diff options
| -rw-r--r-- | cores/arduino/HardwareSerial.cpp | 24 |
1 files changed, 12 insertions, 12 deletions
diff --git a/cores/arduino/HardwareSerial.cpp b/cores/arduino/HardwareSerial.cpp index ffdb82c..9a02f23 100644 --- a/cores/arduino/HardwareSerial.cpp +++ b/cores/arduino/HardwareSerial.cpp @@ -223,22 +223,22 @@ void HardwareSerial::_rx_complete_irq(void) void HardwareSerial::_tx_udr_empty_irq(void) { + // If interrupts are enabled, there must be more data in the output + // buffer. Send the next byte + unsigned char c = _tx_buffer[_tx_buffer_tail]; + _tx_buffer_tail = (_tx_buffer_tail + 1) % SERIAL_BUFFER_SIZE; + + *_udr = c; + + // clear the TXC bit -- "can be cleared by writing a one to its bit + // location". This makes sure flush() won't return until the bytes + // actually got written + sbi(*_ucsra, TXC0); + if (_tx_buffer_head == _tx_buffer_tail) { // Buffer empty, so disable interrupts cbi(*_ucsrb, UDRIE0); } - else { - // There is more data in the output buffer. Send the next byte - unsigned char c = _tx_buffer[_tx_buffer_tail]; - _tx_buffer_tail = (_tx_buffer_tail + 1) % SERIAL_BUFFER_SIZE; - - *_udr = c; - - // clear the TXC bit -- "can be cleared by writing a one to its bit - // location". This makes sure flush() won't return until the bytes - // actually got written - sbi(*_ucsra, TXC0); - } } // Constructors //////////////////////////////////////////////////////////////// |