diff options
| -rw-r--r-- | cores/arduino/HardwareSerial.cpp | 15 |
1 files changed, 8 insertions, 7 deletions
diff --git a/cores/arduino/HardwareSerial.cpp b/cores/arduino/HardwareSerial.cpp index d78c205..1bd3bff 100644 --- a/cores/arduino/HardwareSerial.cpp +++ b/cores/arduino/HardwareSerial.cpp @@ -233,6 +233,11 @@ void HardwareSerial::_tx_udr_empty_irq(void) _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); } } @@ -339,9 +344,9 @@ void HardwareSerial::flush() if (!_written) return; - // UDR is kept full while the buffer is not empty, so TXC triggers - // when EMPTY && SENT - while (bit_is_clear(*_ucsra, TXC0)); + while (bit_is_set(*_ucsrb, UDRIE0) || bit_is_clear(*_ucsra, TXC0)); + // If we get here, nothing is queued anymore (DRIE is disabled) and + // the hardware finished tranmission (TXC is set). } size_t HardwareSerial::write(uint8_t c) @@ -359,10 +364,6 @@ size_t HardwareSerial::write(uint8_t c) sbi(*_ucsrb, UDRIE0); _written = true; - // 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); return 1; } |