Datasheet

Section 16 Serial Pin Multiplexed Modes
Rev. 2.00 Aug. 20, 2008 Page 551 of 1198
REJ09B0403-0200
16.4.5 Serial Pin Multiplexed Mode 4
(SMR0 Register [bits SM2, SM1, SM0] = [1 0 0])
Mode 4 provides the same function as mode 3, but the data lines of SCI_3 and SCIF are cross-
connected.
RxD1/TxD1 of SCI_1 are connected to Tx/Rx of COM1, and internal register bits emulate other
signals of COM1. DCD/RI/DSR/CTS of SCIF are fixed at 1. COM2 is not available (N/A) and Rx
for COM2 is fixed at 1. COM3 is not available (N/A) and Rx for COM3 is fixed at 1. RxD3/TxD3
of SCI_3 are cross-connected to TxDF/RxDF of SCIF internally.
The states of DCD/RI/DSR of COM1 are reflected in bits DCD1/RI1/DSR1 of the SMR0 register,
and CTS of COM1 is reflected to CTS1 bit of SMR1 register.
The values written to bits DTR1/RTS1 of the SMR1 register are output to DTR/RTS of COM1.
The value written to bit RTS3 of SMR1 is reflected in CTS of SCIF, and the state of RTS of SCIF
is reflected in bit CTS3 of SMR1, allowing SCI_3 and SCIF to communicate each other with
virtual flow control.
Figure 16.5 illustrates the pin connection in serial pin multiplexed mode 4.
COM2 COM3
SCI_1 SCI_3
BMC (H8S)
RxD1
TxD1
RxD3
TxD3
Rx Tx Rx Tx
COM1
DCD1
RI1
DSR1
SMR0
SCIF
P24 P25 P26 P27 P64 P65
P86 P87
P51
P50 P53 P52
DCD RI DSR DTR CTS RTS RxDF TxDF
DCD RI DSR DTR CTS RTS Rx Tx
CTS1
DTR1
RTS1
CTS3
SMR1
RTS3
1 1 1 Open
Figure 16.5 Serial Pin Multiplexed Mode 4