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CHAPTER 15 SERIAL INTERFACE CSI1
(3) Communication operation
In the 3-wire serial I/O mode, data is transmitted or received in 8-bit units. Each bit of the data is transmitted
or received in synchronization with the serial clock.
Data can be transmitted or received if bit 6 (TRMD1) of serial operation mode register 1 (CSIM1) is 1.
Transmission/reception is started when a value is written to transmit buffer register 1 (SOTB1). Data can be
received if bit 6 (TRMD1) of serial operation mode register 1 (CSIM1) is 0. Reception is started when data is
read from serial I/O shift register 1 (SIO1).
After communication has been started, bit 0 (CSOT1) of CSIM1 is set to 1. When communication of 8-bit data
has been completed, a communication completion interrupt flag (CSIIF1) is set, and CSOT1 is cleared to 0. Then
the next communication is enabled.
Caution Do not access the control register and data register when CSOT1 = 1 (during serial communi-
cation).
Figure 15-4. Timing in 3-Wire Serial I/O Mode (1/2)
(1) Transmission/reception timing (Type 1; TRMD1 = 1, DIR1 = 0, CKP1 = 0, DAP1 = 0)
SCK1
Read/write trigger
SOTB1
55H (communication data)
ABH
56H
ADH
5AH
B5H
6AH
D5H
AAH
SIO1
CSOT1
INTCSI1
CSIIF1
SI1 (receive AAH)
SO1
55H is written to SOTB1.
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User's Manual U15798EJ2V0UD
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