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https://github.com/digistump/DigistumpArduino.git
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267 lines
7.9 KiB
C++
267 lines
7.9 KiB
C++
/*
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TinySoftwareSerial.cpp - Hardware serial library for Wiring
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Copyright (c) 2006 Nicholas Zambetti. All right reserved.
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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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 GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with this library; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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Modified 23 November 2006 by David A. Mellis
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Modified 28 September 2010 by Mark Sproul
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*/
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#include <stdlib.h>
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#include <stdio.h>
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#include <string.h>
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#include <inttypes.h>
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#include "Arduino.h"
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#include "wiring_private.h"
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#if USE_SOFTWARE_SERIAL
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#include "TinySoftwareSerial.h"
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// Define constants and variables for buffering incoming serial data. We're
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// using a ring buffer (I think), in which rx_buffer_head is the index of the
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// location to which to write the next incoming character and rx_buffer_tail
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// is the index of the location from which to read.
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extern "C"{
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uint8_t getch() {
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uint8_t ch = 0;
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__asm__ __volatile__ (
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" rcall uartDelay\n" // Get to 0.25 of start bit (our baud is too fast, so give room to correct)
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"1: rcall uartDelay\n" // Wait 0.25 bit period
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" rcall uartDelay\n" // Wait 0.25 bit period
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" rcall uartDelay\n" // Wait 0.25 bit period
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" rcall uartDelay\n" // Wait 0.25 bit period
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" clc\n"
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" in r23,%[pin]\n"
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" and r23, %[mask]\n"
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" breq 2f\n"
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" sec\n"
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"2: ror %0\n"
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" dec %[count]\n"
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" breq 3f\n"
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" rjmp 1b\n"
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"3: rcall uartDelay\n" // Wait 0.25 bit period
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" rcall uartDelay\n" // Wait 0.25 bit period
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:
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"=r" (ch)
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:
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"0" ((uint8_t)0),
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[count] "r" ((uint8_t)8),
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[pin] "I" (_SFR_IO_ADDR(ANALOG_COMP_PIN)),
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[mask] "r" (Serial._rxmask)
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:
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"r23",
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"r24",
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"r25"
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);
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return ch;
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}
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void uartDelay() {
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__asm__ __volatile__ (
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"mov r25,%[count]\n"
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"1:dec r25\n"
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"brne 1b\n"
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"ret\n"
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::[count] "r" ((uint8_t)Serial._delayCount)
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);
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}
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#if !defined (ANALOG_COMP_vect) && defined(ANA_COMP_vect)
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//rename the vector so we can use it.
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#define ANALOG_COMP_vect ANA_COMP_vect
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#elif !defined (ANALOG_COMP_vect)
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#error Tiny Software Serial cant find the Analog comparator interrupt vector!
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#endif
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ISR(ANALOG_COMP_vect){
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char ch = getch(); //read in the character softwarily - I know its not a word, but it sounded cool, so you know what: #define softwarily 1
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store_char(ch, Serial._rx_buffer);
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sbi(ACSR,ACI); //clear the flag.
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}
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}
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soft_ring_buffer rx_buffer = { { 0 }, 0, 0 };
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// Constructor ////////////////////////////////////////////////////////////////
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TinySoftwareSerial::TinySoftwareSerial(soft_ring_buffer *rx_buffer, uint8_t txBit, uint8_t rxBit)
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{
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_rx_buffer = rx_buffer;
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_rxmask = _BV(rxBit);
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_txmask = _BV(txBit);
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_txunmask = ~_txmask;
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_delayCount = 0;
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}
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// Public Methods //////////////////////////////////////////////////////////////
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void TinySoftwareSerial::begin(long baud)
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{
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long tempDelay = (((F_CPU/baud)-39)/12);
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if ((tempDelay > 255) || (tempDelay <= 0)){
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end(); //Cannot start as it would screw up uartDelay().
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}
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_delayCount = (uint8_t)tempDelay;
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cbi(ACSR,ACIE); //turn off the comparator interrupt to allow change of ACD
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#ifdef ACBG
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sbi(ACSR,ACBG); //enable the internal bandgap reference - used instead of AIN0 to allow it to be used for TX.
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#endif
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cbi(ACSR,ACD); //turn on the comparator for RX
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#ifdef ACIC
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cbi(ACSR,ACIC); //prevent the comparator from affecting timer1 - just to be safe.
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#endif
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sbi(ACSR,ACIS1); //interrupt on rising edge (this means RX has gone from Mark state to Start bit state).
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sbi(ACSR,ACIS0);
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//Setup the pins in case someone messed with them.
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ANALOG_COMP_DDR &= ~_rxmask; //set RX to an input
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ANALOG_COMP_PORT |= _rxmask; //enable pullup on RX pin - to prevent accidental interrupt triggers.
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ANALOG_COMP_DDR |= _txmask; //set TX to an output.
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ANALOG_COMP_PORT |= _txmask; //set TX pin high
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sbi(ACSR,ACI); //clear the flag.
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sbi(ACSR,ACIE); //turn on the comparator interrupt to allow us to use it for RX
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#ifdef ACSRB
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ACSRB = 0; //Use AIN0 as +, AIN1 as -, no hysteresis - just like ones without this register.
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#endif
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}
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void TinySoftwareSerial::end()
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{
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sbi(ACSR,ACI); //clear the flag.
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cbi(ACSR,ACIE); //turn off the comparator interrupt to allow change of ACD, and because it needs to be turned off now too!
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#ifdef ACBG
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cbi(ACSR,ACBG); //disable the bandgap reference
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#endif
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sbi(ACSR,ACD); //turn off the comparator to save power
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_delayCount = 0;
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_rx_buffer->head = _rx_buffer->tail;
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}
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int TinySoftwareSerial::available(void)
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{
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return (unsigned int)(SERIAL_BUFFER_SIZE + _rx_buffer->head - _rx_buffer->tail) % SERIAL_BUFFER_SIZE;
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}
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void store_char(unsigned char c, soft_ring_buffer *buffer)
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{
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int i = (unsigned int)(buffer->head + 1) % SERIAL_BUFFER_SIZE;
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// if we should be storing the received character into the location
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// just before the tail (meaning that the head would advance to the
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// current location of the tail), we're about to overflow the buffer
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// and so we don't write the character or advance the head.
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if (i != buffer->tail) {
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buffer->buffer[buffer->head] = c;
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buffer->head = i;
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}
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}
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int TinySoftwareSerial::peek(void)
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{
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if (_rx_buffer->head == _rx_buffer->tail) {
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return -1;
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} else {
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return _rx_buffer->buffer[_rx_buffer->tail];
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}
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}
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int TinySoftwareSerial::read(void)
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{
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// if the head isn't ahead of the tail, we don't have any characters
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if (_rx_buffer->head == _rx_buffer->tail) {
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return -1;
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} else {
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unsigned char c = _rx_buffer->buffer[_rx_buffer->tail];
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_rx_buffer->tail = (unsigned int)(_rx_buffer->tail + 1) % SERIAL_BUFFER_SIZE;
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return c;
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}
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}
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size_t TinySoftwareSerial::write(uint8_t ch)
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{
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uint8_t oldSREG = SREG;
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cli(); //Prevent interrupts from breaking the transmission. Note: TinySoftwareSerial is half duplex.
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//it can either recieve or send, not both (because recieving requires an interrupt and would stall transmission
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__asm__ __volatile__ (
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" com %[ch]\n" // ones complement, carry set
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" sec\n"
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"1: brcc 2f\n"
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" in r23,%[uartPort] \n"
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" and r23,%[uartUnmask]\n"
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" out %[uartPort],r23 \n"
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" rjmp 3f\n"
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"2: in r23,%[uartPort] \n"
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" or r23,%[uartMask]\n"
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" out %[uartPort],r23 \n"
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" nop\n"
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"3: rcall uartDelay\n"
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" rcall uartDelay\n"
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" rcall uartDelay\n"
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" rcall uartDelay\n"
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" lsr %[ch]\n"
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" dec %[count]\n"
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" brne 1b\n"
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:
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:
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[ch] "r" (ch),
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[count] "r" ((uint8_t)10),
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[uartPort] "I" (_SFR_IO_ADDR(ANALOG_COMP_PORT)),
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[uartMask] "r" (_txmask),
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[uartUnmask] "r" (_txunmask)
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: "r23",
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"r24",
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"r25"
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);
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SREG = oldSREG;
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return 1;
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}
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void TinySoftwareSerial::flush()
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{
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}
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TinySoftwareSerial::operator bool() {
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return true;
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}
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// Preinstantiate Objects //////////////////////////////////////////////////////
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#ifndef ANALOG_COMP_DDR
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#error Please define ANALOG_COMP_DDR in the pins_arduino.h file!
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#endif
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#ifndef ANALOG_COMP_PORT
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#error Please define ANALOG_COMP_PORT in the pins_arduino.h file!
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#endif
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#ifndef ANALOG_COMP_PIN
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#error Please define ANALOG_COMP_PIN in the pins_arduino.h file!
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#endif
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#ifndef ANALOG_COMP_AIN0_BIT
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#error Please define ANALOG_COMP_AIN0_BIT in the pins_arduino.h file!
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#endif
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#ifndef ANALOG_COMP_AIN1_BIT
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#error Please define ANALOG_COMP_AIN1_BIT in the pins_arduino.h file!
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#endif
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TinySoftwareSerial Serial(&rx_buffer, ANALOG_COMP_AIN0_BIT, ANALOG_COMP_AIN1_BIT);
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#endif // whole file
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