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(b) Busy & strobe control option
Strobe control is used to synchronize data transmission/reception between the master device and
a slave device. The master device outputs a strobe signal from the STB/P23 pin on completion of
transmission/reception of 8-bit data.
transmission/reception completion timing of the master device. Therefore, synchronization can be
established even if bit slippage occurs due to noise carried on the serial clock, keeping bit slippage
from affecting transmission of the next byte.
To use the strobe control option, the following conditions must be satisfied.
• Set bit 5 (ATE) of serial operating mode register 1 (CSIM1) to 1.
• Set bit 2 (STRB) of the automatic data transmit/receive control register (ADTC) to 1.
Usually, the busy control and strobe control options are simultaneously used for handshaking. In
this case, the strobe signal is output from the STB/P23 pin and the BUSY/P24 pin is sampled. While
a busy signal is being input to the pin, transmission/reception can be put into a wait state.
If strobe control is not executed, the P23/STB pin can be used as a normal I/O port pin.
Figure 14-21 shows the operation timing when using the busy & strobe control option.
When the strobe control option is used, the interrupt request flag (CSIIF1) that is set on completion
of transmission/reception is set after the strobe signal has been output.
Figure 14-21. Operation Timing When Using Busy & Strobe Control Option (BUSY0 = 0)
SCK1
SO1
D7
D6 D5 D4 D3 D2 D1 D0
SI1
D7 D6 D5 D4 D3 D2 D1 D0
STB
BUSY
CSIIF1
TRF
Caution
When TRF is cleared, the SO1 pin becomes low level.
Remark CSIIF1: Interrupt request flag
TRF:
294
CHAPTER 14 SERIAL INTERFACE CHANNEL 1
This strobe signal informs the slave device of the data
Bit 3 of the automatic data transmit/receive control register (ADTC)
User's Manual U11302EJ4V0UM
D7 D6 D5 D4 D3 D2 D1 D0
D7 D6 D5 D4 D3 D2 D1 D0
Busy input clear
Busy input valid
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