243
RDR
RSR (receiving)
RXD
pin
RDRF = 0
RDR
RSR (received and transferred)
RXD
pin
RDRF 1
(RXI requested if RIE = 1)
←
↑
Figure 10.4 (a) RDRF Setting and RXI Interrupt
TDR (next transmit data)
TSR (transmitting)
TXD
pin
TDRE = 0
TDR
TSR (transmission complete,
next data transferred)
TXD
pin
TDRE 1
(TXI requested if TIE = 1)
←
↓
Figure 10.4 (b) TDRE Setting and TXI Interrupt
TDR
TSR (transmitting)
TXD
pin
TEND = 0
TDR
TSR (transmission complete)
TXD
pin
TEND 1
(TEI requested if TEIE = 1)
←
Figure 10.4 (c) TEND Setting and TEI Interrupt