Struct CommandPart 

pub struct CommandPart { /* private fields */ }

A part on an I2C bus that takes commands rather than register addresses, answering each with the reply it was given for that command.

This is how Sensirion lays out parts such as the SHT3x and the SCD4x. A write sends a command, and any arguments after it; a read then takes the reply that command left, once. A command given no reply leaves none, and a read then is not acknowledged, which is what the real parts do when asked for data they do not have. A read longer than the reply gets 0xFF for the rest, the level an idle bus reads.

Examples

use pamoja_hal::i2c::I2c;
use pamoja_hal::sim::CommandPart;

// An SHT3x, from its datasheet: the read-status command answers with the status word,
// 0x8010 after a reset, then that word's CRC.
const SHT3X: u8 = 0x44;
const READ_STATUS: [u8; 2] = 0xF32Du16.to_be_bytes();
const STATUS_AFTER_RESET: [u8; 3] = [0x80, 0x10, 0xE1];
let mut part = CommandPart::new(SHT3X, 2).answering(&READ_STATUS, &STATUS_AFTER_RESET);

part.write(SHT3X, &READ_STATUS).unwrap();
let mut status = [0u8; 3];
part.read(SHT3X, &mut status).unwrap();
assert_eq!(status, STATUS_AFTER_RESET);

// The reply was taken, so a second read finds nothing waiting.
assert!(part.read(SHT3X, &mut status).is_err());
assert_eq!(part.received(), [READ_STATUS.to_vec()]);

Implementations

impl CommandPart

pub fn new(address: u8, width: usize) -> CommandPart

A part answering at one address that has been given no replies yet.

Arguments

• address - the address it answers to.
• width - how many bytes a command takes: two for Sensirion’s 16-bit commands.

Returns

The part.

pub fn answering(self, command: &[u8], reply: &[u8]) -> CommandPart

The same part, answering one command with a reply.

Arguments

• command - the command’s bytes.
• reply - what a read after it returns, in place of any reply given before.

Returns

The part.

pub fn answer(&mut self, command: &[u8], reply: &[u8])

Answers one command with a reply from now on, in place of any reply given before.

Arguments

• command - the command’s bytes.
• reply - what a read after it returns.

pub fn received(&self) -> &[Vec<u8>]

Every write the part has received, oldest first.

Returns

The writes, each a command and whatever arguments followed it.

pub const fn address(&self) -> u8

The address this part answers to.

Returns

The address.

pub const fn transfers(&self) -> usize

How many transfers the part has served.

Returns

The count, one for each transfer a driver made, however many operations it held.

Trait Implementations

impl Clone for CommandPart

fn clone(&self) -> CommandPart

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for CommandPart

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl ErrorType for CommandPart

Available on crate feature alloc only.

type Error = PartError

Error type

impl From<CommandPart> for Part

Available on crate feature alloc only.

fn from(part: CommandPart) -> Part

Converts to this type from the input type.

impl FromPart for CommandPart

Available on crate feature alloc only.

fn from_part(part: Part) -> Option<CommandPart>

The part, when it is this kind.

impl I2c for CommandPart

Available on crate feature alloc only.

fn transaction( &mut self, address: SevenBitAddress, operations: &mut [Operation<'_>], ) -> Result<(), Self::Error>

Execute the provided operations on the I2C bus.

fn read(&mut self, address: A, read: &mut [u8]) -> Result<(), Self::Error>

Reads enough bytes from slave with address to fill read.

fn write(&mut self, address: A, write: &[u8]) -> Result<(), Self::Error>

Writes bytes to slave with address address.

fn write_read( &mut self, address: A, write: &[u8], read: &mut [u8], ) -> Result<(), Self::Error>

Writes bytes to slave with address address and then reads enough bytes to fill read in a single transaction.