71 lines
2.4 KiB
C++
71 lines
2.4 KiB
C++
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/* Arduino SdFat Library
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* Copyright (C) 2012 by William Greiman
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*
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* This file is part of the Arduino SdFat Library
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*
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* This Library is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This Library 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 General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with the Arduino SdFat Library. If not, see
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* <http://www.gnu.org/licenses/>.
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*/
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#include <Arduino.h>
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#if defined(UDR0) || defined(DOXYGEN)
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#include <MinimumSerial.h>
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//------------------------------------------------------------------------------
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/**
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* Set baud rate for serial port zero and enable in non interrupt mode.
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* Do not call this function if you use another serial library.
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* \param[in] baud rate
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*/
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void MinimumSerial::begin(unsigned long baud) {
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uint16_t baud_setting;
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// don't worry, the compiler will squeeze out F_CPU != 16000000UL
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if (F_CPU != 16000000UL || baud != 57600) {
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// Double the USART Transmission Speed
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UCSR0A = 1 << U2X0;
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baud_setting = (F_CPU / 4 / baud - 1) / 2;
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} else {
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// hardcoded exception for compatibility with the bootloader shipped
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// with the Duemilanove and previous boards and the firmware on the 8U2
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// on the Uno and Mega 2560.
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UCSR0A = 0;
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baud_setting = (F_CPU / 8 / baud - 1) / 2;
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}
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// assign the baud_setting
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UBRR0H = baud_setting >> 8;
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UBRR0L = baud_setting;
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// enable transmit and receive
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UCSR0B |= (1 << TXEN0) | (1 << RXEN0) ;
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}
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//------------------------------------------------------------------------------
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/**
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* Unbuffered read
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* \return -1 if no character is available or an available character.
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*/
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int MinimumSerial::read() {
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if (UCSR0A & (1 << RXC0)) return UDR0;
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return -1;
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}
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//------------------------------------------------------------------------------
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/**
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* Unbuffered write
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*
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* \param[in] b byte to write.
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* \return 1
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*/
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size_t MinimumSerial::write(uint8_t b) {
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while (((1 << UDRIE0) & UCSR0B) || !(UCSR0A & (1 << UDRE0))) {}
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UDR0 = b;
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return 1;
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}
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MinimumSerial MiniSerial;
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#endif // defined(UDR0) || defined(DOXYGEN)
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