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added parity patch from https://github.com/PaulStoffregen/AltSoftSerial/issues/5 #52

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added parity patch from https://github.com/PaulStoffregen/AltSoftSerial/issues/5 #52

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160 changes: 148 additions & 12 deletions AltSoftSerial.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -56,13 +56,17 @@ static volatile uint8_t tx_buffer_head;
static volatile uint8_t tx_buffer_tail;
#define TX_BUFFER_SIZE 68
static volatile uint8_t tx_buffer[TX_BUFFER_SIZE];
static uint8_t tx_parity;

static uint8_t data_bits, stop_bits;
static uint8_t parity; // 0 for none, 1 for odd, 2 for even
static uint8_t total_bits, almost_total_bits; // these are sums calculated during .begin() to speed up the loop in ISR(CAPTURE_INTERRUPT)

#ifndef INPUT_PULLUP
#define INPUT_PULLUP INPUT
#endif

void AltSoftSerial::init(uint32_t cycles_per_bit)
void AltSoftSerial::init(uint32_t cycles_per_bit, uint8_t config)
{
if (cycles_per_bit < 7085) {
CONFIG_TIMER_NOPRESCALE();
Expand All @@ -85,6 +89,7 @@ void AltSoftSerial::init(uint32_t cycles_per_bit)
tx_state = 0;
tx_buffer_head = 0;
tx_buffer_tail = 0;
setBitCounts(config);
ENABLE_INT_INPUT_CAPTURE();
}

Expand Down Expand Up @@ -119,6 +124,8 @@ void AltSoftSerial::writeByte(uint8_t b)
tx_state = 1;
tx_byte = b;
tx_bit = 0;
if (parity)
tx_parity = parity_even_bit(b) == (parity==2);
ENABLE_INT_COMPARE_A();
CONFIG_MATCH_CLEAR();
SET_COMPARE_A(GET_TIMER_COUNT() + 16);
Expand All @@ -135,7 +142,7 @@ ISR(COMPARE_A_INTERRUPT)
state = tx_state;
byte = tx_byte;
target = GET_COMPARE_A();
while (state < 9) {
while (state < (data_bits+1)) {
target += ticks_per_bit;
bit = byte & 1;
byte >>= 1;
Expand All @@ -154,9 +161,21 @@ ISR(COMPARE_A_INTERRUPT)
return;
}
}
if (state == 9) {
tx_state = 10;
if((!parity && state == (data_bits + 1)) || state == (data_bits + 2)) {
tx_state = data_bits + 3;
CONFIG_MATCH_SET();
SET_COMPARE_A(target + (stop_bits * ticks_per_bit));
return;
} else if (state == (data_bits + 1)) {
tx_state = data_bits + 2;
if (tx_parity != tx_bit) {
if (tx_parity) {
CONFIG_MATCH_SET();
} else {
CONFIG_MATCH_CLEAR();
}
tx_bit = tx_parity;
}
SET_COMPARE_A(target + ticks_per_bit);
return;
}
Expand All @@ -172,6 +191,8 @@ ISR(COMPARE_A_INTERRUPT)
tx_buffer_tail = tail;
tx_byte = tx_buffer[tail];
tx_bit = 0;
if (parity)
tx_parity = parity_even_bit(tx_byte) == (parity==2);
CONFIG_MATCH_CLEAR();
SET_COMPARE_A(target + ticks_per_bit);
// TODO: how to detect timing_error?
Expand All @@ -191,7 +212,7 @@ void AltSoftSerial::flushOutput(void)

ISR(CAPTURE_INTERRUPT)
{
uint8_t state, bit, head;
uint8_t state, bit, head, rx_parity;
uint16_t capture, target;
int16_t offset;

Expand All @@ -217,21 +238,27 @@ ISR(CAPTURE_INTERRUPT)
while (1) {
offset = capture - target;
if (offset < 0) break;
if (state >= 1 && state <= data_bits) // only store data bits
rx_byte = (rx_byte >> 1) | rx_bit;
target += ticks_per_bit;
state++;
if (state >= 9) {
if (state >= total_bits) { // this is 9 for 8N1 or 10 for 8E1
DISABLE_INT_COMPARE_B();
head = rx_buffer_head + 1;
if (head >= RX_BUFFER_SIZE) head = 0;
if (head != rx_buffer_tail) {
rx_buffer[head] = rx_byte;
rx_buffer_head = head;
if (!parity || (parity_even_bit(rx_byte) == (parity==2)) == rx_parity) {
head = rx_buffer_head + 1;
if (head >= RX_BUFFER_SIZE) head = 0;
if (head != rx_buffer_tail) {
rx_buffer[head] = rx_byte;
rx_buffer_head = head;
}
}
CONFIG_CAPTURE_FALLING_EDGE();
rx_bit = 0;
rx_state = 0;
return;
} else if (state < almost_total_bits) {
// in parity bit
rx_parity = rx_bit;
}
}
rx_target = target;
Expand All @@ -248,7 +275,7 @@ ISR(COMPARE_B_INTERRUPT)
CONFIG_CAPTURE_FALLING_EDGE();
state = rx_state;
bit = rx_bit ^ 0x80;
while (state < 9) {
while (state < (data_bits + 1)) {
rx_byte = (rx_byte >> 1) | bit;
state++;
}
Expand Down Expand Up @@ -303,6 +330,115 @@ void AltSoftSerial::flushInput(void)
rx_buffer_head = rx_buffer_tail;
}

void AltSoftSerial::setBitCounts(uint8_t config) {
parity = 0;
stop_bits = 1;
switch (config) {
case SERIAL_5N1:
data_bits = 5;
break;
case SERIAL_6N1:
data_bits = 6;
break;
case SERIAL_7N1:
data_bits = 7;
break;
case SERIAL_8N1:
data_bits = 8;
break;
case SERIAL_5N2:
data_bits = 5;
stop_bits = 2;
break;
case SERIAL_6N2:
data_bits = 6;
stop_bits = 2;
break;
case SERIAL_7N2:
data_bits = 7;
stop_bits = 2;
break;
case SERIAL_8N2:
data_bits = 8;
stop_bits = 2;
break;
case SERIAL_5O1:
parity = 1;
data_bits = 5;
break;
case SERIAL_6O1:
parity = 1;
data_bits = 6;
break;
case SERIAL_7O1:
parity = 1;
data_bits = 7;
break;
case SERIAL_8O1:
parity = 1;
data_bits = 8;
break;
case SERIAL_5O2:
parity = 1;
data_bits = 5;
stop_bits = 2;
break;
case SERIAL_6O2:
parity = 1;
data_bits = 6;
stop_bits = 2;
break;
case SERIAL_7O2:
parity = 1;
data_bits = 7;
stop_bits = 2;
break;
case SERIAL_8O2:
parity = 1;
data_bits = 8;
stop_bits = 2;
break;
case SERIAL_5E1:
parity = 2;
data_bits = 5;
break;
case SERIAL_6E1:
parity = 2;
data_bits = 6;
break;
case SERIAL_7E1:
parity = 2;
data_bits = 7;
break;
case SERIAL_8E1:
parity = 2;
data_bits = 8;
break;
case SERIAL_5E2:
parity = 2;
data_bits = 5;
stop_bits = 2;
break;
case SERIAL_6E2:
parity = 2;
data_bits = 6;
stop_bits = 2;
break;
case SERIAL_7E2:
parity = 2;
data_bits = 7;
stop_bits = 2;
break;
case SERIAL_8E2:
parity = 2;
data_bits = 8;
stop_bits = 2;
break;
}

total_bits = data_bits + (parity ? 1 : 0) + stop_bits;
almost_total_bits = total_bits - stop_bits;
}

#ifdef ALTSS_USE_FTM0
void ftm0_isr(void)
Expand Down
8 changes: 6 additions & 2 deletions AltSoftSerial.h
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Original file line number Diff line number Diff line change
Expand Up @@ -25,6 +25,7 @@
#define AltSoftSerial_h

#include <inttypes.h>
#include <util/parity.h>

#if ARDUINO >= 100
#include "Arduino.h"
Expand All @@ -44,7 +45,9 @@ class AltSoftSerial : public Stream
public:
AltSoftSerial() { }
~AltSoftSerial() { end(); }
static void begin(uint32_t baud) { init((ALTSS_BASE_FREQ + baud / 2) / baud); }
//static void begin(uint32_t baud) { init((ALTSS_BASE_FREQ + baud / 2) / baud); }
static void begin(uint32_t baud, uint8_t config = SERIAL_8N1) { init((F_CPU + baud / 2) / baud, config); }
static void begin(uint32_t baud) { init((ALTSS_BASE_FREQ + baud / 2) / baud, SERIAL_8N1); }
static void end();
int peek();
int read();
Expand All @@ -68,8 +71,9 @@ class AltSoftSerial : public Stream
static void enable_timer0(bool enable) { }
static bool timing_error;
private:
static void init(uint32_t cycles_per_bit);
static void init(uint32_t cycles_per_bit, uint8_t config);
static void writeByte(uint8_t byte);
static void setBitCounts(uint8_t config);
};

#endif