pw::i2c::Message Class Reference

#include <message.h>

Public Member Functions
bool	IsRead () const
bool	IsTenBit () const
bool	IsWriteContinuation () const
Address	GetAddress () const
ByteSpan	GetMutableData () const
ConstByteSpan	GetData () const

Static Public Member Functions
static constexpr Message	WriteMessage (Address address, ConstByteSpan data)
static constexpr Message	WriteMessageContinuation (ConstByteSpan data)
static constexpr Message	ReadMessage (Address address, ByteSpan data)

Detailed Description

A struct that represents I2C read and write messages.

Individual messages can be accumulated into a span and transmitted in one atomic i2c transaction using an Initiator implementation.

#include "pw_i2c/message.h"
 
constexpr auto kAddress = pw::i2c::Address::SevenBit<0x42>()
constexpr chrono::SystemClock::duration kTimeout =
    std::chrono::duration_cast<chrono::SystemClock::duration>(100ms);
const std::array<std::byte, 2> tx_buffer = {std::byte{0xCD},
                                            std::byte{0xEF}};
std::array<std::byte, 2> rx_buffer;
Vector<Message, 2> messages;
if (!tx_buffer.empty()) {
  messages.push_back(Message::WriteMessage(kAddress, tx_buffer));
}
if (!rx_buffer.empty()) {
  messages.push_back(Message::ReadMessage(kAddress, rx_buffer));
}
initiator.TransferFor(messages, kTimeout);

Member Function Documentation

GetAddress()

Address pw::i2c::Message::GetAddress ( ) const

inline

Getter for the address component.

Returns

the Address passed into one of the constructors or factories.

GetData()

ConstByteSpan pw::i2c::Message::GetData ( ) const

inline

Getter for the data component.

Returns

the data passed into one of the constructors or factories.

GetMutableData()

ByteSpan pw::i2c::Message::GetMutableData ( ) const

inline

Getter for the data component.

This method is only valid for Read messages and will runtime ASSERT on other messages.

Returns

the mutable variant of the data passed into one of the constructors or factories.

IsRead()

bool pw::i2c::Message::IsRead ( ) const

inline

Getter for whether this object represents a read operation.

Returns

true if the message represents a read operation.

IsTenBit()

bool pw::i2c::Message::IsTenBit ( ) const

inline

Getter for whether this object represents an operation addressed with a ten-bit address. When true, communicate on the wire using the i2c 10-bit addressing protocol.

Returns

true if the message represents a 10-bit addressed operation.

IsWriteContinuation()

bool pw::i2c::Message::IsWriteContinuation ( ) const

inline

Getter for whether this object represents a continued write.

Returns

true if the message represents a continued write.

ReadMessage()

static constexpr Message pw::i2c::Message::ReadMessage ( Address  address, ByteSpan  data  )

inlinestaticconstexpr

Creates a pw::i2c::Message instance for an i2c read message.

This Message can be passed to Initiator::TransferFor().

constexpr Message kMessage = Message::ReadMessage(
    pw::i2c::Address::SevenBit<0x42>(),
    data
);

Returns

A pw::i2c::Message instance.

WriteMessage()

static constexpr Message pw::i2c::Message::WriteMessage ( Address  address, ConstByteSpan  data  )

inlinestaticconstexpr

Creates a pw::i2c::Message instance for an i2c write message.

This Message can be passed to Initiator::TransferFor().

constexpr Message kMessage = Message::WriteMessage(
    pw::i2c::Address::SevenBit<0x42>(),
    data
);

Returns

A pw::i2c::Message instance.

WriteMessageContinuation()

static constexpr Message pw::i2c::Message::WriteMessageContinuation ( ConstByteSpan  data )

inlinestaticconstexpr

Creates a pw::i2c::Message instance for an i2c write message without a start condition sent on the bus. Chaining one or more of these messages after a regular Write message allows the client to send non-contiguous blocks of memory as one single write message to the i2c target.

Note: This message must follow another write message.

Note: No addresses is needed and no address will be transmitted. The data should immediately follow the data from the previous write message.

This Message can be passed to Initiator::TransferFor().

constexpr Message kMessage = Message::WriteMessageContinuation(data);

Returns

A pw::i2c::Message instance.

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The documentation for this class was generated from the following file:

• pw_i2c/public/pw_i2c/message.h