docs/esp32: Add a factory reset page.

This work was funded through GitHub Sponsors.

Signed-off-by: Angus Gratton <angus@redyak.com.au>

docs/esp32/tutorial/index.rst

@@ -21,3 +21,4 @@ to `<https://www.python.org>`__.
    intro.rst
    pwm.rst
    peripheral_access.rst
+   reset.rst

docs/esp32/tutorial/intro.rst

@@ -50,6 +50,8 @@ features, there are daily builds.  If your board has SPIRAM support you can
 use either the standard firmware or the firmware with SPIRAM support, and in
 the latter case you will have access to more RAM for Python objects.
 
+.. _esp32_flashing:
+
 Deploying the firmware
 ----------------------
 

docs/esp32/tutorial/reset.rst

@@ -0,0 +1,25 @@
+Factory reset
+=============
+
+If something unexpected happens and your ESP32-based board no longer boots
+MicroPython, then you may have to factory reset it. For more details, see
+:ref:`soft_bricking`.
+
+Factory resetting the MicroPython esp32 port involves fully erasing the flash
+and resetting the flash memory, so you will need to re-flash the MicroPython
+firmware afterwards and copy any Python files to the filesystem again.
+
+1. You will need the Espressif `esptool`_ installed on your system. This is the
+   same tool that you may have used to initially install MicroPython on your
+   board (see :ref:`installation instructions <esp32_flashing>`).
+2. Find the serial port name of your board, and then use esptool to erase the
+   entire flash contents::
+
+       esptool.py -p PORTNAME erase_flash
+
+3. Use esptool to flash the MicroPython file to your board again. If needed,
+   this file and flashing instructions can be found on the `MicroPython
+   downloads page`_.
+
+.. _esptool: https://github.com/espressif/esptool
+.. _MicroPython downloads page: https://micropython.org/download/?port=esp32

docs/reference/reset_boot.rst

@@ -244,6 +244,7 @@ two processes:
 The specific process(es) are different on each port:
 
 - :doc:`pyboard and stm32 port instructions </pyboard/tutorial/reset>`
+- :doc:`esp32 port instructions </esp32/tutorial/reset>`
 - :doc:`renesas-ra port instructions </renesas-ra/tutorial/reset>`
 - :doc:`rp2 port instructions </rp2/tutorial/reset>`
 - :doc:`wipy port instructions </wipy/tutorial/reset>`