547 lines
19 KiB
Rust
547 lines
19 KiB
Rust
//! IEEE 802.15.4 radio driver
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use core::sync::atomic::{compiler_fence, Ordering};
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use core::task::Poll;
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use embassy_hal_internal::drop::OnDrop;
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use embassy_hal_internal::{into_ref, PeripheralRef};
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use super::{state, Error, Instance, InterruptHandler, RadioState, TxPower};
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use crate::interrupt::typelevel::Interrupt;
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use crate::interrupt::{self};
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use crate::Peripheral;
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/// Default (IEEE compliant) Start of Frame Delimiter
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pub const DEFAULT_SFD: u8 = 0xA7;
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// TODO expose the other variants in `pac::CCAMODE_A`
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/// Clear Channel Assessment method
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pub enum Cca {
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/// Carrier sense
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CarrierSense,
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/// Energy Detection / Energy Above Threshold
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EnergyDetection {
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/// Energy measurements above this value mean that the channel is assumed to be busy.
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/// Note the measurement range is 0..0xFF - where 0 means that the received power was
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/// less than 10 dB above the selected receiver sensitivity. This value is not given in dBm,
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/// but can be converted. See the nrf52840 Product Specification Section 6.20.12.4
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/// for details.
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ed_threshold: u8,
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},
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}
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/// IEEE 802.15.4 radio driver.
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pub struct Radio<'d, T: Instance> {
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_p: PeripheralRef<'d, T>,
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needs_enable: bool,
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}
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impl<'d, T: Instance> Radio<'d, T> {
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/// Create a new IEEE 802.15.4 radio driver.
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pub fn new(
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radio: impl Peripheral<P = T> + 'd,
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_irq: impl interrupt::typelevel::Binding<T::Interrupt, InterruptHandler<T>> + 'd,
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) -> Self {
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into_ref!(radio);
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let r = T::regs();
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// Disable and enable to reset peripheral
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r.power.write(|w| w.power().disabled());
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r.power.write(|w| w.power().enabled());
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// Enable 802.15.4 mode
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r.mode.write(|w| w.mode().ieee802154_250kbit());
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// Configure CRC skip address
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r.crccnf.write(|w| w.len().two().skipaddr().ieee802154());
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unsafe {
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// Configure CRC polynomial and init
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r.crcpoly.write(|w| w.crcpoly().bits(0x0001_1021));
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r.crcinit.write(|w| w.crcinit().bits(0));
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r.pcnf0.write(|w| {
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// 8-bit on air length
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w.lflen()
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.bits(8)
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// Zero bytes S0 field length
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.s0len()
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.clear_bit()
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// Zero bytes S1 field length
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.s1len()
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.bits(0)
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// Do not include S1 field in RAM if S1 length > 0
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.s1incl()
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.clear_bit()
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// Zero code Indicator length
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.cilen()
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.bits(0)
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// 32-bit zero preamble
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.plen()
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._32bit_zero()
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// Include CRC in length
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.crcinc()
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.include()
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});
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r.pcnf1.write(|w| {
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// Maximum packet length
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w.maxlen()
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.bits(Packet::MAX_PSDU_LEN)
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// Zero static length
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.statlen()
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.bits(0)
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// Zero base address length
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.balen()
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.bits(0)
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// Little-endian
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.endian()
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.clear_bit()
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// Disable packet whitening
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.whiteen()
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.clear_bit()
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});
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}
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// Enable NVIC interrupt
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T::Interrupt::unpend();
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unsafe { T::Interrupt::enable() };
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let mut radio = Self {
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_p: radio,
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needs_enable: false,
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};
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radio.set_sfd(DEFAULT_SFD);
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radio.set_transmission_power(0);
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radio.set_channel(11);
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radio.set_cca(Cca::CarrierSense);
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radio
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}
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/// Changes the radio channel
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pub fn set_channel(&mut self, channel: u8) {
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let r = T::regs();
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if channel < 11 || channel > 26 {
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panic!("Bad 802.15.4 channel");
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}
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let frequency_offset = (channel - 10) * 5;
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self.needs_enable = true;
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r.frequency
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.write(|w| unsafe { w.frequency().bits(frequency_offset).map().default() });
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}
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/// Changes the Clear Channel Assessment method
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pub fn set_cca(&mut self, cca: Cca) {
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let r = T::regs();
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self.needs_enable = true;
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match cca {
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Cca::CarrierSense => r.ccactrl.write(|w| w.ccamode().carrier_mode()),
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Cca::EnergyDetection { ed_threshold } => {
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// "[ED] is enabled by first configuring the field CCAMODE=EdMode in CCACTRL
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// and writing the CCAEDTHRES field to a chosen value."
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r.ccactrl
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.write(|w| unsafe { w.ccamode().ed_mode().ccaedthres().bits(ed_threshold) });
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}
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}
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}
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/// Changes the Start of Frame Delimiter (SFD)
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pub fn set_sfd(&mut self, sfd: u8) {
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let r = T::regs();
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r.sfd.write(|w| unsafe { w.sfd().bits(sfd) });
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}
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/// Clear interrupts
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pub fn clear_all_interrupts(&mut self) {
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let r = T::regs();
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r.intenclr.write(|w| unsafe { w.bits(0xffff_ffff) });
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}
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/// Changes the radio transmission power
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pub fn set_transmission_power(&mut self, power: i8) {
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let r = T::regs();
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self.needs_enable = true;
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let tx_power: TxPower = match power {
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#[cfg(not(any(feature = "nrf52811", feature = "_nrf5340-net")))]
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8 => TxPower::POS8D_BM,
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#[cfg(not(any(feature = "nrf52811", feature = "_nrf5340-net")))]
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7 => TxPower::POS7D_BM,
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#[cfg(not(any(feature = "nrf52811", feature = "_nrf5340-net")))]
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6 => TxPower::POS6D_BM,
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#[cfg(not(any(feature = "nrf52811", feature = "_nrf5340-net")))]
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5 => TxPower::POS5D_BM,
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#[cfg(not(feature = "_nrf5340-net"))]
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4 => TxPower::POS4D_BM,
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#[cfg(not(feature = "_nrf5340-net"))]
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3 => TxPower::POS3D_BM,
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#[cfg(not(any(feature = "nrf52811", feature = "_nrf5340-net")))]
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2 => TxPower::POS2D_BM,
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0 => TxPower::_0D_BM,
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#[cfg(feature = "_nrf5340-net")]
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-1 => TxPower::NEG1D_BM,
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#[cfg(feature = "_nrf5340-net")]
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-2 => TxPower::NEG2D_BM,
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#[cfg(feature = "_nrf5340-net")]
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-3 => TxPower::NEG3D_BM,
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-4 => TxPower::NEG4D_BM,
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#[cfg(feature = "_nrf5340-net")]
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-5 => TxPower::NEG5D_BM,
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#[cfg(feature = "_nrf5340-net")]
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-6 => TxPower::NEG6D_BM,
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#[cfg(feature = "_nrf5340-net")]
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-7 => TxPower::NEG7D_BM,
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-8 => TxPower::NEG8D_BM,
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-12 => TxPower::NEG12D_BM,
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-16 => TxPower::NEG16D_BM,
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-20 => TxPower::NEG20D_BM,
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-30 => TxPower::NEG30D_BM,
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-40 => TxPower::NEG40D_BM,
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_ => panic!("Invalid transmission power value"),
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};
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r.txpower.write(|w| w.txpower().variant(tx_power));
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}
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/// Waits until the radio state matches the given `state`
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fn wait_for_radio_state(&self, state: RadioState) {
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while self.state() != state {}
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}
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/// Get the current radio state
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fn state(&self) -> RadioState {
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state(T::regs())
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}
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/// Moves the radio from any state to the DISABLED state
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fn disable(&mut self) {
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let r = T::regs();
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// See figure 110 in nRF52840-PS
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loop {
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match self.state() {
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RadioState::DISABLED => return,
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// idle or ramping up
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RadioState::RX_RU | RadioState::RX_IDLE | RadioState::TX_RU | RadioState::TX_IDLE => {
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r.tasks_disable.write(|w| w.tasks_disable().set_bit());
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self.wait_for_radio_state(RadioState::DISABLED);
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return;
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}
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// ramping down
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RadioState::RX_DISABLE | RadioState::TX_DISABLE => {
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self.wait_for_radio_state(RadioState::DISABLED);
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return;
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}
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// cancel ongoing transfer or ongoing CCA
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RadioState::RX => {
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r.tasks_ccastop.write(|w| w.tasks_ccastop().set_bit());
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r.tasks_stop.write(|w| w.tasks_stop().set_bit());
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self.wait_for_radio_state(RadioState::RX_IDLE);
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}
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RadioState::TX => {
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r.tasks_stop.write(|w| w.tasks_stop().set_bit());
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self.wait_for_radio_state(RadioState::TX_IDLE);
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}
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}
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}
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}
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fn set_buffer(&mut self, buffer: &[u8]) {
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let r = T::regs();
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r.packetptr.write(|w| unsafe { w.bits(buffer.as_ptr() as u32) });
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}
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/// Moves the radio to the RXIDLE state
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fn receive_prepare(&mut self) {
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// clear related events
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T::regs().events_ccabusy.reset();
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T::regs().events_phyend.reset();
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// NOTE to avoid errata 204 (see rev1 v1.4) we do TX_IDLE -> DISABLED -> RX_IDLE
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let disable = match self.state() {
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RadioState::DISABLED => false,
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RadioState::RX_IDLE => self.needs_enable,
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_ => true,
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};
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if disable {
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self.disable();
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}
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self.needs_enable = false;
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}
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/// Prepare radio for receiving a packet
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fn receive_start(&mut self, packet: &mut Packet) {
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// NOTE we do NOT check the address of `packet` because the mutable reference ensures it's
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// allocated in RAM
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let r = T::regs();
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self.receive_prepare();
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// Configure shortcuts
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//
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// The radio goes through following states when receiving a 802.15.4 packet
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//
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// enable RX → ramp up RX → RX idle → Receive → end (PHYEND)
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r.shorts.write(|w| w.rxready_start().enabled());
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// set up RX buffer
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self.set_buffer(packet.buffer.as_mut());
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// start transfer
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dma_start_fence();
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match self.state() {
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// Re-start receiver
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RadioState::RX_IDLE => r.tasks_start.write(|w| w.tasks_start().set_bit()),
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// Enable receiver
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_ => r.tasks_rxen.write(|w| w.tasks_rxen().set_bit()),
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}
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}
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/// Cancel receiving packet
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fn receive_cancel() {
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let r = T::regs();
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r.shorts.reset();
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r.tasks_stop.write(|w| w.tasks_stop().set_bit());
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loop {
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match state(r) {
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RadioState::DISABLED | RadioState::RX_IDLE => break,
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_ => (),
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}
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}
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// DMA transfer may have been in progress so synchronize with its memory operations
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dma_end_fence();
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}
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/// Receives one radio packet and copies its contents into the given `packet` buffer
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///
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/// This methods returns the `Ok` variant if the CRC included the packet was successfully
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/// validated by the hardware; otherwise it returns the `Err` variant. In either case, `packet`
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/// will be updated with the received packet's data
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pub async fn receive(&mut self, packet: &mut Packet) -> Result<(), Error> {
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let s = T::state();
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let r = T::regs();
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// Start the read
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self.receive_start(packet);
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let dropper = OnDrop::new(|| Self::receive_cancel());
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self.clear_all_interrupts();
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// wait until we have received something
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core::future::poll_fn(|cx| {
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s.event_waker.register(cx.waker());
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if r.events_phyend.read().events_phyend().bit_is_set() {
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r.events_phyend.reset();
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trace!("RX done poll");
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return Poll::Ready(());
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} else {
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r.intenset.write(|w| w.phyend().set());
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};
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Poll::Pending
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})
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.await;
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dma_end_fence();
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dropper.defuse();
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let crc = r.rxcrc.read().rxcrc().bits() as u16;
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if r.crcstatus.read().crcstatus().bit_is_set() {
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Ok(())
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} else {
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Err(Error::CrcFailed(crc))
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}
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}
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/// Tries to send the given `packet`
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///
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/// This method performs Clear Channel Assessment (CCA) first and sends the `packet` only if the
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/// channel is observed to be *clear* (no transmission is currently ongoing), otherwise no
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/// packet is transmitted and the `Err` variant is returned
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///
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/// NOTE this method will *not* modify the `packet` argument. The mutable reference is used to
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/// ensure the `packet` buffer is allocated in RAM, which is required by the RADIO peripheral
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// NOTE we do NOT check the address of `packet` because the mutable reference ensures it's
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// allocated in RAM
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pub async fn try_send(&mut self, packet: &mut Packet) -> Result<(), Error> {
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let s = T::state();
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let r = T::regs();
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// enable radio to perform cca
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self.receive_prepare();
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/// transmit result
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#[derive(Debug, Clone, Copy, PartialEq, Eq)]
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#[cfg_attr(feature = "defmt", derive(defmt::Format))]
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pub enum TransmitResult {
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/// Success
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Success,
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/// Clear channel assessment reported channel in use
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ChannelInUse,
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}
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// Configure shortcuts
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//
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// The radio goes through following states when sending a 802.15.4 packet
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//
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// enable RX → ramp up RX → clear channel assessment (CCA) → CCA result
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// CCA idle → enable TX → start TX → TX → end (PHYEND) → disabled
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//
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// CCA might end up in the event CCABUSY in which there will be no transmission
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r.shorts.write(|w| {
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w.rxready_ccastart()
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.enabled()
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.ccaidle_txen()
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.enabled()
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.txready_start()
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.enabled()
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.ccabusy_disable()
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.enabled()
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.phyend_disable()
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.enabled()
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});
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// Set transmission buffer
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self.set_buffer(packet.buffer.as_mut());
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// the DMA transfer will start at some point after the following write operation so
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// we place the compiler fence here
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dma_start_fence();
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// start CCA. In case the channel is clear, the data at packetptr will be sent automatically
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match self.state() {
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// Re-start receiver
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RadioState::RX_IDLE => r.tasks_ccastart.write(|w| w.tasks_ccastart().set_bit()),
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// Enable receiver
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_ => r.tasks_rxen.write(|w| w.tasks_rxen().set_bit()),
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}
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self.clear_all_interrupts();
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let result = core::future::poll_fn(|cx| {
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s.event_waker.register(cx.waker());
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if r.events_phyend.read().events_phyend().bit_is_set() {
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r.events_phyend.reset();
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r.events_ccabusy.reset();
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trace!("TX done poll");
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return Poll::Ready(TransmitResult::Success);
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} else if r.events_ccabusy.read().events_ccabusy().bit_is_set() {
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r.events_ccabusy.reset();
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trace!("TX no CCA");
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return Poll::Ready(TransmitResult::ChannelInUse);
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}
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r.intenset.write(|w| w.phyend().set().ccabusy().set());
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Poll::Pending
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})
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.await;
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match result {
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TransmitResult::Success => Ok(()),
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TransmitResult::ChannelInUse => Err(Error::ChannelInUse),
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}
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}
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}
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/// An IEEE 802.15.4 packet
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///
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/// This `Packet` is a PHY layer packet. It's made up of the physical header (PHR) and the PSDU
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/// (PHY service data unit). The PSDU of this `Packet` will always include the MAC level CRC, AKA
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/// the FCS (Frame Control Sequence) -- the CRC is fully computed in hardware and automatically
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/// appended on transmission and verified on reception.
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///
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/// The API lets users modify the usable part (not the CRC) of the PSDU via the `deref` and
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/// `copy_from_slice` methods. These methods will automatically update the PHR.
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///
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/// See figure 119 in the Product Specification of the nRF52840 for more details
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pub struct Packet {
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buffer: [u8; Self::SIZE],
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}
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// See figure 124 in nRF52840-PS
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impl Packet {
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// for indexing purposes
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const PHY_HDR: usize = 0;
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const DATA: core::ops::RangeFrom<usize> = 1..;
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/// Maximum amount of usable payload (CRC excluded) a single packet can contain, in bytes
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pub const CAPACITY: u8 = 125;
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const CRC: u8 = 2; // size of the CRC, which is *never* copied to / from RAM
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const MAX_PSDU_LEN: u8 = Self::CAPACITY + Self::CRC;
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const SIZE: usize = 1 /* PHR */ + Self::MAX_PSDU_LEN as usize;
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/// Returns an empty packet (length = 0)
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pub fn new() -> Self {
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let mut packet = Self {
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buffer: [0; Self::SIZE],
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};
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packet.set_len(0);
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packet
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}
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/// Fills the packet payload with given `src` data
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///
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/// # Panics
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///
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/// This function panics if `src` is larger than `Self::CAPACITY`
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pub fn copy_from_slice(&mut self, src: &[u8]) {
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assert!(src.len() <= Self::CAPACITY as usize);
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let len = src.len() as u8;
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self.buffer[Self::DATA][..len as usize].copy_from_slice(&src[..len.into()]);
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self.set_len(len);
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}
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/// Returns the size of this packet's payload
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pub fn len(&self) -> u8 {
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self.buffer[Self::PHY_HDR] - Self::CRC
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}
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/// Changes the size of the packet's payload
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///
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/// # Panics
|
|
///
|
|
/// This function panics if `len` is larger than `Self::CAPACITY`
|
|
pub fn set_len(&mut self, len: u8) {
|
|
assert!(len <= Self::CAPACITY);
|
|
self.buffer[Self::PHY_HDR] = len + Self::CRC;
|
|
}
|
|
|
|
/// Returns the LQI (Link Quality Indicator) of the received packet
|
|
///
|
|
/// Note that the LQI is stored in the `Packet`'s internal buffer by the hardware so the value
|
|
/// returned by this method is only valid after a `Radio.recv` operation. Operations that
|
|
/// modify the `Packet`, like `copy_from_slice` or `set_len`+`deref_mut`, will overwrite the
|
|
/// stored LQI value.
|
|
///
|
|
/// Also note that the hardware will *not* compute a LQI for packets smaller than 3 bytes so
|
|
/// this method will return an invalid value for those packets.
|
|
pub fn lqi(&self) -> u8 {
|
|
self.buffer[1 /* PHY_HDR */ + self.len() as usize /* data */]
|
|
}
|
|
}
|
|
|
|
impl core::ops::Deref for Packet {
|
|
type Target = [u8];
|
|
|
|
fn deref(&self) -> &[u8] {
|
|
&self.buffer[Self::DATA][..self.len() as usize]
|
|
}
|
|
}
|
|
|
|
impl core::ops::DerefMut for Packet {
|
|
fn deref_mut(&mut self) -> &mut [u8] {
|
|
let len = self.len();
|
|
&mut self.buffer[Self::DATA][..len as usize]
|
|
}
|
|
}
|
|
|
|
/// NOTE must be followed by a volatile write operation
|
|
fn dma_start_fence() {
|
|
compiler_fence(Ordering::Release);
|
|
}
|
|
|
|
/// NOTE must be preceded by a volatile read operation
|
|
fn dma_end_fence() {
|
|
compiler_fence(Ordering::Acquire);
|
|
}
|