I want send and receive a 9 bit async-serial protocol with 4800 baud on my Arduino Uno, i have read on the specification from the ATmega328P that the uart can do that. My aim is that when my Uart receive the 9th bit as a 1 he must throw a interrupt. On this interrupt i can recognize that this byte was an adress byte. When he receive a zero he sould do nothing spezial, only transmit it as hex-byte over usb to the pc.
My Problem now, i can´t initialize the Uart right because the command Serial.begin(4800, config) is not enough, i must throw the interrupt and translate the data to hex-bytes. My Question can i modify the Serial.begin() source code respectively where can i find the source code for the Serial.begin function?
When there is no possibility to change the code has someone a other option for me to send and receive the 9 bit protocol with an Arduino Uno?