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Diffstat (limited to 'cores/arduino/HardwareSerial.cpp')
-rwxr-xr-xcores/arduino/HardwareSerial.cpp124
1 files changed, 76 insertions, 48 deletions
diff --git a/cores/arduino/HardwareSerial.cpp b/cores/arduino/HardwareSerial.cpp
index f8a959a..1af6a66 100755
--- a/cores/arduino/HardwareSerial.cpp
+++ b/cores/arduino/HardwareSerial.cpp
@@ -49,41 +49,41 @@ ring_buffer rx_buffer3 = { { 0 }, 0, 0 };
inline void store_char(unsigned char c, ring_buffer *rx_buffer)
{
- int i = (rx_buffer->head + 1) % RX_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->buffer[rx_buffer->head] = c;
- rx_buffer->head = i;
- }
+ int i = (rx_buffer->head + 1) % RX_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->buffer[rx_buffer->head] = c;
+ rx_buffer->head = i;
+ }
}
#if defined(__AVR_ATmega1280__)
SIGNAL(SIG_USART0_RECV)
{
- unsigned char c = UDR0;
+ unsigned char c = UDR0;
store_char(c, &rx_buffer);
}
SIGNAL(SIG_USART1_RECV)
{
- unsigned char c = UDR1;
+ unsigned char c = UDR1;
store_char(c, &rx_buffer1);
}
SIGNAL(SIG_USART2_RECV)
{
- unsigned char c = UDR2;
+ unsigned char c = UDR2;
store_char(c, &rx_buffer2);
}
SIGNAL(SIG_USART3_RECV)
{
- unsigned char c = UDR3;
+ unsigned char c = UDR3;
store_char(c, &rx_buffer3);
}
@@ -96,9 +96,9 @@ SIGNAL(USART_RX_vect)
#endif
{
#if defined(__AVR_ATmega8__)
- unsigned char c = UDR;
+ unsigned char c = UDR;
#else
- unsigned char c = UDR0;
+ unsigned char c = UDR0;
#endif
store_char(c, &rx_buffer);
}
@@ -111,7 +111,7 @@ HardwareSerial::HardwareSerial(ring_buffer *rx_buffer,
volatile uint8_t *ubrrh, volatile uint8_t *ubrrl,
volatile uint8_t *ucsra, volatile uint8_t *ucsrb,
volatile uint8_t *udr,
- uint8_t rxen, uint8_t txen, uint8_t rxcie, uint8_t udre)
+ uint8_t rxen, uint8_t txen, uint8_t rxcie, uint8_t udre, uint8_t u2x)
{
_rx_buffer = rx_buffer;
_ubrrh = ubrrh;
@@ -123,14 +123,43 @@ HardwareSerial::HardwareSerial(ring_buffer *rx_buffer,
_txen = txen;
_rxcie = rxcie;
_udre = udre;
+ _u2x = u2x;
}
// Public Methods //////////////////////////////////////////////////////////////
-void HardwareSerial::begin(long speed)
+void HardwareSerial::begin(long baud)
{
- *_ubrrh = ((F_CPU / 16 + speed / 2) / speed - 1) >> 8;
- *_ubrrl = ((F_CPU / 16 + speed / 2) / speed - 1);
+ uint16_t baud_setting;
+ bool use_u2x;
+
+ // U2X mode is needed for baud rates higher than (CPU Hz / 16)
+ if (baud > F_CPU / 16) {
+ use_u2x = true;
+ } else {
+ // figure out if U2X mode would allow for a better connection
+
+ // calculate the percent difference between the baud-rate specified and
+ // the real baud rate for both U2X and non-U2X mode (0-255 error percent)
+ uint8_t nonu2x_baud_error = abs((int)(255-((F_CPU/(16*(((F_CPU/8/baud-1)/2)+1))*255)/baud)));
+ uint8_t u2x_baud_error = abs((int)(255-((F_CPU/(8*(((F_CPU/4/baud-1)/2)+1))*255)/baud)));
+
+ // prefer non-U2X mode because it handles clock skew better
+ use_u2x = (nonu2x_baud_error > u2x_baud_error);
+ }
+
+ if (use_u2x) {
+ *_ucsra = 1 << _u2x;
+ baud_setting = (F_CPU / 4 / baud - 1) / 2;
+ } else {
+ *_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;
+
sbi(*_ucsrb, _rxen);
sbi(*_ucsrb, _txen);
sbi(*_ucsrb, _rxcie);
@@ -138,54 +167,53 @@ void HardwareSerial::begin(long speed)
uint8_t HardwareSerial::available(void)
{
- return (RX_BUFFER_SIZE + _rx_buffer->head - _rx_buffer->tail) % RX_BUFFER_SIZE;
+ return (RX_BUFFER_SIZE + _rx_buffer->head - _rx_buffer->tail) % RX_BUFFER_SIZE;
}
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->buffer[_rx_buffer->tail];
- _rx_buffer->tail = (_rx_buffer->tail + 1) % RX_BUFFER_SIZE;
- return c;
- }
+ // 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->buffer[_rx_buffer->tail];
+ _rx_buffer->tail = (_rx_buffer->tail + 1) % RX_BUFFER_SIZE;
+ return c;
+ }
}
void HardwareSerial::flush()
{
- // don't reverse this or there may be problems if the RX interrupt
- // occurs after reading the value of rx_buffer_head but before writing
- // the value to rx_buffer_tail; the previous value of rx_buffer_head
- // may be written to rx_buffer_tail, making it appear as if the buffer
- // don't reverse this or there may be problems if the RX interrupt
- // occurs after reading the value of rx_buffer_head but before writing
- // the value to rx_buffer_tail; the previous value of rx_buffer_head
- // may be written to rx_buffer_tail, making it appear as if the buffer
- // were full, not empty.
- _rx_buffer->head = _rx_buffer->tail;
+ // don't reverse this or there may be problems if the RX interrupt
+ // occurs after reading the value of rx_buffer_head but before writing
+ // the value to rx_buffer_tail; the previous value of rx_buffer_head
+ // may be written to rx_buffer_tail, making it appear as if the buffer
+ // don't reverse this or there may be problems if the RX interrupt
+ // occurs after reading the value of rx_buffer_head but before writing
+ // the value to rx_buffer_tail; the previous value of rx_buffer_head
+ // may be written to rx_buffer_tail, making it appear as if the buffer
+ // were full, not empty.
+ _rx_buffer->head = _rx_buffer->tail;
}
void HardwareSerial::write(uint8_t c)
{
- while (!((*_ucsra) & (1 << _udre)))
- ;
+ while (!((*_ucsra) & (1 << _udre)))
+ ;
- *_udr = c;
+ *_udr = c;
}
// Preinstantiate Objects //////////////////////////////////////////////////////
#if defined(__AVR_ATmega8__)
-HardwareSerial Serial(&rx_buffer, &UBRRH, &UBRRL, &UCSRA, &UCSRB, &UDR, RXEN, TXEN, RXCIE, UDRE);
+HardwareSerial Serial(&rx_buffer, &UBRRH, &UBRRL, &UCSRA, &UCSRB, &UDR, RXEN, TXEN, RXCIE, UDRE, U2X);
#else
-HardwareSerial Serial(&rx_buffer, &UBRR0H, &UBRR0L, &UCSR0A, &UCSR0B, &UDR0, RXEN0, TXEN0, RXCIE0, UDRE0);
+HardwareSerial Serial(&rx_buffer, &UBRR0H, &UBRR0L, &UCSR0A, &UCSR0B, &UDR0, RXEN0, TXEN0, RXCIE0, UDRE0, U2X0);
#endif
#if defined(__AVR_ATmega1280__)
-HardwareSerial Serial1(&rx_buffer1, &UBRR1H, &UBRR1L, &UCSR1A, &UCSR1B, &UDR1, RXEN1, TXEN1, RXCIE1, UDRE1);
-HardwareSerial Serial2(&rx_buffer2, &UBRR2H, &UBRR2L, &UCSR2A, &UCSR2B, &UDR2, RXEN2, TXEN2, RXCIE2, UDRE2);
-HardwareSerial Serial3(&rx_buffer3, &UBRR3H, &UBRR3L, &UCSR3A, &UCSR3B, &UDR3, RXEN3, TXEN3, RXCIE3, UDRE3);
+HardwareSerial Serial1(&rx_buffer1, &UBRR1H, &UBRR1L, &UCSR1A, &UCSR1B, &UDR1, RXEN1, TXEN1, RXCIE1, UDRE1, U2X1);
+HardwareSerial Serial2(&rx_buffer2, &UBRR2H, &UBRR2L, &UCSR2A, &UCSR2B, &UDR2, RXEN2, TXEN2, RXCIE2, UDRE2, U2X2);
+HardwareSerial Serial3(&rx_buffer3, &UBRR3H, &UBRR3L, &UCSR3A, &UCSR3B, &UDR3, RXEN3, TXEN3, RXCIE3, UDRE3, U2X3);
#endif
-