NEC PD78F9488 - Manual (Page 240)

CHAPTER 12 SERIAL INTERFACE 1A0
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User’s Manual U15331EJ4V1UD
(b) Basic transmit mode
In this mode, the specified number of 8-bit unit data are transmitted.
Serial transfer is started when any data is written to serial I/O shift register 1A0 (SIO1A0) while bit 7
(CSIE10) of serial operation mode register 1A0 (CSIM1A0) is set to 1, and bit 7 (RE0) of automatic data
transmit/receive control register 0 (ADTC0) is set to 0.
Upon completion of transmission of the last byte, the interrupt request flag (CSIIF10) is set. The
termination of automatic transmission/reception should be checked by using bit 3 (TRF0) of automatic
data transmit/receive control register 0 (ADTC0), not by CSIIF10.
If a receive operation is not executed, the P25/SI10 pin can be use as normal I/O port.
Figure 12-10 shows the basic transmit mode operation timing, and Figure 12-11 shows the operation
flowchart.
Figure 12-12 shows buffer RAM operation when repeatedly transmitting 6 bytes.
Figure 12-10. Basic Transmit Mode Operation Timing
SCK10
SO10 D7 D6 D5 D4 D3 D2 D1 D0 D7 D6 D5 D4 D3 D2 D1 D0
CSIIF10
TRF0
Interval
Cautions 1. Because, in the basic transmit mode, the automatic transmit/receive function reads
data from the buffer RAM after 1-byte transmission, an interval is inserted until the
next transmission. As the buffer RAM read is performed at the same time as CPU
processing, the maximum interval is dependent upon CPU processing and the
value of automatic data transmit/receive interval specification register 0 (ADTI0)
(refer to 12.4.3 (5) Interval time of automatic transmission/reception).
2. When TRF0 is cleared, the SO10 pin becomes low level.
Remark CSIIF10: Interrupt request flag
TRF0: Bit 3 of automatic data transmit/receive control register 0 (ADTC0)