micropython/docs/library/esp32.rst

.. currentmodule:: esp32

:mod:`esp32` --- functionality specific to the ESP32
====================================================

.. module:: esp32
    :synopsis: functionality specific to the ESP32

The ``esp32`` module contains functions and classes specifically aimed at
controlling ESP32 modules.


Functions
---------

.. function:: wake_on_touch(wake)

    Configure whether or not a touch will wake the device from sleep.
    *wake* should be a boolean value.

.. function:: wake_on_ulp(wake)

    Configure whether or not the Ultra-Low-Power co-processor can wake the
    device from sleep. *wake* should be a boolean value.

.. function:: wake_on_ext0(pin, level)

    Configure how EXT0 wakes the device from sleep.  *pin* can be ``None``
    or a valid Pin object.  *level* should be ``esp32.WAKEUP_ALL_LOW`` or
    ``esp32.WAKEUP_ANY_HIGH``.

.. function:: wake_on_ext1(pins, level)

    Configure how EXT1 wakes the device from sleep.  *pins* can be ``None``
    or a tuple/list of valid Pin objects.  *level* should be ``esp32.WAKEUP_ALL_LOW``
    or ``esp32.WAKEUP_ANY_HIGH``.

.. function:: gpio_deep_sleep_hold(enable)

    Configure whether non-RTC GPIO pin configuration is retained during
    deep-sleep mode for held pads. *enable* should be a boolean value.

.. function:: raw_temperature()

    Read the raw value of the internal temperature sensor, returning an integer.

.. function:: idf_heap_info(capabilities)

    Returns information about the ESP-IDF heap memory regions. One of them contains
    the MicroPython heap and the others are used by ESP-IDF, e.g., for network
    buffers and other data. This data is useful to get a sense of how much memory
    is available to ESP-IDF and the networking stack in particular. It may shed
    some light on situations where ESP-IDF operations fail due to allocation failures.

    The capabilities parameter corresponds to ESP-IDF's ``MALLOC_CAP_XXX`` values but the
    two most useful ones are predefined as `esp32.HEAP_DATA` for data heap regions and
    `esp32.HEAP_EXEC` for executable regions as used by the native code emitter.

    The return value is a list of 4-tuples, where each 4-tuple corresponds to one heap
    and contains: the total bytes, the free bytes, the largest free block, and
    the minimum free seen over time.

    Example after booting::

        >>> import esp32; esp32.idf_heap_info(esp32.HEAP_DATA)
        [(240, 0, 0, 0), (7288, 0, 0, 0), (16648, 4, 4, 4), (79912, 35712, 35512, 35108),
         (15072, 15036, 15036, 15036), (113840, 0, 0, 0)]

    .. note:: Free IDF heap memory in the `esp32.HEAP_DATA` region is available
       to be automatically added to the MicroPython heap to prevent a
       MicroPython allocation from failing. However, the information returned
       here is otherwise *not* useful to troubleshoot Python allocation
       failures. :func:`micropython.mem_info()` and :func:`gc.mem_free()` should
       be used instead:

       The "max new split" value in :func:`micropython.mem_info()` output
       corresponds to the largest free block of ESP-IDF heap that could be
       automatically added on demand to the MicroPython heap.

       The result of :func:`gc.mem_free()` is the total of the current "free"
       and "max new split" values printed by :func:`micropython.mem_info()`.


Flash partitions
----------------

This class gives access to the partitions in the device's flash memory and includes
methods to enable over-the-air (OTA) updates.

.. class:: Partition(id, block_size=4096, /)

    Create an object representing a partition.  *id* can be a string which is the label
    of the partition to retrieve, or one of the constants: ``BOOT`` or ``RUNNING``.
    *block_size* specifies the byte size of an individual block.

.. classmethod:: Partition.find(type=TYPE_APP, subtype=0xff, label=None, block_size=4096)

    Find a partition specified by *type*, *subtype* and *label*.  Returns a
    (possibly empty) list of Partition objects. Note: ``subtype=0xff`` matches any subtype
    and ``label=None`` matches any label.

    *block_size* specifies the byte size of an individual block used by the returned
    objects.

.. method:: Partition.info()

    Returns a 6-tuple ``(type, subtype, addr, size, label, encrypted)``.

.. method:: Partition.readblocks(block_num, buf)
            Partition.readblocks(block_num, buf, offset)
.. method:: Partition.writeblocks(block_num, buf)
            Partition.writeblocks(block_num, buf, offset)
.. method:: Partition.ioctl(cmd, arg)

    These methods implement the simple and :ref:`extended
    <block-device-interface>` block protocol defined by
    :class:`vfs.AbstractBlockDev`.

.. method:: Partition.set_boot()

    Sets the partition as the boot partition.

    .. note:: Do not enter :func:`deepsleep<machine.deepsleep>` after changing
       the OTA boot partition, without first performing a hard
       :func:`reset<machine.reset>` or power cycle. This ensures the bootloader
       will validate the new image before booting.

.. method:: Partition.get_next_update()

    Gets the next update partition after this one, and returns a new Partition object.
    Typical usage is ``Partition(Partition.RUNNING).get_next_update()``
    which returns the next partition to update given the current running one.

.. classmethod:: Partition.mark_app_valid_cancel_rollback()

    Signals that the current boot is considered successful.
    Calling ``mark_app_valid_cancel_rollback`` is required on the first boot of a new
    partition to avoid an automatic rollback at the next boot.
    This uses the ESP-IDF "app rollback" feature with "CONFIG_BOOTLOADER_APP_ROLLBACK_ENABLE"
    and  an ``OSError(-261)`` is raised if called on firmware that doesn't have the
    feature enabled.
    It is OK to call ``mark_app_valid_cancel_rollback`` on every boot and it is not
    necessary when booting firmware that was loaded using esptool.

Constants
~~~~~~~~~

.. data:: Partition.BOOT
          Partition.RUNNING

    Used in the `Partition` constructor to fetch various partitions: ``BOOT`` is the
    partition that will be booted at the next reset and ``RUNNING`` is the currently
    running partition.

.. data:: Partition.TYPE_APP
          Partition.TYPE_DATA

    Used in `Partition.find` to specify the partition type: ``APP`` is for bootable
    firmware partitions (typically labelled ``factory``, ``ota_0``, ``ota_1``), and
    ``DATA`` is for other partitions, e.g. ``nvs``, ``otadata``, ``phy_init``, ``vfs``.

.. data:: HEAP_DATA
          HEAP_EXEC

    Used in `idf_heap_info`.

.. _esp32.RMT:

RMT
---

The RMT (Remote Control) module, specific to the ESP32, was originally designed
to send and receive infrared remote control signals. However, due to a flexible
design and very accurate (as low as 12.5ns) pulse generation, it can also be
used to transmit or receive many other types of digital signals::

    import esp32
    from machine import Pin

    r = esp32.RMT(0, pin=Pin(18), clock_div=8)
    r  # RMT(channel=0, pin=18, source_freq=80000000, clock_div=8, idle_level=0)

    # To apply a carrier frequency to the high output
    r = esp32.RMT(0, pin=Pin(18), clock_div=8, tx_carrier=(38000, 50, 1))

    # The channel resolution is 100ns (1/(source_freq/clock_div)).
    r.write_pulses((1, 20, 2, 40), 0)  # Send 0 for 100ns, 1 for 2000ns, 0 for 200ns, 1 for 4000ns

The input to the RMT module is an 80MHz clock (in the future it may be able to
configure the input clock but, for now, it's fixed). ``clock_div`` *divides*
the clock input which determines the resolution of the RMT channel. The
numbers specified in ``write_pulses`` are multiplied by the resolution to
define the pulses.

``clock_div`` is an 8-bit divider (0-255) and each pulse can be defined by
multiplying the resolution by a 15-bit (1-``PULSE_MAX``) number. There are eight
channels (0-7) and each can have a different clock divider.

So, in the example above, the 80MHz clock is divided by 8. Thus the
resolution is (1/(80Mhz/8)) 100ns. Since the ``start`` level is 0 and toggles
with each number, the bitstream is ``0101`` with durations of [100ns, 2000ns,
100ns, 4000ns].

For more details see Espressif's `ESP-IDF RMT documentation.
<https://docs.espressif.com/projects/esp-idf/en/latest/api-reference/peripherals/rmt.html>`_.

.. Warning::
   The current MicroPython RMT implementation lacks some features, most notably
   receiving pulses. RMT should be considered a
   *beta feature* and the interface may change in the future.


.. class:: RMT(channel, *, pin=None, clock_div=8, idle_level=False, tx_carrier=None)

    This class provides access to one of the eight RMT channels. *channel* is
    required and identifies which RMT channel (0-7) will be configured. *pin*,
    also required, configures which Pin is bound to the RMT channel. *clock_div*
    is an 8-bit clock divider that divides the source clock (80MHz) to the RMT
    channel allowing the resolution to be specified. *idle_level* specifies
    what level the output will be when no transmission is in progress and can
    be any value that converts to a boolean, with ``True`` representing high
    voltage and ``False`` representing low.

    To enable the transmission carrier feature, *tx_carrier* should be a tuple
    of three positive integers: carrier frequency, duty percent (``0`` to
    ``100``) and the output level to apply the carrier to (a boolean as per
    *idle_level*).

.. classmethod:: RMT.source_freq()

    Returns the source clock frequency. Currently the source clock is not
    configurable so this will always return 80MHz.

.. method:: RMT.clock_div()

    Return the clock divider. Note that the channel resolution is
    ``1 / (source_freq / clock_div)``.

.. method:: RMT.wait_done(*, timeout=0)

    Returns ``True`` if the channel is idle or ``False`` if a sequence of
    pulses started with `RMT.write_pulses` is being transmitted. If the
    *timeout* keyword argument is given then block for up to this many
    milliseconds for transmission to complete.

.. method:: RMT.loop(enable_loop)

    Configure looping on the channel. *enable_loop* is bool, set to ``True`` to
    enable looping on the *next* call to `RMT.write_pulses`. If called with
    ``False`` while a looping sequence is currently being transmitted then the
    current loop iteration will be completed and then transmission will stop.

.. method:: RMT.write_pulses(duration, data=True)

    Begin transmitting a sequence. There are three ways to specify this:

    **Mode 1:** *duration* is a list or tuple of durations. The optional *data*
    argument specifies the initial output level. The output level will toggle
    after each duration.

    **Mode 2:** *duration* is a positive integer and *data* is a list or tuple
    of output levels. *duration* specifies a fixed duration for each.

    **Mode 3:** *duration* and *data* are lists or tuples of equal length,
    specifying individual durations and the output level for each.

    Durations are in integer units of the channel resolution (as
    described above), between 1 and ``PULSE_MAX`` units. Output levels
    are any value that can be converted to a boolean, with ``True``
    representing high voltage and ``False`` representing low.

    If transmission of an earlier sequence is in progress then this method will
    block until that transmission is complete before beginning the new sequence.

    If looping has been enabled with `RMT.loop`, the sequence will be
    repeated indefinitely. Further calls to this method will block until the
    end of the current loop iteration before immediately beginning to loop the
    new sequence of pulses. Looping sequences longer than 126 pulses is not
    supported by the hardware.

.. staticmethod:: RMT.bitstream_channel([value])

    Select which RMT channel is used by the `machine.bitstream` implementation.
    *value* can be ``None`` or a valid RMT channel number.  The default RMT
    channel is the highest numbered one.

    Passing in ``None`` disables the use of RMT and instead selects a bit-banging
    implementation for `machine.bitstream`.

    Passing in no argument will not change the channel.  This function returns
    the current channel number.

Constants
---------

.. data:: RMT.PULSE_MAX

   Maximum integer that can be set for a pulse duration.

Ultra-Low-Power co-processor
----------------------------

This class gives access to the Ultra Low Power (ULP) co-processor on the ESP32,
ESP32-S2 and ESP32-S3 chips.

.. warning::

    This class does not provide access to the RISCV ULP co-processor available
    on the ESP32-S2 and ESP32-S3 chips.

.. class:: ULP()

    This class provides access to the Ultra-Low-Power co-processor.

.. method:: ULP.set_wakeup_period(period_index, period_us)

    Set the wake-up period.

.. method:: ULP.load_binary(load_addr, program_binary)

    Load a *program_binary* into the ULP at the given *load_addr*.

.. method:: ULP.run(entry_point)

    Start the ULP running at the given *entry_point*.


Constants
---------

.. data:: esp32.WAKEUP_ALL_LOW
          esp32.WAKEUP_ANY_HIGH

   Selects the wake level for pins.

Non-Volatile Storage
--------------------

This class gives access to the Non-Volatile storage managed by ESP-IDF. The NVS is partitioned
into namespaces and each namespace contains typed key-value pairs. The keys are strings and the
values may be various integer types, strings, and binary blobs. The driver currently only
supports 32-bit signed integers and blobs.

.. warning::

    Changes to NVS need to be committed to flash by calling the commit method. Failure
    to call commit results in changes being lost at the next reset.

.. class:: NVS(namespace)

    Create an object providing access to a namespace (which is automatically created if not
    present).

.. method:: NVS.set_i32(key, value)

    Sets a 32-bit signed integer value for the specified key. Remember to call *commit*!

.. method:: NVS.get_i32(key)

    Returns the signed integer value for the specified key. Raises an OSError if the key does not
    exist or has a different type.

.. method:: NVS.set_blob(key, value)

    Sets a binary blob value for the specified key. The value passed in must support the buffer
    protocol, e.g. bytes, bytearray, str. (Note that esp-idf distinguishes blobs and strings, this
    method always writes a blob even if a string is passed in as value.)
    Remember to call *commit*!

.. method:: NVS.get_blob(key, buffer)

    Reads the value of the blob for the specified key into the buffer, which must be a bytearray.
    Returns the actual length read. Raises an OSError if the key does not exist, has a different
    type, or if the buffer is too small.

.. method:: NVS.erase_key(key)

    Erases a key-value pair.

.. method:: NVS.commit()

    Commits changes made by *set_xxx* methods to flash.