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/*
SoftwareSerial.cpp - Implementation of the Arduino software serial for ESP8266.
Copyright (c) 2015-2016 Peter Lerup. All rights 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
*/
#include <Arduino.h>
// The Arduino standard GPIO routines are not enough,
// must use some from the Espressif SDK as well
extern "C" {
#include "gpio.h"
}
#include <SoftwareSerial.h>
#define MAX_PIN 15
// As the Arduino attachInterrupt has no parameter, lists of objects
// and callbacks corresponding to each possible GPIO pins have to be defined
SoftwareSerial *ObjList[MAX_PIN+1];
void ICACHE_RAM_ATTR sws_isr_0() { ObjList[0]->rxRead(); };
void ICACHE_RAM_ATTR sws_isr_1() { ObjList[1]->rxRead(); };
void ICACHE_RAM_ATTR sws_isr_2() { ObjList[2]->rxRead(); };
void ICACHE_RAM_ATTR sws_isr_3() { ObjList[3]->rxRead(); };
void ICACHE_RAM_ATTR sws_isr_4() { ObjList[4]->rxRead(); };
void ICACHE_RAM_ATTR sws_isr_5() { ObjList[5]->rxRead(); };
// Pin 6 to 11 can not be used
void ICACHE_RAM_ATTR sws_isr_12() { ObjList[12]->rxRead(); };
void ICACHE_RAM_ATTR sws_isr_13() { ObjList[13]->rxRead(); };
void ICACHE_RAM_ATTR sws_isr_14() { ObjList[14]->rxRead(); };
void ICACHE_RAM_ATTR sws_isr_15() { ObjList[15]->rxRead(); };
static void (*ISRList[MAX_PIN+1])() = {
sws_isr_0,
sws_isr_1,
sws_isr_2,
sws_isr_3,
sws_isr_4,
sws_isr_5,
NULL,
NULL,
NULL,
NULL,
NULL,
NULL,
sws_isr_12,
sws_isr_13,
sws_isr_14,
sws_isr_15
};
SoftwareSerial::SoftwareSerial(int receivePin, int transmitPin, bool inverse_logic, unsigned int buffSize) {
m_oneWire = (receivePin == transmitPin);
m_rxValid = m_txValid = m_txEnableValid = false;
m_buffer = NULL;
m_invert = inverse_logic;
m_overflow = false;
m_rxEnabled = false;
if (isValidGPIOpin(receivePin)) {
m_rxPin = receivePin;
m_buffSize = buffSize;
m_buffer = (uint8_t*)malloc(m_buffSize);
if (m_buffer != NULL) {
m_rxValid = true;
m_inPos = m_outPos = 0;
pinMode(m_rxPin, INPUT);
ObjList[m_rxPin] = this;
}
}
if (isValidGPIOpin(transmitPin) || (!m_oneWire && (transmitPin == 16))) {
m_txValid = true;
m_txPin = transmitPin;
if (!m_oneWire) {
pinMode(m_txPin, OUTPUT);
digitalWrite(m_txPin, !m_invert);
}
}
// Default speed
begin(9600);
}
SoftwareSerial::~SoftwareSerial() {
enableRx(false);
if (m_rxValid)
ObjList[m_rxPin] = NULL;
if (m_buffer)
free(m_buffer);
}
bool SoftwareSerial::isValidGPIOpin(int pin) {
return (pin >= 0 && pin <= 5) || (pin >= 12 && pin <= MAX_PIN);
}
void SoftwareSerial::begin(long speed) {
// Use getCycleCount() loop to get as exact timing as possible
m_bitTime = F_CPU/speed;
// By default enable interrupt during tx only for low speed
m_intTxEnabled = speed < 9600;
if (!m_rxEnabled)
enableRx(true);
}
long SoftwareSerial::baudRate() {
return F_CPU/m_bitTime;
}
void SoftwareSerial::setTransmitEnablePin(int transmitEnablePin) {
if (isValidGPIOpin(transmitEnablePin)) {
m_txEnableValid = true;
m_txEnablePin = transmitEnablePin;
pinMode(m_txEnablePin, OUTPUT);
digitalWrite(m_txEnablePin, LOW);
} else {
m_txEnableValid = false;
}
}
void SoftwareSerial::enableIntTx(bool on) {
m_intTxEnabled = on;
}
void SoftwareSerial::enableTx(bool on) {
if (m_oneWire && m_txValid) {
if (on) {
enableRx(false);
digitalWrite(m_txPin, !m_invert);
pinMode(m_rxPin, OUTPUT);
} else {
digitalWrite(m_txPin, !m_invert);
pinMode(m_rxPin, INPUT);
enableRx(true);
}
delay(1); // it's important to have a delay after switching
}
}
void SoftwareSerial::enableRx(bool on) {
if (m_rxValid) {
if (on)
attachInterrupt(m_rxPin, ISRList[m_rxPin], m_invert ? RISING : FALLING);
else
detachInterrupt(m_rxPin);
m_rxEnabled = on;
}
}
int SoftwareSerial::read() {
if (!m_rxValid || (m_inPos == m_outPos)) return -1;
uint8_t ch = m_buffer[m_outPos];
m_outPos = (m_outPos+1) % m_buffSize;
return ch;
}
int SoftwareSerial::available() {
if (!m_rxValid) return 0;
int avail = m_inPos - m_outPos;
if (avail < 0) avail += m_buffSize;
return avail;
}
#define WAIT { while (ESP.getCycleCount()-start < wait) if (m_intTxEnabled) optimistic_yield(1); wait += m_bitTime; }
size_t SoftwareSerial::write(uint8_t b) {
if (!m_txValid) return 0;
if (m_invert) b = ~b;
if (!m_intTxEnabled)
// Disable interrupts in order to get a clean transmit
cli();
if (m_txEnableValid) digitalWrite(m_txEnablePin, HIGH);
unsigned long wait = m_bitTime;
digitalWrite(m_txPin, HIGH);
unsigned long start = ESP.getCycleCount();
// Start bit;
digitalWrite(m_txPin, LOW);
WAIT;
for (int i = 0; i < 8; i++) {
digitalWrite(m_txPin, (b & 1) ? HIGH : LOW);
WAIT;
b >>= 1;
}
// Stop bit
digitalWrite(m_txPin, HIGH);
WAIT;
if (m_txEnableValid) digitalWrite(m_txEnablePin, LOW);
if (!m_intTxEnabled)
sei();
return 1;
}
void SoftwareSerial::flush() {
m_inPos = m_outPos = 0;
}
bool SoftwareSerial::overflow() {
bool res = m_overflow;
m_overflow = false;
return res;
}
int SoftwareSerial::peek() {
if (!m_rxValid || (m_inPos == m_outPos)) return -1;
return m_buffer[m_outPos];
}
void ICACHE_RAM_ATTR SoftwareSerial::rxRead() {
// Advance the starting point for the samples but compensate for the
// initial delay which occurs before the interrupt is delivered
unsigned long wait = m_bitTime + m_bitTime/3 - 500;
unsigned long start = ESP.getCycleCount();
uint8_t rec = 0;
for (int i = 0; i < 8; i++) {
WAIT;
rec >>= 1;
if (digitalRead(m_rxPin))
rec |= 0x80;
}
if (m_invert) rec = ~rec;
// Stop bit
WAIT;
// Store the received value in the buffer unless we have an overflow
int next = (m_inPos+1) % m_buffSize;
if (next != m_outPos) {
m_buffer[m_inPos] = rec;
m_inPos = next;
} else {
m_overflow = true;
}
// Must clear this bit in the interrupt register,
// it gets set even when interrupts are disabled
GPIO_REG_WRITE(GPIO_STATUS_W1TC_ADDRESS, 1 << m_rxPin);
}