct.calcsize('IIIIIIhhII'))
+        struct.pack_into('IIIIIIhhII', pcnt_config_struct, 0,
+                pulse_gpio_num, ctrl_gpio_num, lctrl_mode, hctrl_mode, pos_mode, neg_mode,
+                counter_h_lim, counter_l_lim, self.unit, channel)
+        _err_raise(espidf.pcnt_unit_config(pcnt_config_struct))
+        _err_raise(espidf.pcnt_counter_resume(self.unit)) # apparently it starts paused...
+        if reset:
+            _err_raise(espidf.pcnt_counter_clear(self.unit))
+
+    def __del__(self):
+        _err_raise(espidf.pcnt_counter_pause(self.unit))
+        _err_raise(espidf.pcnt_intr_disable(self.unit))
+        _err_raise(espidf.pcnt_set_pin(self.unit, self.channel, -1, -1))
+        self.unit = -1
+        self.pin = -1
+
+    def resume(self):
+        _err_raise(espidf.pcnt_unit_resume(self.unit))
+
+    def pause(self):
+        _err_raise(espidf.pcnt_unit_pause(self.unit))
+
+    def value(self, new_value=None):
+        if new_value == None:
+            # GET value
+            v_raw = bytearray(2)
+            _err_raise(espidf.pcnt_get_counter_value(self.unit, v_raw))
+            v = struct.unpack('h', v_raw)
+            if not self.dir_up:
+                v[0] += self.limit # adjust to limit..0 interval
+            return v[0]
+        else:
+            # SET value
+            if self.dir_up and new_value != 0:
+                raise ValueError("only v=0 supported")
+            if not self.dir_up and new_value != self.limit:
+                raise ValueError("only v=limit supported")
+            _err_raise(espidf.pcnt_counter_clear(self.unit))
+            return None
diff --git a/examples/natmod/esp-counter/dyn_esp32.mk b/examples/natmod/esp-counter/dyn_esp32.mk
new file mode 100644
index 0000000000000..14c4dfca2e43d
--- /dev/null
+++ b/examples/natmod/esp-counter/dyn_esp32.mk
@@ -0,0 +1,239 @@
+# Select the board to build for: if not given on the command line,
+# then default to GENERIC.
+BOARD ?= GENERIC
+
+PORT_DIR := $(MPY_DIR)/ports/esp32
+
+# If the build directory is not given, make it reflect the board name.
+BUILD ?= build
+
+BOARD_DIR ?= $(PORT_DIR)/boards/$(BOARD)
+BOARD_BUILD ?= $(PORT_DIR)/build-$(BOARD)
+#ifeq ($(wildcard $(BOARD_DIR)/.),)
+#$(error Invalid BOARD specified: $(BOARD_DIR))
+#endif
+#
+#include ../../py/mkenv.mk
+#
+## Optional (not currently used for ESP32)
+#-include mpconfigport.mk
+#
+#ifneq ($(SDKCONFIG),)
+#$(error Use the BOARD variable instead of SDKCONFIG)
+#endif
+
+# Expected to set SDKCONFIG
+include $(BOARD_DIR)/mpconfigboard.mk
+SDKCONFIG := $(addprefix $(PORT_DIR)/,$(SDKCONFIG))
+
+## qstr definitions (must come before including py.mk)
+#QSTR_DEFS = qstrdefsport.h
+#QSTR_GLOBAL_DEPENDENCIES = $(BOARD_DIR)/mpconfigboard.h
+#QSTR_GLOBAL_REQUIREMENTS = $(SDKCONFIG_H)
+
+#MICROPY_PY_USSL = 0
+#MICROPY_SSL_AXTLS = 0
+#MICROPY_PY_BTREE = 1
+#MICROPY_VFS_FAT = 1
+#MICROPY_VFS_LFS2 = 1
+
+#FROZEN_MANIFEST ?= boards/manifest.py
+
+## include py core make definitions
+#include $(TOP)/py/py.mk
+
+#GIT_SUBMODULES = lib/berkeley-db-1.xx
+
+#PORT ?= /dev/ttyUSB0
+#BAUD ?= 460800
+#FLASH_MODE ?= dio
+#FLASH_FREQ ?= 40m
+#FLASH_SIZE ?= 4MB
+#CROSS_COMPILE ?= xtensa-esp32-elf-
+#OBJDUMP = $(CROSS_COMPILE)objdump
+
+#SDKCONFIG_COMBINED = $(BUILD)/sdkconfig.combined
+#SDKCONFIG_H = $(BOARD_BUILD)/sdkconfig.h
+
+# the git hash of the currently supported ESP IDF version
+ESPIDF_SUPHASH_V3 := 6ccb4cf5b7d1fdddb8c2492f9cbc926abaf230df
+ESPIDF_SUPHASH_V4 := 463a9d8b7f9af8205222b80707f9bdbba7c530e1
+
+define print_supported_git_hash
+$(info Supported git hash (v3.3): $(ESPIDF_SUPHASH_V3))
+$(info Supported git hash (v4.0) (experimental): $(ESPIDF_SUPHASH_V4))
+endef
+
+# paths to ESP IDF and its components
+ifeq ($(ESPIDF),)
+ifneq ($(IDF_PATH),)
+ESPIDF = $(IDF_PATH)
+else
+$(info The ESPIDF variable has not been set, please set it to the root of the esp-idf repository.)
+$(info See README.md for installation instructions.)
+$(call print_supported_git_hash)
+$(error ESPIDF not set)
+endif
+endif
+
+ESPCOMP = $(ESPIDF)/components
+#ESPTOOL ?= $(ESPCOMP)/esptool_py/esptool/esptool.py
+ESPCOMP_KCONFIGS = $(shell find $(ESPCOMP) -name Kconfig)
+ESPCOMP_KCONFIGS_PROJBUILD = $(shell find $(ESPCOMP) -name Kconfig.projbuild)
+
+# verify the ESP IDF version
+ESPIDF_CURHASH := $(shell git -C $(ESPIDF) show -s --pretty=format:'%H')
+
+ifeq ($(ESPIDF_CURHASH),$(ESPIDF_SUPHASH_V3))
+$(info Building with ESP IDF v3)
+else ifeq ($(ESPIDF_CURHASH),$(ESPIDF_SUPHASH_V4))
+$(info Building with ESP IDF v4)
+
+PYPARSING_VERSION = $(shell python3 -c 'import pyparsing; print(pyparsing.__version__)')
+ifneq ($(PYPARSING_VERSION),2.3.1)
+$(info ** ERROR **)
+$(info EDP IDF requires pyparsing version less than 2.4)
+$(info You will need to set up a Python virtual environment with pyparsing 2.3.1)
+$(info Please see README.md for more information)
+$(error Incorrect pyparsing version)
+endif
+else
+$(info ** WARNING **)
+$(info The git hash of ESP IDF does not match the supported version)
+$(info The build may complete and the firmware may work but it is not guaranteed)
+$(info ESP IDF path:       $(ESPIDF))
+$(info Current git hash:   $(ESPIDF_CURHASH))
+$(call print_supported_git_hash)
+endif
+
+# pretty format of ESP IDF version, used internally by the IDF
+IDF_VER := $(shell git -C $(ESPIDF) describe)
+
+#ifeq ($(shell which $(CC) 2> /dev/null),)
+#$(info ** ERROR **)
+#$(info Cannot find C compiler $(CC))
+#$(info Add the xtensa toolchain to your PATH. See README.md)
+#$(error C compiler missing)
+#endif
+
+## Support BLE by default when building with IDF 4.x.
+## Can be explicitly disabled on the command line or board config.
+#ifeq ($(ESPIDF_CURHASH),$(ESPIDF_SUPHASH_V4))
+#MICROPY_PY_BLUETOOTH ?= 1
+#ifeq ($(MICROPY_PY_BLUETOOTH),1)
+#SDKCONFIG += boards/sdkconfig.ble
+#MICROPY_BLUETOOTH_NIMBLE = 1
+#endif
+#endif
+#
+# include sdkconfig to get needed configuration values
+include $(SDKCONFIG)
+#$(shell cp $(BOARD_BUILD)/sdkconfig* $(BUILD))
+
+################################################################################
+# Compiler and linker flags
+
+INC_ESPCOMP += -I$(PORT_DIR)
+#INC += -I$(TOP)
+#INC += -I$(TOP)/lib/mp-readline
+#INC += -I$(TOP)/lib/netutils
+#INC += -I$(TOP)/lib/timeutils
+INC_ESPCOMP += -I$(BUILD)
+
+INC_ESPCOMP += -I$(ESPCOMP)/bootloader_support/include
+INC_ESPCOMP += -I$(ESPCOMP)/bootloader_support/include_bootloader
+INC_ESPCOMP += -I$(ESPCOMP)/console
+INC_ESPCOMP += -I$(ESPCOMP)/driver/include
+INC_ESPCOMP += -I$(ESPCOMP)/driver/include/driver
+INC_ESPCOMP += -I$(ESPCOMP)/efuse/include
+INC_ESPCOMP += -I$(ESPCOMP)/efuse/esp32/include
+INC_ESPCOMP += -I$(ESPCOMP)/esp32/include
+INC_ESPCOMP += -I$(ESPCOMP)/espcoredump/include
+INC_ESPCOMP += -I$(ESPCOMP)/soc/include
+INC_ESPCOMP += -I$(ESPCOMP)/soc/esp32/include
+INC_ESPCOMP += -I$(ESPCOMP)/heap/include
+INC_ESPCOMP += -I$(ESPCOMP)/log/include
+INC_ESPCOMP += -I$(ESPCOMP)/newlib/platform_include
+INC_ESPCOMP += -I$(ESPCOMP)/newlib/include
+INC_ESPCOMP += -I$(ESPCOMP)/nvs_flash/include
+INC_ESPCOMP += -I$(ESPCOMP)/freertos/include
+INC_ESPCOMP += -I$(ESPCOMP)/esp_ringbuf/include
+INC_ESPCOMP += -I$(ESPCOMP)/esp_event/include
+INC_ESPCOMP += -I$(ESPCOMP)/tcpip_adapter/include
+INC_ESPCOMP += -I$(ESPCOMP)/lwip/lwip/src/include
+INC_ESPCOMP += -I$(ESPCOMP)/lwip/port/esp32/include
+INC_ESPCOMP += -I$(ESPCOMP)/lwip/include/apps
+INC_ESPCOMP += -I$(ESPCOMP)/mbedtls/mbedtls/include
+INC_ESPCOMP += -I$(ESPCOMP)/mbedtls/port/include
+INC_ESPCOMP += -I$(ESPCOMP)/mdns/include
+INC_ESPCOMP += -I$(ESPCOMP)/mdns/private_include
+INC_ESPCOMP += -I$(ESPCOMP)/spi_flash/include
+INC_ESPCOMP += -I$(ESPCOMP)/ulp/include
+INC_ESPCOMP += -I$(ESPCOMP)/vfs/include
+INC_ESPCOMP += -I$(ESPCOMP)/xtensa-debug-module/include
+INC_ESPCOMP += -I$(ESPCOMP)/wpa_supplicant/include
+INC_ESPCOMP += -I$(ESPCOMP)/wpa_supplicant/port/include
+INC_ESPCOMP += -I$(ESPCOMP)/app_trace/include
+INC_ESPCOMP += -I$(ESPCOMP)/app_update/include
+INC_ESPCOMP += -I$(ESPCOMP)/pthread/include
+INC_ESPCOMP += -I$(ESPCOMP)/smartconfig_ack/include
+INC_ESPCOMP += -I$(ESPCOMP)/sdmmc/include
+
+ifeq ($(ESPIDF_CURHASH),$(ESPIDF_SUPHASH_V4))
+INC_ESPCOMP += -I$(ESPCOMP)/esp_common/include
+INC_ESPCOMP += -I$(ESPCOMP)/esp_eth/include
+INC_ESPCOMP += -I$(ESPCOMP)/esp_event/private_include
+INC_ESPCOMP += -I$(ESPCOMP)/esp_rom/include
+INC_ESPCOMP += -I$(ESPCOMP)/esp_wifi/include
+INC_ESPCOMP += -I$(ESPCOMP)/esp_wifi/esp32/include
+INC_ESPCOMP += -I$(ESPCOMP)/lwip/include/apps/sntp
+INC_ESPCOMP += -I$(ESPCOMP)/spi_flash/private_include
+INC_ESPCOMP += -I$(ESPCOMP)/wpa_supplicant/include/esp_supplicant
+INC_ESPCOMP += -I$(ESPCOMP)/xtensa/include
+INC_ESPCOMP += -I$(ESPCOMP)/xtensa/esp32/include
+ifeq ($(CONFIG_BT_NIMBLE_ENABLED),y)
+INC_ESPCOMP += -I$(ESPCOMP)/bt/include
+INC_ESPCOMP += -I$(ESPCOMP)/bt/common/osi/include
+INC_ESPCOMP += -I$(ESPCOMP)/bt/common/btc/include
+INC_ESPCOMP += -I$(ESPCOMP)/bt/common/include
+INC_ESPCOMP += -I$(ESPCOMP)/bt/host/nimble/nimble/porting/nimble/include
+INC_ESPCOMP += -I$(ESPCOMP)/bt/host/nimble/port/include
+INC_ESPCOMP += -I$(ESPCOMP)/bt/host/nimble/nimble/nimble/include
+INC_ESPCOMP += -I$(ESPCOMP)/bt/host/nimble/nimble/nimble/host/include
+INC_ESPCOMP += -I$(ESPCOMP)/bt/host/nimble/nimble/nimble/host/services/ans/include
+INC_ESPCOMP += -I$(ESPCOMP)/bt/host/nimble/nimble/nimble/host/services/bas/include
+INC_ESPCOMP += -I$(ESPCOMP)/bt/host/nimble/nimble/nimble/host/services/gap/include
+INC_ESPCOMP += -I$(ESPCOMP)/bt/host/nimble/nimble/nimble/host/services/gatt/include
+INC_ESPCOMP += -I$(ESPCOMP)/bt/host/nimble/nimble/nimble/host/services/ias/include
+INC_ESPCOMP += -I$(ESPCOMP)/bt/host/nimble/nimble/nimble/host/services/lls/include
+INC_ESPCOMP += -I$(ESPCOMP)/bt/host/nimble/nimble/nimble/host/services/tps/include
+INC_ESPCOMP += -I$(ESPCOMP)/bt/host/nimble/nimble/nimble/host/util/include
+INC_ESPCOMP += -I$(ESPCOMP)/bt/host/nimble/nimble/nimble/host/store/ram/include
+INC_ESPCOMP += -I$(ESPCOMP)/bt/host/nimble/nimble/nimble/host/store/config/include
+INC_ESPCOMP += -I$(ESPCOMP)/bt/host/nimble/nimble/porting/npl/freertos/include
+INC_ESPCOMP += -I$(ESPCOMP)/bt/host/nimble/nimble/ext/tinycrypt/include
+INC_ESPCOMP += -I$(ESPCOMP)/bt/host/nimble/esp-hci/include
+endif
+else
+INC_ESPCOMP += -I$(ESPCOMP)/ethernet/include
+INC_ESPCOMP += -I$(ESPCOMP)/expat/expat/expat/lib
+INC_ESPCOMP += -I$(ESPCOMP)/expat/port/include
+INC_ESPCOMP += -I$(ESPCOMP)/json/include
+INC_ESPCOMP += -I$(ESPCOMP)/json/port/include
+INC_ESPCOMP += -I$(ESPCOMP)/micro-ecc/micro-ecc
+INC_ESPCOMP += -I$(ESPCOMP)/nghttp/port/include
+INC_ESPCOMP += -I$(ESPCOMP)/nghttp/nghttp2/lib/includes
+endif
+
+ifeq ($(ESPIDF_CURHASH),$(ESPIDF_SUPHASH_V4))
+ifeq ($(MICROPY_PY_BLUETOOTH),1)
+CFLAGS_MOD += -DMICROPY_PY_BLUETOOTH=1
+CFLAGS_MOD += -DMICROPY_PY_BLUETOOTH_ENABLE_CENTRAL_MODE=1
+
+ifeq ($(MICROPY_BLUETOOTH_NIMBLE),1)
+CFLAGS_MOD += -DMICROPY_BLUETOOTH_NIMBLE=1
+endif
+endif
+endif
+
+CFLAGS = $(INC_ESPCOMP) $(CFLAGS_MOD)
diff --git a/examples/natmod/esp-idf/Makefile b/examples/natmod/esp-idf/Makefile
new file mode 100644
index 0000000000000..0aa05d76cca5e
--- /dev/null
+++ b/examples/natmod/esp-idf/Makefile
@@ -0,0 +1,23 @@
+# Location of top-level MicroPython directory
+MPY_DIR = ../../..
+
+# Espressif ESP-IDF path
+IDF_PATH := /home/src/esp32/esp-idf-micropython
+# Board to get correct ESP-IDF config
+BOARD := GENERIC
+# xtensa toolchain bin dir
+PATH := $(IDF_PATH)/xtensa-esp32-elf/bin:$(PATH)
+
+# Name of module
+MOD = counter
+
+# Source files (.c or .py)
+SRC = counter.c
+
+# Architecture to build for (x86, x64, armv7m, xtensa, xtensawin)
+ARCH = xtensawin
+
+# Include to get the rules for compiling and linking the module
+include dyn_esp32.mk
+include $(MPY_DIR)/py/dynruntime.mk
+CFLAGS += -std=gnu99 # override -std=c99 in dynruntime.mk
diff --git a/examples/natmod/esp-idf/counter.c b/examples/natmod/esp-idf/counter.c
new file mode 100644
index 0000000000000..fd8c5247a926c
--- /dev/null
+++ b/examples/natmod/esp-idf/counter.c
@@ -0,0 +1,58 @@
+/* This example demonstrates using an ESP32 esp-idf function
+*/
+
+// Include the header file to get access to the MicroPython API
+#include "py/dynruntime.h"
+
+// ESP-IDF imports
+#include <driver/pcnt.h>
+#include <esp_err.h>
+
+// This is the function which will be called from Python as counter_init(x)
+STATIC mp_obj_t counter_init(mp_obj_t x_obj) {
+    // Extract the integer from the MicroPython input object
+    mp_int_t x = mp_obj_get_int(x_obj);
+    // Call pcnt_unit_config
+    pcnt_config_t cfg = {
+        .unit = 0,
+        .channel = 0,
+        .pulse_gpio_num = x,
+        .ctrl_gpio_num = -1, // not yet supported
+        .counter_h_lim = 0,
+        .counter_l_lim = 0,
+        .pos_mode = PCNT_COUNT_DIS, // positive edge is no-op
+        .neg_mode = PCNT_COUNT_DIS, // negative edge is no-op
+        .lctrl_mode = PCNT_MODE_KEEP, // ctrl pin is no-op
+        .hctrl_mode = PCNT_MODE_KEEP, // ctrl pin is no-op
+    };
+    esp_err_t err = pcnt_unit_config(&cfg);
+    // Convert the result to a MicroPython integer object and return it
+    return mp_obj_new_int(err);
+}
+// Define a Python reference to the function above
+STATIC MP_DEFINE_CONST_FUN_OBJ_1(counter_init_obj, counter_init);
+
+// Another function that calls into the firmware, this time to mp_micropython_mem_info()
+// just as a simple demo which prints something to make it easy to see whether it's working or not.
+STATIC mp_obj_t mem_info() {
+    extern int mp_micropython_mem_info(int, int);
+    mp_printf(&mp_plat_print, "mp_fun_table is at 0x%x\n", &mp_fun_table);
+    mp_printf(&mp_plat_print, "calling mp_micropython_mem_info\n");
+    int i = mp_micropython_mem_info(0, 0);
+    mp_printf(&mp_plat_print, "mp_micropython_mem_info: %d/0x%x\n", i, i);
+    return mp_const_none;
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_0(mem_info_obj, mem_info);
+
+// This is the entry point and is called when the module is imported
+mp_obj_t mpy_init(mp_obj_fun_bc_t *self, size_t n_args, size_t n_kw, mp_obj_t *args) {
+    // This must be first, it sets up the globals dict and other things
+    MP_DYNRUNTIME_INIT_ENTRY
+
+    // Make the function available in the module's namespace
+    mp_store_global(MP_QSTR_counter_init, MP_OBJ_FROM_PTR(&counter_init_obj));
+    mp_store_global(MP_QSTR_mem_info, MP_OBJ_FROM_PTR(&mem_info_obj));
+
+    // This must be last, it restores the globals dict
+    MP_DYNRUNTIME_INIT_EXIT
+}
diff --git a/examples/natmod/esp-idf/dyn_esp32.mk b/examples/natmod/esp-idf/dyn_esp32.mk
new file mode 100644
index 0000000000000..5995e80090513
--- /dev/null
+++ b/examples/natmod/esp-idf/dyn_esp32.mk
@@ -0,0 +1,239 @@
+# Select the board to build for: if not given on the command line,
+# then default to GENERIC.
+BOARD ?= GENERIC
+
+PORT_DIR := $(MPY_DIR)/ports/esp32
+
+# If the build directory is not given, make it reflect the board name.
+BUILD ?= build
+
+BOARD_DIR ?= $(PORT_DIR)/boards/$(BOARD)
+BOARD_BUILD ?= $(PORT_DIR)/build-$(BOARD)
+#ifeq ($(wildcard $(BOARD_DIR)/.),)
+#$(error Invalid BOARD specified: $(BOARD_DIR))
+#endif
+#
+#include ../../py/mkenv.mk
+#
+## Optional (not currently used for ESP32)
+#-include mpconfigport.mk
+#
+#ifneq ($(SDKCONFIG),)
+#$(error Use the BOARD variable instead of SDKCONFIG)
+#endif
+
+# Expected to set SDKCONFIG
+include $(BOARD_DIR)/mpconfigboard.mk
+SDKCONFIG := $(addprefix $(PORT_DIR)/,$(SDKCONFIG))
+
+## qstr definitions (must come before including py.mk)
+#QSTR_DEFS = qstrdefsport.h
+#QSTR_GLOBAL_DEPENDENCIES = $(BOARD_DIR)/mpconfigboard.h
+#QSTR_GLOBAL_REQUIREMENTS = $(SDKCONFIG_H)
+
+#MICROPY_PY_USSL = 0
+#MICROPY_SSL_AXTLS = 0
+#MICROPY_PY_BTREE = 1
+#MICROPY_VFS_FAT = 1
+#MICROPY_VFS_LFS2 = 1
+
+#FROZEN_MANIFEST ?= boards/manifest.py
+
+## include py core make definitions
+#include $(TOP)/py/py.mk
+
+#GIT_SUBMODULES = lib/berkeley-db-1.xx
+
+#PORT ?= /dev/ttyUSB0
+#BAUD ?= 460800
+#FLASH_MODE ?= dio
+#FLASH_FREQ ?= 40m
+#FLASH_SIZE ?= 4MB
+#CROSS_COMPILE ?= xtensa-esp32-elf-
+#OBJDUMP = $(CROSS_COMPILE)objdump
+
+#SDKCONFIG_COMBINED = $(BUILD)/sdkconfig.combined
+#SDKCONFIG_H = $(BOARD_BUILD)/sdkconfig.h
+
+# the git hash of the currently supported ESP IDF version
+ESPIDF_SUPHASH_V3 := 6ccb4cf5b7d1fdddb8c2492f9cbc926abaf230df
+ESPIDF_SUPHASH_V4 := 463a9d8b7f9af8205222b80707f9bdbba7c530e1
+
+define print_supported_git_hash
+$(info Supported git hash (v3.3): $(ESPIDF_SUPHASH_V3))
+$(info Supported git hash (v4.0) (experimental): $(ESPIDF_SUPHASH_V4))
+endef
+
+# paths to ESP IDF and its components
+ifeq ($(ESPIDF),)
+ifneq ($(IDF_PATH),)
+ESPIDF = $(IDF_PATH)
+else
+$(info The ESPIDF variable has not been set, please set it to the root of the esp-idf repository.)
+$(info See README.md for installation instructions.)
+$(call print_supported_git_hash)
+$(error ESPIDF not set)
+endif
+endif
+
+ESPCOMP = $(ESPIDF)/components
+#ESPTOOL ?= $(ESPCOMP)/esptool_py/esptool/esptool.py
+ESPCOMP_KCONFIGS = $(shell find $(ESPCOMP) -name Kconfig)
+ESPCOMP_KCONFIGS_PROJBUILD = $(shell find $(ESPCOMP) -name Kconfig.projbuild)
+
+# verify the ESP IDF version
+ESPIDF_CURHASH := $(shell git -C $(ESPIDF) show -s --pretty=format:'%H')
+
+ifeq ($(ESPIDF_CURHASH),$(ESPIDF_SUPHASH_V3))
+$(info Building with ESP IDF v3)
+else ifeq ($(ESPIDF_CURHASH),$(ESPIDF_SUPHASH_V4))
+$(info Building with ESP IDF v4)
+
+PYPARSING_VERSION = $(shell python3 -c 'import pyparsing; print(pyparsing.__version__)')
+ifneq ($(PYPARSING_VERSION),2.3.1)
+$(info ** ERROR **)
+$(info EDP IDF requires pyparsing version less than 2.4)
+$(info You will need to set up a Python virtual environment with pyparsing 2.3.1)
+$(info Please see README.md for more information)
+$(error Incorrect pyparsing version)
+endif
+else
+$(info ** WARNING **)
+$(info The git hash of ESP IDF does not match the supported version)
+$(info The build may complete and the firmware may work but it is not guaranteed)
+$(info ESP IDF path:       $(ESPIDF))
+$(info Current git hash:   $(ESPIDF_CURHASH))
+$(call print_supported_git_hash)
+endif
+
+# pretty format of ESP IDF version, used internally by the IDF
+IDF_VER := $(shell git -C $(ESPIDF) describe)
+
+#ifeq ($(shell which $(CC) 2> /dev/null),)
+#$(info ** ERROR **)
+#$(info Cannot find C compiler $(CC))
+#$(info Add the xtensa toolchain to your PATH. See README.md)
+#$(error C compiler missing)
+#endif
+
+## Support BLE by default when building with IDF 4.x.
+## Can be explicitly disabled on the command line or board config.
+#ifeq ($(ESPIDF_CURHASH),$(ESPIDF_SUPHASH_V4))
+#MICROPY_PY_BLUETOOTH ?= 1
+#ifeq ($(MICROPY_PY_BLUETOOTH),1)
+#SDKCONFIG += boards/sdkconfig.ble
+#MICROPY_BLUETOOTH_NIMBLE = 1
+#endif
+#endif
+#
+# include sdkconfig to get needed configuration values
+include $(SDKCONFIG)
+$(shell cp $(BOARD_BUILD)/sdkconfig* $(BUILD))
+
+################################################################################
+# Compiler and linker flags
+
+INC_ESPCOMP += -I$(PORT_DIR)
+#INC += -I$(TOP)
+#INC += -I$(TOP)/lib/mp-readline
+#INC += -I$(TOP)/lib/netutils
+#INC += -I$(TOP)/lib/timeutils
+INC_ESPCOMP += -I$(BUILD)
+
+INC_ESPCOMP += -I$(ESPCOMP)/bootloader_support/include
+INC_ESPCOMP += -I$(ESPCOMP)/bootloader_support/include_bootloader
+INC_ESPCOMP += -I$(ESPCOMP)/console
+INC_ESPCOMP += -I$(ESPCOMP)/driver/include
+INC_ESPCOMP += -I$(ESPCOMP)/driver/include/driver
+INC_ESPCOMP += -I$(ESPCOMP)/efuse/include
+INC_ESPCOMP += -I$(ESPCOMP)/efuse/esp32/include
+INC_ESPCOMP += -I$(ESPCOMP)/esp32/include
+INC_ESPCOMP += -I$(ESPCOMP)/espcoredump/include
+INC_ESPCOMP += -I$(ESPCOMP)/soc/include
+INC_ESPCOMP += -I$(ESPCOMP)/soc/esp32/include
+INC_ESPCOMP += -I$(ESPCOMP)/heap/include
+INC_ESPCOMP += -I$(ESPCOMP)/log/include
+INC_ESPCOMP += -I$(ESPCOMP)/newlib/platform_include
+INC_ESPCOMP += -I$(ESPCOMP)/newlib/include
+INC_ESPCOMP += -I$(ESPCOMP)/nvs_flash/include
+INC_ESPCOMP += -I$(ESPCOMP)/freertos/include
+INC_ESPCOMP += -I$(ESPCOMP)/esp_ringbuf/include
+INC_ESPCOMP += -I$(ESPCOMP)/esp_event/include
+INC_ESPCOMP += -I$(ESPCOMP)/tcpip_adapter/include
+INC_ESPCOMP += -I$(ESPCOMP)/lwip/lwip/src/include
+INC_ESPCOMP += -I$(ESPCOMP)/lwip/port/esp32/include
+INC_ESPCOMP += -I$(ESPCOMP)/lwip/include/apps
+INC_ESPCOMP += -I$(ESPCOMP)/mbedtls/mbedtls/include
+INC_ESPCOMP += -I$(ESPCOMP)/mbedtls/port/include
+INC_ESPCOMP += -I$(ESPCOMP)/mdns/include
+INC_ESPCOMP += -I$(ESPCOMP)/mdns/private_include
+INC_ESPCOMP += -I$(ESPCOMP)/spi_flash/include
+INC_ESPCOMP += -I$(ESPCOMP)/ulp/include
+INC_ESPCOMP += -I$(ESPCOMP)/vfs/include
+INC_ESPCOMP += -I$(ESPCOMP)/xtensa-debug-module/include
+INC_ESPCOMP += -I$(ESPCOMP)/wpa_supplicant/include
+INC_ESPCOMP += -I$(ESPCOMP)/wpa_supplicant/port/include
+INC_ESPCOMP += -I$(ESPCOMP)/app_trace/include
+INC_ESPCOMP += -I$(ESPCOMP)/app_update/include
+INC_ESPCOMP += -I$(ESPCOMP)/pthread/include
+INC_ESPCOMP += -I$(ESPCOMP)/smartconfig_ack/include
+INC_ESPCOMP += -I$(ESPCOMP)/sdmmc/include
+
+ifeq ($(ESPIDF_CURHASH),$(ESPIDF_SUPHASH_V4))
+INC_ESPCOMP += -I$(ESPCOMP)/esp_common/include
+INC_ESPCOMP += -I$(ESPCOMP)/esp_eth/include
+INC_ESPCOMP += -I$(ESPCOMP)/esp_event/private_include
+INC_ESPCOMP += -I$(ESPCOMP)/esp_rom/include
+INC_ESPCOMP += -I$(ESPCOMP)/esp_wifi/include
+INC_ESPCOMP += -I$(ESPCOMP)/esp_wifi/esp32/include
+INC_ESPCOMP += -I$(ESPCOMP)/lwip/include/apps/sntp
+INC_ESPCOMP += -I$(ESPCOMP)/spi_flash/private_include
+INC_ESPCOMP += -I$(ESPCOMP)/wpa_supplicant/include/esp_supplicant
+INC_ESPCOMP += -I$(ESPCOMP)/xtensa/include
+INC_ESPCOMP += -I$(ESPCOMP)/xtensa/esp32/include
+ifeq ($(CONFIG_BT_NIMBLE_ENABLED),y)
+INC_ESPCOMP += -I$(ESPCOMP)/bt/include
+INC_ESPCOMP += -I$(ESPCOMP)/bt/common/osi/include
+INC_ESPCOMP += -I$(ESPCOMP)/bt/common/btc/include
+INC_ESPCOMP += -I$(ESPCOMP)/bt/common/include
+INC_ESPCOMP += -I$(ESPCOMP)/bt/host/nimble/nimble/porting/nimble/include
+INC_ESPCOMP += -I$(ESPCOMP)/bt/host/nimble/port/include
+INC_ESPCOMP += -I$(ESPCOMP)/bt/host/nimble/nimble/nimble/include
+INC_ESPCOMP += -I$(ESPCOMP)/bt/host/nimble/nimble/nimble/host/include
+INC_ESPCOMP += -I$(ESPCOMP)/bt/host/nimble/nimble/nimble/host/services/ans/include
+INC_ESPCOMP += -I$(ESPCOMP)/bt/host/nimble/nimble/nimble/host/services/bas/include
+INC_ESPCOMP += -I$(ESPCOMP)/bt/host/nimble/nimble/nimble/host/services/gap/include
+INC_ESPCOMP += -I$(ESPCOMP)/bt/host/nimble/nimble/nimble/host/services/gatt/include
+INC_ESPCOMP += -I$(ESPCOMP)/bt/host/nimble/nimble/nimble/host/services/ias/include
+INC_ESPCOMP += -I$(ESPCOMP)/bt/host/nimble/nimble/nimble/host/services/lls/include
+INC_ESPCOMP += -I$(ESPCOMP)/bt/host/nimble/nimble/nimble/host/services/tps/include
+INC_ESPCOMP += -I$(ESPCOMP)/bt/host/nimble/nimble/nimble/host/util/include
+INC_ESPCOMP += -I$(ESPCOMP)/bt/host/nimble/nimble/nimble/host/store/ram/include
+INC_ESPCOMP += -I$(ESPCOMP)/bt/host/nimble/nimble/nimble/host/store/config/include
+INC_ESPCOMP += -I$(ESPCOMP)/bt/host/nimble/nimble/porting/npl/freertos/include
+INC_ESPCOMP += -I$(ESPCOMP)/bt/host/nimble/nimble/ext/tinycrypt/include
+INC_ESPCOMP += -I$(ESPCOMP)/bt/host/nimble/esp-hci/include
+endif
+else
+INC_ESPCOMP += -I$(ESPCOMP)/ethernet/include
+INC_ESPCOMP += -I$(ESPCOMP)/expat/expat/expat/lib
+INC_ESPCOMP += -I$(ESPCOMP)/expat/port/include
+INC_ESPCOMP += -I$(ESPCOMP)/json/include
+INC_ESPCOMP += -I$(ESPCOMP)/json/port/include
+INC_ESPCOMP += -I$(ESPCOMP)/micro-ecc/micro-ecc
+INC_ESPCOMP += -I$(ESPCOMP)/nghttp/port/include
+INC_ESPCOMP += -I$(ESPCOMP)/nghttp/nghttp2/lib/includes
+endif
+
+ifeq ($(ESPIDF_CURHASH),$(ESPIDF_SUPHASH_V4))
+ifeq ($(MICROPY_PY_BLUETOOTH),1)
+CFLAGS_MOD += -DMICROPY_PY_BLUETOOTH=1
+CFLAGS_MOD += -DMICROPY_PY_BLUETOOTH_ENABLE_CENTRAL_MODE=1
+
+ifeq ($(MICROPY_BLUETOOTH_NIMBLE),1)
+CFLAGS_MOD += -DMICROPY_BLUETOOTH_NIMBLE=1
+endif
+endif
+endif
+
+CFLAGS = $(INC_ESPCOMP) $(CFLAGS_MOD)
diff --git a/ports/esp32/Makefile b/ports/esp32/Makefile
index fe4787b7ae338..ef826ea64e438 100644
--- a/ports/esp32/Makefile
+++ b/ports/esp32/Makefile
@@ -761,20 +761,30 @@ APP_LD_ARGS += -L$(ESPCOMP)/esp32/lib -lcore -lmesh -lnet80211 -lphy -lrtc -lpp
 endif
 APP_LD_ARGS += $(OBJ)
 APP_LD_ARGS += $(LIB)
+APP_LD_ARGS += $(BUILD)/plat_relo.o
 APP_LD_ARGS += --end-group
 
 $(BUILD)/esp32_out.ld: $(SDKCONFIG_H)
 	$(Q)$(CC) -I$(BUILD) -C -P -x c -E $(ESPCOMP)/esp32/ld/esp32.ld -o $@
 
-$(BUILD)/application.bin: $(BUILD)/application.elf
+$(BUILD)/application.bin: $(BUILD)/application.elf $(BUILD)/application.sym
 	$(ECHO) "Create $@"
 	$(Q)$(ESPTOOL) --chip esp32 elf2image --flash_mode $(FLASH_MODE) --flash_freq $(FLASH_FREQ) --flash_size $(FLASH_SIZE) $<
 
-$(BUILD)/application.elf: $(OBJ) $(LIB) $(BUILD)/esp32_out.ld $(BUILD)/esp32.project.ld
+# Memory map produced by nm, for troubleshooting purposes, not required for operation
+$(BUILD)/application.sym: $(BUILD)/application.elf
+	$(ECHO) "Create $@"
+	$(Q)xtensa-esp32-elf-nm -l -n $< >$@
+
+$(BUILD)/application.elf: $(OBJ) $(LIB) $(BUILD)/esp32_out.ld $(BUILD)/esp32.project.ld $(BUILD)/plat_relo.o
 	$(ECHO) "LINK $@"
 	$(Q)$(LD) $(LDFLAGS) -o $@ $(APP_LD_ARGS)
 	$(Q)$(SIZE) $@
 
+$(BUILD)/plat_relo.s: plat_relo.py
+	$(ECHO) "GEN platform relocations"
+	$(Q)./plat_relo.py --tab >$@
+
 define compile_cxx
 $(ECHO) "CXX $<"
 $(Q)$(CXX) $(CXXFLAGS) -c -MD -o $@ $<
diff --git a/ports/esp32/mpconfigport.h b/ports/esp32/mpconfigport.h
index bca68538b13db..236866f9e4a33 100644
--- a/ports/esp32/mpconfigport.h
+++ b/ports/esp32/mpconfigport.h
@@ -162,6 +162,7 @@
 #define MICROPY_PY_USOCKET_EVENTS           (MICROPY_PY_WEBREPL)
 #define MICROPY_PY_BLUETOOTH_RANDOM_ADDR    (1)
 #define MICROPY_PY_BLUETOOTH_DEFAULT_NAME   ("ESP32")
+#define MICROPY_PY_PLAT_RELO                (1)
 
 // fatfs configuration
 #define MICROPY_FATFS_ENABLE_LFN            (1)
@@ -191,6 +192,7 @@ extern const struct _mp_obj_module_t mp_module_machine;
 extern const struct _mp_obj_module_t mp_module_network;
 extern const struct _mp_obj_module_t mp_module_onewire;
 
+
 #define MICROPY_PORT_BUILTIN_MODULES \
     { MP_OBJ_NEW_QSTR(MP_QSTR_esp), (mp_obj_t)&esp_module }, \
     { MP_OBJ_NEW_QSTR(MP_QSTR_esp32), (mp_obj_t)&esp32_module }, \
diff --git a/ports/esp32/plat_relo.py b/ports/esp32/plat_relo.py
new file mode 100755
index 0000000000000..398a500ecf89f
--- /dev/null
+++ b/ports/esp32/plat_relo.py
@@ -0,0 +1,116 @@
+#! /usr/bin/python3
+
+# Linking table for platform-specific functions.
+#
+# The entry points below list a number of functions in the MP firmware that are to be exposed to
+# native modules. This is typically used to expose ESP-IDF functions so they can be called directly
+# from C code in dynamically loaded native modules. The native module can then #include the esp-idf
+# header files as usual and call the functions normally.
+
+# TODO: this needs to be loaded from a file, not hard-coded here
+entry_points = [
+    ("esp_chip_info", "P", ""),
+    ("esp_get_idf_version", "", "s"),
+    ("esp_err_to_name", "I", "s"),
+    ("pcnt_unit_config", "P", "I"),
+    ("pcnt_get_counter_value", "IP", "I"),
+    ("pcnt_counter_pause", "I", "I"),
+    ("pcnt_counter_resume", "I", "I"),
+    ("pcnt_counter_clear", "I", "I"),
+    ("pcnt_intr_disable", "I", "I"),
+    ]
+
+imports = [
+    "esp_err.h",
+    "esp_idf_version.h",
+    "esp_system.h",
+    "driver/pcnt.h",
+    ]
+
+type_map = { "I": "uint", "i": "int", "H": "uint16", "h": "int16", "B": "uint8", "b": "int8",
+        "P": "void*", "s": "char*", "": "void" }
+
+return_map = { "I": "mp_obj_new_int({})", "s": "mp_obj_new_str({0}, strlen({0}))", "": "{}" }
+
+import sys
+
+if len(sys.argv) > 1 and sys.argv[1] == '--tab':
+    # Generate platform relocation table compiled into the MP firmware
+    print('\t.file\t"plat_relo.py"')
+    print('\t.section\t.rodata.plat_relo_tab,"a",@progbits')
+    print('\t.align\t4')
+    print('\t.global\tplat_relo_tab')
+    print('\t.type\tplat_relo_tab, @object')
+    print('plat_relo_tab:')
+    for name, _, _ in entry_points:
+        print('\t.word\t' + name)
+    print('\t.size\tplat_relo_tab, .-plat_relo_tab')
+
+elif len(sys.argv) > 1 and (sys.argv[1] == '--module' or sys.argv[1] == '--builtin'):
+    # Generate espidf module to expose functions to python
+    builtin = sys.argv[1] == '--builtin'
+    print('#include <assert.h>')
+    print('#include <string.h>')
+    if builtin:
+        print('#include "py/runtime.h"')
+    else:
+        print('#include "py/dynruntime.h"')
+
+    print('// ESP-IDF imports')
+    for im in imports:
+        print("#include <{}>".format(im))
+    for name, args, res in entry_points:
+        print()
+        print("STATIC mp_obj_t espidf_{}(".format(name), end='')
+        print(", ".join(["mp_obj_t arg{}".format(ix) for ix in range(len(args))]), end='')
+        print(") {")
+        for ix, fmt in enumerate(args):
+            print("\t// convert arg{}".format(ix))
+            if fmt == "P":
+                print("\tmp_buffer_info_t val{}_buf;".format(ix))
+                print("\tmp_get_buffer_raise(arg{0}, &val{0}_buf, MP_BUFFER_RW);".format(ix))
+                print("\tvoid *val{0} = (void *)(val{0}_buf.buf);".format(ix))
+
+            elif fmt in frozenset(["I", "i", "H", "h", "B", "b"]):
+                print("\t{1} val{0} = ({1})mp_obj_get_int(arg{0});".format(ix, type_map[fmt]))
+        print("\t// call")
+        if res == "":
+            print("\tmp_obj_t ret = mp_const_none;")
+            print("\t{}(".format(name), end='')
+        else:
+            print("\tconst {} ret = {}(".format(type_map[res], name), end='')
+        print(", ".join([ "val{}".format(ix) for ix in range(len(args)) ]), end='')
+        print(");")
+        print("\treturn " + return_map[res].format('ret') + ";\n}")
+        if len(args) < 4:
+            print("STATIC MP_DEFINE_CONST_FUN_OBJ_{}(espidf_{}_obj, espidf_{});".format(
+                len(args), name, name))
+        else:
+            print("STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(espidf_{}_obj, {}, {}, espidf_{});".format(
+                len(args), len(args), name, name))
+    print()
+    if sys.argv[1] == '--builtin':
+        # generate module built into the firmware
+        print("STATIC const mp_rom_map_elem_t mp_module_espidf_globals_table[] = {")
+        print("\t{ MP_ROM_QSTR(MP_QSTR___name__), MP_ROM_QSTR(MP_QSTR_espidf) },")
+        for name, _, _ in entry_points:
+            print("\t{{ MP_ROM_QSTR(MP_QSTR_{}), MP_ROM_PTR(&espidf_{}) }},".format(name, name))
+        print('''\
+};
+STATIC MP_DEFINE_CONST_DICT(mp_module_espidf_globals, mp_module_espidf_globals_table);
+
+const mp_obj_module_t mp_module_espidf = {
+    .base = { &mp_type_module },
+    .globals = (mp_obj_dict_t*)&mp_module_espidf_globals,
+};
+
+#endif
+''', end='')
+    else:
+        # generate dynamically loadable module
+        print("mp_obj_t mpy_init(mp_obj_fun_bc_t *self, size_t n_args, size_t n_kw, mp_obj_t *args) {")
+        print("\tMP_DYNRUNTIME_INIT_ENTRY")
+        for name, _, _ in entry_points:
+            print("\tmp_store_global(MP_QSTR_{0}, MP_OBJ_FROM_PTR(&espidf_{0}_obj));".format(name))
+        print("\tMP_DYNRUNTIME_INIT_EXIT")
+        print("}")
diff --git a/py/dynruntime.mk b/py/dynruntime.mk
index 8b65745afdf78..9b459cf6a7a64 100644
--- a/py/dynruntime.mk
+++ b/py/dynruntime.mk
@@ -128,6 +128,11 @@ $(BUILD)/%.o: %.c $(CONFIG_H) Makefile
 	$(ECHO) "CC $<"
 	$(Q)$(CROSS)gcc $(CFLAGS) -o $@ -c $<
 
+# Build .o from .s source files
+%.o: %.s $(CONFIG_H) Makefile
+	$(ECHO) "AS $<"
+	$(Q)$(CROSS)gcc $(CFLAGS) -o $@ -c $<
+
 # Build .mpy from .py source files
 $(BUILD)/%.mpy: %.py
 	$(ECHO) "MPY $<"
diff --git a/py/persistentcode.c b/py/persistentcode.c
index 7039f9f57a3c6..4369df831fbf9 100644
--- a/py/persistentcode.c
+++ b/py/persistentcode.c
@@ -189,12 +189,16 @@ STATIC void arch_link_qstr(uint8_t *pc, bool is_obj, qstr qst) {
     #endif
 }
 
+extern size_t plat_relo_tab[];
+
 void mp_native_relocate(void *ri_in, uint8_t *text, uintptr_t reloc_text) {
     // Relocate native code
     reloc_info_t *ri = ri_in;
     uint8_t op;
     uintptr_t *addr_to_adjust = NULL;
     while ((op = read_byte(ri->reader)) != 0xff) {
+        mp_printf(&mp_plat_print, "mp_native_relocate %d\n", op);
+        // if lsb==1 then an offset follows the op byte, else addr_to_adjust auto-increments
         if (op & 1) {
             // Point to new location to make adjustments
             size_t addr = read_uint(ri->reader, NULL);
@@ -225,14 +229,20 @@ void mp_native_relocate(void *ri_in, uint8_t *text, uintptr_t reloc_text) {
         } else if (op == 6) {
             // Destination is mp_fun_table itself
             dest = (uintptr_t)&mp_fun_table;
+        } else if (op == 126) {
+            size_t index = read_uint(ri->reader, NULL);
+            dest = ((uintptr_t*)&plat_relo_tab)[index];
+            mp_printf(&mp_plat_print, "mp_native_relocate: op=%d, index=%d, dest=0x%08x\n", op, index, dest);
         } else {
             // Destination is an entry in mp_fun_table
             dest = ((uintptr_t*)&mp_fun_table)[op - 7];
+            mp_printf(&mp_plat_print, "mp_native_relocate: op=%d, dest=0x%08x\n", op, dest);
         }
         while (n--) {
             *addr_to_adjust++ += dest;
         }
     }
+    mp_printf(&mp_plat_print, "mp_native_relocate DONE\n");
 }
 
 #endif
diff --git a/tools/mpy_ld.py b/tools/mpy_ld.py
index 31c3912991c48..bd11b164c0ff3 100755
--- a/tools/mpy_ld.py
+++ b/tools/mpy_ld.py
@@ -34,6 +34,26 @@
 sys.path.append(os.path.dirname(__file__) + '/../py')
 import makeqstrdata as qstrutil
 
+# Platform-specific relocation table, which contains the addresses of a number of platform specific
+# functions compiled into the firmware. These entries are used by the dynamic linker to fix-up
+# relocation entries in dynamically loaded mpy modules.
+# TODO: this needs to be loaded from a file, not hard-coded here.
+plat_relo_entries = { name : idx
+    for idx, name in enumerate([
+        "esp_chip_info",
+        "esp_get_idf_version",
+        "esp_err_to_name",
+        "pcnt_unit_config",
+        "pcnt_get_counter_value",
+        "pcnt_counter_pause",
+        "pcnt_counter_resume",
+        "pcnt_counter_clear",
+        "pcnt_intr_disable",
+        "mp_micropython_mem_info",
+        "strlen",
+    ])
+}
+
 # MicroPython constants
 MPY_VERSION = 5
 MP_NATIVE_ARCH_X86 = 1
@@ -256,6 +276,10 @@ def isrodata(self):
     def isbss(self):
         return self.sec_name.startswith('.bss')
 
+    def __repr__(self): # for debugging purposes
+        keys = ['name', 'sym', 'offset', 'link_addr', 'sec_name']
+        return "GOTEntry(" + repr({ k:getattr(self, k) for k in keys}) + ")"
+
 class LiteralEntry:
     def __init__(self, value, offset):
         self.value = value
@@ -381,8 +405,11 @@ def populate_got(env):
             dest = '.data.rel.ro'
         elif got_entry.sec_name.startswith('.bss'):
             dest = '.bss'
+        elif got_entry.sec_name == '.external.plat_relo_tab':
+            dest = 1000+got_entry.sym.plat_relo_offset
+            print("GOT entry: {}->{} ({})".format(got_entry.name, dest, repr(got_entry)))
         else:
-            assert 0, (got_entry.name, got_entry.sec_name)
+            assert 0, repr(got_entry)
         env.mpy_relocs.append(('.text', env.got_section.addr + got_entry.offset, dest))
 
     # Print out the final GOT
@@ -680,6 +707,7 @@ def link_objects(env, native_qstr_vals_len, native_qstr_objs_len):
             'mp_stream_write_obj',
         ])
     }
+    plat_relo_sec = Section('.external.plat_relo_tab', b'', 0)
     for sym in env.unresolved_syms:
         assert sym['st_value'] == 0
         if sym.name == '_GLOBAL_OFFSET_TABLE_':
@@ -692,12 +720,15 @@ def link_objects(env, native_qstr_vals_len, native_qstr_objs_len):
             sym.section = env.qstr_obj_section
         elif sym.name in env.known_syms:
             sym.resolved = env.known_syms[sym.name]
+        elif sym.name in fun_table:
+            sym.section = mp_fun_table_sec
+            sym.mp_fun_table_offset = fun_table[sym.name]
+        elif sym.name in plat_relo_entries:
+            sym.section = plat_relo_sec
+            sym.plat_relo_offset = plat_relo_entries[sym.name]
+            print("Unresolved: {} -> plat_relo_sec+{}".format(sym.name, sym.plat_relo_offset))
         else:
-            if sym.name in fun_table:
-                sym.section = mp_fun_table_sec
-                sym.mp_fun_table_offset = fun_table[sym.name]
-            else:
-                raise LinkError('{}: undefined symbol: {}'.format(sym.filename, sym.name))
+            raise LinkError('{}: undefined symbol: {}'.format(sym.filename, sym.name))
 
     # Align sections, assign their addresses, and create full_text
     env.full_text = bytearray(env.arch.asm_jump(8)) # dummy, to be filled in later
@@ -766,12 +797,29 @@ def write_qstr(self, s):
             self.write_bytes(s)
 
     def write_reloc(self, base, offset, dest, n):
+        """
+        Write a relocation entry into the mpy that the dynamic linker will have to resolve
+        when the mpy is loaded. A relocation entry consists of a kind/op byte, followed by an
+        optional offset word, followed by an optional count word.
+        - base+offset is the location where the fixup is to be done, base is '.text' or 'rodata'.
+        - dest is the target whose address needs to be placed into the fixup: 0=string table,
+          1=rodata_const_table, 2=bss_const_table, 3..5: unused, 6=mp_fun_table,
+          7..126:entry in mp_fun_table, 1000..66535:entry in plat_relo_tab.
+        - n is number of consecutive words to fix up.
+        """
         need_offset = not (base == self.prev_base and offset == self.prev_offset + 1)
         self.prev_offset = offset + n - 1
+        index = None
         if dest <= 2:
             dest = (dest << 1) | (n > 1)
+        elif dest >= 1000:
+            # offset into plat_relo_tab
+            assert dest < 1000+65536
+            index = dest-1000
+            dest = 126
+            print("write_reloc plat_relo_tab+{}".format(index))
         else:
-            assert 6 <= dest <= 127
+            assert 6 <= dest < 126
             assert n == 1
         dest = dest << 1 | need_offset
         assert 0 <= dest <= 0xfe, dest
@@ -782,6 +830,8 @@ def write_reloc(self, base, offset, dest, n):
             elif base == '.rodata':
                 base = 1
             self.write_uint(offset << 1 | base)
+        if index is not None:
+            self.write_uint(index)
         if n > 1:
             self.write_uint(n)
 
@@ -865,8 +915,14 @@ def build_mpy(env, entry_offset, fmpy, native_qstr_vals, native_qstr_objs):
             kind = bss_const_table_idx
         elif kind == 'mp_fun_table':
             kind = 6
+        elif isinstance(kind, int):
+            if kind < 1000:
+                # element of mp_fun_table
+                kind = 7 + kind
+            else: # element of plat_relo_tab
+                pass
         else:
-            kind = 7 + kind
+            assert 0, kind
         assert addr % env.arch.word_size == 0, addr
         offset = addr // env.arch.word_size
         if kind == prev_kind and base == prev_base and offset == prev_offset + 1: