Datasheet

Table Of Contents
Section 18 Serial Communication Interface 4 (SCI4)
Rev. 2.00 Jul. 04, 2007 Page 425 of 692
REJ09B0309-0200
During transmission, the SCI4 operates as shown below.
1. The SCI4 sets the TE bit to 1 and clears the TDRE flag to 0 when transmit data is written to in
TDR4 to transmit data from TDR4 to SR4. After that, the SCI4 sets the TDRE flag to 1 to start
transmission. At this time, when the TIE bit in SCR4 is set to 1, a TXI is generated.
2. In clock output mode, the SCI4 outputs eight pulses of the synchronous clock. When the
external clock is selected, the SCI4 outputs data in synchronization with the input clock.
3. Serial data is output from the LSB (bit 0) to MSB (bit 7) on pin SO4. The SCI4 checks the
TDRE flag at the timing of outputting the MSB (bit 7).
4. When TDRE = 0, data in TDR4 is transmitted to SR4 and then the data of the next frame starts
to be transmitted. When TDRE = 1, the SCI4 sets the TEND bit to 1 and holds the output level
after transmitting the MSB (bit 7). At this time, when the TEIE bit in SCR4 is set to 1, a TEI is
generated.
5. After the transmission, the output level on pin SCK4 is fixed high.
Note: Transmission cannot be performed when the error flag (ORER) which indicates the data
reception status is set to 1. Before transmission, confirm that the ORER flag is cleared to
0.
Figure 18.5 shows the example of transmission operation.
Synchronous clock
Serial data Bit 0 Bit 1 Bit 7 Bit 0 Bit 1 Bit 6 Bit 7
TDRE
TEND
LSI operation
User operation
TXI
generated
TDRE
cleared
TEI
generated
TXI
generated
1 frame
Data written
to TDR4
1 frame
Figure 18.5 Transmit Operation Example