Wireless Chat using NRF24L01+ 2.4GHz RF Transceiver on Arduino & Raspberry Pi Ubuntu Linux

After a bit of success implementing an Arduino 2.4GHz Transceiver, I was encouraged to explore a more familiar environment, something with Python and Linux in the mix.

After a short period of research I landed on the circuitpython-nrf24l01 pypi project page, and quickly began digging through their examples.

It wasn’t long after I had a working prototype that mirrored my Arduino code quite closely:

Components

import sys
import select

from circuitpython_nrf24l01 import RF24
import board
import digitalio as dio

# addresses needs to be in a buffer protocol object (bytearray)
address = b'Nessy'

# change these (digital output) pins accordingly
ce = dio.DigitalInOut(board.D4)
csn = dio.DigitalInOut(board.D5)

# using board.SPI() automatically selects the MCU's
# available SPI pins, board.SCK, board.MOSI, board.MISO
spi = board.SPI()  # init spi bus object

# initialize the nRF24L01 on the spi bus object
nrf = RF24(spi, csn, ce, ask_no_ack=False, data_rate=250)
nrf.dynamic_payloads = False # this is the default in the TMRh20 arduino library
nrf.payload_length = 32

# get username
username = input('Enter Username: ')

# set address of RX node into a TX pipe
nrf.open_tx_pipe(address)

# set address of TX node into a RX pipe
nrf.open_rx_pipe(1, address)

nrf.listen = True

print('Welcome %s' % username)
while True:

    # handle write
    if select.select([sys.stdin,],[],[],0.0)[0]:
        nrf.listen = False
        for line in sys.stdin:
            msg = b'[%b] %b' % (username.encode(), line.rstrip().encode())
            nrf.send(msg)
            break

    # handle recieve
    if not nrf.listen:
        nrf.listen = True

    if nrf.any():
        # retreive the received packet's payload
        buffer = nrf.recv()
        data = buffer.decode().replace('\x00', '')
        print(data)

Wireless Chat using Arduino & NRF24L01+ 2.4GHz RF Transceiver

It has been quite some time since I’ve tinkered with an Arduino, and this go around I decided to learn something new.

The NRF24L01 2.4GHz Transceiver is an extremely affordable wireless chip, I managed to pickup 10 units for around $12. This chip allows sending and receiving on the 2.4GHz wireless band.

Lucky for us there is a great Arduino library just waiting to be imported, thanks maniacbug!

So what did I set out to accomplish you ask? Why a chat application of course!

Components

Source Code

#include <SPI.h>
#include <nRF24L01.h>
#include <RF24.h>

#define CE_PIN   9
#define CSN_PIN 10

const byte Address[5] = {'N','e','s','s','y'};

RF24 radio(CE_PIN, CSN_PIN);

String username = "";
String dataInput;
char dataToSend[32];
char dataReceived[32];


void setup() {
    Serial.begin(9600);
    Serial.println("Enter username...");
    
    radio.begin();
    radio.setDataRate(RF24_250KBPS);
    radio.setRetries(3, 5);
    radio.openWritingPipe(Address);
    radio.openReadingPipe(1, Address);
}


void loop() {

  // set username
  while (username == "") {
    if ( Serial.available() ) {
      username = Serial.readStringUntil('\n');
      Serial.print("Welcome ");
      Serial.println(username);
    }
  }

  // listen for radio data
  radio.startListening();
  
  if ( radio.available() ) {
    // read data from radio
    radio.read( &dataReceived, sizeof(dataReceived) );
    Serial.println(dataReceived);  
  }

  if( Serial.available() ) {
    // stop listening on radio
    radio.stopListening();
     
    // get serial input
    dataInput = "[" + username + "] " + Serial.readStringUntil('\n');
    Serial.println(dataInput);
    dataInput.toCharArray(dataToSend, 32);

    // send data
    radio.write( &dataToSend, sizeof(dataToSend) );  
  }
  
}

Using Magic the Gathering Art for D&D Ideas

Recently I’ve spent a bit time reading some of Dragon+ Magazine articles, one particularly grabbed my attention. Using Magic Cards as D&D Items presents a very interesting way to craft items, using Magic the Gathering cards, one can gain inspiration for their next +1 Dagger, or even an Elven Stronghold.

I think the reason I so quickly latched on to this idea was because Magic the Gathering and Dungeons & Dragons are two of my favorite games, plus I really dig the Ixala art work, I mean who hasn’t fantasized about riding a dinosaur to work.

Now I absolutely own tons of Magic the Gathering cards, and I could easily grab a handful and start coming up with an epic dungeon delve, but I thought, why not include a little bit of technology.

Lucky for me, I was able to recycle much of the work I did on Dungeon Brawl to make Magic Inspiration. So just what exactly is Magic Inspiration? Using this application, a Game Master can easily gain inspiration using Magic the Gathering artwork. Then when the ideas come flooding in, weave an amazing story.

It’s time to give credit where credit is due, this application was only made possible using Scryfall‘s bulk data. These people truly provide an awesome dataset!

Anyways, please feel free to grab the application from my Github, and let me know what you think.

Until next time. . .