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188 | """
A simple example of streaming data from 1 nRF24L01 transceiver to another.
This example was written to be used on 2 devices acting as 'nodes'.
See documentation at https://nRF24.github.io/RF24
"""
import time
from RF24 import RF24, RF24_PA_LOW, RF24_DRIVER
print(__file__) # print example name
########### USER CONFIGURATION ###########
# See https://github.com/TMRh20/RF24/blob/master/pyRF24/readme.md
# Radio CE Pin, CSN Pin, SPI Speed
# CE Pin uses GPIO number with BCM and SPIDEV drivers, other platforms use
# their own pin numbering
# CS Pin addresses the SPI bus number at /dev/spidev<a>.<b>
# ie: RF24 radio(<ce_pin>, <a>*10+<b>); spidev1.0 is 10, spidev1.1 is 11 etc..
CSN_PIN = 0 # GPIO8 aka CE0 on SPI bus 0: /dev/spidev0.0
if RF24_DRIVER == "MRAA":
CE_PIN = 15 # for GPIO22
elif RF24_DRIVER == "wiringPi":
CE_PIN = 3 # for GPIO22
else:
CE_PIN = 22
radio = RF24(CE_PIN, CSN_PIN)
# initialize the nRF24L01 on the spi bus
if not radio.begin():
raise RuntimeError("radio hardware is not responding")
# For this example, we will use different addresses
# An address need to be a buffer protocol object (bytearray)
address = [b"1Node", b"2Node"]
# It is very helpful to think of an address as a path instead of as
# an identifying device destination
# 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 the Power Amplifier level to -12 dBm since this test example is
# usually run with nRF24L01 transceivers in close proximity of each other
radio.setPALevel(RF24_PA_LOW) # RF24_PA_MAX is default
# set the TX address of the RX node into the TX pipe
radio.openWritingPipe(address[radio_number]) # always uses pipe 0
# set the RX address of the TX node into a RX pipe
radio.openReadingPipe(1, address[not radio_number]) # using pipe 1
# Specify the number of bytes in the payload. This is also used to
# specify the number of payloads in 1 stream of data
SIZE = 32 # this is the default maximum payload size
# To save time during transmission, we'll set the payload size to be only
# what we need. For this example, we'll be using the default maximum 32
radio.payloadSize = SIZE
# for debugging, we have 2 options that print a large block of details
# (smaller) function that prints raw register values
# radio.printDetails()
# (larger) function that prints human readable data
# radio.printPrettyDetails()
def make_buffer(buf_iter: int) -> bytes:
"""Returns a dynamically created payloads
:param int buf_iter: The position of the payload in the data stream
"""
# we'll use `SIZE` for the number of payloads in the list and the
# payloads' length
# prefix payload with a sequential letter to indicate which
# payloads were lost (if any)
buff = bytes([buf_iter + (65 if 0 <= buf_iter < 26 else 71)])
for j in range(SIZE - 1):
char = bool(j >= (SIZE - 1) / 2 + abs((SIZE - 1) / 2 - buf_iter))
char |= bool(j < (SIZE - 1) / 2 - abs((SIZE - 1) / 2 - buf_iter))
buff += bytes([char + 48])
return buff
def master(count: int = 1):
"""Uses all 3 levels of the TX FIFO to send a stream of data
:param int count: how many times to transmit the stream of data.
"""
radio.stopListening() # put radio in TX mode
radio.flush_tx() # clear the TX FIFO so we can use all 3 levels
failures = 0 # keep track of manual retries
start_timer = time.monotonic_ns() # start timer
for multiplier in range(count): # repeat transmit the same data stream
buf_iter = 0 # iterator of payloads for the while loop
while buf_iter < SIZE: # cycle through all the payloads
buffer = make_buffer(buf_iter) # make a payload
if not radio.writeFast(buffer): # transmission failed
failures += 1 # increment manual retry count
if failures > 99 and buf_iter < 7 and multiplier < 2:
# we need to prevent an infinite loop
print("Too many failures detected. Aborting at payload ", buffer[0])
multiplier = count # be sure to exit the for loop
break # exit the while loop
radio.reUseTX() # resend payload in top level of TX FIFO
else: # transmission succeeded
buf_iter += 1
end_timer = time.monotonic_ns() # end timer
print(
f"Time to transmit data = {(end_timer - start_timer) / 1000} us.",
f"Detected {failures} failures.",
)
def slave(timeout: int = 6):
"""Listen for any payloads and print them out (suffixed with received
counter)
:param int timeout: The number of seconds to wait (with no transmission)
until exiting function.
"""
radio.startListening() # put radio in RX mode
count = 0 # keep track of the number of received payloads
start_timer = time.monotonic() # start timer
while (time.monotonic() - start_timer) < timeout:
if radio.available():
count += 1
# retrieve the received packet's payload
receive_payload = radio.read(radio.payloadSize)
print("Received:", receive_payload, "-", count)
start_timer = time.monotonic() # reset timer on every RX payload
print("Nothing received in", timeout, "seconds. Leaving RX role")
# recommended behavior is to keep in TX mode while idle
radio.stopListening() # put the radio in TX mode
def set_role() -> bool:
"""Set the role using stdin stream. Role args can be specified using space
delimiters (e.g. 'R 10' calls `slave(10)` & 'T 3' calls `master(3)`)
:return:
- True when role is complete & app should continue running.
- False when app should exit
"""
user_input = (
input(
"*** Enter 'R' for receiver role.\n"
"*** Enter 'T' for transmitter role.\n"
"*** Enter 'Q' to quit example.\n"
)
or "?"
)
user_input = user_input.split()
if user_input[0].upper().startswith("R"):
if len(user_input) > 1:
slave(int(user_input[1]))
else:
slave()
return True
if user_input[0].upper().startswith("T"):
if len(user_input) > 1:
master(int(user_input[1]))
else:
master()
return True
if user_input[0].upper().startswith("Q"):
radio.powerDown()
return False
print(user_input[0], "is an unrecognized input. Please try again.")
return set_role()
if __name__ == "__main__":
try:
while set_role():
pass # continue example until 'Q' is entered
except KeyboardInterrupt:
print(" Keyboard Interrupt detected. Powering down radio.")
radio.powerDown()
else:
print(" Run slave() on receiver\n Run master() on transmitter")
|