embedded-nrf24l01

Features

• Designed for use with the embedded-hal crate
• Safe and declarative register definitions
• Chip operation modes lifted to the type-level
• Lets you go straight into RX/TX with the default config

Reference datasheets

• nRF24L01+

Usage

Parameters

Get the *-hal crate for your micro-controller unit. Figure out how to get to the peripherals implementing these embedded-hal traits:

• embedded_hal::spi::SpiDevice for the SPI peripheral

  We provide a mod setup with a few constants for SPI.

• embedded_hal::digital::OutputPin for the CE pin

Constructor

let mut nrf24 = NRF24L01::new(ce, spi).unwrap();

This will provide an instance of Standby and activate acknoladgements and dynamic payload length. You can use .rx() or .tx() to transfer into a RXMode and TXMode instances. They implement .standby() methods to get back to Standby and then switch to the other mode.

Configuration

Before you start transmission, the device must be configured. Example with an nrf24l01+:

nrf24.set_frequency(8).unwrap();
nrf24.set_auto_retransmit(15, 15).unwrap();
nrf24.set_rf(&DataRate::R2Mbps, 0).unwrap();
nrf24
    .set_pipes_rx_enable(&[true, false, false, false, false, false])
    .unwrap();
nrf24
    .set_auto_ack(&[true, false, false, false, false, false])
    .unwrap();
nrf24.set_pipes_rx_lengths(&[None; 6]).unwrap();
nrf24.set_crc(CrcMode::TwoBytes).unwrap();
nrf24.set_rx_addr(0, &b"fnord"[..]).unwrap();
nrf24.set_tx_addr(&b"fnord"[..]).unwrap();
nrf24.flush_rx().unwrap();
nrf24.flush_tx().unwrap();

RXMode

Use rx.can_read() to poll, then rx.read() to receive payload.

If can_read() always returns true, it's usually a power supply issue. You can attach a 1uF or 10uF capacitor as close to the module as possible or upgrade to a better 3.3v regulator.

TXMode

1. Use tx.can_send() to prevent sending on a full queue. Note: not needed if poll_send or wait_empty was used after send.
2. Use tx.send() to enqueue a packet.
3. Use tx.wait_empty() to synchronously flush. Or tx.poll_send() to asynchronously flush and get whether package transmission was successful.

Note

Automatic retransmission (for TX) and acknowledgement (for RX) features go hand in hand. Since setting retransmissions means TX device is expecting an ack, and auto acknowledgement means RX device will check if received packet isn't a duplicate + send an ack back. Turn them both on for tx.poll_send() to be reliable.