#187 nRF24/PingPong

Two Arduino’s entertaining themselves with a game of “ping pong” over nRF24L01+ 2.4GHz RF.

Here’s a quick video of a “game” in action:

Notes

This is a quick first test of Arudino 2.4GHz RF communications using nRF24L01+ modules.

I’m using the maniacbug/RF24 library and the code is based on examples provided.

The PingPong.ino script runs on both the “ping” and “pong” node. A ground link on pin 8 tells that aRduino to play “pong”. Here are the rules of the game:

• “ping” serves: sends a packet and flashes its LED if successful, and waits for reply
• “pong” receives the message, flashes its LED and sends the message back
• if/when “ping” gets the reply, it waits a bit and starts again (else logs an error before restarting).

This is not really stressing the communications, but a nice way to prove the basics are working.

NB: I’m using these nRF24Breakout modules to make it easy to breadboard the circuit.

Connections

See the schematic for details. Here’s the summary of pin connections to the nRF24L01+ module:

Power

According to the datasheet:

• 1.9 to 3.6V supply range
• 5V tolerant inputs (5.25V max)
• 60mA maximum power dissipation; 13.5mA RX at 2Mbps air data rate

That’s almost perfect for driving with an Arduino Uno, with the exception of the maximum current draw:

• 5V GPIO pins are acceptable
• 3.3V pin is within the voltage supply range
• the Arduino specifications state a 50mA limit for 3.3V Pin

But I’m going to chance it for a quick demo, as many others seem to have done quite succesfully. For a fixed installation, I think I would provide a stiffer external 3.3V supply to avoid overloading the Arduino’s onboard regulators.

In practice, I’m seeing no more than 14.8mA drawn by the nRF24L01+ module (send or receive).

Construction

Credits and References

• nRF24L01+ fritzing part - vdemay’s GitHub repo
• nRF24L01+ datasheet
• maniacbug RF24 library
• nRF24Breakout - custom breadboard adapters for the nRF24L01+
• ..as mentioned on my blog