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.. 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_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:: raw_temperature()
Read the raw value of the internal temperature sensor, returning an integer.
.. function:: hall_sensor()
Read the raw value of the internal Hall 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 information returned is *not* useful to troubleshoot Python allocation failures,
use `micropython.mem_info()` instead.
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)]
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)
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``.
.. classmethod:: Partition.find(type=TYPE_APP, subtype=0xff, label=None)
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.
.. 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:`os.AbstractBlockDev`.
.. method:: Partition.set_boot()
Sets the partition as the boot partition.
.. 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 firmare 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 (0-32,768) 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*).
.. method:: 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 32767 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.
Ultra-Low-Power co-processor
----------------------------
.. 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.
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