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espnow – ESP-NOW asyncio support.

ESP-NOW asyncio support.

Attributes

`ADDR_LEN`
`KEY_LEN`
`MAX_DATA_LEN`
`MAX_ENCRYPT_PEER_NUM`
`MAX_TOTAL_PEER_NUM`

Classes

`AIOESPNow`	The `AIOESPNow` class inherits all the methods of `ESPNow`
`ESPNow`	Returns the singleton ESPNow object. As this is a singleton, all calls to

Module Contents

class espnow.AIOESPNow

Bases: ESPNow

The AIOESPNow class inherits all the methods of ESPNow and extends the interface with the following async methods.

async __anext__() → Incomplete

AIOESPNow also supports reading incoming messages by asynchronous iteration using async for; eg:

e = AIOESPNow()
e.active(True)
async def recv_till_halt(e):
    async for mac, msg in e:
        print(mac, msg)
        if msg == b'halt':
          break
asyncio.run(recv_till_halt(e))

_aiter__() → Incomplete

AIOESPNow also supports reading incoming messages by asynchronous iteration using async for; eg:

e = AIOESPNow()
e.active(True)
async def recv_till_halt(e):
    async for mac, msg in e:
        print(mac, msg)
        if msg == b'halt':
          break
asyncio.run(recv_till_halt(e))

async airecv() → Incomplete: Asyncio support for ESPNow.irecv(). Note that this method does not take a timeout value as argument.

async arecv() → Incomplete: Asyncio support for ESPNow.recv(). Note that this method does not take a timeout value as argument.

async asend(msg) → Incomplete: Asyncio support for ESPNow.send().

class espnow.ESPNow

Bases: _espnow.ESPNowBase, Iterator

Returns the singleton ESPNow object. As this is a singleton, all calls to espnow.ESPNow() return a reference to the same object.

Note

Some methods are available only on the ESP32 due to code size restrictions on the ESP8266 and differences in the Espressif API.

active(flag: Any | None = None) → Incomplete

Initialise or de-initialise the ESP-NOW communication protocol depending on the value of the flag optional argument.

Arguments:

flag: Any python value which can be converted to a boolean type.
- True: Prepare the software and hardware for use of the ESP-NOW communication protocol, including:
  - initialise the ESPNow data structures,
  - allocate the recv data buffer,
  - invoke esp_now_init() and
  - register the send and recv callbacks.
- False: De-initialise the Espressif ESP-NOW software stack (esp_now_deinit()), disable callbacks, deallocate the recv data buffer and deregister all peers.

If flag is not provided, return the current status of the ESPNow interface.

Returns:: True if interface is currently active, else False.

add_peer(mac, lmk: Any | None = None, channel: Any | None = None, ifidx: Any | None = None, encrypt: Any | None = None) → Incomplete

Add/register the provided mac address as a peer. Additional parameters may also be specified as positional or keyword arguments (any parameter set to None will be set to it’s default value):

Arguments:

mac: The MAC address of the peer (as a 6-byte byte-string).
lmk: The Local Master Key (LMK) key used to encrypt data transfers with this peer (unless the encrypt parameter is set to False). Must be:
- a byte-string or bytearray or string of length espnow.KEY_LEN (16 bytes), or
- any non True python value (default= b''), signifying an empty key which will disable encryption.
channel: The wifi channel (2.4GHz) to communicate with this peer. Must be an integer from 0 to 14. If channel is set to 0 the current channel of the wifi device will be used. (default=0)
ifidx: (ESP32 only) Index of the wifi interface which will be used to send data to this peer. Must be an integer set to network.STA_IF (=0) or network.AP_IF (=1). (default=0/network.STA_IF). See `ESPNow and Wifi Operation`_ below for more information.
encrypt: (ESP32 only) If set to True data exchanged with this peer will be encrypted with the PMK and LMK. (default = True if lmk is set to a valid key, else False)

ESP8266: Keyword args may not be used on the ESP8266.

Note: The maximum number of peers which may be registered is 20 (espnow.MAX_TOTAL_PEER_NUM), with a maximum of 6 (espnow.MAX_ENCRYPT_PEER_NUM) of those peers with encryption enabled (see ESP_NOW_MAX_ENCRYPT_PEER_NUM in the Espressif API docs).

Raises:

OSError(num, "ESP_ERR_ESPNOW_NOT_INIT") if not initialised.
OSError(num, "ESP_ERR_ESPNOW_EXIST") if mac is already registered.
OSError(num, "ESP_ERR_ESPNOW_FULL") if too many peers are already registered.
ValueError() on invalid keyword args or values.

any() → Incomplete

Check if data is available to be read with ESPNow.recv().

For more sophisticated querying of available characters use select.poll():

import select
import espnow

e = espnow.ESPNow()
poll = select.poll()
poll.register(e, select.POLLIN)
poll.poll(timeout)

Returns:: True if data is available to be read, else False.

config(param) → str

Set or get configuration values of the ESPNow interface. To set values, use the keyword syntax, and one or more parameters can be set at a time. To get a value the parameter name should be quoted as a string, and just one parameter is queried at a time.

Note: Getting parameters is not supported on the ESP8266.

Options:

rxbuf: (default=526) Get/set the size in bytes of the internal buffer used to store incoming ESPNow packet data. The default size is selected to fit two max-sized ESPNow packets (250 bytes) with associated mac_address (6 bytes), a message byte count (1 byte) and RSSI data plus buffer overhead. Increase this if you expect to receive a lot of large packets or expect bursty incoming traffic.

Note: The recv buffer is allocated by ESPNow.active(). Changing this value will have no effect until the next call of ESPNow.active(True).

timeout_ms: (default=300,000) Default timeout (in milliseconds) for receiving ESPNow messages. If timeout_ms is less than zero, then wait forever. The timeout can also be provided as arg to recv()/irecv()/recvinto().

rate: (ESP32 only, IDF>=4.3.0 only) Set the transmission speed for ESPNow packets. Must be set to a number from the allowed numeric values in enum wifi_phy_rate_t.

Returns:: None or the value of the parameter being queried.

Raises:

OSError(num, "ESP_ERR_ESPNOW_NOT_INIT") if not initialised.
ValueError() on invalid configuration options or values.

del_peer(mac) → Incomplete

Deregister the peer associated with the provided mac address.

Returns:: None

Raises:

OSError(num, "ESP_ERR_ESPNOW_NOT_INIT") if not initialised.
OSError(num, "ESP_ERR_ESPNOW_NOT_FOUND") if mac is not registered.
ValueError() on invalid mac values.

get_peer(mac) → Incomplete

Return information on a registered peer.

Returns:: (mac, lmk, channel, ifidx, encrypt): a tuple of the “peer info” associated with the given mac address.

Raises:

OSError(num, "ESP_ERR_ESPNOW_NOT_INIT") if not initialised.
OSError(num, "ESP_ERR_ESPNOW_NOT_FOUND") if mac is not registered.
ValueError() on invalid mac values.

get_peers() → Tuple: Return the “peer info” parameters for all the registered peers (as a tuple of tuples).

irecv(timeout_ms: Any | None = None) → Incomplete

Works like ESPNow.recv() but will reuse internal bytearrays to store the return values: [mac, msg], so that no new memory is allocated on each call.

Arguments:: timeout_ms: (Optional) Timeout in milliseconds (see ESPNow.recv()).

Returns:

As for ESPNow.recv(), except that msg is a bytearray, instead of a bytestring. On the ESP8266, mac will also be a bytearray.

Raises:

See ESPNow.recv().

Note: You may also read messages by iterating over the ESPNow object, which will use the irecv() method for alloc-free reads, eg:

import espnow
e = espnow.ESPNow(); e.active(True)
for mac, msg in e:
    print(mac, msg)
    if mac is None:   # mac, msg will equal (None, None) on timeout
        break

irq(callback) → Incomplete

Set a callback function to be called as soon as possible after a message has been received from another ESPNow device. The callback function will be called with the ESPNow instance object as an argument. For more reliable operation, it is recommended to read out as many messages as are available when the callback is invoked and to set the read timeout to zero, eg:

def recv_cb(e):
    while True:  # Read out all messages waiting in the buffer
        mac, msg = e.irecv(0)  # Don't wait if no messages left
        if mac is None:
            return
        print(mac, msg)
e.irq(recv_cb)

The irq() callback method is an alternative method for processing incoming messages, especially if the data rate is moderate and the device is not too busy but there are some caveats:

The scheduler stack can overflow and callbacks will be missed if packets are arriving at a sufficient rate or if other MicroPython components (eg, bluetooth, machine.Pin.irq(), machine.timer, i2s, …) are exercising the scheduler stack. This method may be less reliable for dealing with bursts of messages, or high throughput or on a device which is busy dealing with other hardware operations.
For more information on scheduled function callbacks see: micropython.schedule().

mod_peer(mac, param=value, *args, **kwargs) → None: Modify the parameters of the peer associated with the provided mac address. Parameters may be provided as positional or keyword arguments (see ESPNow.add_peer()). Any parameter that is not set (or set to None) will retain the existing value for that parameter.

peer_count() → int

Return the number of registered peers:

(peer_num, encrypt_num): where
- peer_num is the number of peers which are registered, and
- encrypt_num is the number of encrypted peers.

recv(timeout_ms: Any | None = None) → List | Tuple[None, None]

Wait for an incoming message and return the mac address of the peer and the message. Note: It is not necessary to register a peer (using add_peer()) to receive a message from that peer.

Arguments:

timeout_ms: (Optional): May have the following values.
- 0: No timeout. Return immediately if no data is available;
- > 0: Specify a timeout value in milliseconds;
- < 0: Do not timeout, ie. wait forever for new messages; or
- None (or not provided): Use the default timeout value set with ESPNow.config().

Returns:

(None, None) if timeout is reached before a message is received, or
[mac, msg]: where:
- mac is a bytestring containing the address of the device which sent the message, and
- msg is a bytestring containing the message.

Raises:

OSError(num, "ESP_ERR_ESPNOW_NOT_INIT") if not initialised.
OSError(num, "ESP_ERR_ESPNOW_IF") if the wifi interface is not active().
ValueError() on invalid timeout_ms values.

ESPNow.recv() will allocate new storage for the returned list and the peer and msg bytestrings. This can lead to memory fragmentation if the data rate is high. See ESPNow.irecv() for a memory-friendly alternative.

recvinto(data, timeout_ms: Any | None = None) → int

Wait for an incoming message and return the length of the message in bytes. This is the low-level method used by both recv() and irecv() to read messages.

Arguments:

data: A list of at least two elements, [peer, msg]. msg must be a bytearray large enough to hold the message (250 bytes). On the ESP8266, peer should be a bytearray of 6 bytes. The MAC address of the sender and the message will be stored in these bytearrays (see Note on ESP32 below).

timeout_ms: (Optional) Timeout in milliseconds (see ESPNow.recv()).

Returns:

Length of message in bytes or 0 if timeout_ms is reached before a message is received.

Raises:

See ESPNow.recv().

Note: On the ESP32:

It is unnecessary to provide a bytearray in the first element of the data list because it will be replaced by a reference to a unique peer address in the peer device table (see ESPNow.peers_table).
If the list is at least 4 elements long, the rssi and timestamp values will be saved as the 3rd and 4th elements.

send(peer, msg, mac=None, sync=True) → Incomplete

Send the data contained in msg to the peer with given network mac address. In the second form, mac=None and sync=True. The peer must be registered with ESPNow.add_peer() before the message can be sent.

Arguments:

mac: byte string exactly espnow.ADDR_LEN (6 bytes) long or None. If mac is None (ESP32 only) the message will be sent to all registered peers, except any broadcast or multicast MAC addresses.
msg: string or byte-string up to espnow.MAX_DATA_LEN (250) bytes long.
sync:
- True: (default) send msg to the peer(s) and wait for a response (or not).
- False send msg and return immediately. Responses from the peers will be discarded.

Returns:: True if sync=False or if sync=True and all peers respond, else False.

Raises:

OSError(num, "ESP_ERR_ESPNOW_NOT_INIT") if not initialised.
OSError(num, "ESP_ERR_ESPNOW_NOT_FOUND") if peer is not registered.
OSError(num, "ESP_ERR_ESPNOW_IF") the wifi interface is not active().
OSError(num, "ESP_ERR_ESPNOW_NO_MEM") internal ESP-NOW buffers are full.
ValueError() on invalid values for the parameters.

Note: A peer will respond with success if its wifi interface is active() and set to the same channel as the sender, regardless of whether it has initialised it’s ESP-NOW system or is actively listening for ESP-NOW traffic (see the Espressif ESP-NOW docs).

set_pmk(pmk) → None

Set the Primary Master Key (PMK) which is used to encrypt the Local Master Keys (LMK) for encrypting messages. If this is not set, a default PMK is used by the underlying Espressif ESP-NOW software stack.

Note: messages will only be encrypted if lmk is also set in ESPNow.add_peer() (see Security in the Espressif API docs).

Arguments:: pmk: Must be a byte string, bytearray or string of length espnow.KEY_LEN (16 bytes).

Returns:: None

Raises:: ValueError() on invalid pmk values.

stats() → Incomplete

Returns:

A 5-tuple containing the number of packets sent/received/lost:

(tx_pkts, tx_responses, tx_failures, rx_packets, rx_dropped_packets)

Incoming packets are dropped when the recv buffers are full. To reduce packet loss, increase the rxbuf config parameters and ensure you are reading messages as quickly as possible.

Note: Dropped packets will still be acknowledged to the sender as received.

peers_table: Dict

a dict of known peer devices and rssi values:

{peer: [rssi, time_ms], ...}

where:

peer is the peer MAC address (as bytes);
rssi is the wifi signal strength in dBm (-127 to 0) of the last

message received from the peer; and - time_ms is the time the message was received (in milliseconds since system boot - wraps every 12 days).

Example:

>>> e.peers_table

{b’ªªªªªª’: [-31, 18372], b’»»»»»»’: [-43, 12541]}

Note: the mac addresses returned by recv() are references to the peer key values in the peer device table.

Note: RSSI and timestamp values in the device table are updated only when the message is read by the application.

Type:: A reference to the peer device table

espnow.ADDR_LEN: Incomplete = 6

espnow.KEY_LEN: Incomplete = 16

espnow.MAX_DATA_LEN: Incomplete = 250

espnow.MAX_ENCRYPT_PEER_NUM: Incomplete = 6

espnow.MAX_TOTAL_PEER_NUM: Incomplete = 20