Examples
nRF24L01 Features
Simple test
Changed in version 2.0.0:
Ensure your device works with this simple test.
examples/nrf24l01_simple_test.py
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120 | import time
import struct
import board
from digitalio import DigitalInOut
# if running this on a ATSAMD21 M0 based board
# from circuitpython_nrf24l01.rf24_lite import RF24
from circuitpython_nrf24l01.rf24 import RF24
# invalid default values for scoping
SPI_BUS, CSN_PIN, CE_PIN = (None, None, None)
try: # on Linux
import spidev
SPI_BUS = spidev.SpiDev() # for a faster interface on linux
CSN_PIN = 0 # use CE0 on default bus (even faster than using any pin)
CE_PIN = DigitalInOut(board.D22) # using pin gpio22 (BCM numbering)
except ImportError: # on CircuitPython only
# using board.SPI() automatically selects the MCU's
# available SPI pins, board.SCK, board.MOSI, board.MISO
SPI_BUS = board.SPI() # init spi bus object
# change these (digital output) pins accordingly
CE_PIN = DigitalInOut(board.D4)
CSN_PIN = DigitalInOut(board.D5)
# initialize the nRF24L01 on the spi bus object
nrf = RF24(SPI_BUS, CSN_PIN, CE_PIN)
# On Linux, csn value is a bit coded
# 0 = bus 0, CE0 # SPI bus 0 is enabled by default
# 10 = bus 1, CE0 # enable SPI bus 2 prior to running this
# 21 = bus 2, CE1 # enable SPI bus 1 prior to running this
# set the Power Amplifier level to -12 dBm since this test example is
# usually run with nRF24L01 transceivers in close proximity
nrf.pa_level = -12
# addresses needs to be in a buffer protocol object (bytearray)
address = [b"1Node", b"2Node"]
# to use different addresses on a pair of radios, we need a variable to
# uniquely identify which address this radio will use to transmit
# 0 uses address[0] to transmit, 1 uses address[1] to transmit
radio_number = bool(
int(input("Which radio is this? Enter '0' or '1'. Defaults to '0' ") or 0)
)
# set TX address of RX node into the TX pipe
nrf.open_tx_pipe(address[radio_number]) # always uses pipe 0
# set RX address of TX node into an RX pipe
nrf.open_rx_pipe(1, address[not radio_number]) # using pipe 1
# using the python keyword global is bad practice. Instead we'll use a 1 item
# list to store our float number for the payloads sent
payload = [0.0]
# uncomment the following 3 lines for compatibility with TMRh20 library
# nrf.allow_ask_no_ack = False
# nrf.dynamic_payloads = False
# nrf.payload_length = 4
def master(count=5): # count = 5 will only transmit 5 packets
"""Transmits an incrementing integer every second"""
nrf.listen = False # ensures the nRF24L01 is in TX mode
while count:
# use struct.pack to structure your data
# into a usable payload
buffer = struct.pack("<f", payload[0])
# "<f" means a single little endian (4 byte) float value.
start_timer = time.monotonic_ns() # start timer
result = nrf.send(buffer)
end_timer = time.monotonic_ns() # end timer
if not result:
print("send() failed or timed out")
else:
print(
"Transmission successful! Time to Transmit:",
"{} us. Sent: {}".format((end_timer - start_timer) / 1000, payload[0]),
)
payload[0] += 0.01
time.sleep(1)
count -= 1
def slave(timeout=6):
"""Polls the radio and prints the received value. This method expires
after 6 seconds of no received transmission"""
nrf.listen = True # put radio into RX mode and power up
start = time.monotonic()
while (time.monotonic() - start) < timeout:
if nrf.available():
# grab information about the received payload
payload_size, pipe_number = (nrf.any(), nrf.pipe)
# fetch 1 payload from RX FIFO
buffer = nrf.read() # also clears nrf.irq_dr status flag
# expecting a little endian float, thus the format string "<f"
# buffer[:4] truncates padded 0s if dynamic payloads are disabled
payload[0] = struct.unpack("<f", buffer[:4])[0]
# print details about the received packet
print(
"Received {} bytes on pipe {}: {}".format(
payload_size, pipe_number, payload[0]
)
)
start = time.monotonic()
# recommended behavior is to keep in TX mode while idle
nrf.listen = False # put the nRF24L01 is in TX mode
|
ACK Payloads Example
Changed in version 2.0.0:
This is a test to show how to use custom acknowledgment payloads.
See Also
More details are found in the documentation on ack and load_ack().
examples/nrf24l01_ack_payload_test.py
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146 | import time
import board
from digitalio import DigitalInOut
# if running this on a ATSAMD21 M0 based board
# from circuitpython_nrf24l01.rf24_lite import RF24
from circuitpython_nrf24l01.rf24 import RF24
# invalid default values for scoping
SPI_BUS, CSN_PIN, CE_PIN = (None, None, None)
try: # on Linux
import spidev
SPI_BUS = spidev.SpiDev() # for a faster interface on linux
CSN_PIN = 0 # use CE0 on default bus (even faster than using any pin)
CE_PIN = DigitalInOut(board.D22) # using pin gpio22 (BCM numbering)
except ImportError: # on CircuitPython only
# using board.SPI() automatically selects the MCU's
# available SPI pins, board.SCK, board.MOSI, board.MISO
SPI_BUS = board.SPI() # init spi bus object
# change these (digital output) pins accordingly
CE_PIN = DigitalInOut(board.D4)
CSN_PIN = DigitalInOut(board.D5)
# initialize the nRF24L01 on the spi bus object
nrf = RF24(SPI_BUS, CSN_PIN, CE_PIN)
# On Linux, csn value is a bit coded
# 0 = bus 0, CE0 # SPI bus 0 is enabled by default
# 10 = bus 1, CE0 # enable SPI bus 2 prior to running this
# 21 = bus 2, CE1 # enable SPI bus 1 prior to running this
# the custom ACK payload feature is disabled by default
# NOTE the the custom ACK payload feature will be enabled
# automatically when you call load_ack() passing:
# a buffer protocol object (bytearray) of
# length ranging [1,32]. And pipe number always needs
# to be an int ranging [0, 5]
# to enable the custom ACK payload feature
nrf.ack = True # False disables again
# set the Power Amplifier level to -12 dBm since this test example is
# usually run with nRF24L01 transceivers in close proximity
nrf.pa_level = -12
# addresses needs to be in a buffer protocol object (bytearray)
address = [b"1Node", b"2Node"]
# to use different addresses on a pair of radios, we need a variable to
# uniquely identify which address this radio will use to transmit
# 0 uses address[0] to transmit, 1 uses address[1] to transmit
radio_number = bool(
int(input("Which radio is this? Enter '0' or '1'. Defaults to '0' ") or 0)
)
# set TX address of RX node into the TX pipe
nrf.open_tx_pipe(address[radio_number]) # always uses pipe 0
# set RX address of TX node into an RX pipe
nrf.open_rx_pipe(1, address[not radio_number]) # using pipe 1
# using the python keyword global is bad practice. Instead we'll use a 1 item
# list to store our integer number for the payloads' counter
counter = [0]
def master(count=5): # count = 5 will only transmit 5 packets
"""Transmits a payload every second and prints the ACK payload"""
nrf.listen = False # put radio in TX mode
while count:
# construct a payload to send
# add b"\0" as a c-string NULL terminating char
buffer = b"Hello \0" + bytes([counter[0]])
start_timer = time.monotonic_ns() # start timer
result = nrf.send(buffer) # save the response (ACK payload)
end_timer = time.monotonic_ns() # stop timer
if result:
# print the received ACK that was automatically
# fetched and saved to "result" via send()
# print timer results upon transmission success
print(
"Transmission successful! Time to transmit:",
int((end_timer - start_timer) / 1000),
"us. Sent: {}{}".format(buffer[:6].decode("utf-8"), counter[0]),
end=" ",
)
if isinstance(result, bool):
print("Received an empty ACK packet")
else:
# result[:6] truncates c-string NULL termiating char
# received counter is a unsigned byte, thus result[7:8][0]
print(
"Received: {}{}".format(result[:6].decode("utf-8"), result[7:8][0])
)
counter[0] += 1 # increment payload counter
elif not result:
print("send() failed or timed out")
time.sleep(1) # let the RX node prepare a new ACK payload
count -= 1
def slave(timeout=6):
"""Prints the received value and sends an ACK payload"""
nrf.listen = True # put radio into RX mode, power it up
# setup the first transmission's ACK payload
# add b"\0" as a c-string NULL terminating char
buffer = b"World \0" + bytes([counter[0]])
# we must set the ACK payload data and corresponding
# pipe number [0, 5]. We'll be acknowledging pipe 1
nrf.load_ack(buffer, 1) # load ACK for first response
start = time.monotonic() # start timer
while (time.monotonic() - start) < timeout:
if nrf.available():
# grab information about the received payload
length, pipe_number = (nrf.any(), nrf.pipe)
# retreive the received packet's payload
received = nrf.read()
# increment counter from received payload
# received counter is a unsigned byte, thus result[7:8][0]
counter[0] = received[7:8][0] + 1
# the [:6] truncates the c-string NULL termiating char
print(
"Received {} bytes on pipe {}:".format(length, pipe_number),
"{}{}".format(received[:6].decode("utf-8"), received[7:8][0]),
"Sent: {}{}".format(buffer[:6].decode("utf-8"), buffer[7:8][0]),
)
start = time.monotonic() # reset timer
buffer = b"World \0" + bytes([counter[0]]) # build new ACK
nrf.load_ack(buffer, 1) # load ACK for next response
# recommended behavior is to keep in TX mode while idle
nrf.listen = False # put radio in TX mode
nrf.flush_tx() # flush any ACK payloads that remain
|
Multiceiver Example
Changed in version 2.0.0: no longer uses ACK payloads for responding to node 1.
This example shows how use a group of 6 nRF24L01 transceivers to transmit to 1 nRF24L01
transceiver. This technique is called “Multiceiver” in the nRF24L01 Specifications Sheet
Hint
A paraphrased note from the the nRF24L01 Specifications Sheet:
Only when a data pipe receives a complete packet can other data pipes begin
to receive data. When multiple [nRF24L01]s are transmitting to [one nRF24L01],
the ard can be used to skew the auto retransmission so that they only block
each other once.
This basically means that it might help packets get received if the ard attribute
is set to various values among multiple transmitting nRF24L01 transceivers.
examples/nrf24l01_multiceiver_test.py
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114 | import time
import struct
import board
from digitalio import DigitalInOut
# if running this on a ATSAMD21 M0 based board
# from circuitpython_nrf24l01.rf24_lite import RF24
from circuitpython_nrf24l01.rf24 import RF24
# invalid default values for scoping
SPI_BUS, CSN_PIN, CE_PIN = (None, None, None)
try: # on Linux
import spidev
SPI_BUS = spidev.SpiDev() # for a faster interface on linux
CSN_PIN = 0 # use CE0 on default bus (even faster than using any pin)
CE_PIN = DigitalInOut(board.D22) # using pin gpio22 (BCM numbering)
except ImportError: # on CircuitPython only
# using board.SPI() automatically selects the MCU's
# available SPI pins, board.SCK, board.MOSI, board.MISO
SPI_BUS = board.SPI() # init spi bus object
# change these (digital output) pins accordingly
CE_PIN = DigitalInOut(board.D4)
CSN_PIN = DigitalInOut(board.D5)
# initialize the nRF24L01 on the spi bus object
nrf = RF24(SPI_BUS, CSN_PIN, CE_PIN)
# On Linux, csn value is a bit coded
# 0 = bus 0, CE0 # SPI bus 0 is enabled by default
# 10 = bus 1, CE0 # enable SPI bus 2 prior to running this
# 21 = bus 2, CE1 # enable SPI bus 1 prior to running this
# set the Power Amplifier level to -12 dBm since this test example is
# usually run with nRF24L01 transceivers in close proximity
nrf.pa_level = -12
# setup the addresses for all transmitting nRF24L01 nodes
addresses = [
b"\x78" * 5,
b"\xF1\xB6\xB5\xB4\xB3",
b"\xCD\xB6\xB5\xB4\xB3",
b"\xA3\xB6\xB5\xB4\xB3",
b"\x0F\xB6\xB5\xB4\xB3",
b"\x05\xB6\xB5\xB4\xB3",
]
# uncomment the following 3 lines for compatibility with TMRh20 library
# nrf.allow_ask_no_ack = False
# nrf.dynamic_payloads = False
# nrf.payload_length = 8
def base(timeout=10):
"""Use the nRF24L01 as a base station for listening to all nodes"""
# write the addresses to all pipes.
for pipe_n, addr in enumerate(addresses):
nrf.open_rx_pipe(pipe_n, addr)
nrf.listen = True # put base station into RX mode
start_timer = time.monotonic() # start timer
while time.monotonic() - start_timer < timeout:
while not nrf.fifo(False, True): # keep RX FIFO empty for reception
# show the pipe number that received the payload
# NOTE read() clears the pipe number and payload length data
print("Received", nrf.any(), "on pipe", nrf.pipe, end=" ")
node_id, payload_id = struct.unpack("<ii", nrf.read())
print("from node {}. PayloadID: {}".format(node_id, payload_id))
start_timer = time.monotonic() # reset timer with every payload
nrf.listen = False
def node(node_number=0, count=6):
"""start transmitting to the base station.
:param int node_number: the node's identifying index (from the
the `addresses` list)
:param int count: the number of times that the node will transmit
to the base station.
"""
nrf.listen = False
# set the TX address to the address of the base station.
nrf.open_tx_pipe(addresses[node_number])
counter = 0
# use the node_number to identify where the payload came from
while counter < count:
counter += 1
# payloads will include the node_number and a payload ID character
payload = struct.pack("<ii", node_number, counter)
# show something to see it isn't frozen
start_timer = time.monotonic_ns()
report = nrf.send(payload)
end_timer = time.monotonic_ns()
# show something to see it isn't frozen
if report:
print(
"Transmission of payloadID {} as node {} successfull!".format(
counter, node_number
),
"Transmission time: {} us".format(
int((end_timer - start_timer) / 1000)
),
)
else:
print("Transmission failed or timed out")
time.sleep(0.5) # slow down the test for readability
|
Scanner Example
This example simply scans the entire RF frequency (2.4 GHz to 2.525 GHz)
and outputs a vertical graph of how many signals (per
channel) were detected. This example
can be used to find a frequency with the least ambient interference from other
radio-emitting sources (i.e. WiFi, Bluetooth, or etc).
examples/nrf24l01_scanner_test.py
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117 | import time
import board
from digitalio import DigitalInOut
# if running this on a ATSAMD21 M0 based board
# from circuitpython_nrf24l01.rf24_lite import RF24
from circuitpython_nrf24l01.rf24 import RF24, address_repr
# invalid default values for scoping
SPI_BUS, CSN_PIN, CE_PIN = (None, None, None)
try: # on Linux
import spidev
SPI_BUS = spidev.SpiDev() # for a faster interface on linux
CSN_PIN = 0 # use CE0 on default bus (even faster than using any pin)
CE_PIN = DigitalInOut(board.D22) # using pin gpio22 (BCM numbering)
except ImportError: # on CircuitPython only
# using board.SPI() automatically selects the MCU's
# available SPI pins, board.SCK, board.MOSI, board.MISO
SPI_BUS = board.SPI() # init spi bus object
# change these (digital output) pins accordingly
CE_PIN = DigitalInOut(board.D4)
CSN_PIN = DigitalInOut(board.D5)
# initialize the nRF24L01 on the spi bus object
nrf = RF24(SPI_BUS, CSN_PIN, CE_PIN)
# On Linux, csn value is a bit coded
# 0 = bus 0, CE0 # SPI bus 0 is enabled by default
# 10 = bus 1, CE0 # enable SPI bus 2 prior to running this
# 21 = bus 2, CE1 # enable SPI bus 1 prior to running this
# turn off RX features specific to the nRF24L01 module
nrf.auto_ack = False
nrf.dynamic_payloads = False
nrf.crc = 0
nrf.arc = 0
nrf.allow_ask_no_ack = False
# use reverse engineering tactics for a better "snapshot"
nrf.address_length = 2
nrf.open_rx_pipe(1, b"\0\x55")
nrf.open_rx_pipe(0, b"\0\xAA")
def scan(timeout=30):
"""Traverse the spectrum of accessible frequencies and print any detection
of ambient signals.
:param int timeout: The number of seconds in which scanning is performed.
"""
# print the vertical header of channel numbers
print("0" * 100 + "1" * 26)
for i in range(13):
print(str(i % 10) * (10 if i < 12 else 6), sep="", end="")
print("") # endl
for i in range(126):
print(str(i % 10), sep="", end="")
print("\n" + "~" * 126)
signals = [0] * 126 # store the signal count for each channel
curr_channel = 0
start_timer = time.monotonic() # start the timer
while time.monotonic() - start_timer < timeout:
nrf.channel = curr_channel
if nrf.available():
nrf.flush_rx() # flush the RX FIFO because it asserts the RPD flag
nrf.listen = 1 # start a RX session
time.sleep(0.00013) # wait 130 microseconds
signals[curr_channel] += nrf.rpd # if interference is present
nrf.listen = 0 # end the RX session
curr_channel = curr_channel + 1 if curr_channel < 125 else 0
# output the signal counts per channel
sig_cnt = signals[curr_channel]
print(
("%X" % min(15, sig_cnt)) if sig_cnt else "-",
sep="",
end="" if curr_channel < 125 else "\r",
)
# finish printing results and end with a new line
while curr_channel < len(signals) - 1:
curr_channel += 1
sig_cnt = signals[curr_channel]
print(("%X" % min(15, sig_cnt)) if sig_cnt else "-", sep="", end="")
print("")
def noise(timeout=1, channel=None):
"""print a stream of detected noise for duration of time.
:param int timeout: The number of seconds to scan for ambient noise.
:param int channel: The specific channel to focus on. If not provided, then the
radio's current setting is used.
"""
if channel is not None:
nrf.channel = channel
nrf.listen = True
timeout += time.monotonic()
while time.monotonic() < timeout:
signal = nrf.read()
if signal:
print(address_repr(signal, False, " "))
nrf.listen = False
while not nrf.fifo(False, True):
# dump the left overs in the RX FIFO
print(address_repr(nrf.read(), False, " "))
|
Reading the scanner output
Hint
Make sure the terminal window used to run the scanner example is expanded
to fit 125 characters. Otherwise the output will look weird.
The output of the scanner example is supposed to be read vertically (as columns).
So, the following
should be interpreted as
1 signal detected on channel 017
3 signals detected on channel 018
no signal (-) detected on channel 019
The ~ is just a divider between the vertical header and the signal counts.
IRQ Pin Example
Changed in version 1.2.0: uses ACK payloads to trigger all 3 IRQ events.
Changed in version 2.0.0: uses 2 addresses on pipes 1 & 0 to demonstrate proper addressing convention.
This is a test to show how to use nRF24L01’s interrupt pin using the non-blocking
write(). Also the ack attribute is enabled to trigger the irq_dr event when
the master node receives ACK payloads. Simply put, this example is the most advanced
example script (in this library), and it runs very quickly.
examples/nrf24l01_interrupt_test.py
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139 | import time
import board
import digitalio
# if running this on a ATSAMD21 M0 based board
# from circuitpython_nrf24l01.rf24_lite import RF24
from circuitpython_nrf24l01.rf24 import RF24
# select your digital input pin that's connected to the IRQ pin on the nRF4L01
irq_pin = digitalio.DigitalInOut(board.D12)
irq_pin.switch_to_input() # make sure its an input object
# change these (digital output) pins accordingly
CE_PIN = digitalio.DigitalInOut(board.D4)
CSN_PIN = digitalio.DigitalInOut(board.D5)
# using board.SPI() automatically selects the MCU's
# available SPI pins, board.SCK, board.MOSI, board.MISO
SPI_BUS = board.SPI() # init spi bus object
# we'll be using the dynamic payload size feature (enabled by default)
# initialize the nRF24L01 on the spi bus object
nrf = RF24(SPI_BUS, CSN_PIN, CE_PIN)
# this example uses the ACK payload to trigger the IRQ pin active for
# the "on data received" event
nrf.ack = True # enable ACK payloads
# set the Power Amplifier level to -12 dBm since this test example is
# usually run with nRF24L01 transceivers in close proximity
nrf.pa_level = -12
# address needs to be in a buffer protocol object (bytearray is preferred)
address = [b"1Node", b"2Node"]
# to use different addresses on a pair of radios, we need a variable to
# uniquely identify which address this radio will use to transmit
# 0 uses address[0] to transmit, 1 uses address[1] to transmit
radio_number = bool(
int(input("Which radio is this? Enter '0' or '1'. Defaults to '0' ") or 0)
)
# set TX address of RX node into the TX pipe
nrf.open_tx_pipe(address[radio_number]) # always uses pipe 0
# set RX address of TX node into an RX pipe
nrf.open_rx_pipe(1, address[not radio_number]) # using pipe 1
def _ping_and_prompt():
"""transmit 1 payload, wait till irq_pin goes active, print IRQ status
flags."""
nrf.ce_pin = 1 # tell the nRF24L01 to prepare sending a single packet
time.sleep(0.00001) # mandatory 10 microsecond pulse starts transmission
nrf.ce_pin = 0 # end 10 us pulse; use only 1 buffer from TX FIFO
while irq_pin.value: # IRQ pin is active when LOW
pass
print("IRQ pin went active LOW.")
nrf.update() # update irq_d? status flags
print(
"\tirq_ds: {}, irq_dr: {}, irq_df: {}".format(
nrf.irq_ds, nrf.irq_dr, nrf.irq_df
)
)
def master():
"""Transmits 3 times: successfully receive ACK payload first, successfully
transmit on second, and intentionally fail transmit on the third"""
nrf.listen = False # ensures the nRF24L01 is in TX mode
# NOTE nrf.write() internally calls nrf.clear_status_flags() first
# load 2 buffers into the TX FIFO; write_only=True leaves CE pin LOW
nrf.write(b"Ping ", write_only=True)
nrf.write(b"Pong ", write_only=True)
# on data ready test
print("\nConfiguring IRQ pin to only ignore 'on data sent' event")
nrf.interrupt_config(data_sent=False)
print(" Pinging slave node for an ACK payload...", end=" ")
_ping_and_prompt() # CE pin is managed by this function
print('\t"on data ready" event test {}successful'.format("un" * nrf.irq_dr))
# on data sent test
print("\nConfiguring IRQ pin to only ignore 'on data ready' event")
nrf.interrupt_config(data_recv=False)
print(" Pinging slave node again... ", end=" ")
_ping_and_prompt() # CE pin is managed by this function
print('\t"on data sent" event test {}successful'.format("un" * nrf.irq_ds))
# trigger slave node to exit by filling the slave node's RX FIFO
print("\nSending one extra payload to fill RX FIFO on slave node.")
if nrf.send(b"Radio", send_only=True):
# when send_only parameter is True, send() ignores RX FIFO usage
if nrf.fifo(False, False): # is RX FIFO full?
print("Slave node should not be listening anymore.")
else:
print("transmission succeeded, but slave node might still be listening")
else:
print("Slave node was unresponsive.")
# on data fail test
print("\nConfiguring IRQ pin to go active for all events.")
nrf.interrupt_config()
print(" Sending a ping to inactive slave node...", end=" ")
nrf.flush_tx() # just in case any previous tests failed
nrf.write(b"Dummy", write_only=True) # CE pin is left LOW
_ping_and_prompt() # CE pin is managed by this function
print('\t"on data failed" event test {}successful'.format("un" * nrf.irq_df))
nrf.flush_tx() # flush artifact payload in TX FIFO from last test
# all 3 ACK payloads received were 4 bytes each, and RX FIFO is full
# so, fetching 12 bytes from the RX FIFO also flushes RX FIFO
print("\nComplete RX FIFO:", nrf.read(12))
def slave(timeout=6): # will listen for 6 seconds before timing out
"""Only listen for 3 payload from the master node"""
# setup radio to receive pings, fill TX FIFO with ACK payloads
nrf.load_ack(b"Yak ", 1)
nrf.load_ack(b"Back", 1)
nrf.load_ack(b" ACK", 1)
nrf.listen = True # start listening & clear irq_dr flag
start_timer = time.monotonic() # start timer now
while not nrf.fifo(0, 0) and time.monotonic() - start_timer < timeout:
# if RX FIFO is not full and timeout is not reached, then keep going
pass
nrf.listen = False # put nRF24L01 in Standby-I mode when idling
if not nrf.fifo(False, True): # if RX FIFO is not empty
# all 3 payloads received were 5 bytes each, and RX FIFO is full
# so, fetching 15 bytes from the RX FIFO also flushes RX FIFO
print("Complete RX FIFO:", nrf.read(15))
nrf.flush_tx() # discard any pending ACK payloads
|
Library-Specific Features
Stream Example
Changed in version 1.2.3: added master_fifo() to demonstrate using full TX FIFO to stream data.
Changed in version 2.0.0: uses 2 addresses on pipes 1 & 0 to demonstrate proper addressing convention.
This is a test to show how to stream data. The master() uses the
send() function to transmit multiple payloads with
1 function call. However master() only uses 1 level of the nRF24L01’s TX FIFO. An
alternate function, called master_fifo() uses all 3 levels of the nRF24L01’s TX FIFO to
stream data, but it uses the write() function to do so.
examples/nrf24l01_stream_test.py
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159 | import time
import board
from digitalio import DigitalInOut
# if running this on a ATSAMD21 M0 based board
# from circuitpython_nrf24l01.rf24_lite import RF24
from circuitpython_nrf24l01.rf24 import RF24
# invalid default values for scoping
SPI_BUS, CSN_PIN, CE_PIN = (None, None, None)
try: # on Linux
import spidev
SPI_BUS = spidev.SpiDev() # for a faster interface on linux
CSN_PIN = 0 # use CE0 on default bus (even faster than using any pin)
CE_PIN = DigitalInOut(board.D22) # using pin gpio22 (BCM numbering)
except ImportError: # on CircuitPython only
# using board.SPI() automatically selects the MCU's
# available SPI pins, board.SCK, board.MOSI, board.MISO
SPI_BUS = board.SPI() # init spi bus object
# change these (digital output) pins accordingly
CE_PIN = DigitalInOut(board.D4)
CSN_PIN = DigitalInOut(board.D5)
# initialize the nRF24L01 on the spi bus object
nrf = RF24(SPI_BUS, CSN_PIN, CE_PIN)
# On Linux, csn value is a bit coded
# 0 = bus 0, CE0 # SPI bus 0 is enabled by default
# 10 = bus 1, CE0 # enable SPI bus 2 prior to running this
# 21 = bus 2, CE1 # enable SPI bus 1 prior to running this
# set the Power Amplifier level to -12 dBm since this test example is
# usually run with nRF24L01 transceivers in close proximity
nrf.pa_level = -12
# addresses needs to be in a buffer protocol object (bytearray)
address = [b"1Node", b"2Node"]
# to use different addresses on a pair of radios, we need a variable to
# uniquely identify which address this radio will use to transmit
# 0 uses address[0] to transmit, 1 uses address[1] to transmit
radio_number = bool(
int(input("Which radio is this? Enter '0' or '1'. Defaults to '0' ") or 0)
)
# set TX address of RX node into the TX pipe
nrf.open_tx_pipe(address[radio_number]) # always uses pipe 0
# set RX address of TX node into an RX pipe
nrf.open_rx_pipe(1, address[not radio_number]) # using pipe 1
# uncomment the following 2 lines for compatibility with TMRh20 library
# nrf.allow_ask_no_ack = False
nrf.dynamic_payloads = False
def make_buffers(size=32):
"""return a list of payloads"""
buffers = []
# we'll use `size` for the number of payloads in the list and the
# payloads' length
for i in range(size):
# prefix payload with a sequential letter to indicate which
# payloads were lost (if any)
buff = bytes([i + (65 if 0 <= i < 26 else 71)])
for j in range(size - 1):
char = j >= (size - 1) / 2 + abs((size - 1) / 2 - i)
char |= j < (size - 1) / 2 - abs((size - 1) / 2 - i)
buff += bytes([char + 48])
buffers.append(buff)
del buff
return buffers
def master(count=1, size=32): # count = 5 will transmit the list 5 times
"""Transmits multiple payloads using `RF24.send()` and `RF24.resend()`."""
buffers = make_buffers(size) # make a list of payloads
nrf.listen = False # ensures the nRF24L01 is in TX mode
successful = 0 # keep track of success rate
for _ in range(count):
start_timer = time.monotonic_ns() # start timer
# NOTE force_retry=2 internally invokes `RF24.resend()` 2 times at
# most for payloads that fail to transmit.
result = nrf.send(buffers, force_retry=2) # result is a list
end_timer = time.monotonic_ns() # end timer
print("Transmission took", (end_timer - start_timer) / 1000, "us")
for r in result: # tally the resulting success rate
successful += 1 if r else 0
print(
"successfully sent {}%".format(successful / (size * count) * 100),
"({}/{})".format(successful, size * count),
)
def master_fifo(count=1, size=32):
"""Similar to the `master()` above except this function uses the full
TX FIFO and `RF24.write()` instead of `RF24.send()`"""
buf = make_buffers(size) # make a list of payloads
nrf.listen = False # ensures the nRF24L01 is in TX mode
for cnt in range(count): # transmit the same payloads this many times
nrf.flush_tx() # clear the TX FIFO so we can use all 3 levels
# NOTE the write_only parameter does not initiate sending
buf_iter = 0 # iterator of payloads for the while loop
failures = 0 # keep track of manual retries
start_timer = time.monotonic_ns() # start timer
while buf_iter < size: # cycle through all the payloads
nrf.ce_pin = False
while buf_iter < size and nrf.write(buf[buf_iter], write_only=1):
# NOTE write() returns False if TX FIFO is already full
buf_iter += 1 # increment iterator of payloads
nrf.ce_pin = True
while not nrf.fifo(True, True): # updates irq_df flag
if nrf.irq_df:
# reception failed; we need to reset the irq_rf flag
nrf.ce_pin = False # fall back to Standby-I mode
failures += 1 # increment manual retries
nrf.clear_status_flags() # clear the irq_df flag
if failures > 99 and buf_iter < 7 and cnt < 2:
# we need to prevent an infinite loop
print(
"Make sure slave() node is listening."
" Quiting master_fifo()"
)
buf_iter = size + 1 # be sure to exit the while loop
nrf.flush_tx() # discard all payloads in TX FIFO
else:
nrf.ce_pin = True # start re-transmitting
nrf.ce_pin = False
end_timer = time.monotonic_ns() # end timer
print(
"Transmission took {} us".format((end_timer - start_timer) / 1000),
"with {} failures detected.".format(failures),
)
def slave(timeout=5):
"""Stops listening after a `timeout` with no response"""
nrf.listen = True # put radio into RX mode and power up
count = 0 # keep track of the number of received payloads
start_timer = time.monotonic() # start timer
while time.monotonic() < start_timer + timeout:
if nrf.available():
count += 1
# retreive the received packet's payload
buffer = nrf.read() # clears flags & empties RX FIFO
print("Received:", buffer, "-", count)
start_timer = time.monotonic() # reset timer on every RX payload
# recommended behavior is to keep in TX mode while idle
nrf.listen = False # put the nRF24L01 is in TX mode
|
Context Example
Changed in version 1.2.0: demonstrates switching between FakeBLE object & RF24 object with the same nRF24L01
This is a test to show how to use The with statement blocks to manage multiple different nRF24L01 configurations on 1 transceiver.
examples/nrf24l01_context_test.py
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83 | from circuitpython_nrf24l01.rf24 import RF24
from circuitpython_nrf24l01.fake_ble import FakeBLE
# invalid default values for scoping
SPI_BUS, CSN_PIN, CE_PIN = (None, None, None)
try: # on Linux
import spidev
SPI_BUS = spidev.SpiDev() # for a faster interface on linux
CSN_PIN = 0 # use CE0 on default bus (even faster than using any pin)
CE_PIN = DigitalInOut(board.D22) # using pin gpio22 (BCM numbering)
except ImportError: # on CircuitPython only
# using board.SPI() automatically selects the MCU's
# available SPI pins, board.SCK, board.MOSI, board.MISO
SPI_BUS = board.SPI() # init spi bus object
# change these (digital output) pins accordingly
CE_PIN = DigitalInOut(board.D4)
CSN_PIN = DigitalInOut(board.D5)
# initialize the nRF24L01 objects on the spi bus object
# the first object will have all the features enabled
nrf = RF24(SPI_BUS, CSN_PIN, CE_PIN)
# On Linux, csn value is a bit coded
# 0 = bus 0, CE0 # SPI bus 0 is enabled by default
# 10 = bus 1, CE0 # enable SPI bus 2 prior to running this
# 21 = bus 2, CE1 # enable SPI bus 1 prior to running this
# enable the option to use custom ACK payloads
nrf.ack = True
# set the static payload length to 8 bytes
nrf.payload_length = 8
# RF power amplifier is set to -18 dbm
nrf.pa_level = -18
# the second object has most features disabled/altered
ble = FakeBLE(SPI_BUS, CSN_PIN, CE_PIN)
# the IRQ pin is configured to only go active on "data fail"
# NOTE BLE operations prevent the IRQ pin going active on "data fail" events
ble.interrupt_config(data_recv=False, data_sent=False)
# using a channel 2
ble.channel = 2
# RF power amplifier is set to -12 dbm
ble.pa_level = -12
print("\nsettings configured by the nrf object")
with nrf:
# only the first character gets written because it is on a pipe_number > 1
nrf.open_rx_pipe(5, b"1Node") # NOTE we do this inside the "with" block
# display current settings of the nrf object
nrf.print_details(True) # True dumps pipe info
print("\nsettings configured by the ble object")
with ble as nerf: # the "as nerf" part is optional
nerf.print_details(1)
# if you examine the outputs from print_details() you'll see:
# pipe 5 is opened using the nrf object, but closed using the ble object.
# pipe 0 is closed using the nrf object, but opened using the ble object.
# also notice the different addresses bound to the RX pipes
# this is because the "with" statements load the existing settings
# for the RF24 object specified after the word "with".
# NOTE it is not advised to manipulate separate RF24 objects outside of the
# "with" block; you will encounter bugs about configurations when doing so.
# Be sure to use 1 "with" block per RF24 object when instantiating multiple
# RF24 objects in your program.
# NOTE exiting a "with" block will always power down the nRF24L01
# NOTE upon instantiation, this library closes all RX pipes &
# extracts the TX/RX addresses from the nRF24L01 registers
|
Manual ACK Example
New in version 2.0.0: Previously, this example was strictly made for TMRh20’s RF24 library example
titled “GettingStarted_HandlingData.ino”. With the latest addition of new
examples to the TMRh20 RF24 library, this example was renamed from
“nrf24l01_2arduino_handling_data.py” and adapted for both this library and
TMRh20’s RF24 library.
This is a test to show how to use the library for acknowledgement (ACK) responses
without using the automatic ACK packets (like the ACK Payloads Example does).
Beware, that this technique is not faster and can be more prone to communication
failure. However, This technique has the advantage of using more updated information
in the responding payload as information in ACK payloads are always outdated by 1
transmission.
examples/nrf24l01_manual_ack_test.py
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146 | import time
import board
from digitalio import DigitalInOut
# if running this on a ATSAMD21 M0 based board
# from circuitpython_nrf24l01.rf24_lite import RF24
from circuitpython_nrf24l01.rf24 import RF24
# invalid default values for scoping
SPI_BUS, CSN_PIN, CE_PIN = (None, None, None)
try: # on Linux
import spidev
SPI_BUS = spidev.SpiDev() # for a faster interface on linux
CSN_PIN = 0 # use CE0 on default bus (even faster than using any pin)
CE_PIN = DigitalInOut(board.D22) # using pin gpio22 (BCM numbering)
except ImportError: # on CircuitPython only
# using board.SPI() automatically selects the MCU's
# available SPI pins, board.SCK, board.MOSI, board.MISO
SPI_BUS = board.SPI() # init spi bus object
# change these (digital output) pins accordingly
CE_PIN = DigitalInOut(board.D4)
CSN_PIN = DigitalInOut(board.D5)
# initialize the nRF24L01 on the spi bus object
nrf = RF24(SPI_BUS, CSN_PIN, CE_PIN)
# On Linux, csn value is a bit coded
# 0 = bus 0, CE0 # SPI bus 0 is enabled by default
# 10 = bus 1, CE0 # enable SPI bus 2 prior to running this
# 21 = bus 2, CE1 # enable SPI bus 1 prior to running this
# set the Power Amplifier level to -12 dBm since this test example is
# usually run with nRF24L01 transceivers in close proximity
nrf.pa_level = -12
# addresses needs to be in a buffer protocol object (bytearray)
address = [b"1Node", b"2Node"]
# to use different addresses on a pair of radios, we need a variable to
# uniquely identify which address this radio will use to transmit
# 0 uses address[0] to transmit, 1 uses address[1] to transmit
radio_number = bool(
int(input("Which radio is this? Enter '0' or '1'. Defaults to '0' ") or 0)
)
# set TX address of RX node into the TX pipe
nrf.open_tx_pipe(address[radio_number]) # always uses pipe 0
# set RX address of TX node into an RX pipe
nrf.open_rx_pipe(1, address[not radio_number]) # using pipe 1
# nrf.open_rx_pipe(2, address[radio_number]) # for getting responses on pipe 2
# using the python keyword global is bad practice. Instead we'll use a 1 item
# list to store our integer number for the payloads' counter
counter = [0]
# uncomment the following 3 lines for compatibility with TMRh20 library
# nrf.allow_ask_no_ack = False
# nrf.dynamic_payloads = False
# nrf.payload_length = 8
def master(count=5): # count = 5 will only transmit 5 packets
"""Transmits an arbitrary unsigned long value every second"""
nrf.listen = False # ensures the nRF24L01 is in TX mode
while count:
# construct a payload to send
# add b"\0" as a c-string NULL terminating char
buffer = b"Hello \0" + bytes([counter[0]])
start_timer = time.monotonic_ns() # start timer
result = nrf.send(buffer) # save the response (ACK payload)
if not result:
print("send() failed or timed out")
else: # sent successful; listen for a response
nrf.listen = True # get radio ready to receive a response
timeout = time.monotonic_ns() + 200000000 # set sentinel for timeout
while not nrf.available() and time.monotonic_ns() < timeout:
# this loop hangs for 200 ms or until response is received
pass
nrf.listen = False # put the radio back in TX mode
end_timer = time.monotonic_ns() # stop timer
print(
"Transmission successful! Time to transmit:",
int((end_timer - start_timer) / 1000),
"us. Sent: {}{}".format(buffer[:6].decode("utf-8"), counter[0]),
end=" ",
)
if nrf.pipe is None: # is there a payload?
# nrf.pipe is also updated using `nrf.listen = False`
print("Received no response.")
else:
length = nrf.any() # reset with read()
pipe_number = nrf.pipe # reset with read()
received = nrf.read() # grab the response
# save new counter from response
counter[0] = received[7:8][0]
print(
"Received {} bytes with pipe {}:".format(length, pipe_number),
"{}{}".format(bytes(received[:6]).decode("utf-8"), counter[0]),
)
count -= 1
# make example readable in REPL by slowing down transmissions
time.sleep(1)
def slave(timeout=6):
"""Polls the radio and prints the received value. This method expires
after 6 seconds of no received transmission"""
nrf.listen = True # put radio into RX mode and power up
start_timer = time.monotonic() # used as a timeout
while (time.monotonic() - start_timer) < timeout:
if nrf.available():
length = nrf.any() # grab payload length info
pipe = nrf.pipe # grab pipe number info
received = nrf.read(length) # clears info from any() and nrf.pipe
# increment counter before sending it back in responding payload
counter[0] = received[7:8][0] + 1
nrf.listen = False # put the radio in TX mode
result = False
ack_timeout = time.monotonic_ns() + 200000000
while not result and time.monotonic_ns() < ack_timeout:
# try to send reply for 200 milliseconds (at most)
result = nrf.send(b"World \0" + bytes([counter[0]]))
nrf.listen = True # put the radio back in RX mode
print(
"Received {} on pipe {}:".format(length, pipe),
"{}{}".format(bytes(received[:6]).decode("utf-8"), received[7:8][0]),
end=" Sent: ",
)
if not result:
print("Response failed or timed out")
else:
print("World", counter[0])
start_timer = time.monotonic() # reset timeout
# recommended behavior is to keep in TX mode when in idle
nrf.listen = False # put the nRF24L01 in TX mode + Standby-I power state
|
Network Test
The following network example is designed to be compatible with most of TMRh20’s C++
examples for the RF24Mesh and RF24Network libraries. However, due to some slight differences
this example prompts for user input which can cover a broader spectrum of usage scenarios.
examples/nrf24l01_network_test.py
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168 | import time
import struct
import board
from digitalio import DigitalInOut
from circuitpython_nrf24l01.network.constants import MAX_FRAG_SIZE, NETWORK_DEFAULT_ADDR
IS_MESH = (
(
input(
" nrf24l01_network_test example\n"
"Would you like to run as a mesh network node (y/n)? Defaults to 'Y' "
)
or "Y"
)
.upper()
.startswith("Y")
)
# to use different addresses on a set of radios, we need a variable to
# uniquely identify which address this radio will use
THIS_NODE = 0
print(
"Remember, the master node always uses `0` as the node_address and node_id."
"\nWhich node is this? Enter",
end=" ",
)
if IS_MESH:
# node_id must be less than 256
THIS_NODE = int(input("a unique int. Defaults to '0' ") or "0") & 0xFF
else:
# logical node_address is in octal
THIS_NODE = int(input("an octal int. Defaults to '0' ") or "0", 8)
if IS_MESH:
if THIS_NODE: # if this is not a mesh network master node
from circuitpython_nrf24l01.rf24_mesh import RF24MeshNoMaster as Network
else:
from circuitpython_nrf24l01.rf24_mesh import RF24Mesh as Network
print("Using RF24Mesh{} class".format("" if not THIS_NODE else "NoMaster"))
else:
from circuitpython_nrf24l01.rf24_network import RF24Network as Network
# we need to construct frame headers for RF24Network.send()
from circuitpython_nrf24l01.network.structs import RF24NetworkHeader
# we need to construct entire frames for RF24Network.write() (not for this example)
# from circuitpython_nrf24l01.network.structs import RF24NetworkFrame
print("Using RF24Network class")
# invalid default values for scoping
SPI_BUS, CSN_PIN, CE_PIN = (None, None, None)
try: # on Linux
import spidev
SPI_BUS = spidev.SpiDev() # for a faster interface on linux
CSN_PIN = 0 # use CE0 on default bus (even faster than using any pin)
CE_PIN = DigitalInOut(board.D22) # using pin gpio22 (BCM numbering)
except ImportError: # on CircuitPython only
# using board.SPI() automatically selects the MCU's
# available SPI pins, board.SCK, board.MOSI, board.MISO
SPI_BUS = board.SPI() # init spi bus object
# change these (digital output) pins accordingly
CE_PIN = DigitalInOut(board.D4)
CSN_PIN = DigitalInOut(board.D5)
# initialize this node as the network
nrf = Network(SPI_BUS, CSN_PIN, CE_PIN, THIS_NODE)
# TMRh20 examples use channel 97 for RF24Mesh library
# TMRh20 examples use channel 90 for RF24Network library
nrf.channel = 90 + IS_MESH * 7
# set the Power Amplifier level to -12 dBm since this test example is
# usually run with nRF24L01 transceivers in close proximity
nrf.pa_level = -12
# using the python keyword global is bad practice. Instead we'll use a 1 item
# list to store our number of the payloads sent
packets_sent = [0]
if THIS_NODE: # if this node is not the network master node
if IS_MESH: # mesh nodes need to bond with the master node
print("Connecting to mesh network...", end=" ")
# get this node's assigned address and connect to network
if nrf.renew_address() is None:
print("failed. Please try again manually with `nrf.renew_address()`")
else:
print("assigned address:", oct(nrf.node_address))
else:
print("Acting as network master node.")
def idle(timeout: int = 30, strict_timeout: bool = False):
"""Listen for any payloads and print the transaction
:param int timeout: The number of seconds to wait (with no transmission)
until exiting function.
:param bool strict_timeout: If set to True, then the timer is not reset when
processing incoming traffic
"""
print("idling for", timeout, "seconds")
start_timer = time.monotonic()
while (time.monotonic() - start_timer) < timeout:
nrf.update() # keep the network layer current
while nrf.available():
if not strict_timeout:
start_timer = time.monotonic() # reset timer
frame = nrf.read()
message_len = len(frame.message)
print("Received payload", end=" ")
# TMRh20 examples only use 1 or 2 long ints as small messages
if message_len < MAX_FRAG_SIZE and message_len % 4 == 0:
# if not a large fragmented message and multiple of 4 bytes
fmt = "<" + "L" * int(message_len / 4)
print(struct.unpack(fmt, bytes(frame.message)), end=" ")
print(frame.header.to_string(), "length", message_len)
def emit(
node: int = not THIS_NODE, frag: bool = False, count: int = 5, interval: int = 1
):
"""Transmits 1 (or 2) integers or a large buffer
:param int node: The target node for network transmissions.
If using RF24Mesh, this is a unique node_id.
If using RF24Network, this is the node's logical address.
:param bool frag: Only use fragmented messages?
:param int count: The max number of messages to transmit.
:param int interval: time (in seconds) between transmitting messages.
"""
while count:
idle(interval, True) # idle till its time to emit
count -= 1
packets_sent[0] += 1
# TMRh20's RF24Mesh examples use 1 long int containing a timestamp (in ms)
message = struct.pack("<L", int(time.monotonic() * 1000))
if frag:
message = bytes(
range((packets_sent[0] + MAX_FRAG_SIZE) % nrf.max_message_length)
)
elif not IS_MESH: # if using RF24Network
# TMRh20's RF24Network examples use 2 long ints, so add another
message += struct.pack("<L", packets_sent[0])
result = False
start = time.monotonic_ns()
# pylint: disable=no-value-for-parameter
if IS_MESH: # send() is a little different for RF24Mesh vs RF24Network
result = nrf.send(node, "M", message)
else:
result = nrf.send(RF24NetworkHeader(node, "T"), message)
# pylint: enable=no-value-for-parameter
end = time.monotonic_ns()
print(
"Sending {} (len {})...".format(packets_sent[0], len(message)),
"ok." if result else "failed.",
"Transmission took {} ms".format(int((end - start) / 1000000)),
)
|
OTA compatibility
Fake BLE Example
Changed in version 2.1.0: A new slave() function was added to demonstrate receiving BLE data.
This is a test to show how to use the nRF24L01 as a BLE advertising beacon using the
FakeBLE class.
examples/nrf24l01_fake_ble_test.py
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174 | import time
import board
from digitalio import DigitalInOut
from circuitpython_nrf24l01.fake_ble import (
chunk,
FakeBLE,
UrlServiceData,
BatteryServiceData,
TemperatureServiceData,
)
from circuitpython_nrf24l01.rf24 import address_repr
# invalid default values for scoping
SPI_BUS, CSN_PIN, CE_PIN = (None, None, None)
try: # on Linux
import spidev
SPI_BUS = spidev.SpiDev() # for a faster interface on linux
CSN_PIN = 0 # use CE0 on default bus (even faster than using any pin)
CE_PIN = DigitalInOut(board.D22) # using pin gpio22 (BCM numbering)
except ImportError: # on CircuitPython only
# using board.SPI() automatically selects the MCU's
# available SPI pins, board.SCK, board.MOSI, board.MISO
SPI_BUS = board.SPI() # init spi bus object
# change these (digital output) pins accordingly
CE_PIN = DigitalInOut(board.D4)
CSN_PIN = DigitalInOut(board.D5)
# initialize the nRF24L01 on the spi bus object as a BLE compliant radio
nrf = FakeBLE(SPI_BUS, CSN_PIN, CE_PIN)
# On Linux, csn value is a bit coded
# 0 = bus 0, CE0 # SPI bus 0 is enabled by default
# 10 = bus 1, CE0 # enable SPI bus 2 prior to running this
# 21 = bus 2, CE1 # enable SPI bus 1 prior to running this
# the name parameter is going to be its broadcasted BLE name
# this can be changed at any time using the `name` attribute
# nrf.name = b"foobar"
# you can optionally set the arbitrary MAC address to be used as the
# BLE device's MAC address. Otherwise this is randomly generated upon
# instantiation of the FakeBLE object.
# nrf.mac = b"\x19\x12\x14\x26\x09\xE0"
# set the Power Amplifier level to -12 dBm since this test example is
# usually run with nRF24L01 transceiver in close proximity to the
# BLE scanning application
nrf.pa_level = -12
def _prompt(remaining):
if remaining % 5 == 0 or remaining < 5:
if remaining - 1:
print(remaining, "advertisements left to go!")
else:
print(remaining, "advertisement left to go!")
# create an object for manipulating the battery level data
battery_service = BatteryServiceData()
# battery level data is 1 unsigned byte representing a percentage
battery_service.data = 85
def master(count=50):
"""Sends out the device information."""
# using the "with" statement is highly recommended if the nRF24L01 is
# to be used for more than a BLE configuration
with nrf as ble:
ble.name = b"nRF24L01"
# include the radio's pa_level attribute in the payload
ble.show_pa_level = True
print(
"available bytes in next payload:",
ble.len_available(chunk(battery_service.buffer)),
) # using chunk() gives an accurate estimate of available bytes
for i in range(count): # advertise data this many times
if ble.len_available(chunk(battery_service.buffer)) >= 0:
_prompt(count - i) # something to show that it isn't frozen
# broadcast the device name, MAC address, &
# battery charge info; 0x16 means service data
ble.advertise(battery_service.buffer, data_type=0x16)
# channel hoping is recommended per BLE specs
ble.hop_channel()
time.sleep(0.5) # wait till next broadcast
# nrf.show_pa_level & nrf.name both are set to false when
# exiting a with statement block
# create an object for manipulating temperature measurements
temperature_service = TemperatureServiceData()
# temperature's float data has up to 2 decimal places of precision
temperature_service.data = 42.0
def send_temp(count=50):
"""Sends out a fake temperature."""
with nrf as ble:
ble.name = b"nRF24L01"
print(
"available bytes in next payload:",
ble.len_available(chunk(temperature_service.buffer)),
)
for i in range(count):
if ble.len_available(chunk(temperature_service.buffer)) >= 0:
_prompt(count - i)
# broadcast a temperature measurement; 0x16 means service data
ble.advertise(temperature_service.buffer, data_type=0x16)
ble.hop_channel()
time.sleep(0.2)
# use the Eddystone protocol from Google to broadcast a URL as
# service data. We'll need an object to manipulate that also
url_service = UrlServiceData()
# the data attribute converts a URL string into a simplified
# bytes object using byte codes defined by the Eddystone protocol.
url_service.data = "http://www.google.com"
# Eddystone protocol requires an estimated TX PA level at 1 meter
# lower this estimate since we lowered the actual `ble.pa_level`
url_service.pa_level_at_1_meter = -45 # defaults to -25 dBm
def send_url(count=50):
"""Sends out a URL."""
with nrf as ble:
print(
"available bytes in next payload:",
ble.len_available(chunk(url_service.buffer)),
)
# NOTE we did NOT set a device name in this with block
for i in range(count):
# URLs easily exceed the nRF24L01's max payload length
if ble.len_available(chunk(url_service.buffer)) >= 0:
_prompt(count - i)
ble.advertise(url_service.buffer, 0x16)
ble.hop_channel()
time.sleep(0.2)
def slave(timeout=6):
"""read and decipher BLE payloads for `timeout` seconds."""
nrf.listen = True
end_timer = time.monotonic() + timeout
while time.monotonic() <= end_timer:
if nrf.available():
result = nrf.read()
print(
"received payload from MAC address",
address_repr(result.mac, delimit=":"),
)
if result.name is not None:
print("\tdevice name:", result.name)
if result.pa_level is not None:
print("\tdevice transmitting PA Level:", result.pa_level, "dbm")
for service_data in result.data:
if isinstance(service_data, (bytearray, bytes)):
print("\traw buffer:", address_repr(service_data, False, " "))
else:
print("\t" + repr(service_data))
nrf.listen = False
nrf.flush_rx() # discard any received raw BLE data
|
TMRh20’s C++ libraries
All examples are designed to work with TMRh20’s RF24, RF24Network, and RF24Mesh libraries’ examples.
This Circuitpython library uses dynamic payloads enabled by default.
TMRh20’s RF24 library uses static payload lengths by default.
To make this circuitpython library compatible with
TMRh20’s RF24 library:
set dynamic_payloads to False.
set allow_ask_no_ack to False.
set payload_length to the value that
is passed to TMRh20’s RF24::setPayloadSize(). 32 is the default (& maximum)
payload length/size for both libraries.
Warning
Certain C++ datatypes allocate a different amount of memory depending on
the board being used in the Arduino IDE. For example, uint8_t isn’t always
allocated to 1 byte of memory for certain boards.
Make sure you understand the amount of memory that different datatypes occupy in C++.
This will help you comprehend how to configure
payload_length.
For completeness, TMRh20’s RF24 library uses a default value of 15 for the ard attribute,
but this Circuitpython library uses a default value of 3.
Corresponding examples
circuitpython_nrf24l01 |
TMRh20’s C++ examples |
|---|
nrf24l01_simple_test () |
RF24 gettingStarted |
nrf24l01_ack_payload_test |
RF24 acknowledgementPayloads |
nrf24l01_manual_ack_test () |
RF24 manualAcknowledgements |
nrf24l01_multiceiver_test () |
RF24 multiceiverDemo |
nrf24l01_stream_test () |
RF24 streamingData |
nrf24l01_interrupt_test |
RF24 interruptConfigure |
nrf24l01_context_test |
feature is not available in C++ |
nrf24l01_fake_ble_test |
feature is available via floe’s BTLE library |
nrf24l01_network_test () |
|