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(d) Automatic transmission/reception suspending and restart
Automatic transmission/reception can be temporarily suspended by setting bit 7 (CSIE1) of the serial
operating mode register 1 (CSIM1) to 0.
If during 8-bit data transfer, 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 used with the serial interface pins for dual function (P20/
SI1, P21/SO1, P22/SCK1, P23/STB and P24/BUSY) are set to the port mode.
To restart auto send and receive, set CSIE1 at 1 and write the desired value in serial I/O shift register
1 (SIO1). The remaining can be transmitted in this way.
Cautions 1. If the HALT instruction is executed during automatic transmission/reception, trans-
fer is suspended and the HALT mode is set if during 8-bit data transfer. When the
HALT mode is cleared, automatic transmission/reception is restarted from 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 18-17. Automatic Transmission/Reception Suspension and Restart
CSIE1 = 0 (Suspended Command)
SCK1
SO1
D7 D6 D5 D4 D3 D2 D1 D0
SI1
D7 D6 D5 D4 D3 D2 D1 D0
CSIE1: Bit 7 of serial operation mode register 1 (CSIM1)
CHAPTER 18 SERIAL INTERFACE CHANNEL 1
Suspend
Restart Command
CSIE1 = 1, Write to SIO1
D7 D6 D5 D4 D3 D2 D1 D0
D7 D6 D5 D4 D3 D2 D1 D0
423
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