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com: Traditionally the first module of my libs is an i2c implementation

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Christos Houtouridis 6 years ago
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      include/utl/com/i2c.h
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/*!
* \file /utl/com/i2c.h
* \brief An Abstract base class interface for the i2c bus
*
* Copyright (C) 2018 Christos Choutouridis
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation, either version 3
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
*/
#ifndef _utl_com_i2c_h__
#define _utl_com_i2c_h__
#include <utl/impl/impl.h>
#include <utl/helper/crtp.h>
#include <utl/meta/sfinae.h>
namespace utl {
/*!
* \ingroup Communication
* \brief Abstract base class for i2c bus
*/
//!@{
/*!
* \brief
* this class force a common interface for I2C communication
* protocol implementations using CRTP
* \param impl_t The CRTP type (the derived/implementation class typename).
*/
template <typename impl_t>
class i2c_i {
_CRTP_IMPL(impl_t);
public:
using type = i2c_i<impl_t>; //!< Export type as identity meta-function
//! I2C transmit/receive sequence
enum class Sequence {
BYTE =0, //!< Only read/write byte [8 clocks]
ACK, //!< Only send/receive ack [1 clock]
BYTEnACK //!< Read/Write byte and ack [9 clocks]
};
/*!
* \name Object lifetime
*/
//!@{
protected:
i2c_i () = default; //!< Allow constructor from derived only
~i2c_i () = default; //!< Allow destructor from derived only
i2c_i (const type&) = delete; //!< No copies
type& operator= (const type&) = delete;
//!@}
/*!
* \name Implementation requirements
* \note
* In order for the implementation to have the following as private members
* it also need to declare this class as friend
*/
//!@{
//! uint32_t _frequency () const; < clock frequency of the bus [Hz]
//! void _frequency (uint32_t); < set clock frequency of the bus [Hz]
//! void _start(); < Send start functionality
//! void _stop(); < Send stop functionality
//! byte_t _read (bool ack, Sequence seq); < Receive a byte from the i2c bus.
//! bool _write (byte_t byte, Sequence seq);< Transmit a byte to the i2c bus.
//!@}
/*!
* \name Get/Set functions
*/
//!@{
public:
uint32_t frequency () const { return impl()._frequency (); } //!< \return clock frequency of the bus
void frequency (uint32_t f) { impl()._frequency (f); } //!< \brief set clock frequency of the bus
//!@}
/*!
* \name User functions
*/
//!@{
public:
void start() { impl()._start (); } //!< Send start functionality
void stop () { impl()._stop (); } //!< Send stop functionality
/*!
* \brief
* Receive a byte from the i2c bus.
* \param ack Optional ack bit.
* \arg 1 ACK the reception
* \arg 0 Don't ACK the reception.
* \param seq The operation sequence to execute
* \arg Sequence::BYTE Receive only the byte, do not send ack clock
* \arg Sequence::ACK Send only the ack bit
* \arg Sequence::BYTEnACK Receive the byte and send the ack bit
* \return The byte received.
*/
byte_t read (bool ack, Sequence seq =Sequence::BYTEnACK) {
return impl()._read (ack, seq);
}
/*!
* \brief
* Transmit a byte to the i2c bus.
* \param byte The byte to send.
* \param seq The operation sequence to execute
* \arg Sequence::BYTE Transmit only the byte, do not read ack bit
* \arg Sequence::ACK Read only the ack bit
* \arg Sequence::BYTEnACK Transmit the byte and read the ack bit
* \return Slave's ACK bit
* \arg false Slave didn't ACK
* \arg true Slave did ACK
*/
bool write (byte_t byte, Sequence seq =Sequence::BYTEnACK) {
return impl()._write (byte, seq);
}
//!@}
};
/*!
* \brief
* A virtual base class specialization
* \param impl_t = virtual_tag
*/
template<>
class i2c_i <virtual_tag> {
public:
using type = i2c_i <virtual_tag>; //!< Export type as identity meta-function
//! I2C transmit/receive sequence
enum class Sequence {
BYTE=0, //!< Only read/write byte [8 clocks]
ACK, //!< Only send/receive ack [1 clock]
BYTEnACK //!< Read/Write byte and ack [9 clocks]
};
/*!
* \name Object lifetime
*/
//!@{
protected:
i2c_i () = default; //!< Allow constructor from derived only
i2c_i (const type&) = delete; //!< No copies
type& operator= (const type&) = delete;
public:
virtual ~i2c_i () = default; //!< Virtual default destructor
//!@}
/*!
* \name Implementation requirements
*/
//!@{
private:
virtual uint32_t _frequency () const = 0; //!< \return clock frequency of the bus [Hz]
virtual void _frequency (uint32_t) = 0; //!< \brief set clock frequency of the bus [Hz]
virtual void _start() = 0; //!< Send start functionality
virtual void _stop() = 0; //!< Send stop functionality
virtual byte_t _read (bool ack, Sequence seq) = 0; //!< Receive a byte from the i2c bus.
virtual bool _write (byte_t byte, Sequence seq) = 0; //!< Transmit a byte to the i2c bus.
//!@}
/*!
* \name Get/Set functions
*/
//!@{
public:
uint32_t frequency () const { return _frequency(); } //!< \return clock frequency of the bus [Hz]
void frequency (uint32_t f) { _frequency(f); } //!< \brief set clock frequency of the bus [Hz]
//!@}
/*!
* \name User functions
*/
//!@{
public:
void start () { _start(); }
void stop () { _stop(); }
/*!
* \brief
* Receive a byte from the i2c bus.
* \param ack Optional ack bit.
* \arg 1 ACK the reception
* \arg 0 Don't ACK the reception.
* \param seq The operation sequence to execute
* \arg Sequence::BYTE Receive only the byte, do not send ack clock
* \arg Sequence::ACK Send only the ack bit
* \arg Sequence::BYTEnACK Receive the byte and send the ack bit
* \return The byte received.
*/
byte_t read (bool ack, Sequence seq =Sequence::BYTEnACK) {
return _read (ack, seq);
}
/*!
* \brief
* Transmit a byte to the i2c bus.
* \param byte The byte to send.
* \param seq The operation sequence to execute
* \arg Sequence::BYTE Transmit only the byte, do not read ack bit
* \arg Sequence::ACK Read only the ack bit
* \arg Sequence::BYTEnACK Transmit the byte and read the ack bit
* \return Slave's ACK bit
* \arg false Slave didn't ACK
* \arg true Slave did ACK
*/
bool write (byte_t byte, Sequence seq =Sequence::BYTEnACK) {
return _write (byte, seq);
}
//!@}
};
#if defined _utl_have_concepts
/*!
* i2c interface concept
*/
template <typename T>
concept bool i2c_c = requires (T t, const T ct, typename T::Sequence s) {
// Object type
requires not_<std::is_copy_constructible<T>::value>::value;
requires not_<std::is_copy_assignable<T>::value>::value;
// Methods
{ct.frequency()} -> uint32_t;
{t.frequency(0)} -> void;
{t.start()} -> void;
{t.stop()} -> void;
{t.read (1, s)} -> byte_t;
{t.write(0, s)} -> bool;
};
#else
namespace i2c_t_cnpt {
using std::declval;
template <class _Tp> using try_cfreq_t = decltype (declval<const _Tp>().frequency());
template <class _Tp> using try_freq_t = decltype (declval<_Tp>().frequency(declval<uint32_t>()));
template <class _Tp> using try_start_t = decltype (declval<_Tp>().start());
template <class _Tp> using try_stop_t = decltype (declval<_Tp>().stop());
template <class _Tp> using try_read_t
= decltype (declval<_Tp>().read (declval<bool>(), declval<typename _Tp::Sequence>()));
template <class _Tp> using try_write_t
= decltype (declval<_Tp>().write (declval<byte_t>(), declval<typename _Tp::Sequence>()));
//! Primary template to catch any non I2C interface types
template <typename _Tp, typename =void>
struct is_i2c_ : false_ { };
//! template to catch a proper I2C interface type
template <typename _Tp>
struct is_i2c_ <_Tp,
void_t <
typename _Tp::Sequence,
use_if_same_t <uint32_t,try_cfreq_t <_Tp>>,
use_if_same_t <void, try_freq_t <_Tp>>,
use_if_same_t <void, try_start_t <_Tp>>,
use_if_same_t <void, try_stop_t <_Tp>>,
use_if_same_t <byte_t, try_read_t <_Tp>>,
use_if_same_t <bool, try_write_t <_Tp>>
> //!^ SFINAE may apply inside if_same_t<> also
> : true_ { };
}
/*!
* Value meta-programming function alias for I2C interface checking
* \param _Tp Type to check
* \return True if _Tp is a i2c interface
*/
template <typename _Tp>
constexpr bool i2c_c = i2c_t_cnpt::is_i2c_<_Tp>::value;
#endif
//!@}
} // namespace utl
#endif // _utl_com_i2c_h__

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/*!
* \file utl/com/i2c_bb.h
* \brief A bit banking implementation of i2c bus inherited from
* i2c_i base class.
*
* Copyright (C) 2018 Christos Choutouridis
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation, either version 3
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
*/
#ifndef __utl_com_i2c_bb_h__
#define __utl_com_i2c_bb_h__
#include <utl/impl/impl.h>
#include <utl/helper/crtp.h>
#include <utl/com/i2c.h>
namespace utl {
/*!
* \ingroup Communication
* \brief A bit banking implementation of i2c bus
* inherited from \ref i2c_i base class.
* \sa i2c_i
*/
//!@{
/*!
* \brief
* I2C bit banking interface template class providing
* an I2C using bit banking using CRTP.
* \param impl_t The CRTP type (the derived/implementation class typename).
*/
template <typename impl_t>
class i2c_bb_i : public i2c_i<i2c_bb_i<impl_t>> {
_CRTP_IMPL(impl_t);
friend i2c_i<i2c_bb_i<impl_t>>;
public:
using type = i2c_bb_i<impl_t>; //!< Export type as identity meta-function
using Sequence = typename i2c_i<type>::Sequence;
//! SDA pin direction enumerator
enum class SDAMode {
INPUT =0,
OUTPUT
};
/*!
* \name Object lifetime
*/
//!@{
protected:
//! \brief A default destructor, allow destructor from derived only
~i2c_bb_i () noexcept = default;
//! \brief A default constructor
i2c_bb_i (uint32_t frequency =100000) noexcept
: usec_ {1000000/(2*frequency)} { }
//!@}
/*!
* \name Implementation requirements
* \note
* In order for the implementation to have the following as private members
* it also need to declare this class as friend
* bool SDA (SDAMode mode, bool st);
* void SCL (uint8_t st);
* void delay (uint32_t usec);
*/
//!@{
private:
/*!
* Implementers's sda pin function
* \param st In SDA_OUTPUT mode, selects the pin output state
* \return In SDA_INPUT mode return the pin input state
*/
bool SDA (SDAMode mode, bool st) { return impl().SDA (mode, st); }
void SCL (uint8_t st) { impl().SCL (st); } //!< Implementers's scl pin function
void delay (uint32_t usec) { impl().delay(usec); } //!< Implementers's usec delay function
//!@}
/*!
* \name Implementation of base requirements
*/
//!@{
private:
uint32_t _frequency () const { return 1000000/(2*usec_); }
void _frequency (uint32_t f) { usec_ = 1000000/(2*f); }
void _start (); //!< Send start functionality
void _stop (); //!< Send stop functionality
byte_t _read (bool ack, Sequence seq);
bool _write (byte_t byte, Sequence seq);
uint32_t usec_; //!< half period of I2C nus
//!@}
};
/*
* ============= User functions ================
*/
/*!
* \brief
* Send a START bit to the bus
* \return none
*/
template <typename impl_t>
void i2c_bb_i<impl_t>::_start (void) {
//Initially set pins
SDA (SDAMode::OUTPUT, 1);
SCL (1);
delay (usec_);
SDA (SDAMode::OUTPUT, 0);
delay (usec_);
SCL (0); //Clear Clock
}
/*!
* \brief
* Send a START bit to the bus
* \return none
*/
template <typename impl_t>
void i2c_bb_i<impl_t>::_stop (void) {
//Stop bit Operation
SDA (SDAMode::OUTPUT, 0);
SCL (0);
SCL (1);
delay (usec_);
SDA (SDAMode::OUTPUT, 1);
delay (usec_);
}
/*!
* \brief
* Receive a byte from the i2c bus.
* \param ack Optional ack bit.
* \arg 1 ACK the reception
* \arg 0 Don't ACK the reception.
* \param seq The operation sequence to execute
* \arg Sequence::BYTE Receive only the byte, do not send ack clock
* \arg Sequence::ACK Send only the ack bit
* \arg Sequence::BYTEnACK Receive the byte and send the ack bit
* \return The byte received.
*/
template <typename impl_t>
byte_t i2c_bb_i<impl_t>::_read (bool ack, Sequence seq) {
byte_t byte {0};
//Initial conditions
SCL (0);
SDA (SDAMode::INPUT, 0);
if (seq == Sequence::BYTE || seq == Sequence::BYTEnACK) {
// read 8 data bits
for (int i=8 ; i!=0 ; --i) {
byte <<= 1;
SCL (1);
delay (usec_);
byte |= SDA (SDAMode::INPUT, 0);
SCL (0);
delay (usec_);
}
}
if (seq == Sequence::ACK || seq == Sequence::BYTEnACK) {
SDA (SDAMode::OUTPUT, !ack); //Send (or not) ACK bit
SCL (1);
delay (usec_);
SCL (0); // Keep the bus busy
SDA (SDAMode::OUTPUT, 0);
}
return byte;
}
/*!
* \brief
* Transmit a byte to the i2c bus.
* \param byte The byte to send.
* \param seq The operation sequence to execute
* \arg Sequence::BYTE Transmit only the byte, do not read ack bit
* \arg Sequence::ACK Read only the ack bit
* \arg Sequence::BYTEnACK Transmit the byte and read the ack bit
* \return Slave's ACK bit
* \arg false Slave didn't ACK
* \arg true Slave did ACK
*/
template <typename impl_t>
bool i2c_bb_i<impl_t>::_write (byte_t byte, Sequence seq) {
bool ack {false};
//Initial conditions
SCL (0);
SDA (SDAMode::OUTPUT, 0);
if (seq == Sequence::BYTE || seq == Sequence::BYTEnACK) {
//Send 8 bit data
for (int i=8 ; i!=0 ; --i) {
//Send MSB
SDA (SDAMode::OUTPUT, byte & 0x80);
byte <<= 1;
SCL (1);
delay (usec_);
SCL (0);
delay (usec_);
}
}
if (seq == Sequence::ACK || seq == Sequence::BYTEnACK) {
// Get ACK
SDA (SDAMode::INPUT, 0);
SCL (1);
delay (usec_);
ack = !SDA (SDAMode::INPUT, 0);
SCL (0); // Keep the bus busy
delay (usec_);
SDA (SDAMode::OUTPUT, 0);
}
return ack;
}
/*!
* \brief
* A virtual base class interface specialization.
* Using the private virtual interface we provide the interface from
* i2c_i<virtual_tag>
* \param impl_t = virtual_tag
*/
template<>
class i2c_bb_i<virtual_tag> : public i2c_i<virtual_tag> {
public:
using type = i2c_bb_i<virtual_tag>; //!< Export type as identity meta-function
using Sequence = typename i2c_i<virtual_tag>::Sequence;
//! SDA pin direction enumerator
enum class SDAMode {
INPUT =0,
OUTPUT
};
/*!
* \name Object lifetime
*/
//!@{
protected:
//! \brief Constructor
i2c_bb_i (uint32_t frequency =100000) noexcept
: usec_ {1000000/(2*frequency)} { }
//! \brief Virtual destructor
virtual ~i2c_bb_i () noexcept = default;
//!@}
/*!
* \name Implementation requirements
*/
//!@{
private:
/*!
* Implementers's sda pin function
* \param st In SDA_OUTPUT mode, selects the pin output state
* \return In SDA_INPUT mode return the pin input state
*/
virtual bool SDA (SDAMode mode, bool st) =0;
virtual void SCL (bool st) =0; //!< Implementers's scl pin function
virtual void delay (uint32_t usec) =0; //!< Implementers's usec delay function
//!@}
/*!
* \name Implementation of base requirements
*/
//!@{
private:
uint32_t _frequency () const final { return 1000000/(2*usec_); }
void _frequency (uint32_t f) final { usec_ = 1000000/(2*f); }
void _start () final;
void _stop () final;
byte_t _read (bool ack, Sequence seq) final;
bool _write (byte_t byte, Sequence seq) final;
//!< half period of I2C bus
uint32_t usec_;
//!@}
};
/*!
* \brief
* Send a START bit to the bus
* \return none
*/
void i2c_bb_i<virtual_tag>::_start (void) {
//Initially set pins
SDA (SDAMode::OUTPUT, 1);
SCL (1);
delay (usec_);
SDA (SDAMode::OUTPUT, 0);
delay (usec_);
SCL (0); //Clear Clock
}
/*!
* \brief
* Send a START bit to the bus
* \return none
*/
void i2c_bb_i<virtual_tag>::_stop (void) {
//Stop bit Operation
SDA (SDAMode::OUTPUT, 0);
SCL (0);
SCL (1);
delay (usec_);
SDA (SDAMode::OUTPUT, 1);
delay (usec_);
}
/*!
* \brief
* Receive a byte from the i2c bus.
* \param ack Optional ack bit.
* \arg 1 ACK the reception
* \arg 0 Don't ACK the reception.
* \param seq The operation sequence to execute
* \arg Sequence::BYTE Receive only the byte, do not send ack clock
* \arg Sequence::ACK Send only the ack bit
* \arg Sequence::BYTEnACK Receive the byte and send the ack bit
* \return The byte received.
*/
byte_t i2c_bb_i<virtual_tag>::_read (bool ack, Sequence seq) {
byte_t byte {0};
//Initial conditions
SCL (0);
SDA (SDAMode::INPUT, 0);
if (seq == Sequence::BYTE || seq == Sequence::BYTEnACK) {
// read 8 data bits
for (int i=8 ; i!=0 ; --i) {
byte <<= 1;
SCL (1);
delay (usec_);
byte |= SDA (SDAMode::INPUT, 0);
SCL (0);
delay (usec_);
}
}
if (seq == Sequence::ACK || seq == Sequence::BYTEnACK) {
SDA (SDAMode::OUTPUT, !ack); //Send (or not) ACK bit
SCL (1);
delay (usec_);
SCL (0); // Keep the bus busy
SDA (SDAMode::OUTPUT, 0);
}
return byte;
}
/*!
* \brief
* Transmit a byte to the i2c bus.
* \param byte The byte to send.
* \param seq The operation sequence to execute
* \arg Sequence::BYTE Transmit only the byte, do not read ack bit
* \arg Sequence::ACK Read only the ack bit
* \arg Sequence::BYTEnACK Transmit the byte and read the ack bit
* \return Slave's ACK bit
* \arg false Slave didn't ACK
* \arg true Slave did ACK
*/
bool i2c_bb_i<virtual_tag>::_write (byte_t byte, Sequence seq) {
bool ack {false};
//Initial conditions
SCL (0);
SDA (SDAMode::OUTPUT, 0);
if (seq == Sequence::BYTE || seq == Sequence::BYTEnACK) {
//Send 8 bit data
for (int i=8 ; i!=0 ; --i) {
//Send MSB
SDA (SDAMode::OUTPUT, byte & 0x80);
byte <<= 1;
SCL (1);
delay (usec_);
SCL (0);
delay (usec_);
}
}
if (seq == Sequence::ACK || seq == Sequence::BYTEnACK) {
// Get ACK
SDA (SDAMode::INPUT, 0);
SCL (1);
delay (usec_);
ack = !SDA (SDAMode::INPUT, 0);
SCL (0); // Keep the bus busy
delay (usec_);
SDA (SDAMode::OUTPUT, 0);
}
return ack;
}
//!@}
} // namspace utl
#endif // #ifndef __utl_com_i2c_bb_h__

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