334 lines
11 KiB
C++
334 lines
11 KiB
C++
/*!
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* \file utl/com/_1wire_uart.h
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* \brief
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* A 1-wire implementation using a microprocessor's uart for bit timing
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* \note
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* This 1-wire implementation is based on MCU UART functionality. The implementation
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* expects:
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* 1) An Open drain tx and a floating(or pull-up) rx UART pin configuration with both pins
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* connected to the 1-wire bus wire
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* 2) A Transmit/receive function even in blocking/polling mode
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* 3) A baudrate set function
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*
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* Copyright (C) 2018 Christos Choutouridis
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License as
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* published by the Free Software Foundation, either version 3
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*
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*/
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#ifndef __utl_com_1wire_uart_h__
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#define __utl_com_1wire_uart_h__
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#include <utl/core/impl.h>
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#include <utl/core/crtp.h>
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#include <utl/com/_1wire.h>
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namespace utl {
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/*!
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* \ingroup Communication
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* A 1-wire implementation using a microprocessor's uart for bit timing
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* inherited from \ref _1wire_i base class.
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* \sa _1wire_i
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*/
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//!@{
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/*!
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* \brief
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* 1-wire UART interface template class using CRTP
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* Using the private virtual interface we provide the interface from
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* _1wire_i<>
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*/
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template <typename Impl_t>
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class _1wire_uart_i : public _1wire_i<_1wire_uart_i<Impl_t>> {
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_CRTP_IMPL(Impl_t); //! \brief Syntactic sugar to CRTP casting
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friend _1wire_i <_1wire_uart_i<Impl_t>>;
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public:
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using type = _1wire_uart_i<Impl_t>; //!< Export type as identity meta-function
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using Speed = typename _1wire_i<type>::Speed; //!< Bring bus speed
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/*!
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* \name Object lifetime
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*/
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//!@{
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protected:
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_1wire_uart_i () = default; //!< Allow constructor from derived only
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~_1wire_uart_i () = default; //!< Allow destructor from derived only
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//!@}
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/*!
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* \name Implementation requirements
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* \note
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* In order for the implementation to have the following as private members
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* it also need to declare this class as friend
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*/
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//!@{
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private:
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/*!
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* \brief
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* Implementers's (driver) read-write function. We expect the following
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* USART configuration:
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* - Word Length = 8 Bits
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* - Stop Bit = One Stop bit
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* - Parity = No parity
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* \param The byte to send
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* \return The byte received.
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* \note
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* Due to the nature of the technique, the received byte is the actual bus
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* condition during the communication frame (time slot)
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*/
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byte_t UART_RW (byte_t byte) { return impl().UART_RW (byte); }
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/*!
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* \brief
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* Implementers's (driver) baudrate function.
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* \param The desired Baudrate
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*/
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void UART_BR (uint32_t br) { impl().UART_BR (br); }
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//!@}
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//! \name Implementation of base requirements
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//!@{
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private:
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//! 1-wire UART baudrates
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enum BR {
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BR_STD_RST =9600,
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BR_OVR_RST =57600,
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BR_STD =115200,
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BR_OVR =921600
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};
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Speed _speed {Speed::STD};
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Speed speed () const { return _speed; } //!< Get the 1-wire bus speed
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void speed (Speed s); //!< Set the 1-wire bus speed
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/*!
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* \brief
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* Send a 1-Wire write bit and read the response
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*
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* Write 1 --- --------------------------------------
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* Read 0/1 \ /
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* ----
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* RS: | | | | | | | | | | |
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* bit: ST 0 1 2 3 4 5 6 7 SP
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* TX: 0xFF RX: 0xFF->1, less->0
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*
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* Write 0 --- ------
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* Read 0 \ /
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* -------------------------------------
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* RS: | | | | | | | | | | |
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* bit: ST 0 1 2 3 4 5 6 7 SP
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* < ------------- 87/11 usec ------------->
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* TX: 0x00 RX: 0x00
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*
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* \param b The bit to send
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* \return The response
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*/
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bool bit (bool b) {
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if (b)
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return (UART_RW (0xFF) < 0xFF) ? 0 : 1;
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else {
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UART_RW (0x00);
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return 0;
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}
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}
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bool _reset (Speed s);
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//!@}
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};
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/*!
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* Set the 1-wire bus speed for normal operation only
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* \note
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* We have moved the BR set functionality here to reduce the code inside bit().
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* This is OK as long as the _1wire_i<> always check speed.
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* \param s The desired speed
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*/
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template <typename Impl_t>
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void _1wire_uart_i<Impl_t>::speed (Speed s) {
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switch (_speed = s) {
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case Speed::STD: UART_BR (BR_STD); break;
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case Speed::OVDR: UART_BR (BR_OVR); break;
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}
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}
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/*!
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* \brief
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* Generate a 1-wire reset
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* --- ---- - - - -------
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* Reset \ / \ X X X /
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* -------------------- - - - -
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* RS: | | | | | | | | | | |
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* bit: ST 0 1 2 3 4 5 6 7 SP
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* < ---------- 1024/174 usec ------------->
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*
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* TX: (STD)0xF0, (OVDR)0xF8 RX: less if present
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*
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* \param t Timing
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* \return The status of the operation
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* \arg 0 Fail
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* \arg 1 Success
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*/
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template <typename Impl_t>
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bool _1wire_uart_i<Impl_t>::_reset (Speed s) {
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// Select frame to send
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uint8_t w = ((_speed = s) == Speed::STD) ? 0xF0 : 0xF8;
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// Select baudrate
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impl().UART_BR ((_speed == Speed::STD) ? BR_STD_RST : BR_OVR_RST);
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// Send frame and check the result
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return (impl().UART_RW (w) < w);
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}
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/*!
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* \brief
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* A virtual base class interface implementation.
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* Using the private virtual interface we provide the interface from
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* _1wire_i<virtual_tag>
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* \param impl_t = virtual_tag
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*/
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template <>
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class _1wire_uart_i<virtual_tag> : public _1wire_i<virtual_tag> {
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public:
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using type = _1wire_uart_i<virtual_tag>; //!< Export type as identity meta-function
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using Speed = typename _1wire_i<virtual_tag>::Speed; //!< Bring bus speed
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/*!
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* \name Object lifetime
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*/
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//!@{
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protected:
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_1wire_uart_i () = default; //!< Allow constructor from derived only
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~_1wire_uart_i () = default; //!< Allow destructor from derived only
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//!@}
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/*!
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* \name Implementation requirements
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*/
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//!@{
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private:
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/*!
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* \brief
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* Implementers's (driver) read-write function. We use the following
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* USART configuration:
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* - Word Length = 8 Bits
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* - Stop Bit = One Stop bit
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* - Parity = No parity
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* \param The byte to send
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* \return The byte received.
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* \note
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* Due to the nature of the technique, the received byte is the actual bus
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* condition during the communication frame (time slot)
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*/
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virtual byte_t UART_RW (byte_t byte) =0;
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/*!
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* \brief
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* Implementers's (driver) baudrate function.
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* \param The desired Baudrate
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*/
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virtual void UART_BR (uint32_t br) =0;
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//!@}
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//! \name Implementation of base requirements
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//!@{
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private:
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//! 1-wire UART baudrates
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enum BR {
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BR_STD_RST =9600,
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BR_OVR_RST =57600,
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BR_STD =115200,
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BR_OVR =921600
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};
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Speed _speed {Speed::STD};
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Speed speed () const { return _speed; } //!< Get the 1-wire bus speed
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void speed (Speed s); //!< Set the 1-wire bus speed
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/*!
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* \brief
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* Send a 1-Wire write bit and read the response
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*
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* Write 1 --- --------------------------------------
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* Read 0/1 \ /
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* ----
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* RS: | | | | | | | | | | |
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* bit: ST 0 1 2 3 4 5 6 7 SP
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* TX: 0xFF RX: 0xFF->1, less->0
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*
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* Write 0 --- ------
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* Read 0 \ /
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* -------------------------------------
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* RS: | | | | | | | | | | |
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* bit: ST 0 1 2 3 4 5 6 7 SP
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* < ------------- 87/11 usec ------------->
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* TX: 0x00 RX: 0x00
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*
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* \param b The bit to send
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* \return The response
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*/
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bool bit (bool b) {
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if (b)
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return (UART_RW (0xFF) < 0xFF) ? 0 : 1;
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else {
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UART_RW (0x00);
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return 0;
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}
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}
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bool _reset (Speed s);
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//!@}
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};
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/*!
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* Set the 1-wire bus speed for normal operation only
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* \note
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* We have moved the BR set functionality here to reduce the code inside bit().
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* This is OK as long as the _1wire_i<> always check speed.
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* \param s The desired speed
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*/
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void _1wire_uart_i<virtual_tag>::speed (Speed s) {
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switch (_speed = s) {
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case Speed::STD: UART_BR (BR_STD); break;
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case Speed::OVDR: UART_BR (BR_OVR); break;
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}
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}
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/*!
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* \brief
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* Generate a 1-wire reset
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* --- ---- - - - -------
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* Reset \ / \ X X X /
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* -------------------- - - - -
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* RS: | | | | | | | | | | |
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* bit: ST 0 1 2 3 4 5 6 7 SP
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* < ---------- 1024/174 usec ------------->
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*
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* TX: (STD)0xF0, (OVDR)0xF8 RX: less if present
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*
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* \param t Timing
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* \return The status of the operation
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* \arg 0 Fail
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* \arg 1 Success
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*/
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bool _1wire_uart_i<virtual_tag>::_reset (Speed s) {
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// Select frame to send
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uint8_t w = ((_speed = s) == Speed::STD) ? 0xF0 : 0xF8;
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// Select baudrate
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UART_BR ((_speed == Speed::STD) ? BR_STD_RST : BR_OVR_RST);
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// Send frame and check the result
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return (UART_RW (w) < w);
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}
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//!@}
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} // namespace utl
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#endif /* __utl_com_1wire_uart_h__ */
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