mirror of
https://github.com/embassy-rs/embassy.git
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Move FrameOptions and related function to module itself
This commit is contained in:
Sebastian Goll
parent
b299266cd2
commit
7e44db099c
@ -6,6 +6,7 @@
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mod _version;
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use core::future::Future;
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use core::iter;
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use core::marker::PhantomData;
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use embassy_hal_internal::{into_ref, Peripheral, PeripheralRef};
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@ -335,3 +336,132 @@ impl<'d, T: Instance, TXDMA: TxDma<T>, RXDMA: RxDma<T>> embedded_hal_async::i2c:
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self.transaction(address, operations).await
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}
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}
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/// Frame type in I2C transaction.
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///
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/// This tells each method what kind of framing to use, to generate a (repeated) start condition (ST
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/// or SR), and/or a stop condition (SP). For read operations, this also controls whether to send an
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/// ACK or NACK after the last byte received.
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///
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/// For write operations, the following options are identical because they differ only in the (N)ACK
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/// treatment relevant for read operations:
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///
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/// - `FirstFrame` and `FirstAndNextFrame`
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/// - `NextFrame` and `LastFrameNoStop`
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///
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/// Abbreviations used below:
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///
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/// - `ST` = start condition
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/// - `SR` = repeated start condition
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/// - `SP` = stop condition
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/// - `ACK`/`NACK` = last byte in read operation
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#[derive(Copy, Clone)]
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enum FrameOptions {
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/// `[ST/SR]+[NACK]+[SP]` First frame (of this type) in transaction and also last frame overall.
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FirstAndLastFrame,
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/// `[ST/SR]+[NACK]` First frame of this type in transaction, last frame in a read operation but
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/// not the last frame overall.
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FirstFrame,
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/// `[ST/SR]+[ACK]` First frame of this type in transaction, neither last frame overall nor last
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/// frame in a read operation.
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FirstAndNextFrame,
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/// `[ACK]` Middle frame in a read operation (neither first nor last).
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NextFrame,
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/// `[NACK]+[SP]` Last frame overall in this transaction but not the first frame.
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LastFrame,
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/// `[NACK]` Last frame in a read operation but not last frame overall in this transaction.
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LastFrameNoStop,
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}
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impl FrameOptions {
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/// Sends start or repeated start condition before transfer.
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fn send_start(self) -> bool {
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match self {
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Self::FirstAndLastFrame | Self::FirstFrame | Self::FirstAndNextFrame => true,
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Self::NextFrame | Self::LastFrame | Self::LastFrameNoStop => false,
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}
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}
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/// Sends stop condition after transfer.
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fn send_stop(self) -> bool {
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match self {
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Self::FirstAndLastFrame | Self::LastFrame => true,
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Self::FirstFrame | Self::FirstAndNextFrame | Self::NextFrame | Self::LastFrameNoStop => false,
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}
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}
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/// Sends NACK after last byte received, indicating end of read operation.
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fn send_nack(self) -> bool {
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match self {
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Self::FirstAndLastFrame | Self::FirstFrame | Self::LastFrame | Self::LastFrameNoStop => true,
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Self::FirstAndNextFrame | Self::NextFrame => false,
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}
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}
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}
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/// Iterates over operations in transaction.
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///
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/// Returns necessary frame options for each operation to uphold the [transaction contract] and have
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/// the right start/stop/(N)ACK conditions on the wire.
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///
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/// [transaction contract]: embedded_hal_1::i2c::I2c::transaction
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fn operation_frames<'a, 'b: 'a>(
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operations: &'a mut [embedded_hal_1::i2c::Operation<'b>],
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) -> Result<impl IntoIterator<Item = (&'a mut embedded_hal_1::i2c::Operation<'b>, FrameOptions)>, Error> {
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use embedded_hal_1::i2c::Operation;
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// Check empty read buffer before starting transaction. Otherwise, we would risk halting with an
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// error in the middle of the transaction.
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if operations.iter().any(|op| match op {
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Operation::Read(read) => read.is_empty(),
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Operation::Write(_) => false,
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}) {
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return Err(Error::Overrun);
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}
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let mut operations = operations.iter_mut().peekable();
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let mut next_first_frame = true;
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Ok(iter::from_fn(move || {
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let Some(op) = operations.next() else {
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return None;
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};
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// Is `op` first frame of its type?
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let first_frame = next_first_frame;
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let next_op = operations.peek();
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// Get appropriate frame options as combination of the following properties:
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//
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// - For each first operation of its type, generate a (repeated) start condition.
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// - For the last operation overall in the entire transaction, generate a stop condition.
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// - For read operations, check the next operation: if it is also a read operation, we merge
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// these and send ACK for all bytes in the current operation; send NACK only for the final
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// read operation's last byte (before write or end of entire transaction) to indicate last
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// byte read and release the bus for transmission of the bus master's next byte (or stop).
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//
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// We check the third property unconditionally, i.e. even for write opeartions. This is okay
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// because the resulting frame options are identical for write operations.
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let frame = match (first_frame, next_op) {
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(true, None) => FrameOptions::FirstAndLastFrame,
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(true, Some(Operation::Read(_))) => FrameOptions::FirstAndNextFrame,
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(true, Some(Operation::Write(_))) => FrameOptions::FirstFrame,
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//
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(false, None) => FrameOptions::LastFrame,
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(false, Some(Operation::Read(_))) => FrameOptions::NextFrame,
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(false, Some(Operation::Write(_))) => FrameOptions::LastFrameNoStop,
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};
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// Pre-calculate if `next_op` is the first operation of its type. We do this here and not at
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// the beginning of the loop because we hand out `op` as iterator value and cannot access it
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// anymore in the next iteration.
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next_first_frame = match (&op, next_op) {
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(_, None) => false,
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(Operation::Read(_), Some(Operation::Write(_))) | (Operation::Write(_), Some(Operation::Read(_))) => true,
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(Operation::Read(_), Some(Operation::Read(_))) | (Operation::Write(_), Some(Operation::Write(_))) => false,
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};
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Some((op, frame))
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}))
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}
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@ -5,7 +5,7 @@
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//! All other devices (as of 2023-12-28) use [`v2`](super::v2) instead.
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use core::future::poll_fn;
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use core::{iter, task::Poll};
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use core::task::Poll;
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use embassy_embedded_hal::SetConfig;
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use embassy_futures::select::{select, Either};
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@ -41,133 +41,6 @@ pub unsafe fn on_interrupt<T: Instance>() {
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});
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}
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/// Frame type in I2C transaction.
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///
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/// This tells each method what kind of framing to use, to generate a (repeated) start condition (ST
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/// or SR), and/or a stop condition (SP). For read operations, this also controls whether to send an
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/// ACK or NACK after the last byte received.
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///
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/// For write operations, the following options are identical because they differ only in the (N)ACK
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/// treatment relevant for read operations:
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///
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/// - `FirstFrame` and `FirstAndNextFrame`
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/// - `NextFrame` and `LastFrameNoStop`
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///
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/// Abbreviations used below:
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///
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/// - `ST` = start condition
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/// - `SR` = repeated start condition
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/// - `SP` = stop condition
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/// - `ACK`/`NACK` = last byte in read operation
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#[derive(Copy, Clone)]
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enum FrameOptions {
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/// `[ST/SR]+[NACK]+[SP]` First frame (of this type) in transaction and also last frame overall.
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FirstAndLastFrame,
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/// `[ST/SR]+[NACK]` First frame of this type in transaction, last frame in a read operation but
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/// not the last frame overall.
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FirstFrame,
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/// `[ST/SR]+[ACK]` First frame of this type in transaction, neither last frame overall nor last
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/// frame in a read operation.
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FirstAndNextFrame,
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/// `[ACK]` Middle frame in a read operation (neither first nor last).
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NextFrame,
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/// `[NACK]+[SP]` Last frame overall in this transaction but not the first frame.
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LastFrame,
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/// `[NACK]` Last frame in a read operation but not last frame overall in this transaction.
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LastFrameNoStop,
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}
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impl FrameOptions {
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/// Sends start or repeated start condition before transfer.
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fn send_start(self) -> bool {
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match self {
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Self::FirstAndLastFrame | Self::FirstFrame | Self::FirstAndNextFrame => true,
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Self::NextFrame | Self::LastFrame | Self::LastFrameNoStop => false,
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}
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}
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/// Sends stop condition after transfer.
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fn send_stop(self) -> bool {
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match self {
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Self::FirstAndLastFrame | Self::LastFrame => true,
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Self::FirstFrame | Self::FirstAndNextFrame | Self::NextFrame | Self::LastFrameNoStop => false,
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}
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}
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/// Sends NACK after last byte received, indicating end of read operation.
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fn send_nack(self) -> bool {
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match self {
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Self::FirstAndLastFrame | Self::FirstFrame | Self::LastFrame | Self::LastFrameNoStop => true,
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Self::FirstAndNextFrame | Self::NextFrame => false,
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}
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}
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}
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/// Iterates over operations in transaction.
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///
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/// Returns necessary frame options for each operation to uphold the [transaction contract] and have
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/// the right start/stop/(N)ACK conditions on the wire.
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///
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/// [transaction contract]: embedded_hal_1::i2c::I2c::transaction
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fn operation_frames<'a, 'b: 'a>(
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operations: &'a mut [Operation<'b>],
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) -> Result<impl IntoIterator<Item = (&'a mut Operation<'b>, FrameOptions)>, Error> {
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// Check empty read buffer before starting transaction. Otherwise, we would risk halting with an
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// error in the middle of the transaction.
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if operations.iter().any(|op| match op {
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Operation::Read(read) => read.is_empty(),
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Operation::Write(_) => false,
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}) {
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return Err(Error::Overrun);
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}
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let mut operations = operations.iter_mut().peekable();
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let mut next_first_frame = true;
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Ok(iter::from_fn(move || {
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let Some(op) = operations.next() else {
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return None;
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};
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// Is `op` first frame of its type?
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let first_frame = next_first_frame;
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let next_op = operations.peek();
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// Get appropriate frame options as combination of the following properties:
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//
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// - For each first operation of its type, generate a (repeated) start condition.
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// - For the last operation overall in the entire transaction, generate a stop condition.
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// - For read operations, check the next operation: if it is also a read operation, we merge
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// these and send ACK for all bytes in the current operation; send NACK only for the final
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// read operation's last byte (before write or end of entire transaction) to indicate last
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// byte read and release the bus for transmission of the bus master's next byte (or stop).
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//
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// We check the third property unconditionally, i.e. even for write opeartions. This is okay
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// because the resulting frame options are identical for write operations.
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let frame = match (first_frame, next_op) {
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(true, None) => FrameOptions::FirstAndLastFrame,
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(true, Some(Operation::Read(_))) => FrameOptions::FirstAndNextFrame,
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(true, Some(Operation::Write(_))) => FrameOptions::FirstFrame,
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//
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(false, None) => FrameOptions::LastFrame,
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(false, Some(Operation::Read(_))) => FrameOptions::NextFrame,
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(false, Some(Operation::Write(_))) => FrameOptions::LastFrameNoStop,
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};
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// Pre-calculate if `next_op` is the first operation of its type. We do this here and not at
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// the beginning of the loop because we hand out `op` as iterator value and cannot access it
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// anymore in the next iteration.
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next_first_frame = match (&op, next_op) {
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(_, None) => false,
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(Operation::Read(_), Some(Operation::Write(_))) | (Operation::Write(_), Some(Operation::Read(_))) => true,
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(Operation::Read(_), Some(Operation::Read(_))) | (Operation::Write(_), Some(Operation::Write(_))) => false,
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};
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Some((op, frame))
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}))
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}
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impl<'d, T: Instance, TXDMA, RXDMA> I2c<'d, T, TXDMA, RXDMA> {
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pub(crate) fn init(&mut self, freq: Hertz, _config: Config) {
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T::regs().cr1().modify(|reg| {
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