diff options
| -rw-r--r-- | cores/arduino/HardwareSerial.cpp | 26 |
1 files changed, 21 insertions, 5 deletions
diff --git a/cores/arduino/HardwareSerial.cpp b/cores/arduino/HardwareSerial.cpp index 1bd3bff..ffdb82c 100644 --- a/cores/arduino/HardwareSerial.cpp +++ b/cores/arduino/HardwareSerial.cpp @@ -344,7 +344,14 @@ void HardwareSerial::flush() if (!_written) return; - while (bit_is_set(*_ucsrb, UDRIE0) || bit_is_clear(*_ucsra, TXC0)); + while (bit_is_set(*_ucsrb, UDRIE0) || bit_is_clear(*_ucsra, TXC0)) { + if (bit_is_clear(SREG, SREG_I) && bit_is_set(*_ucsrb, UDRIE0)) + // Interrupts are globally disabled, but the DR empty + // interrupt should be enabled, so poll the DR empty flag to + // prevent deadlock + if (bit_is_set(*_ucsra, UDRE0)) + _tx_udr_empty_irq(); + } // If we get here, nothing is queued anymore (DRIE is disabled) and // the hardware finished tranmission (TXC is set). } @@ -355,10 +362,19 @@ size_t HardwareSerial::write(uint8_t c) // If the output buffer is full, there's nothing for it other than to // wait for the interrupt handler to empty it a bit - // ???: return 0 here instead? - while (i == _tx_buffer_tail) - ; - + while (i == _tx_buffer_tail) { + if (bit_is_clear(SREG, SREG_I)) { + // Interrupts are disabled, so we'll have to poll the data + // register empty flag ourselves. If it is set, pretend an + // interrupt has happened and call the handler to free up + // space for us. + if(bit_is_set(*_ucsra, UDRE0)) + _tx_udr_empty_irq(); + } else { + // nop, the interrupt handler will free up space for us + } + } + _tx_buffer[_tx_buffer_head] = c; _tx_buffer_head = i; |