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/*
SoftwareSerial.cpp - Software serial library
Copyright (c) 2006 David A. Mellis. 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
*/
/******************************************************************************
* Includes
******************************************************************************/
#include "WConstants.h"
#include "SoftwareSerial.h"
/******************************************************************************
* Definitions
******************************************************************************/
/******************************************************************************
* Constructors
******************************************************************************/
SoftwareSerial::SoftwareSerial(uint8_t receivePin, uint8_t transmitPin)
{
_receivePin = receivePin;
_transmitPin = transmitPin;
_baudRate = 0;
}
/******************************************************************************
* User API
******************************************************************************/
void SoftwareSerial::begin(long speed)
{
_baudRate = speed;
_bitPeriod = 1000000 / _baudRate;
digitalWrite(_transmitPin, HIGH);
delayMicroseconds( _bitPeriod); // if we were low this establishes the end
}
int SoftwareSerial::read()
{
int val = 0;
int bitDelay = _bitPeriod - clockCyclesToMicroseconds(50);
// one byte of serial data (LSB first)
// ...--\ /--\/--\/--\/--\/--\/--\/--\/--\/--...
// \--/\--/\--/\--/\--/\--/\--/\--/\--/
// start 0 1 2 3 4 5 6 7 stop
while (digitalRead(_receivePin));
// confirm that this is a real start bit, not line noise
if (digitalRead(_receivePin) == LOW) {
// frame start indicated by a falling edge and low start bit
// jump to the middle of the low start bit
delayMicroseconds(bitDelay / 2 - clockCyclesToMicroseconds(50));
// offset of the bit in the byte: from 0 (LSB) to 7 (MSB)
for (int offset = 0; offset < 8; offset++) {
// jump to middle of next bit
delayMicroseconds(bitDelay);
// read bit
val |= digitalRead(_receivePin) << offset;
}
delayMicroseconds(_bitPeriod);
return val;
}
return -1;
}
void SoftwareSerial::print(uint8_t b)
{
if (_baudRate == 0)
return;
int bitDelay = _bitPeriod - clockCyclesToMicroseconds(50); // a digitalWrite is about 50 cycles
byte mask;
digitalWrite(_transmitPin, LOW);
delayMicroseconds(bitDelay);
for (mask = 0x01; mask; mask <<= 1) {
if (b & mask){ // choose bit
digitalWrite(_transmitPin,HIGH); // send 1
}
else{
digitalWrite(_transmitPin,LOW); // send 1
}
delayMicroseconds(bitDelay);
}
digitalWrite(_transmitPin, HIGH);
delayMicroseconds(bitDelay);
}
void SoftwareSerial::print(const char *s)
{
while (*s)
print(*s++);
}
void SoftwareSerial::print(char c)
{
print((uint8_t) c);
}
void SoftwareSerial::print(int n)
{
print((long) n);
}
void SoftwareSerial::print(unsigned int n)
{
print((unsigned long) n);
}
void SoftwareSerial::print(long n)
{
if (n < 0) {
print('-');
n = -n;
}
printNumber(n, 10);
}
void SoftwareSerial::print(unsigned long n)
{
printNumber(n, 10);
}
void SoftwareSerial::print(long n, int base)
{
if (base == 0)
print((char) n);
else if (base == 10)
print(n);
else
printNumber(n, base);
}
void SoftwareSerial::println(void)
{
print('\r');
print('\n');
}
void SoftwareSerial::println(char c)
{
print(c);
println();
}
void SoftwareSerial::println(const char c[])
{
print(c);
println();
}
void SoftwareSerial::println(uint8_t b)
{
print(b);
println();
}
void SoftwareSerial::println(int n)
{
print(n);
println();
}
void SoftwareSerial::println(long n)
{
print(n);
println();
}
void SoftwareSerial::println(unsigned long n)
{
print(n);
println();
}
void SoftwareSerial::println(long n, int base)
{
print(n, base);
println();
}
// Private Methods /////////////////////////////////////////////////////////////
void SoftwareSerial::printNumber(unsigned long n, uint8_t base)
{
unsigned char buf[8 * sizeof(long)]; // Assumes 8-bit chars.
unsigned long i = 0;
if (n == 0) {
print('0');
return;
}
while (n > 0) {
buf[i++] = n % base;
n /= base;
}
for (; i > 0; i--)
print((char) (buf[i - 1] < 10 ? '0' + buf[i - 1] : 'A' + buf[i - 1] - 10));
}
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