CCS/EK-TM4C123GXL: UART TIVA C

Hi,
Not clear on your question. The size (16 bytes) of the FIFO doesn't prevent you from receiving more than 16 bytes of data. The CPU needs to process these data before the buffer is full or the you will have a overrun error. The number of bytes to receive in the FIFO before generating an interrupt is programmable. For example, you can set the watermark threshold at half of the FIFO by which time when full an interrupt is generated to notify the CPU to process the received data while new data is being streamed in. You can receive N bytes of data but the CPU will be notified whenever there are 8 bytes of data in the FIFO.