Hitachi H8/3637 Hardware Manual page 247

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