esp32 — functionality specific to the ESP32

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

Functions

esp32.wake_on_touch(wake)

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

esp32.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.

esp32.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.

esp32.raw_temperature()

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

esp32.hall_sensor()

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

esp32.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 esp32.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=255, 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.

Partition.info()

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

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

These methods implement the simple and extended block protocol defined by uos.AbstractBlockDev.

Partition.set_boot()

Sets the partition as the boot partition.

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

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.

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.

esp32.HEAP_DATA
esp32.HEAP_EXEC

Used in idf_heap_info.

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)

# To use carrier frequency
r = esp32.RMT(0, pin=Pin(18), clock_div=8, carrier_freq=38000)
r  # RMT(channel=0, pin=18, source_freq=80000000, clock_div=8, carrier_freq=38000, carrier_duty_percent=50)

# The channel resolution is 100ns (1/(source_freq/clock_div)).
r.write_pulses((1, 20, 2, 40), start=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 specificed 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.

To enable the carrier frequency feature of the esp32 hardware, specify the carrier_freq as something like 38000, a typical IR carrier frequency.

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..

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 esp32.RMT(channel, \*, pin=None, clock_div=8, carrier_freq=0, carrier_duty_percent=50)

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. carrier_freq is used to enable the carrier feature and specify its frequency, default value is 0 (not enabled). To enable, specify a positive integer. carrier_duty_percent defaults to 50.

RMT.source_freq()

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

RMT.clock_div()

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

RMT.wait_done(timeout=0)

Returns True if RMT.write_pulses has completed.

If timeout (defined in ticks of source_freq / clock_div) is specified the method will wait for timeout or until RMT.write_pulses is complete, returning False if the channel continues to transmit.

Warning

Avoid using wait_done() if looping is enabled.

RMT.loop(enable_loop)

Configure looping on the channel, allowing a stream of pulses to be indefinitely repeated. enable_loop is bool, set to True to enable looping.

RMT.write_pulses(pulses, start)

Begin sending pulses, a list or tuple defining the stream of pulses. The length of each pulse is defined by a number to be multiplied by the channel resolution (1 / (source_freq / clock_div)). start defines whether the stream starts at 0 or 1.

Ultra-Low-Power co-processor

class esp32.ULP

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

ULP.set_wakeup_period(period_index, period_us)

Set the wake-up period.

ULP.load_binary(load_addr, program_binary)

Load a program_binary into the ULP at the given load_addr.

ULP.run(entry_point)

Start the ULP running at the given entry_point.

Constants

esp32.WAKEUP_ALL_LOW
esp32.WAKEUP_ANY_HIGH

Selects the wake level for pins.