#[repr(C)]pub struct Segment<'a, 'b> { /* private fields */ }Expand description
Part of a multi-segment transfer.
Segments are transferred using the Spi::transfer_segments method.
Construct a new Segment for a simultaneous (full-duplex) read/write
transfer using new. For read operations without any outgoing data,
use with_read. For write operations where any incoming data
should be discarded, use with_write.
Implementations§
source§impl<'a, 'b> Segment<'a, 'b>
impl<'a, 'b> Segment<'a, 'b>
sourcepub fn new(read_buffer: &'a mut [u8], write_buffer: &'b [u8]) -> Segment<'a, 'b>
pub fn new(read_buffer: &'a mut [u8], write_buffer: &'b [u8]) -> Segment<'a, 'b>
Constructs a new Segment with the default settings, and configures it
for a simultaneous (full-duplex) read/write transfer.
For Segments that only require either a read or write operation, call
with_read or with_write instead of new.
Spi::transfer_segments will only transfer as many bytes as the shortest of
the two buffers contains.
By default, all customizable settings are set to 0, which means it uses
the same values as set for Spi.
sourcepub fn with_read(buffer: &mut [u8]) -> Segment<'_, '_>
pub fn with_read(buffer: &mut [u8]) -> Segment<'_, '_>
Constructs a new Segment with the default settings, and configures it
for a read operation.
Incoming data from the slave device is written to buffer. The total
number of bytes read depends on the length of buffer. A zero-value
byte is sent for every byte read.
By default, all customizable settings are set to 0, which means it uses
the same values as set for Spi.
sourcepub fn with_write(buffer: &[u8]) -> Segment<'_, '_>
pub fn with_write(buffer: &[u8]) -> Segment<'_, '_>
Constructs a new Segment with the default settings, and configures it
for a write operation.
Outgoing data from buffer is sent to the slave device. Any
incoming data is discarded.
By default, all customizable settings are set to 0, which means it uses
the same values as set for Spi.
sourcepub fn with_settings(
read_buffer: Option<&'a mut [u8]>,
write_buffer: Option<&'b [u8]>,
clock_speed: u32,
delay: u16,
bits_per_word: u8,
ss_change: bool
) -> Segment<'a, 'b>
pub fn with_settings( read_buffer: Option<&'a mut [u8]>, write_buffer: Option<&'b [u8]>, clock_speed: u32, delay: u16, bits_per_word: u8, ss_change: bool ) -> Segment<'a, 'b>
Constructs a new Segment with the specified settings.
These settings override the values set for Spi, and are only used
for this specific segment.
If read_buffer is set to None, any incoming data is discarded.
If write_buffer is set to None, a zero-value byte is sent for every
byte read.
If both read_buffer and write_buffer are specified, Spi::transfer_segments
will only transfer as many bytes as the shortest of the two buffers contains.
clock_speed sets a custom clock speed in hertz (Hz).
delay sets a delay in microseconds (µs).
bits_per_word sets the number of bits per word. The Raspberry Pi currently only supports 8 bits per word.
ss_change changes how Slave Select behaves in between two segments (toggle SS), or after the final segment (keep SS active).
sourcepub fn len(&self) -> usize
pub fn len(&self) -> usize
Returns the number of bytes that will be transferred.
If both a read buffer and write buffer are supplied,
Spi::transfer_segments only transfers as many bytes as the
shortest of the two buffers contains.
sourcepub fn clock_speed(&self) -> u32
pub fn clock_speed(&self) -> u32
Gets the custom clock speed in hertz (Hz) for this segment.
sourcepub fn set_clock_speed(&mut self, clock_speed: u32)
pub fn set_clock_speed(&mut self, clock_speed: u32)
Sets a custom clock speed in hertz (Hz) for this segment.
The SPI driver will automatically select the closest valid frequency.
By default, clock_speed is set to 0, which means
it will use the same value as configured for Spi.
sourcepub fn set_delay(&mut self, delay: u16)
pub fn set_delay(&mut self, delay: u16)
Sets a delay in microseconds (µs) for this segment.
set_delay adds a delay at the end of this segment,
before the (optional) Slave Select change.
By default, delay is set to 0.
sourcepub fn bits_per_word(&self) -> u8
pub fn bits_per_word(&self) -> u8
Gets the number of bits per word for this segment.
sourcepub fn set_bits_per_word(&mut self, bits_per_word: u8)
pub fn set_bits_per_word(&mut self, bits_per_word: u8)
Sets the number of bits per word for this segment.
The Raspberry Pi currently only supports 8 bit words.
By default, bits_per_word is set to 0, which means
it will use the same value as configured for Spi.
sourcepub fn set_ss_change(&mut self, ss_change: bool)
pub fn set_ss_change(&mut self, ss_change: bool)
Changes Slave Select’s behavior for this segment.
If ss_change is set to true, and this is not the last
segment of the transfer, the Slave Select line will briefly
change to inactive between this segment and the next.
If this is the last segment, setting ss_change to true will
keep Slave Select active after the transfer ends.
By default, ss_change is set to false.