123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252 |
- /*
- HardwareSerial.cpp - Hardware serial library for Wiring
- Copyright (c) 2006 Nicholas Zambetti. All right reserved.
- This library 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 2.1 of the License, or (at your option) any later version.
- This library 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 library; if not, write to the Free Software
- Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
-
- Modified 23 November 2006 by David A. Mellis
- Modified 28 September 2010 by Mark Sproul
- Modified 14 August 2012 by Alarus
- Modified 3 December 2013 by Matthijs Kooijman
- */
- #include <stdlib.h>
- #include <stdio.h>
- #include <string.h>
- #include <inttypes.h>
- #include "Arduino.h"
- #include "HardwareSerial.h"
- #include "HardwareSerial_private.h"
- // this next line disables the entire HardwareSerial.cpp,
- // this is so I can support Attiny series and any other chip without a uart
- #if defined(HAVE_HWSERIAL0) || defined(HAVE_HWSERIAL1) || defined(HAVE_HWSERIAL2) || defined(HAVE_HWSERIAL3)
- // SerialEvent functions are weak, so when the user doesn't define them,
- // the linker just sets their address to 0 (which is checked below).
- // The Serialx_available is just a wrapper around Serialx.available(),
- // but we can refer to it weakly so we don't pull in the entire
- // HardwareSerial instance if the user doesn't also refer to it.
- #if defined(HAVE_HWSERIAL0)
- void serialEvent() __attribute__((weak));
- bool Serial0_available() __attribute__((weak));
- #endif
- #if defined(HAVE_HWSERIAL1)
- void serialEvent1() __attribute__((weak));
- bool Serial1_available() __attribute__((weak));
- #endif
- #if defined(HAVE_HWSERIAL2)
- void serialEvent2() __attribute__((weak));
- bool Serial2_available() __attribute__((weak));
- #endif
- #if defined(HAVE_HWSERIAL3)
- void serialEvent3() __attribute__((weak));
- bool Serial3_available() __attribute__((weak));
- #endif
- void serialEventRun(void)
- {
- #if defined(HAVE_HWSERIAL0)
- if (Serial0_available && serialEvent && Serial0_available()) serialEvent();
- #endif
- #if defined(HAVE_HWSERIAL1)
- if (Serial1_available && serialEvent1 && Serial1_available()) serialEvent1();
- #endif
- #if defined(HAVE_HWSERIAL2)
- if (Serial2_available && serialEvent2 && Serial2_available()) serialEvent2();
- #endif
- #if defined(HAVE_HWSERIAL3)
- if (Serial3_available && serialEvent3 && Serial3_available()) serialEvent3();
- #endif
- }
- // Actual interrupt handlers //////////////////////////////////////////////////////////////
- void HardwareSerial::_tx_udr_empty_irq(void)
- {
- // If interrupts are enabled, there must be more data in the output
- // buffer. Send the next byte
- unsigned char c = _tx_buffer[_tx_buffer_tail];
- _tx_buffer_tail = (_tx_buffer_tail + 1) % SERIAL_TX_BUFFER_SIZE;
- *_udr = c;
- // clear the TXC bit -- "can be cleared by writing a one to its bit
- // location". This makes sure flush() won't return until the bytes
- // actually got written
- sbi(*_ucsra, TXC0);
- if (_tx_buffer_head == _tx_buffer_tail) {
- // Buffer empty, so disable interrupts
- cbi(*_ucsrb, UDRIE0);
- }
- }
- // Public Methods //////////////////////////////////////////////////////////////
- void HardwareSerial::begin(unsigned long baud, byte config)
- {
- // Try u2x mode first
- uint16_t baud_setting = (F_CPU / 4 / baud - 1) / 2;
- *_ucsra = 1 << U2X0;
- // hardcoded exception for 57600 for compatibility with the bootloader
- // shipped with the Duemilanove and previous boards and the firmware
- // on the 8U2 on the Uno and Mega 2560. Also, The baud_setting cannot
- // be > 4095, so switch back to non-u2x mode if the baud rate is too
- // low.
- if (((F_CPU == 16000000UL) && (baud == 57600)) || (baud_setting >4095))
- {
- *_ucsra = 0;
- baud_setting = (F_CPU / 8 / baud - 1) / 2;
- }
- // assign the baud_setting, a.k.a. ubrr (USART Baud Rate Register)
- *_ubrrh = baud_setting >> 8;
- *_ubrrl = baud_setting;
- _written = false;
- //set the data bits, parity, and stop bits
- #if defined(__AVR_ATmega8__)
- config |= 0x80; // select UCSRC register (shared with UBRRH)
- #endif
- *_ucsrc = config;
-
- sbi(*_ucsrb, RXEN0);
- sbi(*_ucsrb, TXEN0);
- sbi(*_ucsrb, RXCIE0);
- cbi(*_ucsrb, UDRIE0);
- }
- void HardwareSerial::end()
- {
- // wait for transmission of outgoing data
- while (_tx_buffer_head != _tx_buffer_tail)
- ;
- cbi(*_ucsrb, RXEN0);
- cbi(*_ucsrb, TXEN0);
- cbi(*_ucsrb, RXCIE0);
- cbi(*_ucsrb, UDRIE0);
-
- // clear any received data
- _rx_buffer_head = _rx_buffer_tail;
- }
- int HardwareSerial::available(void)
- {
- return ((unsigned int)(SERIAL_RX_BUFFER_SIZE + _rx_buffer_head - _rx_buffer_tail)) % SERIAL_RX_BUFFER_SIZE;
- }
- int HardwareSerial::peek(void)
- {
- if (_rx_buffer_head == _rx_buffer_tail) {
- return -1;
- } else {
- return _rx_buffer[_rx_buffer_tail];
- }
- }
- int HardwareSerial::read(void)
- {
- // if the head isn't ahead of the tail, we don't have any characters
- if (_rx_buffer_head == _rx_buffer_tail) {
- return -1;
- } else {
- unsigned char c = _rx_buffer[_rx_buffer_tail];
- _rx_buffer_tail = (rx_buffer_index_t)(_rx_buffer_tail + 1) % SERIAL_RX_BUFFER_SIZE;
- return c;
- }
- }
- int HardwareSerial::availableForWrite(void)
- {
- #if (SERIAL_TX_BUFFER_SIZE>256)
- uint8_t oldSREG = SREG;
- cli();
- #endif
- tx_buffer_index_t head = _tx_buffer_head;
- tx_buffer_index_t tail = _tx_buffer_tail;
- #if (SERIAL_TX_BUFFER_SIZE>256)
- SREG = oldSREG;
- #endif
- if (head >= tail) return SERIAL_TX_BUFFER_SIZE - 1 - head + tail;
- return tail - head - 1;
- }
- void HardwareSerial::flush()
- {
- // If we have never written a byte, no need to flush. This special
- // case is needed since there is no way to force the TXC (transmit
- // complete) bit to 1 during initialization
- if (!_written)
- return;
- while (bit_is_set(*_ucsrb, UDRIE0) || bit_is_clear(*_ucsra, TXC0)) {
- if (bit_is_clear(SREG, SREG_I) && bit_is_set(*_ucsrb, UDRIE0))
- // Interrupts are globally disabled, but the DR empty
- // interrupt should be enabled, so poll the DR empty flag to
- // prevent deadlock
- if (bit_is_set(*_ucsra, UDRE0))
- _tx_udr_empty_irq();
- }
- // If we get here, nothing is queued anymore (DRIE is disabled) and
- // the hardware finished tranmission (TXC is set).
- }
- size_t HardwareSerial::write(uint8_t c)
- {
- // If the buffer and the data register is empty, just write the byte
- // to the data register and be done. This shortcut helps
- // significantly improve the effective datarate at high (>
- // 500kbit/s) bitrates, where interrupt overhead becomes a slowdown.
- if (_tx_buffer_head == _tx_buffer_tail && bit_is_set(*_ucsra, UDRE0)) {
- *_udr = c;
- sbi(*_ucsra, TXC0);
- return 1;
- }
- tx_buffer_index_t i = (_tx_buffer_head + 1) % SERIAL_TX_BUFFER_SIZE;
-
- // If the output buffer is full, there's nothing for it other than to
- // wait for the interrupt handler to empty it a bit
- while (i == _tx_buffer_tail) {
- if (bit_is_clear(SREG, SREG_I)) {
- // Interrupts are disabled, so we'll have to poll the data
- // register empty flag ourselves. If it is set, pretend an
- // interrupt has happened and call the handler to free up
- // space for us.
- if(bit_is_set(*_ucsra, UDRE0))
- _tx_udr_empty_irq();
- } else {
- // nop, the interrupt handler will free up space for us
- }
- }
- _tx_buffer[_tx_buffer_head] = c;
- _tx_buffer_head = i;
-
- sbi(*_ucsrb, UDRIE0);
- _written = true;
-
- return 1;
- }
- #endif // whole file
|