Merge branch 'master' into feature/Unity_codecheck_setup

Author: LinjingZhang

cores/HardwareSerial.cpp

@@ -166,6 +166,21 @@ size_t HardwareSerial::write(const uint8_t uc_data) {
         int nextWrite = _tx_buffer->_iHead + 1;
         if (nextWrite >= SERIAL_BUFFER_SIZE)
             nextWrite = 0;
+
+        // This should always be false but in case transmission is completed before buffer, we need
+        // to reenable IRQ
+        if (XMC_USIC_CH_GetTransmitBufferStatus(_XMC_UART_config->channel) !=
+            XMC_USIC_CH_TBUF_STATUS_BUSY) {
+            XMC_UART_CH_EnableEvent(_XMC_UART_config->channel, XMC_UART_CH_EVENT_TRANSMIT_BUFFER);
+            XMC_UART_CH_Transmit(_XMC_UART_config->channel,
+                                 _tx_buffer->_aucBuffer[_tx_buffer->_iTail]);
+            _tx_buffer->_iTail++;
+            if (_tx_buffer->_iTail >= SERIAL_BUFFER_SIZE)
+                _tx_buffer->_iTail = _tx_buffer->_iTail -
+                                     SERIAL_BUFFER_SIZE; // If iTail is larger than Serial Buffer
+                                                         // Size calculate the correct index value
+        }
+
         while (_tx_buffer->_iTail == nextWrite)
             ; // Spin locks if we're about to overwrite the buffer. This continues once the data is
               // sent
@@ -207,9 +222,10 @@ void HardwareSerial::IrqHandler(void) {
             _tx_buffer->_iTail++;
             if (_tx_buffer->_iTail >= SERIAL_BUFFER_SIZE)
                 _tx_buffer->_iTail = 0;
-        } else
+        } else {
             // Mask off transmit interrupt so we don't get it any more
             XMC_UART_CH_DisableEvent(_XMC_UART_config->channel, XMC_UART_CH_EVENT_TRANSMIT_BUFFER);
+        }
     }
 }