CHAPTER 14 SERIAL INTERFACE CHANNEL 1
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User’s Manual U11302EJ4V0UM
(d) Automatic transmission/reception suspension and restart
Automatic transmission/reception can be temporarily suspended by resetting 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
reset 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 used alternately as serial interface pins (P20/
SI1, P21/SO1, P22/SCK1, P23/STB, and P24/BUSY) are set to the port mode.
To resume automatic transmission/reception, set CSIE1 to 1 and write any value to serial I/O shift
register 1 (SIO1). This enables transmission of the remaining data.
Cautions 1. If the HALT instruction is executed during automatic transmission/reception,
transfer is suspended and the HALT mode is set even during 8-bit data transfer.
When the HALT mode is cleared, automatic transmission/reception is restarted
at the suspended point.
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
D7 D6 D5 D4 D3 D2 D1 D0
SI1
D7 D6 D5 D4 D3 D2 D1 D0
D7 D6 D5 D4 D3 D2 D1 D0
Restart command
CSIE1 = 1, Write to SIO1
Suspend
CSIE1 = 0 (Suspend command)