/*!
* \file utl/com/_1wire_uart.h
* \brief
* A 1-wire implementation using a microprocessor's uart for bit timing
* \note
* This 1-wire implementation is based on MCU UART functionality. The implementation
* expects:
* 1) An Open drain tx and a floating(or pull-up) rx UART pin configuration with both pins
* connected to the 1-wire bus wire
* 2) A Transmit/receive function even in blocking/polling mode
* 3) A baudrate set function
*
* 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 .
*
*/
#ifndef __utl_com_1wire_uart_h__
#define __utl_com_1wire_uart_h__
#include
#include
#include
namespace utl {
/*!
* \ingroup Communication
* A 1-wire implementation using a microprocessor's uart for bit timing
* inherited from \ref _1wire_i base class.
* \sa _1wire_i
*/
//!@{
/*!
* \brief
* 1-wire UART interface template class using CRTP
* Using the private virtual interface we provide the interface from
* _1wire_i<>
*/
template
class _1wire_uart_i : public _1wire_i<_1wire_uart_i> {
_CRTP_IMPL(Impl_t); //! \brief Syntactic sugar to CRTP casting
friend _1wire_i <_1wire_uart_i>;
public:
using type = _1wire_uart_i; //!< Export type as identity meta-function
using Speed = typename _1wire_i::Speed; //!< Bring bus speed
/*!
* \name Object lifetime
*/
//!@{
protected:
_1wire_uart_i () = default; //!< Allow constructor from derived only
~_1wire_uart_i () = default; //!< Allow destructor from derived only
//!@}
/*!
* \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
*/
//!@{
private:
/*!
* \brief
* Implementers's (driver) read-write function. We expect the following
* USART configuration:
* - Word Length = 8 Bits
* - Stop Bit = One Stop bit
* - Parity = No parity
* \param The byte to send
* \return The byte received.
* \note
* Due to the nature of the technique, the received byte is the actual bus
* condition during the communication frame (time slot)
*/
byte_t UART_RW (byte_t byte) { return impl().UART_RW (byte); }
/*!
* \brief
* Implementers's (driver) baudrate function.
* \param The desired Baudrate
*/
void UART_BR (uint32_t br) { impl().UART_BR (br); }
//!@}
//! \name Implementation of base requirements
//!@{
private:
//! 1-wire UART baudrates
enum BR {
BR_STD_RST =9600,
BR_OVR_RST =57600,
BR_STD =115200,
BR_OVR =921600
};
Speed _speed {Speed::STD};
Speed speed () const { return _speed; } //!< Get the 1-wire bus speed
void speed (Speed s); //!< Set the 1-wire bus speed
/*!
* \brief
* Send a 1-Wire write bit and read the response
*
* Write 1 --- --------------------------------------
* Read 0/1 \ /
* ----
* RS: | | | | | | | | | | |
* bit: ST 0 1 2 3 4 5 6 7 SP
* TX: 0xFF RX: 0xFF->1, less->0
*
* Write 0 --- ------
* Read 0 \ /
* -------------------------------------
* RS: | | | | | | | | | | |
* bit: ST 0 1 2 3 4 5 6 7 SP
* < ------------- 87/11 usec ------------->
* TX: 0x00 RX: 0x00
*
* \param b The bit to send
* \return The response
*/
bool bit (bool b) {
if (b)
return (UART_RW (0xFF) < 0xFF) ? 0 : 1;
else {
UART_RW (0x00);
return 0;
}
}
bool _reset (Speed s);
//!@}
};
/*!
* Set the 1-wire bus speed for normal operation only
* \note
* We have moved the BR set functionality here to reduce the code inside bit().
* This is OK as long as the _1wire_i<> always check speed.
* \param s The desired speed
*/
template
void _1wire_uart_i::speed (Speed s) {
switch (_speed = s) {
case Speed::STD: UART_BR (BR_STD); break;
case Speed::OVDR: UART_BR (BR_OVR); break;
}
}
/*!
* \brief
* Generate a 1-wire reset
* --- ---- - - - -------
* Reset \ / \ X X X /
* -------------------- - - - -
* RS: | | | | | | | | | | |
* bit: ST 0 1 2 3 4 5 6 7 SP
* < ---------- 1024/174 usec ------------->
*
* TX: (STD)0xF0, (OVDR)0xF8 RX: less if present
*
* \param t Timing
* \return The status of the operation
* \arg 0 Fail
* \arg 1 Success
*/
template
bool _1wire_uart_i::_reset (Speed s) {
// Select frame to send
uint8_t w = ((_speed = s) == Speed::STD) ? 0xF0 : 0xF8;
// Select baudrate
impl().UART_BR ((_speed == Speed::STD) ? BR_STD_RST : BR_OVR_RST);
// Send frame and check the result
return (impl().UART_RW (w) < w);
}
/*!
* \brief
* A virtual base class interface implementation.
* Using the private virtual interface we provide the interface from
* _1wire_i
* \param impl_t = virtual_tag
*/
template <>
class _1wire_uart_i : public _1wire_i {
public:
using type = _1wire_uart_i; //!< Export type as identity meta-function
using Speed = typename _1wire_i::Speed; //!< Bring bus speed
/*!
* \name Object lifetime
*/
//!@{
protected:
_1wire_uart_i () = default; //!< Allow constructor from derived only
~_1wire_uart_i () = default; //!< Allow destructor from derived only
//!@}
/*!
* \name Implementation requirements
*/
//!@{
private:
/*!
* \brief
* Implementers's (driver) read-write function. We use the following
* USART configuration:
* - Word Length = 8 Bits
* - Stop Bit = One Stop bit
* - Parity = No parity
* \param The byte to send
* \return The byte received.
* \note
* Due to the nature of the technique, the received byte is the actual bus
* condition during the communication frame (time slot)
*/
virtual byte_t UART_RW (byte_t byte) =0;
/*!
* \brief
* Implementers's (driver) baudrate function.
* \param The desired Baudrate
*/
virtual void UART_BR (uint32_t br) =0;
//!@}
//! \name Implementation of base requirements
//!@{
private:
//! 1-wire UART baudrates
enum BR {
BR_STD_RST =9600,
BR_OVR_RST =57600,
BR_STD =115200,
BR_OVR =921600
};
Speed _speed {Speed::STD};
Speed speed () const { return _speed; } //!< Get the 1-wire bus speed
void speed (Speed s); //!< Set the 1-wire bus speed
/*!
* \brief
* Send a 1-Wire write bit and read the response
*
* Write 1 --- --------------------------------------
* Read 0/1 \ /
* ----
* RS: | | | | | | | | | | |
* bit: ST 0 1 2 3 4 5 6 7 SP
* TX: 0xFF RX: 0xFF->1, less->0
*
* Write 0 --- ------
* Read 0 \ /
* -------------------------------------
* RS: | | | | | | | | | | |
* bit: ST 0 1 2 3 4 5 6 7 SP
* < ------------- 87/11 usec ------------->
* TX: 0x00 RX: 0x00
*
* \param b The bit to send
* \return The response
*/
bool bit (bool b) {
if (b)
return (UART_RW (0xFF) < 0xFF) ? 0 : 1;
else {
UART_RW (0x00);
return 0;
}
}
bool _reset (Speed s);
//!@}
};
/*!
* Set the 1-wire bus speed for normal operation only
* \note
* We have moved the BR set functionality here to reduce the code inside bit().
* This is OK as long as the _1wire_i<> always check speed.
* \param s The desired speed
*/
void _1wire_uart_i::speed (Speed s) {
switch (_speed = s) {
case Speed::STD: UART_BR (BR_STD); break;
case Speed::OVDR: UART_BR (BR_OVR); break;
}
}
/*!
* \brief
* Generate a 1-wire reset
* --- ---- - - - -------
* Reset \ / \ X X X /
* -------------------- - - - -
* RS: | | | | | | | | | | |
* bit: ST 0 1 2 3 4 5 6 7 SP
* < ---------- 1024/174 usec ------------->
*
* TX: (STD)0xF0, (OVDR)0xF8 RX: less if present
*
* \param t Timing
* \return The status of the operation
* \arg 0 Fail
* \arg 1 Success
*/
bool _1wire_uart_i::_reset (Speed s) {
// Select frame to send
uint8_t w = ((_speed = s) == Speed::STD) ? 0xF0 : 0xF8;
// Select baudrate
UART_BR ((_speed == Speed::STD) ? BR_STD_RST : BR_OVR_RST);
// Send frame and check the result
return (UART_RW (w) < w);
}
//!@}
} // namespace utl
#endif /* __utl_com_1wire_uart_h__ */