diff options
| -rw-r--r-- | cores/arduino/CDC.cpp | 12 |
1 files changed, 11 insertions, 1 deletions
diff --git a/cores/arduino/CDC.cpp b/cores/arduino/CDC.cpp index 7d9d682..7da9077 100644 --- a/cores/arduino/CDC.cpp +++ b/cores/arduino/CDC.cpp @@ -155,7 +155,17 @@ void Serial_::flush(void) void Serial_::write(uint8_t c) { - USB_Send(CDC_TX,&c,1); + /* only try to send bytes if the high-level CDC connection itself + is open (not just the pipe) - the OS should set lineState when the port + is opened and clear lineState when the port is closed. + bytes sent before the user opens the connection or after + the connection is closed are lost - just like with a UART. */ + + // TODO - ZE - check behavior on different OSes and test what happens if an + // open connection isn't broken cleanly (cable is yanked out, host dies + // or locks up, or host virtual serial port hangs) + if (_usbLineInfo.lineState > 0) + USB_Send(CDC_TX,&c,1); } Serial_ Serial; |