CircuitPython example for Espressif ESP-NOW protocol

espnow_receiver.py

# SPDX-FileCopyrightText: 2023 anecdata
#
# SPDX-License-Identifier: MIT

import time
import traceback
import supervisor
import os
import rtc
import espnow
import espidf
import wifi
import socketpool
import adafruit_ntp

from sekrets import *


#### ESPNOW Receiver
TZ_DEFAULT = -5
SNDR_CH = 0  # channel 1 (unless connected to an AP or acting as an AP)


def struct_time_to_iso_time():
    st = time.localtime()
    tz = TZ_DEFAULT
    return f"{st[0]:04d}-{st[1]:02d}-{st[2]:02d}T{st[3]:02d}:{st[4]:02d}:{st[5]:02d}{tz:+03}:00"

def connect():
    try:
        wifi.radio.connect(os.getenv("WIFI_SSID"), os.getenv("WIFI_PASSWORD"), bssid=AP_BSSID)  # use AP on channel <> 1
        time.sleep(1)  # wait for ap_info
        print(f"{struct_time_to_iso_time()} ipv4={wifi.radio.ipv4_address} channel={wifi.radio.ap_info.channel} rssi={wifi.radio.ap_info.rssi}")
    except ConnectionError as ex:
        traceback.print_exception(ex, ex, ex.__traceback__)

def ntp_to_rtc():
    wifi.radio.enabled = True
    connect()
    try:
        ntp = adafruit_ntp.NTP(pool, tz_offset=TZ_DEFAULT)
        rtc.RTC().datetime = ntp.datetime
        print(f"{struct_time_to_iso_time()} RTC time set with NTP time")
    except Exception as e:
        traceback.print_exception(e, e, e.__traceback__)
    wifi.radio.enabled = False  # lose the wifi channel


time.sleep(3)  # wait for serial
print(f"{'='*25}")
pool = socketpool.SocketPool(wifi.radio)
ntp_to_rtc()

peers = [espnow.Peer(mac=SNDR_MAC, lmk=SNDR_LMK, encrypted=True, channel=SNDR_CH),]
while True:
    with espnow.ESPNow() as e:
        e.set_pmk(RCVR_PMK)

        peers_report = ""
        for peer in peers:
            e.peers.append(peer)
            peers_report += f"mac={peer.mac} lmk={peer.lmk} ch={peer.channel} if={peer.interface} enc={peer.encrypted}\n"

        print(f"{'-'*25}\n{struct_time_to_iso_time()} Receiving...", end=" ")
        while True:
            if e:
                try:
                    packet = e.read()
                    print(f"{packet}")
                    break
                except ValueError as ex:  # Invalid buffer
                    traceback.print_exception(ex, ex, ex.__traceback__)
                    supervisor.reload()
                    break
        print(f"send=[{e.send_success} {e.send_failure}] read=[{e.read_success} {e.read_failure}] buf={e.buffer_size} phy={e.phy_rate} peers={peers_report}", end="")

Do you have examples of how this data should be formatted? For example, the mac address should be AB:CD:EF:GH:IJ or something like ['0x24', '0xec', '0x4a', '0x26', '0x8d', '0xb0'] ?

oh yeah, good question, PMK and LMK are bytes (or, ReadableBuffer), e.g., b'shufyrgetsfdtfyg'
https://docs.circuitpython.org/en/latest/shared-bindings/espnow/index.html#espnow.Peer
https://docs.circuitpython.org/en/latest/shared-bindings/espnow/index.html#espnow.ESPNow.set_pmk
Similarly, MAC address like b'\x00\x1A\xDD\x17\xC2\xA5' (or any equivalent form)
https://docs.circuitpython.org/en/latest/shared-bindings/espnow/index.html#espnow.ESPNowPacket.mac

Thanks!

How about setting the data rate for long range?
The doc says "espnow.ESPNow(buffer_size: = 526, phy_rate: int = 0), but I don't see what 0 means (1mbps? 56mbps?)
The values in the reference https://docs.espressif.com/projects/esp-idf/en/release-v4.4/esp32/api-reference/network/esp_wifi.html#_CPPv415wifi_phy_rate_t are not integer values, as expected by the Circuitpython library.

@stanelie it's an enumeration, so increasing integer values
https://github.com/espressif/esp-idf/blob/a9d0f22193acdf47a5a4db36832ae7068818962b/components/esp_wifi/include/esp_wifi_types.h#L594
the default is 0 (1Mbps), but you can change it

Thanks. Is there a better place for my questions than this thread?

I've tried all the phy_rate values between 0 and 32, and 16 and up do not work. So, I am unable to select the 31 or 32nd values (lora 250 and lora 500) that I want to enable long range. Where should I file a bug report about this issue?

(adafruit/circuitpython#9790)