Współpraca nRF24L01 z MicroPython

Poniżej znajdziesz przykładowy kod w języku MicroPython dla dwóch mikroprocesorów ESP8266, które komunikują się ze sobą za pomocą modułów nRF24L01. Do tego celu użyłem biblioteki “rf24” dostępnej dla MicroPython.

Kod biblioteki nrf24l01.py

"""NRF24L01 driver for MicroPython
"""

from micropython import const
import utime

# nRF24L01+ registers
CONFIG = const(0x00)
EN_RXADDR = const(0x02)
SETUP_AW = const(0x03)
SETUP_RETR = const(0x04)
RF_CH = const(0x05)
RF_SETUP = const(0x06)
STATUS = const(0x07)
RX_ADDR_P0 = const(0x0A)
TX_ADDR = const(0x10)
RX_PW_P0 = const(0x11)
FIFO_STATUS = const(0x17)
DYNPD = const(0x1C)

# CONFIG register
EN_CRC = const(0x08)  # enable CRC
CRCO = const(0x04)  # CRC encoding scheme; 0=1 byte, 1=2 bytes
PWR_UP = const(0x02)  # 1=power up, 0=power down
PRIM_RX = const(0x01)  # RX/TX control; 0=PTX, 1=PRX

# RF_SETUP register
POWER_0 = const(0x00)  # -18 dBm
POWER_1 = const(0x02)  # -12 dBm
POWER_2 = const(0x04)  # -6 dBm
POWER_3 = const(0x06)  # 0 dBm
SPEED_1M = const(0x00)
SPEED_2M = const(0x08)
SPEED_250K = const(0x20)

# STATUS register
RX_DR = const(0x40)  # RX data ready; write 1 to clear
TX_DS = const(0x20)  # TX data sent; write 1 to clear
MAX_RT = const(0x10)  # max retransmits reached; write 1 to clear

# FIFO_STATUS register
RX_EMPTY = const(0x01)  # 1 if RX FIFO is empty

# constants for instructions
R_RX_PL_WID = const(0x60)  # read RX payload width
R_RX_PAYLOAD = const(0x61)  # read RX payload
W_TX_PAYLOAD = const(0xA0)  # write TX payload
FLUSH_TX = const(0xE1)  # flush TX FIFO
FLUSH_RX = const(0xE2)  # flush RX FIFO
NOP = const(0xFF)  # use to read STATUS register


class NRF24L01:
    def __init__(self, spi, cs, ce, channel=46, payload_size=16):
        assert payload_size <= 32

        self.buf = bytearray(1)

        # store the pins
        self.spi = spi
        self.cs = cs
        self.ce = ce

        # init the SPI bus and pins
        self.init_spi(4000000)

        # reset everything
        ce.init(ce.OUT, value=0)
        cs.init(cs.OUT, value=1)

        self.payload_size = payload_size
        self.pipe0_read_addr = None
        utime.sleep_ms(5)

        # set address width to 5 bytes and check for device present
        self.reg_write(SETUP_AW, 0b11)
        if self.reg_read(SETUP_AW) != 0b11:
            raise OSError("nRF24L01+ Hardware not responding")

        # disable dynamic payloads
        self.reg_write(DYNPD, 0)

        # auto retransmit delay: 1750us
        # auto retransmit count: 8
        self.reg_write(SETUP_RETR, (6 << 4) | 8)

        # set rf power and speed
        self.set_power_speed(POWER_3, SPEED_250K)  # Best for point to point links

        # init CRC
        self.set_crc(2)

        # clear status flags
        self.reg_write(STATUS, RX_DR | TX_DS | MAX_RT)

        # set channel
        self.set_channel(channel)

        # flush buffers
        self.flush_rx()
        self.flush_tx()

    def init_spi(self, baudrate):
        try:
            master = self.spi.MASTER
        except AttributeError:
            self.spi.init(baudrate=baudrate, polarity=0, phase=0)
        else:
            self.spi.init(master, baudrate=baudrate, polarity=0, phase=0)

    def reg_read(self, reg):
        self.cs(0)
        self.spi.readinto(self.buf, reg)
        self.spi.readinto(self.buf)
        self.cs(1)
        return self.buf[0]

    def reg_write_bytes(self, reg, buf):
        self.cs(0)
        self.spi.readinto(self.buf, 0x20 | reg)
        self.spi.write(buf)
        self.cs(1)
        return self.buf[0]

    def reg_write(self, reg, value):
        self.cs(0)
        self.spi.readinto(self.buf, 0x20 | reg)
        ret = self.buf[0]
        self.spi.readinto(self.buf, value)
        self.cs(1)
        return ret

    def flush_rx(self):
        self.cs(0)
        self.spi.readinto(self.buf, FLUSH_RX)
        self.cs(1)

    def flush_tx(self):
        self.cs(0)
        self.spi.readinto(self.buf, FLUSH_TX)
        self.cs(1)

    # power is one of POWER_x defines; speed is one of SPEED_x defines
    def set_power_speed(self, power, speed):
        setup = self.reg_read(RF_SETUP) & 0b11010001
        self.reg_write(RF_SETUP, setup | power | speed)

    # length in bytes: 0, 1 or 2
    def set_crc(self, length):
        config = self.reg_read(CONFIG) & ~(CRCO | EN_CRC)
        if length == 0:
            pass
        elif length == 1:
            config |= EN_CRC
        else:
            config |= EN_CRC | CRCO
        self.reg_write(CONFIG, config)

    def set_channel(self, channel):
        self.reg_write(RF_CH, min(channel, 125))

    # address should be a bytes object 5 bytes long
    def open_tx_pipe(self, address):
        assert len(address) == 5
        self.reg_write_bytes(RX_ADDR_P0, address)
        self.reg_write_bytes(TX_ADDR, address)
        self.reg_write(RX_PW_P0, self.payload_size)

    # address should be a bytes object 5 bytes long
    # pipe 0 and 1 have 5 byte address
    # pipes 2-5 use same 4 most-significant bytes as pipe 1, plus 1 extra byte
    def open_rx_pipe(self, pipe_id, address):
        assert len(address) == 5
        assert 0 <= pipe_id <= 5
        if pipe_id == 0:
            self.pipe0_read_addr = address
        if pipe_id < 2:
            self.reg_write_bytes(RX_ADDR_P0 + pipe_id, address)
        else:
            self.reg_write(RX_ADDR_P0 + pipe_id, address[0])
        self.reg_write(RX_PW_P0 + pipe_id, self.payload_size)
        self.reg_write(EN_RXADDR, self.reg_read(EN_RXADDR) | (1 << pipe_id))

    def start_listening(self):
        self.reg_write(CONFIG, self.reg_read(CONFIG) | PWR_UP | PRIM_RX)
        self.reg_write(STATUS, RX_DR | TX_DS | MAX_RT)

        if self.pipe0_read_addr is not None:
            self.reg_write_bytes(RX_ADDR_P0, self.pipe0_read_addr)

        self.flush_rx()
        self.flush_tx()
        self.ce(1)
        utime.sleep_us(130)

    def stop_listening(self):
        self.ce(0)
        self.flush_tx()
        self.flush_rx()

    # returns True if any data available to recv
    def any(self):
        return not bool(self.reg_read(FIFO_STATUS) & RX_EMPTY)

    def recv(self):
        # get the data
        self.cs(0)
        self.spi.readinto(self.buf, R_RX_PAYLOAD)
        buf = self.spi.read(self.payload_size)
        self.cs(1)
        # clear RX ready flag
        self.reg_write(STATUS, RX_DR)

        return buf

    # blocking wait for tx complete
    def send(self, buf, timeout=500):
        self.send_start(buf)
        start = utime.ticks_ms()
        result = None
        while result is None and utime.ticks_diff(utime.ticks_ms(), start) < timeout:
            result = self.send_done()  # 1 == success, 2 == fail
        if result == 2:
            raise OSError("send failed")

    # non-blocking tx
    def send_start(self, buf):
        # power up
        self.reg_write(CONFIG, (self.reg_read(CONFIG) | PWR_UP) & ~PRIM_RX)
        utime.sleep_us(150)
        # send the data
        self.cs(0)
        self.spi.readinto(self.buf, W_TX_PAYLOAD)
        self.spi.write(buf)
        if len(buf) < self.payload_size:
            self.spi.write(b"\x00" * (self.payload_size - len(buf)))  # pad out data
        self.cs(1)

        # enable the chip so it can send the data
        self.ce(1)
        utime.sleep_us(15)  # needs to be >10us
        self.ce(0)

    # returns None if send still in progress, 1 for success, 2 for fail
    def send_done(self):
        if not (self.reg_read(STATUS) & (TX_DS | MAX_RT)):
            return None  # tx not finished

        # either finished or failed: get and clear status flags, power down
        status = self.reg_write(STATUS, RX_DR | TX_DS | MAX_RT)
        self.reg_write(CONFIG, self.reg_read(CONFIG) & ~PWR_UP)
        return 1 if status & TX_DS else 2

ESP8266 #1 (Nadawca):

from machine import Pin, SPI
from nrf24 import NRF24L01

# Konfiguracja pinów
ce_pin = Pin(5)  # D1
cs_pin = Pin(4)  # D2

# Konfiguracja SPI
spi = SPI(1, baudrate=1000000, polarity=0, phase=0, sck=Pin(14), mosi=Pin(13), miso=Pin(12))

# Inicjalizacja modułu nRF24L01
radio = NRF24L01(spi, cs_pin, ce_pin)
radio.open_tx_pipe(b'NODE')

# Funkcja do wysyłania wiadomości
def send_message(message):
    radio.send(message.encode('utf-8'))
    print("Sent message:", message)

# Pętla główna
while True:
    send_message("Hello from Node 1!")

ESP8266 #2 (Odbiorca):

from machine import Pin, SPI
from nrf24 import NRF24L01

# Konfiguracja pinów
ce_pin = Pin(5)  # D1
cs_pin = Pin(4)  # D2

# Konfiguracja SPI
spi = SPI(1, baudrate=1000000, polarity=0, phase=0, sck=Pin(14), mosi=Pin(13), miso=Pin(12))

# Inicjalizacja modułu nRF24L01
radio = NRF24L01(spi, cs_pin, ce_pin)
radio.open_rx_pipe(1, b'NODE')

# Funkcja do odbierania wiadomości
def receive_message():
    if radio.any():
        message = radio.recv().decode('utf-8')
        print("Received message:", message)

# Pętla główna
while True:
    receive_message()

  • ESP8266 #1 (Nadawca):
    • VCC -> 3.3V
    • GND -> GND
    • CE -> D5 (Pin 5)
    • CSN -> D4 (Pin 4)
    • SCK -> D14 (Pin 14)
    • MOSI -> D13 (Pin 13)
    • MISO -> D12 (Pin 12)
  • ESP8266 #2 (Odbiorca):
    • VCC -> 3.3V
    • GND -> GND
    • CE -> D5 (Pin 5)
    • CSN -> D4 (Pin 4)
    • SCK -> D14 (Pin 14)
    • MOSI -> D13 (Pin 13)
    • MISO -> D12 (Pin 12)

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