340 lines
13 KiB
ReStructuredText
340 lines
13 KiB
ReStructuredText
.. currentmodule:: esp32
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:mod:`esp32` --- functionality specific to the ESP32
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====================================================
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.. module:: esp32
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:synopsis: functionality specific to the ESP32
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The ``esp32`` module contains functions and classes specifically aimed at
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controlling ESP32 modules.
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Functions
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---------
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.. function:: wake_on_touch(wake)
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Configure whether or not a touch will wake the device from sleep.
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*wake* should be a boolean value.
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.. function:: wake_on_ext0(pin, level)
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Configure how EXT0 wakes the device from sleep. *pin* can be ``None``
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or a valid Pin object. *level* should be ``esp32.WAKEUP_ALL_LOW`` or
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``esp32.WAKEUP_ANY_HIGH``.
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.. function:: wake_on_ext1(pins, level)
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Configure how EXT1 wakes the device from sleep. *pins* can be ``None``
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or a tuple/list of valid Pin objects. *level* should be ``esp32.WAKEUP_ALL_LOW``
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or ``esp32.WAKEUP_ANY_HIGH``.
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.. function:: raw_temperature()
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Read the raw value of the internal temperature sensor, returning an integer.
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.. function:: hall_sensor()
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Read the raw value of the internal Hall sensor, returning an integer.
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.. function:: idf_heap_info(capabilities)
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Returns information about the ESP-IDF heap memory regions. One of them contains
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the MicroPython heap and the others are used by ESP-IDF, e.g., for network
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buffers and other data. This data is useful to get a sense of how much memory
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is available to ESP-IDF and the networking stack in particular. It may shed
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some light on situations where ESP-IDF operations fail due to allocation failures.
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The information returned is *not* useful to troubleshoot Python allocation failures,
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use `micropython.mem_info()` instead.
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The capabilities parameter corresponds to ESP-IDF's ``MALLOC_CAP_XXX`` values but the
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two most useful ones are predefined as `esp32.HEAP_DATA` for data heap regions and
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`esp32.HEAP_EXEC` for executable regions as used by the native code emitter.
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The return value is a list of 4-tuples, where each 4-tuple corresponds to one heap
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and contains: the total bytes, the free bytes, the largest free block, and
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the minimum free seen over time.
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Example after booting::
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>>> import esp32; esp32.idf_heap_info(esp32.HEAP_DATA)
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[(240, 0, 0, 0), (7288, 0, 0, 0), (16648, 4, 4, 4), (79912, 35712, 35512, 35108),
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(15072, 15036, 15036, 15036), (113840, 0, 0, 0)]
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Flash partitions
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----------------
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This class gives access to the partitions in the device's flash memory and includes
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methods to enable over-the-air (OTA) updates.
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.. class:: Partition(id)
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Create an object representing a partition. *id* can be a string which is the label
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of the partition to retrieve, or one of the constants: ``BOOT`` or ``RUNNING``.
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.. classmethod:: Partition.find(type=TYPE_APP, subtype=0xff, label=None)
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Find a partition specified by *type*, *subtype* and *label*. Returns a
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(possibly empty) list of Partition objects. Note: ``subtype=0xff`` matches any subtype
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and ``label=None`` matches any label.
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.. method:: Partition.info()
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Returns a 6-tuple ``(type, subtype, addr, size, label, encrypted)``.
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.. method:: Partition.readblocks(block_num, buf)
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Partition.readblocks(block_num, buf, offset)
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.. method:: Partition.writeblocks(block_num, buf)
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Partition.writeblocks(block_num, buf, offset)
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.. method:: Partition.ioctl(cmd, arg)
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These methods implement the simple and :ref:`extended
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<block-device-interface>` block protocol defined by
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:class:`os.AbstractBlockDev`.
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.. method:: Partition.set_boot()
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Sets the partition as the boot partition.
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.. method:: Partition.get_next_update()
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Gets the next update partition after this one, and returns a new Partition object.
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Typical usage is ``Partition(Partition.RUNNING).get_next_update()``
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which returns the next partition to update given the current running one.
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.. classmethod:: Partition.mark_app_valid_cancel_rollback()
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Signals that the current boot is considered successful.
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Calling ``mark_app_valid_cancel_rollback`` is required on the first boot of a new
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partition to avoid an automatic rollback at the next boot.
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This uses the ESP-IDF "app rollback" feature with "CONFIG_BOOTLOADER_APP_ROLLBACK_ENABLE"
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and an ``OSError(-261)`` is raised if called on firmware that doesn't have the
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feature enabled.
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It is OK to call ``mark_app_valid_cancel_rollback`` on every boot and it is not
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necessary when booting firmare that was loaded using esptool.
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Constants
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~~~~~~~~~
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.. data:: Partition.BOOT
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Partition.RUNNING
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Used in the `Partition` constructor to fetch various partitions: ``BOOT`` is the
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partition that will be booted at the next reset and ``RUNNING`` is the currently
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running partition.
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.. data:: Partition.TYPE_APP
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Partition.TYPE_DATA
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Used in `Partition.find` to specify the partition type: ``APP`` is for bootable
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firmware partitions (typically labelled ``factory``, ``ota_0``, ``ota_1``), and
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``DATA`` is for other partitions, e.g. ``nvs``, ``otadata``, ``phy_init``, ``vfs``.
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.. data:: HEAP_DATA
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HEAP_EXEC
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Used in `idf_heap_info`.
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.. _esp32.RMT:
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RMT
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---
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The RMT (Remote Control) module, specific to the ESP32, was originally designed
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to send and receive infrared remote control signals. However, due to a flexible
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design and very accurate (as low as 12.5ns) pulse generation, it can also be
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used to transmit or receive many other types of digital signals::
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import esp32
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from machine import Pin
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r = esp32.RMT(0, pin=Pin(18), clock_div=8)
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r # RMT(channel=0, pin=18, source_freq=80000000, clock_div=8, idle_level=0)
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# To apply a carrier frequency to the high output
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r = esp32.RMT(0, pin=Pin(18), clock_div=8, tx_carrier=(38000, 50, 1))
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# The channel resolution is 100ns (1/(source_freq/clock_div)).
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r.write_pulses((1, 20, 2, 40), 0) # Send 0 for 100ns, 1 for 2000ns, 0 for 200ns, 1 for 4000ns
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The input to the RMT module is an 80MHz clock (in the future it may be able to
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configure the input clock but, for now, it's fixed). ``clock_div`` *divides*
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the clock input which determines the resolution of the RMT channel. The
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numbers specified in ``write_pulses`` are multiplied by the resolution to
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define the pulses.
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``clock_div`` is an 8-bit divider (0-255) and each pulse can be defined by
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multiplying the resolution by a 15-bit (0-32,768) number. There are eight
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channels (0-7) and each can have a different clock divider.
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So, in the example above, the 80MHz clock is divided by 8. Thus the
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resolution is (1/(80Mhz/8)) 100ns. Since the ``start`` level is 0 and toggles
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with each number, the bitstream is ``0101`` with durations of [100ns, 2000ns,
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100ns, 4000ns].
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For more details see Espressif's `ESP-IDF RMT documentation.
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<https://docs.espressif.com/projects/esp-idf/en/latest/api-reference/peripherals/rmt.html>`_.
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.. Warning::
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The current MicroPython RMT implementation lacks some features, most notably
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receiving pulses. RMT should be considered a
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*beta feature* and the interface may change in the future.
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.. class:: RMT(channel, *, pin=None, clock_div=8, idle_level=False, tx_carrier=None)
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This class provides access to one of the eight RMT channels. *channel* is
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required and identifies which RMT channel (0-7) will be configured. *pin*,
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also required, configures which Pin is bound to the RMT channel. *clock_div*
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is an 8-bit clock divider that divides the source clock (80MHz) to the RMT
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channel allowing the resolution to be specified. *idle_level* specifies
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what level the output will be when no transmission is in progress and can
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be any value that converts to a boolean, with ``True`` representing high
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voltage and ``False`` representing low.
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To enable the transmission carrier feature, *tx_carrier* should be a tuple
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of three positive integers: carrier frequency, duty percent (``0`` to
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``100``) and the output level to apply the carrier to (a boolean as per
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*idle_level*).
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.. method:: RMT.source_freq()
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Returns the source clock frequency. Currently the source clock is not
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configurable so this will always return 80MHz.
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.. method:: RMT.clock_div()
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Return the clock divider. Note that the channel resolution is
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``1 / (source_freq / clock_div)``.
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.. method:: RMT.wait_done(*, timeout=0)
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Returns ``True`` if the channel is idle or ``False`` if a sequence of
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pulses started with `RMT.write_pulses` is being transmitted. If the
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*timeout* keyword argument is given then block for up to this many
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milliseconds for transmission to complete.
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.. method:: RMT.loop(enable_loop)
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Configure looping on the channel. *enable_loop* is bool, set to ``True`` to
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enable looping on the *next* call to `RMT.write_pulses`. If called with
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``False`` while a looping sequence is currently being transmitted then the
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current loop iteration will be completed and then transmission will stop.
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.. method:: RMT.write_pulses(duration, data=True)
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Begin transmitting a sequence. There are three ways to specify this:
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**Mode 1:** *duration* is a list or tuple of durations. The optional *data*
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argument specifies the initial output level. The output level will toggle
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after each duration.
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**Mode 2:** *duration* is a positive integer and *data* is a list or tuple
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of output levels. *duration* specifies a fixed duration for each.
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**Mode 3:** *duration* and *data* are lists or tuples of equal length,
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specifying individual durations and the output level for each.
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Durations are in integer units of the channel resolution (as described
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above), between 1 and 32767 units. Output levels are any value that can
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be converted to a boolean, with ``True`` representing high voltage and
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``False`` representing low.
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If transmission of an earlier sequence is in progress then this method will
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block until that transmission is complete before beginning the new sequence.
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If looping has been enabled with `RMT.loop`, the sequence will be
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repeated indefinitely. Further calls to this method will block until the
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end of the current loop iteration before immediately beginning to loop the
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new sequence of pulses. Looping sequences longer than 126 pulses is not
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supported by the hardware.
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.. staticmethod:: RMT.bitstream_channel([value])
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Select which RMT channel is used by the `machine.bitstream` implementation.
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*value* can be ``None`` or a valid RMT channel number. The default RMT
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channel is the highest numbered one.
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Passing in ``None`` disables the use of RMT and instead selects a bit-banging
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implementation for `machine.bitstream`.
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Passing in no argument will not change the channel. This function returns
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the current channel number.
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Ultra-Low-Power co-processor
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----------------------------
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.. class:: ULP()
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This class provides access to the Ultra-Low-Power co-processor.
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.. method:: ULP.set_wakeup_period(period_index, period_us)
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Set the wake-up period.
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.. method:: ULP.load_binary(load_addr, program_binary)
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Load a *program_binary* into the ULP at the given *load_addr*.
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.. method:: ULP.run(entry_point)
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Start the ULP running at the given *entry_point*.
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Constants
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---------
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.. data:: esp32.WAKEUP_ALL_LOW
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esp32.WAKEUP_ANY_HIGH
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Selects the wake level for pins.
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Non-Volatile Storage
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--------------------
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This class gives access to the Non-Volatile storage managed by ESP-IDF. The NVS is partitioned
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into namespaces and each namespace contains typed key-value pairs. The keys are strings and the
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values may be various integer types, strings, and binary blobs. The driver currently only
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supports 32-bit signed integers and blobs.
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.. warning::
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Changes to NVS need to be committed to flash by calling the commit method. Failure
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to call commit results in changes being lost at the next reset.
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.. class:: NVS(namespace)
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Create an object providing access to a namespace (which is automatically created if not
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present).
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.. method:: NVS.set_i32(key, value)
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Sets a 32-bit signed integer value for the specified key. Remember to call *commit*!
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.. method:: NVS.get_i32(key)
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Returns the signed integer value for the specified key. Raises an OSError if the key does not
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exist or has a different type.
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.. method:: NVS.set_blob(key, value)
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Sets a binary blob value for the specified key. The value passed in must support the buffer
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protocol, e.g. bytes, bytearray, str. (Note that esp-idf distinguishes blobs and strings, this
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method always writes a blob even if a string is passed in as value.)
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Remember to call *commit*!
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.. method:: NVS.get_blob(key, buffer)
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Reads the value of the blob for the specified key into the buffer, which must be a bytearray.
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Returns the actual length read. Raises an OSError if the key does not exist, has a different
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type, or if the buffer is too small.
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.. method:: NVS.erase_key(key)
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Erases a key-value pair.
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.. method:: NVS.commit()
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Commits changes made by *set_xxx* methods to flash.
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