M5-ESPNOW

M5-ESPNOW is a connection-less wireless communication protocol supporting:

  • Direct communication between up to 20 registered peers:

    • Without the need for a wireless access point (AP),

  • Encrypted and unencrypted communication (up to 6 encrypted peers),

  • Message sizes up to 250 bytes,

  • Can operate alongside Wifi operation (network.WLAN) on ESP32 Series.

It provides simpler and more user-friendly APIs.

ESPNOW example:

import os, sys, io
import M5
from M5 import *
from m5espnow import *
import time
import random

def espnow_recv_callback(espnow_obj):
    espnow_mac, espnow_data = espnow_obj.recv_data()
    print(espnow_mac)
    print(espnow_data)

espnow_0 = M5ESPNow(0)
espnow_0.set_irq_callback(espnow_recv_callback)
espnow_0.set_add_peer('xxxxxxxxxxxx', 1, 0, False)

while True::
    espnow_0.send_data(1, random.randint(1000000, 9999999))
    time.sleep(2)

UIFLOW2 Example:

m5espnow-example.png

m5espnow-example.m5f2

class M5ESPNow

Constructors

class M5ESPNow(wifi_ch)

Create a M5ESPNow object

Arguments:

  • wifi_ch: 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)

UIFLOW2:

init.png

M5ESPNow.deinit()

De-initialise the ESP-NOW software stack, disable callbacks, deallocate the recv data buffer and deregister all peers.

UIFLOW2:

deinit.png

M5ESPNow.get_mac(mode)

Get the device network MAC address.

Arguments:

mode: 0: M5ESPNow.STA 1: M5ESPNow.AP

  • Return: bytes

UIFLOW2:

get_mac.png

M5ESPNow.get_peer_list(encrypt)

Return the parameters for all the registered peers (as a list).

Arguments:

encrypt: 0: normal peer MAC address 1: encrypt peer MAC address

  • Return: list

UIFLOW2:

get_peer_list.png

M5ESPNow.get_remote_mac(select, ssid)

To find remote mac by remote ssid.

Arguments:

select: 0: channel 1: MAC.

ssid: WiFi access point name in string.

UIFLOW2:

get_remote_mac.png

M5ESPNow.set_ap_ssid(ssid)

Set the SSID configure in AP mode.

Arguments:

ssid: WiFi access point name in string.

UIFLOW2:

set_ap_ssid.png

Methods

M5ESPNow.set_add_peer(peer_mac, peer_id, ifidx, encrypt, lmk)

Add/register the provided mac address as a peer.

Arguments:

  • peer_mac: The MAC address of the peer (as a Hex-string).

  • peer_id: The MAC address is stored in the ID list. ID is must be an integer from 1 to 20

  • ifidx: 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).

  • encrypt: If set to True data exchanged with this peer will be encrypted with the PMK and LMK. (default = False if lmk is set to a valid key, else False)

  • 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 16 bytes.

UIFLOW2:

set_add_peer.png

M5ESPNow.set_delete_peer(peer_id)

Deregister the peer associated with the provided peer_mac address.

Arguments:

  • peer_id: The MAC address is stored in the ID list. ID is must be an integer from 1 to 20

UIFLOW2:

set_delete_peer.png

M5ESPNow.set_pmk_encrypt(pmk)

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.

Arguments:

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

UIFLOW2:

set_pmk_encrypt.png

M5ESPNow.send_data(peer_id, msg)

Send the data in msg to the stored peer ID peer_id with the given network.

Arguments:

  • peer_id: The MAC address is stored in the ID list. ID is must be an integer from 1 to 20

  • msg: int, float, list, string and byte-string up to 250 bytes

UIFLOW2:

send_data.png

send_data1.png

send_data2.png

M5ESPNow.broadcast_data(msg)

All devices will also receive messages sent to the broadcast MAC address (b'\xff\xff\xff\xff\xff\xff')

Arguments:

  • msg: int, float, list, string and byte-string up to 250 bytes

UIFLOW2:

broadcast_data.png

broadcast_data1.png

broadcast_data2.png

M5ESPNow.set_irq_callback(callback)

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.

def espnow_recv_callback(espnow_obj):
    espnow_mac, espnow_data = espnow_obj.recv_data()
    print(espnow_mac, espnow_data)

M5ESPNow.set_irq_callback(espnow_recv_callback)
recv_data()

Wait for an incoming message and return values: [mac, msg].

UIFLOW2:

set_irq_callback.png

M5ESPNow._bytes_to_hex_str(bytes)

To get a hex string from a bytes string

Arguments:

bytes: bytearray

  • Return: string: Hex-string

UIFLOW2:

_bytes_to_hex_str.png

M5ESPNow._hex_str_to_bytes(hexstr)

To get a bytes string from a hex string

Arguments:

hexstr: Hex-string

  • Return: bytes: bytearray

UIFLOW2:

_hex_str_to_bytes.png

M5ESPNow._bytes_to(bytes, format)

To get a int or float or list valuefrom a bytes string.

Arguments:

bytes: bytearray.

format: 0: int, 1: float.

  • Return: int or float

UIFLOW2:

_bytes_to.png

M5ESPNow._to_bytes(variable)

To get a bytes string from a int or float or list value

Arguments:

variable: int or float or list

  • Return: bytes: bytearray

UIFLOW2:

_to_bytes.png