Datasheet

323
11011B–ATARM–21-Feb-12
SAM3N
22.4.5.4 Transmit Buffer Empty
This flag is set when PERIPH_TCR register reaches zero with PERIPH_TNCR also set to zero
and the last data has been written into peripheral THR.
It is reset by writing a non zero value in PERIPH_TCR or PERIPH_TNCR.