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CHAPTER 14
SERIAL INTERFACE SIO1
User’s Manual U12790EJ2V0UD
(d) Automatic transmission/reception suspension and restart
Automatic transmission/reception can be temporarily suspended by setting bit 7 (CSIE1) of serial
operating mode register 1 (CSIM1) to 0.
If 8-bit data transfer is in progress, the transmission/reception is not suspended if bit 7 (CSIE1) is set
to 0. It is suspended upon completion of 8-bit data transfer.
When suspended, bit 3 (TRF) of the automatic data transmit/receive control register (ADTC) is set to 0
after transfer of the 8th bit, and all the port pins that function alternately as serial interface pins (P20/SI1,
P21/SO1, P22/SCK1, P23/STB and P24/BUSY) are set to the port mode.
During restart of transmission/reception, the remaining data can be transferred by setting CSIE1 to 1 and
writing any data to serial I/O shift register 1 (SIO1).
Cautions 1. If the HALT instruction is executed during automatic transmission/reception, transfer
is suspended and the HALT mode is set if 8-bit data transfer is in progress.
2. When suspending automatic transmission/reception, do not change the operating
mode to 3-wire serial I/O mode while TRF = 1.
Figure 14-17. Automatic Transmission/Reception Suspension and Restart
CSIE1: Bit 7 of serial operating mode register 1 (CSIM1)
SCK1
SO1
D7 D6 D5 D4 D3 D2 D1 D0
SI1
D7 D6 D5 D4 D3 D2 D1 D0
CSIE1 = 0 (suspend command)
Suspend
Restart command
CSIE1 = 1, write to SIO1