Introduce frame options to control start/stop conditions
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7bf4710f3f
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1 changed files with 138 additions and 59 deletions
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@ -41,6 +41,68 @@ pub unsafe fn on_interrupt<T: Instance>() {
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});
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});
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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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#[derive(Copy, Clone)]
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enum FrameOptions {
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/// `[ST/SR]+[NACK]+[SP]` First frame (of this type) in operation and last frame overall in this
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/// transaction.
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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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impl<'d, T: Instance, TXDMA, RXDMA> I2c<'d, T, TXDMA, RXDMA> {
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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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pub(crate) fn init(&mut self, freq: Hertz, _config: Config) {
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T::regs().cr1().modify(|reg| {
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T::regs().cr1().modify(|reg| {
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@ -124,46 +186,57 @@ impl<'d, T: Instance, TXDMA, RXDMA> I2c<'d, T, TXDMA, RXDMA> {
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Ok(sr1)
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Ok(sr1)
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}
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}
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fn write_bytes(&mut self, addr: u8, bytes: &[u8], timeout: Timeout) -> Result<(), Error> {
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fn write_bytes(&mut self, addr: u8, bytes: &[u8], timeout: Timeout, frame: FrameOptions) -> Result<(), Error> {
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// Send a START condition
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if frame.send_start() {
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// Send a START condition
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T::regs().cr1().modify(|reg| {
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T::regs().cr1().modify(|reg| {
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reg.set_start(true);
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reg.set_start(true);
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});
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});
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// Wait until START condition was generated
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// Wait until START condition was generated
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while !Self::check_and_clear_error_flags()?.start() {
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while !Self::check_and_clear_error_flags()?.start() {
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timeout.check()?;
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timeout.check()?;
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}
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// Also wait until signalled we're master and everything is waiting for us
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while {
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Self::check_and_clear_error_flags()?;
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let sr2 = T::regs().sr2().read();
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!sr2.msl() && !sr2.busy()
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} {
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timeout.check()?;
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}
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// Set up current address, we're trying to talk to
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T::regs().dr().write(|reg| reg.set_dr(addr << 1));
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// Wait until address was sent
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// Wait for the address to be acknowledged
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// Check for any I2C errors. If a NACK occurs, the ADDR bit will never be set.
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while !Self::check_and_clear_error_flags()?.addr() {
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timeout.check()?;
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}
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// Clear condition by reading SR2
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let _ = T::regs().sr2().read();
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}
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}
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// Also wait until signalled we're master and everything is waiting for us
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while {
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Self::check_and_clear_error_flags()?;
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let sr2 = T::regs().sr2().read();
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!sr2.msl() && !sr2.busy()
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} {
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timeout.check()?;
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}
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// Set up current address, we're trying to talk to
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T::regs().dr().write(|reg| reg.set_dr(addr << 1));
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// Wait until address was sent
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// Wait for the address to be acknowledged
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// Check for any I2C errors. If a NACK occurs, the ADDR bit will never be set.
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while !Self::check_and_clear_error_flags()?.addr() {
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timeout.check()?;
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}
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// Clear condition by reading SR2
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let _ = T::regs().sr2().read();
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// Send bytes
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// Send bytes
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for c in bytes {
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for c in bytes {
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self.send_byte(*c, timeout)?;
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self.send_byte(*c, timeout)?;
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}
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}
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if frame.send_stop() {
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// Send a STOP condition
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T::regs().cr1().modify(|reg| reg.set_stop(true));
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// Wait for STOP condition to transmit.
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while T::regs().cr1().read().stop() {
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timeout.check()?;
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}
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}
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// Fallthrough is success
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// Fallthrough is success
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Ok(())
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Ok(())
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}
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}
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@ -205,8 +278,18 @@ impl<'d, T: Instance, TXDMA, RXDMA> I2c<'d, T, TXDMA, RXDMA> {
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Ok(value)
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Ok(value)
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}
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}
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fn blocking_read_timeout(&mut self, addr: u8, buffer: &mut [u8], timeout: Timeout) -> Result<(), Error> {
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fn blocking_read_timeout(
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if let Some((last, buffer)) = buffer.split_last_mut() {
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&mut self,
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addr: u8,
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buffer: &mut [u8],
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timeout: Timeout,
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frame: FrameOptions,
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) -> Result<(), Error> {
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let Some((last, buffer)) = buffer.split_last_mut() else {
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return Err(Error::Overrun);
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};
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if frame.send_start() {
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// Send a START condition and set ACK bit
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// Send a START condition and set ACK bit
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T::regs().cr1().modify(|reg| {
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T::regs().cr1().modify(|reg| {
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reg.set_start(true);
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reg.set_start(true);
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@ -237,49 +320,45 @@ impl<'d, T: Instance, TXDMA, RXDMA> I2c<'d, T, TXDMA, RXDMA> {
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// Clear condition by reading SR2
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// Clear condition by reading SR2
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let _ = T::regs().sr2().read();
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let _ = T::regs().sr2().read();
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}
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// Receive bytes into buffer
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// Receive bytes into buffer
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for c in buffer {
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for c in buffer {
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*c = self.recv_byte(timeout)?;
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*c = self.recv_byte(timeout)?;
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}
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}
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// Prepare to send NACK then STOP after next byte
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// Prepare to send NACK then STOP after next byte
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T::regs().cr1().modify(|reg| {
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T::regs().cr1().modify(|reg| {
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if frame.send_nack() {
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reg.set_ack(false);
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reg.set_ack(false);
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}
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if frame.send_stop() {
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reg.set_stop(true);
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reg.set_stop(true);
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});
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}
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});
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// Receive last byte
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// Receive last byte
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*last = self.recv_byte(timeout)?;
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*last = self.recv_byte(timeout)?;
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if frame.send_stop() {
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// Wait for the STOP to be sent.
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// Wait for the STOP to be sent.
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while T::regs().cr1().read().stop() {
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while T::regs().cr1().read().stop() {
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timeout.check()?;
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timeout.check()?;
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}
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}
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// Fallthrough is success
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Ok(())
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} else {
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Err(Error::Overrun)
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}
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}
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// Fallthrough is success
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Ok(())
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}
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}
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/// Blocking read.
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/// Blocking read.
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pub fn blocking_read(&mut self, addr: u8, read: &mut [u8]) -> Result<(), Error> {
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pub fn blocking_read(&mut self, addr: u8, read: &mut [u8]) -> Result<(), Error> {
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self.blocking_read_timeout(addr, read, self.timeout())
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self.blocking_read_timeout(addr, read, self.timeout(), FrameOptions::FirstAndLastFrame)
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}
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}
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/// Blocking write.
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/// Blocking write.
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pub fn blocking_write(&mut self, addr: u8, write: &[u8]) -> Result<(), Error> {
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pub fn blocking_write(&mut self, addr: u8, write: &[u8]) -> Result<(), Error> {
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let timeout = self.timeout();
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self.write_bytes(addr, write, self.timeout(), FrameOptions::FirstAndLastFrame)?;
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self.write_bytes(addr, write, timeout)?;
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// Send a STOP condition
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T::regs().cr1().modify(|reg| reg.set_stop(true));
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// Wait for STOP condition to transmit.
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while T::regs().cr1().read().stop() {
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timeout.check()?;
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}
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// Fallthrough is success
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// Fallthrough is success
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Ok(())
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Ok(())
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@ -289,8 +368,8 @@ impl<'d, T: Instance, TXDMA, RXDMA> I2c<'d, T, TXDMA, RXDMA> {
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pub fn blocking_write_read(&mut self, addr: u8, write: &[u8], read: &mut [u8]) -> Result<(), Error> {
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pub fn blocking_write_read(&mut self, addr: u8, write: &[u8], read: &mut [u8]) -> Result<(), Error> {
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let timeout = self.timeout();
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let timeout = self.timeout();
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self.write_bytes(addr, write, timeout)?;
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self.write_bytes(addr, write, timeout, FrameOptions::FirstFrame)?;
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self.blocking_read_timeout(addr, read, timeout)?;
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self.blocking_read_timeout(addr, read, timeout, FrameOptions::FirstAndLastFrame)?;
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Ok(())
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Ok(())
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}
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}
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