How do I know NAT9914 received the last character in the DMA mode

[ANDY.CT.CHEN]

Hi,  

   I set NAT9914 in the DMA mode to improve transmission speed.
   I check the END bit in the ISR0 register after received a Byte, because I don't know when the end of this transmission.
   However, the transfer speed does not improve.
   Do you know the other way to sense the NAT9914 received the last character in the DMA mode?

Best regards

Andy