#include <modm/architecture/interface/i2c_master.hpp>

Inheritance diagram for modm::I2cMaster:

Public Typedefs
using	ConfigurationHandler = void (*)()
	The signature of the configuration function.

Public Types
enum	Error : uint8_t { Error::NoError, Error::SoftwareReset, Error::AddressNack, Error::DataNack, Error::ArbitrationLost, Error::BusCondition, Error::BusBusy, Error::Unknown }
	Errors that can happen during master operation. More...

enum	PullUps { PullUps::External, PullUps::Internal }

enum	ResetDevices : uint32_t { ResetDevices::NoReset = 0, ResetDevices::LowSpeed = 10'000, ResetDevices::Standard = 100'000, ResetDevices::Fast = 400'000 }

enum	DetachCause : uint8_t { DetachCause::NormalStop, DetachCause::ErrorCondition, DetachCause::FailedToAttach }

enum	TransactionState : uint8_t { TransactionState::Idle, TransactionState::Busy, TransactionState::Error }
	State of a I2c Transaction. More...


enum	Operation : uint8_t { Operation::Stop = 0, Operation::Restart = 1, Operation::Write = 2, Operation::Read = 3 }
	All possible I2C Operations. More...

enum	OperationAfterRead : uint8_t { OperationAfterRead::Stop = uint8_t(Operation::Stop), OperationAfterRead::Restart = uint8_t(Operation::Restart) }
	Further operations after read operation. More...

enum	OperationAfterStart : uint8_t { OperationAfterStart::Stop = uint8_t(Operation::Stop), OperationAfterStart::Write = uint8_t(Operation::Write), OperationAfterStart::Read = uint8_t(Operation::Read) }
	Further operations after start operation. More...

enum	OperationAfterWrite : uint8_t { OperationAfterWrite::Stop = uint8_t(Operation::Stop), OperationAfterWrite::Restart = uint8_t(Operation::Restart), OperationAfterWrite::Write = uint8_t(Operation::Write) }
	Further operations after write operation. More...

Static Public Member Functions
template<class... Signals>
static void	connect (PullUps pullups=PullUps::External, ResetDevices reset=ResetDevices::Standard)

template<class SystemClock , baudrate_t baudrate = 100_kBd, percent_t tolerance = 5_pct>
static void	initialize ()

static bool	start (I2cTransaction *transaction, ConfigurationHandler handler=nullptr)

static void	reset ()

static Error	getErrorState ()

static void	acknowledgeInterruptFlag ()

template<uint64_t available, uint64_t requested, percent_t tolerance>
static void	assertBaudrateInTolerance ()

template<double available, double requested, percent_t tolerance>
static void	assertDurationInTolerance ()

static void	configurePurpose ()
	configures a peripheral for a specific purpose

static bool	getInterruptFlag ()
	Read an interrupt flag.

static void	getParameter ()
	returns a parameter

static void	initialize ()
	initializes the peripheral, must be called before use.

static void	setParameter ()
	sets a parameter

template<class Scl >
static void	resetDevices (uint32_t baudrate=100'000)

Static Public Attributes
static constexpr size_t	TransactionBufferSize = 8
	Number of transactions which can be queued in this driver.

static constexpr uint8_t	Read = 0x01
	Add the Read bit to the slave address.

static constexpr uint8_t	Write = 0x00
	Add the Write bit to the slave address.

Detailed Description

Interface of a I2C master.

Performing transfers in background allows the use of DMA etc. and enables the program to do other things while the operation is going on.

Author: Georgi Grinshpun; Niklas Hauser

Member Enumeration Documentation

enum modm::I2c::DetachCause : uint8_t

inheritedstrong

This tells the I2cTransaction why it was detached

See also: I2cTransaction

Enum Values	Documentation
NormalStop	All operations finished normally.
ErrorCondition	A bus error occurred and the bus was reset.
FailedToAttach	The I2cTransaction failed to attach to the I2cMaster.

enum modm::I2cMaster::Error : uint8_t

strong

Errors that can happen during master operation.

Enum Values	Documentation
NoError	No Error occurred.
SoftwareReset	The master was reset in software.
AddressNack	Address was transmitted and NACK received.
DataNack	Data was transmitted and NACK received.
ArbitrationLost	Arbitration was lost during writing or reading.
BusCondition	Misplaced Start or Stop condition.
BusBusy	Bus is busy during Start condition.
Unknown	Unknown error condition.

enum modm::I2c::Operation : uint8_t

inheritedstrong

All possible I2C Operations.

I2C Operations that the I2cTransaction can give the master on callback

See also: I2cTransaction

Enum Values	Documentation
Stop	Generate a Stop Condition.
Restart	Generate a Restart.
Write	Write data to the slave.
Read	Read data from the slave.

enum modm::I2c::OperationAfterRead : uint8_t

inheritedstrong

Further operations after read operation.

Enum Values	Documentation
Stop	Generate a Stop Condition.
Restart	Generate a Restart.

enum modm::I2c::OperationAfterStart : uint8_t

inheritedstrong

Further operations after start operation.

Enum Values	Documentation
Stop	Generate a Stop Condition.
Write	Write data to the slave.
Read	Read data from the slave.

enum modm::I2c::OperationAfterWrite : uint8_t

inheritedstrong

Further operations after write operation.

Enum Values	Documentation
Stop	Generate a Stop Condition.
Restart	Generate a Restart.
Write	Write data to the slave.

enum modm::I2cMaster::PullUps

strong

Enum Values	Documentation
External	External pull-ups exists in SDA and SCL.
Internal	Use weak internal pull-ups on SDA and SCL.

enum modm::I2cMaster::ResetDevices : uint32_t

strong

Enum Values	Documentation
NoReset	Do not reset devices.
LowSpeed	Low-Speed datarate of 10kHz.
Standard	Standard datarate of 100kHz.
Fast	Fast datarate of 400kHz.

enum modm::I2c::TransactionState : uint8_t

inheritedstrong

State of a I2c Transaction.

Enum Values	Documentation
Idle	No error occurred, detached normally.
Busy	The transaction object is busy with data transfer.
Error	An error occurred, check the masters `getErrorCode()`

Member Function Documentation

static void modm::PeripheralDriver::acknowledgeInterruptFlag ( )

inheritedstatic

Acknowledge an interrupt flag.

We use acknowledge here, since it describes the intention rather than the actual implementation.

template<uint64_t available, uint64_t requested, percent_t tolerance>

static void modm::PeripheralDriver::assertBaudrateInTolerance ( )

inheritedinlinestatic

Since baudrates are usually generated by prescaling a system clock, only several distinct values can be generated. This method checks if the user requested baudrate is within error tolerance of the system achievable baudrate.

template<class... Signals>

static void modm::I2cMaster::connect	(	PullUps	pullups = `PullUps::External`,
		ResetDevices	reset = `ResetDevices::Standard`
	)

static

Configures the Scl and Sda signals and connects them.

This configures the Scl and Sda signals as open-drain outputs with optional weak internal pullups and optionally resets all slave devices on the bus.

Warning: Using weak internal pullups is not recommended and will require a slow baudrate. You must use external pullups for a reliable bus.

Template Parameters

Signals One Scl and one Sda signal are required and can be passed out-of-order.

Parameters

pullups	Use external or weak internal pullups.
reset	Choose a speed to reset the I2C devices with. Can be disabled with `ResetDevices::NoReset`.

static Error modm::I2cMaster::getErrorState ( )

static

Check the error state of the driver.

The error states are hardware and implementation specific.

template<class SystemClock , baudrate_t baudrate = 100_kBd, percent_t tolerance = 5_pct>

static void modm::I2cMaster::initialize ( )

static

Initializes the hardware and sets the datarate.

Template Parameters

SystemClock	the currently active system clock
baudrate	the desired baudrate in Hz
tolerance	the allowed absolute tolerance for the resulting baudrate

static void modm::I2cMaster::reset ( )

static

Perform a software reset of the driver in case of an error and detach the transaction object.

It is strongly recommended to reset the slave devices on the bus after a master reset. You can use the connect() method for that.

template<class Scl >

static void modm::I2c::resetDevices ( uint32_t baudrate = 100'000 )

inheritedinlinestatic

Reset all slave devices connected to an I2C bus.

During normal operation, I2C slave device may pull the SDA line low. However, if the master is reset during a transaction, the I2C clock may stop while the slave is outputting a low data bit and the slave will continue to hold this bit (forever, and ever and ever). The I2C master is then unable to generate a I2C start condition, since SDA is still held low by the slave device, resulting in a deadlock.

"You can always get it back to standby mode by allowing the SDA line to float high and give it 9 clocks. This assures that the device will not receive the acknowledge bit at the end the current byte and will abort the command and go to standby."

See also: Application Note AN572 by Microchip

Warning: Must be called before connecting SDA and SCL to I2cMaster!

Template Parameters

Scl	The clock pin of the bus to be reset.

static bool modm::I2cMaster::start	(	I2cTransaction *	transaction,
		ConfigurationHandler	handler = `nullptr`
	)

static

Requests transaction attachment.

Parameters

transaction	object that inherits from the I2cTransaction class.
configuration	function which configures the master for this transaction.

Returns: Caller gains control if true. Call has no effect if false.

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

i2c_master.hpp

Public Typedefs

Public Types

Static Public Member Functions

Static Public Attributes

Detailed Description

Member Enumeration Documentation

Member Function Documentation