diff --git a/ports/esp32s2/.gitignore b/ports/esp32s2/.gitignore
index 4bfc5e7845..2e3080a40d 100644
--- a/ports/esp32s2/.gitignore
+++ b/ports/esp32s2/.gitignore
@@ -1,2 +1,2 @@
-build*
+build*/
 sdkconfig.old
diff --git a/ports/esp32s2/Makefile b/ports/esp32s2/Makefile
index 590750afcf..85d8e04332 100644
--- a/ports/esp32s2/Makefile
+++ b/ports/esp32s2/Makefile
@@ -316,11 +316,11 @@ esp-idf-stamp: $(BUILD)/esp-idf/config/sdkconfig.h
 $(BUILD)/firmware.elf: $(OBJ) | esp-idf-stamp
 	$(STEPECHO) "LINK $@"
 	$(Q)$(CC) -o $@ $(LDFLAGS) $^ -Wl,--start-group $(ESP_IDF_COMPONENTS_EXPANDED) $(BINARY_BLOBS) $(MBEDTLS_COMPONENTS_LINK_EXPANDED) build-$(BOARD)/esp-idf/esp-idf/newlib/libnewlib.a  -Wl,--end-group -u newlib_include_pthread_impl -Wl,--start-group $(LIBS) -Wl,--end-group build-$(BOARD)/esp-idf/esp-idf/pthread/libpthread.a  -u __cxx_fatal_exception
-	# $(Q)$(SIZE) $@ | $(PYTHON3) $(TOP)/tools/build_memory_info.py $(BUILD)/esp-idf/esp-idf/esp32s2/esp32s2_out.ld
 
-$(BUILD)/circuitpython-firmware.bin: $(BUILD)/firmware.elf
+$(BUILD)/circuitpython-firmware.bin: $(BUILD)/firmware.elf | tools/build_memory_info.py
 	$(STEPECHO) "Create $@"
 	$(Q)esptool.py --chip esp32s2 elf2image $(FLASH_FLAGS) --elf-sha256-offset 0xb0 -o $@ $^
+	$(Q)$(PYTHON3) tools/build_memory_info.py $< $(BUILD)/esp-idf/sdkconfig $@
 
 $(BUILD)/firmware.bin: $(BUILD)/circuitpython-firmware.bin | esp-idf-stamp
 	$(Q)$(PYTHON) ../../tools/join_bins.py $@ 0x1000 $(BUILD)/esp-idf/bootloader/bootloader.bin 0x8000 $(BUILD)/esp-idf/partition_table/partition-table.bin 0x10000 $(BUILD)/circuitpython-firmware.bin
diff --git a/ports/esp32s2/tools/build_memory_info.py b/ports/esp32s2/tools/build_memory_info.py
new file mode 100644
index 0000000000..94fd07bb52
--- /dev/null
+++ b/ports/esp32s2/tools/build_memory_info.py
@@ -0,0 +1,84 @@
+#!/usr/bin/env python3
+
+# SPDX-FileCopyrightText: Copyright (c) 2017 Scott Shawcroft for Adafruit Industries
+# SPDX-FileCopyrightText: 2014 MicroPython & CircuitPython contributors (https://github.com/adafruit/circuitpython/graphs/contributors)
+#
+# SPDX-License-Identifier: MIT
+
+import os
+import re
+import sys
+
+from elftools.elf.elffile import ELFFile
+
+print()
+
+internal_memory = [
+    # Name, Start, Length
+    ("RTC Fast Memory", (0x3FF9_E000, 0x4007_0000), 8 * 1024),
+    ("RTC Slow Memory", (0x5000_0000,), 8 * 1024),
+    ("Internal SRAM 0", (0x3FFB_0000, 0x4002_0000), 32 * 1024),
+    ("Internal SRAM 1", (0x3FFB_8000, 0x4002_8000), 288 * 1024),
+]
+
+
+def partition_size(arg):
+    if "4MB" in arg:
+        return 1408 * 1024
+    else:
+        return 2048 * 1024
+
+
+def align(n, m):
+    return m * ((n + m - 1) // m)
+
+
+regions = dict((name, 0) for name, _, _ in internal_memory)
+
+# This file is the elf
+with open(sys.argv[1], "rb") as stream:
+    elffile = ELFFile(stream)
+    for section in elffile.iter_sections():
+        start = section["sh_addr"]
+        size = section["sh_size"]
+        offset = section["sh_offset"]
+        if not size or not start:
+            continue
+        for name, starts, length in internal_memory:
+            for mem_start in starts:
+                mem_end = mem_start + length
+                if start >= mem_start and start < mem_end:
+                    regions[name] = max(regions.get(name, 0), size)
+                    # print("# putting %s in %s (start=0x%x, size=%d)" % (section.name, name, start, size))
+
+# This file is the sdkconfig
+with open(sys.argv[2], "r") as f:
+    for line in f:
+        line = line.strip()
+        if line.startswith("CONFIG_PARTITION_TABLE_FILENAME"):
+            firmware_region = int(partition_size(line.split("=")[-1]))
+
+# This file is the bin
+used_flash = os.stat(sys.argv[3]).st_size
+
+free_flash = firmware_region - used_flash
+print(
+    "{:7} bytes used, {:7} bytes free in flash firmware space out of {} bytes ({}kB).".format(
+        used_flash, free_flash, firmware_region, firmware_region / 1024
+    )
+)
+for name, mem_start, length in internal_memory:
+    if name in regions:
+        print(
+            "{:7} bytes used, {:7} bytes free in '{}' out of {} bytes ({}kB).".format(
+                regions[name], length - regions[name], name, length, length / 1024
+            )
+        )
+print()
+
+# Check that we have free flash space. GCC doesn't fail when the text + data
+# sections don't fit in FLASH. It only counts data in RAM.
+if free_flash < 0:
+    print("Too little flash!!!")
+    print()
+    sys.exit(-1)