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ArduinoCore-avr/cores/arduino/HardwareSerial.cpp

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/*
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
*/
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <inttypes.h>
#include "Arduino.h"
#include "wiring_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(UBRRH) || defined(UBRR0H) || defined(UBRR1H) || defined(UBRR2H) || defined(UBRR3H)
#include "HardwareSerial.h"
// Ensure that the various bit positions we use are available with a 0
// postfix, so we can always use the values for UART0 for all UARTs. The
// alternative, passing the various values for each UART to the
// HardwareSerial constructor also works, but makes the code bigger and
// slower.
#if !defined(TXC0)
#if defined(TXC)
// On ATmega8, the uart and its bits are not numbered, so there is no TXC0 etc.
#define TXC0 TXC
#define RXEN0 RXEN
#define TXEN0 TXEN
#define RXCIE0 RXCIE
#define UDRIE0 UDRIE
#define U2X0 U2X
#define UPE0 UPE
#define UDRE0 UDRE
#elif defined(TXC1)
// Some devices have uart1 but no uart0
#define TXC0 TXC1
#define RXEN0 RXEN1
#define TXEN0 TXEN1
#define RXCIE0 RXCIE1
#define UDRIE0 UDRIE1
#define U2X0 U2X1
#define UPE0 UPE1
#define UDRE0 UDRE1
#else
#error No UART found in HardwareSerial.cpp
#endif
#endif // !defined TXC0
// Check at compiletime that it is really ok to use the bit positions of
// UART0 for the other UARTs as well, in case these values ever get
// changed for future hardware.
#if defined(TXC1) && (TXC1 != TXC0 || RXEN1 != RXEN0 || RXCIE1 != RXCIE0 || \
UDRIE1 != UDRIE0 || U2X1 != U2X0 || UPE1 != UPE0 || \
UDRE1 != UDRE0)
#error "Not all bit positions for UART1 are the same as for UART0"
#endif
#if defined(TXC2) && (TXC2 != TXC0 || RXEN2 != RXEN0 || RXCIE2 != RXCIE0 || \
UDRIE2 != UDRIE0 || U2X2 != U2X0 || UPE2 != UPE0 || \
UDRE2 != UDRE0)
#error "Not all bit positions for UART2 are the same as for UART0"
#endif
#if defined(TXC3) && (TXC3 != TXC0 || RXEN3 != RXEN0 || RXCIE3 != RXCIE0 || \
UDRIE3 != UDRIE0 || U3X3 != U3X0 || UPE3 != UPE0 || \
UDRE3 != UDRE0)
#error "Not all bit positions for UART3 are the same as for UART0"
#endif
#if !defined(USART0_RX_vect) && defined(USART1_RX_vect)
// do nothing - on the 32u4 the first USART is USART1
#else
#if !defined(USART_RX_vect) && !defined(USART0_RX_vect) && \
!defined(USART_RXC_vect)
#error "Don't know what the Data Received vector is called for the first UART"
#else
void serialEvent() __attribute__((weak));
void serialEvent() {}
#define serialEvent_implemented
#if defined(USART_RX_vect)
ISR(USART_RX_vect)
#elif defined(USART0_RX_vect)
ISR(USART0_RX_vect)
#elif defined(USART_RXC_vect)
ISR(USART_RXC_vect) // ATmega8
#endif
{
Serial._rx_complete_irq();
}
#endif
#endif
#if defined(USART1_RX_vect)
void serialEvent1() __attribute__((weak));
void serialEvent1() {}
#define serialEvent1_implemented
ISR(USART1_RX_vect)
{
Serial1._rx_complete_irq();
}
#endif
#if defined(USART2_RX_vect) && defined(UDR2)
void serialEvent2() __attribute__((weak));
void serialEvent2() {}
#define serialEvent2_implemented
ISR(USART2_RX_vect)
{
Serial2._rx_complete_irq();
}
#endif
#if defined(USART3_RX_vect) && defined(UDR3)
void serialEvent3() __attribute__((weak));
void serialEvent3() {}
#define serialEvent3_implemented
ISR(USART3_RX_vect)
{
Serial3._rx_complete_irq();
}
#endif
void serialEventRun(void)
{
#ifdef serialEvent_implemented
if (Serial.available()) serialEvent();
#endif
#ifdef serialEvent1_implemented
if (Serial1.available()) serialEvent1();
#endif
#ifdef serialEvent2_implemented
if (Serial2.available()) serialEvent2();
#endif
#ifdef serialEvent3_implemented
if (Serial3.available()) serialEvent3();
#endif
}
#if !defined(USART0_UDRE_vect) && defined(USART1_UDRE_vect)
// do nothing - on the 32u4 the first USART is USART1
#else
#if !defined(UART0_UDRE_vect) && !defined(UART_UDRE_vect) && !defined(USART0_UDRE_vect) && !defined(USART_UDRE_vect)
#error "Don't know what the Data Register Empty vector is called for the first UART"
#else
#if defined(UART0_UDRE_vect)
ISR(UART0_UDRE_vect)
#elif defined(UART_UDRE_vect)
ISR(UART_UDRE_vect)
#elif defined(USART0_UDRE_vect)
ISR(USART0_UDRE_vect)
#elif defined(USART_UDRE_vect)
ISR(USART_UDRE_vect)
#endif
{
Serial._tx_udr_empty_irq();
}
#endif
#endif
#ifdef USART1_UDRE_vect
ISR(USART1_UDRE_vect)
{
Serial1._tx_udr_empty_irq();
}
#endif
#ifdef USART2_UDRE_vect
ISR(USART2_UDRE_vect)
{
Serial2._tx_udr_empty_irq();
}
#endif
#ifdef USART3_UDRE_vect
ISR(USART3_UDRE_vect)
{
Serial3._tx_udr_empty_irq();
}
#endif
// Actual interrupt handlers //////////////////////////////////////////////////////////////
void HardwareSerial::_rx_complete_irq(void)
{
if (bit_is_clear(*_ucsra, UPE0)) {
// No Parity error, read byte and store it in the buffer if there is
// room
unsigned char c = *_udr;
int i = (unsigned int)(_rx_buffer_head + 1) % SERIAL_BUFFER_SIZE;
// if we should be storing the received character into the location
// just before the tail (meaning that the head would advance to the
// current location of the tail), we're about to overflow the buffer
// and so we don't write the character or advance the head.
if (i != _rx_buffer_tail) {
_rx_buffer[_rx_buffer_head] = c;
_rx_buffer_head = i;
}
} else {
// Parity error, read byte but discard it
unsigned char c = *_udr;
};
}
void HardwareSerial::_tx_udr_empty_irq(void)
{
if (_tx_buffer_head == _tx_buffer_tail) {
// Buffer empty, so disable interrupts
cbi(*_ucsrb, UDRIE0);
}
else {
// There is 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_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);
}
}
// Constructors ////////////////////////////////////////////////////////////////
HardwareSerial::HardwareSerial(
volatile uint8_t *ubrrh, volatile uint8_t *ubrrl,
volatile uint8_t *ucsra, volatile uint8_t *ucsrb,
volatile uint8_t *ucsrc, volatile uint8_t *udr)
{
_tx_buffer_head = _tx_buffer_tail = 0;
_rx_buffer_head = _rx_buffer_tail = 0;
_ubrrh = ubrrh;
_ubrrl = ubrrl;
_ucsra = ucsra;
_ucsrb = ucsrb;
_ucsrc = ucsrc;
_udr = udr;
}
// 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. ubbr (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_BUFFER_SIZE + _rx_buffer_head - _rx_buffer_tail) % SERIAL_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 = (unsigned int)(_rx_buffer_tail + 1) % SERIAL_BUFFER_SIZE;
return c;
}
}
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 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)
{
int i = (_tx_buffer_head + 1) % SERIAL_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
// ???: return 0 here instead?
while (i == _tx_buffer_tail)
;
_tx_buffer[_tx_buffer_head] = c;
_tx_buffer_head = i;
sbi(*_ucsrb, UDRIE0);
_written = true;
return 1;
}
// Preinstantiate Objects //////////////////////////////////////////////////////
#if defined(UBRRH) && defined(UBRRL)
HardwareSerial Serial(&UBRRH, &UBRRL, &UCSRA, &UCSRB, &UCSRC, &UDR);
#elif defined(UBRR0H) && defined(UBRR0L)
HardwareSerial Serial(&UBRR0H, &UBRR0L, &UCSR0A, &UCSR0B, &UCSR0C, &UDR0);
#elif defined(USBCON)
// do nothing - Serial object and buffers are initialized in CDC code
#else
#error no serial port defined (port 0)
#endif
#if defined(UBRR1H)
HardwareSerial Serial1(&UBRR1H, &UBRR1L, &UCSR1A, &UCSR1B, &UCSR1C, &UDR1);
#endif
#if defined(UBRR2H)
HardwareSerial Serial2(&UBRR2H, &UBRR2L, &UCSR2A, &UCSR2B, &UCSR2C, &UDR2);
#endif
#if defined(UBRR3H)
HardwareSerial Serial3(&UBRR3H, &UBRR3L, &UCSR3A, &UCSR3B, &UCSR3C, &UDR3);
#endif
#endif // whole file
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