274
RDR
RSR (reception in progress)
RDRF = 0
RXD
3x
pin
RDR
RSR
↑
(reception completed, transfer)
RDRF
←
1
(RXI request when RIE = 1)
RXD
3x
pin
Figure 10.2 (a) RDRF Setting and RXI Interrupt
TDR (next transmit data)
TSR (transmission in progress)
TDRE = 0
TXD
3x
pin
TDR
TSR
↓
(transmission completed, transfer)
TDRE
←
1
(TXI request when TIE = 1)
TXD
3x
pin
Figure 10.2 (b) TDRE Setting and TXI Interrupt
TDR
TSR (transmission in progress)
TEND = 0
TXD
3x
pin
TDR
TSR
(reception completed)
TEND
←
1
(TEI request when TEIE = 1)
TXD
3x
pin
Figure 10.2 (c) TEND Setting and TEI Interrupt