81 lines
2.1 KiB
C++
81 lines
2.1 KiB
C++
/*
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This file is part of the AVR-uart_ni.
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Copyright (C) 2009 Daniel Otte (daniel.otte@rub.de)
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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 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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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 General Public License for more details.
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You should have received a copy of the GNU 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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/* #include <util/setbaud.h> */
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/* we use a modifyed version of util/setbaud where the UL suffix is removed
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* since the preprocessor can not handle that.
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*/
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#ifndef F_CPU
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# error "uart_i requires F_CPU to be defined"
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#endif
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#ifndef BAUD
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# error "uart_i requires UART0_BAUD_RATE to be defined"
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#endif
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#if !(F_CPU)
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# error "F_CPU must be a constant value"
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#endif
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#if !(BAUD)
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# error "UART0_BAUD_RATE must be a constant value"
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#endif
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#undef USE_2X
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/* Baud rate tolerance is 2 % unless previously defined */
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#ifndef BAUD_TOL
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# define BAUD_TOL 2
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#endif
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#define UBRR_VALUE (((F_CPU) + 8 * (BAUD)) / (16 * (BAUD)) -1)
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#if 100 * (F_CPU) > \
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(16 * ((UBRR_VALUE) + 1)) * (100 * (BAUD) + (BAUD) * (BAUD_TOL))
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# define USE_2X 1
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#elif 100 * (F_CPU) < \
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(16 * ((UBRR_VALUE) + 1)) * (100 * (BAUD) - (BAUD) * (BAUD_TOL))
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# define USE_2X 1
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#else
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# define USE_2X 0
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#endif
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#if USE_2X
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/* U2X required, recalculate */
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#undef UBRR_VALUE
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#define UBRR_VALUE (((F_CPU) + 4 * (BAUD)) / (8 * (BAUD)) -1)
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#if 100 * (F_CPU) > \
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(8 * ((UBRR_VALUE) + 1)) * (100 * (BAUD) + (BAUD) * (BAUD_TOL))
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# warning "Baud rate achieved is higher than allowed"
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#endif
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#if 100 * (F_CPU) < \
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(8 * ((UBRR_VALUE) + 1)) * (100 * (BAUD) - (BAUD) * (BAUD_TOL))
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# warning "Baud rate achieved is lower than allowed"
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#endif
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#endif /* USE_U2X */
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#ifdef UBRR_VALUE
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# define UBRRL_VALUE ((UBRR_VALUE) & 0xff)
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# define UBRRH_VALUE ((UBRR_VALUE) >> 8)
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#endif
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