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CHAPTER 17 SERIAL INTERFACE CHANNEL 1
(c) Repetitive transmit mode
This mode is to repeatedly transmit the data stored in the buffer RAM.
The serial transfer is started by writing any data to the serial I/O shift register 1 (SIO1) when the bit 7
(CSIE1) of the serial operation mode register 1 (CSIM1) is set to 1.
Unlike the basic transmit mode, the interrupt request flag (CSIIF1) is not set after the last byte (data at
address FAC0H) has been transmitted, the value at which the transmission/reception has been started
is set again to the automatic data transmit/receive address pointer (ADTP), and the contents of the buffer
RAM are transmitted again.
When receive operation, busy control, and strobe control are not performed, the P20/SI1, P23/STB, and
P24/BUSY pins can be used as ordinary I/O ports.
Figure 17-14 shows the operation timing of the repetitive transmit mode, and Figure 17-15 shows an
operation flowchart.
And, Figure 17-16 shows the operation of the buffer RAM when 6 bytes are transmitted in the repetitive
transmit mode.
Figure 17-14. Operation Timing of Repetitive Transmit Mode
Caution
In the repetitive transmit mode, the buffer RAM is read after 1-byte data has been
transmitted. Therefore, there is interval time until the next transmission is executed.
Because the buffer RAM is read simultaneously with the CPU processing, the maximum
interval time depends on the CPU processing and the value of the automatic data
transmit/receive time interval specification register (ADTI) (refer to (5) Interval time of
automatic transmission/reception).
SCK1
SO1
D7 D6 D5 D4 D3 D2 D1 D0
D7 D6 D5 D4 D3 D2 D1 D0
Interval
Interval
D7 D6 D5