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(c) Repeat transmit mode
In this mode, data stored in the buffer RAM is transmitted repeatedly.
Serial transfer starts by writing any data to the serial I/O shift register 1 (SIO1) when 1 is set in the serial
operating mode register 1 (CSIM1) bit 7 (CSIE1).
Unlike the basic transmit mode, after the last byte (data in address FAC0H) has been transmitted, the interrupt
request flag (CSIIF1) is not set, the value at the time when the transmission was started is set in the automatic
data transmit/receive address pointer (ADTP) again, and the buffer RAM contents are transmitted again.
When a reception operation, busy control and strobe control are not performed, the P20/SI1, P23/STB and
P24/BUSY pins can be used as normal input/output ports.
The repeat transmission mode operation timing is shown in Figure 17-13, and the operation flowchart in
Figure 17-14. In addition, buffer RAM operation in 6-byte transmission in the repeat transmit mode is shown
in Figure 17-15.
SCK1
SO1
Caution Because, in the repeat transmission mode, the automatic transmit/receive function reads
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CHAPTER 17 SERIAL INTERFACE CHANNEL 1
Figure 17-13. Repeat Transmit Mode Operation Timings
D7 D6
D5 D4 D3 D2 D1 D0
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 (see (5) Automatic data
transmit/receive interval).
Interval
D7 D6 D5 D4 D3 D2 D1 D0
Interval
D7 D6 D5
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