pynrf24

Python port of the RF24 (https://github.com/maniacbug/RF24/) library for NRF24L01+ radios, adapted for the BeagleBone Black and the Raspberry Pi.

All methods were ported and most methods prototypes were kept similar. This should facilitate the adaptation of existing code. Limitations were also ported and unfortunately some bugs may have been introduced.

For more information regarding how to use this library, check the RF24 documentation: http://maniacbug.github.io/RF24/ Most of the information there will also be valid to this library.

Tested in a BeagleBoneBlack using spi0 and NRF24L01+ radios. Should work without problems in a Raspberry Pi or with NRF24L01 (non +) radios.

Do not forget to check this great tutorial or the original datasheet

Contact

For any information regarding this library you can contact me at jpbarraca at gmail.

Improvements to the code base are also welcome.

Requirements

• Python 2
• SPI Enabled on the device: check the spi directory in the repository
• SPI communication requires spidev: https://pypi.python.org/pypi/spidev
• BBB: GPIO access requires Adafruit BBIO library: https://github.com/adafruit/adafruit-beaglebone-io-python

Wiring

nRF24L01+ (top view)     BeagleBoneBlack
+-+-+                    (header)
|8|7|	1: GND      ->   P9 GND (P9_1 and P9_2)
+-+-+	2: 3.3V     ->   P9 3.3v (P9_3 and P9_4)
|6|5|	3: CE       ->   P9_15 (configurable)
+-+-+	4: CSN      ->   SPI0.CS (P9_17)
|4|3|	5: SCKL     ->   SPI0.SCLK (P9_22)
+-+-+	6: MOSI     ->   SPI0.D1 (P9_18)
|2|1|	7: MISO     ->   SPI0.D0 (P9_21)
+-+-+	8: IRQ      ->   P9_16 (configurable)

Examples

Initialization:

	pipes = [ [0xe7, 0xe7, 0xe7, 0xe7, 0xe7], [0xc2, 0xc2, 0xc2, 0xc2, 0xc2] ]

	radio = NRF24()
	radio.begin(1,0,"P9_15", "P9_16") #Set CE and IRQ pins
	radio.setRetries(15,15)
	radio.setPayloadSize(8)
	radio.setChannel(0x60)
	radio.setDataRate(NRF24.BR_250KBPS)
	radio.setPALevel(NRF24.PA_MAX)
	radio.openWritingPipe(pipes[0])
	radio.openReadingPipe(1,pipes[1])

	radio.printDetails()

Sending Data:

buffer = ['H','E','L','L','O']
status = radio.write(buffer)

Receiving Data:

#Wait for data
pipe =[0]
while not radio.available(pipe):
	time.sleep(10000/1000000.0)

#Receive Data
recv_buffer = []
radio.read(recv_buffer)

#Print the buffer
print recv_buffer

Caveats

Performance with this driver (as well as with any other Python "driver") may be lower than expected. Python is a high level language and there is too much stuff going on (e.g, Garbage Collection) for timing constrains to be respected. There is no assurance that you can transmit at 2MBits/s, or even at 250KBits/s. Actually, the hardware can only provide maximum bitrates when using large packets, no CRC, and without any retransmissions. Which means that radios must be very close to each other, and in practice you will never get the advertised bitrate. Actually, maybe Python actually isn't a bottleneck :).

It works great in my case. Use AS-IS, but remember that YMMV.

License

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program. If not, see http://www.gnu.org/licenses/.