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CHAPTER 16 SERIAL INTERFACE (SIO31)
Preliminary User’s Manual U13420EJ2V0UM00
16.3 Register to Control Serial Interface (SIO31)
The serial interface (SIO31) uses the following type of register to control functions.
• Serial operation mode register 31 (CSIM31)
(1) Serial operation mode register 31 (CSIM31)
This register is used to enable or disable SIO31’s serial clock, operation modes, and specific operations.
CSIM31 can be set by a 1-bit or 8-bit memory manipulation instruction.
RESET input sets CSIM31 to 00H.
Caution
In 3-wire serial I/O mode, set the port mode register (PMXX) as follows. In each case, set the output
latch to 0.
• During serial clock output (master transmission or master reception)
Set P90 (SCK31) to output mode (PM90 = 0)
• During serial clock input (slave transmission or slave reception)
Set P90 to input mode (PM90 = 1)
• During transmit/transmit and receive mode
Set P91 (SO31) to output mode (PM91 = 0)
• During receive mode
Set P92 (SI31) to input mode (PM92 = 1)
Figure 16-2. Format of Serial Operation Mode Register 31 (CSIM31)
Address: FFB1H After reset: 00H R/W
Symbol
7
6
5
4
3
2
1
0
CSIM31
CSIE31
0
0
0
0
MODE1
SCL311
SCL310
CSIE31
Enable/disable specification for SIO31
Shift register operation
Serial counter
Port
0
Operation stop
Clear
Port function
Note 1
1
Operation enable
Count operation enable
Serial fu port function
Note 2
MODE1
Transfer operation modes and flags
Operation mode
Transfer start trigger
SO31 output
0
Transmit/transmit and receive mode
Write to SIO31
Normal output
1
Receive-only mode
Read from SIO31
Fixed at low level
SCL311
SCL310
Clock selection
0
0
External clock input to SCK31
0
1
f
X
/2
3
(1.05 MHz)
1
0
f
X
/2
4
(524 kHz)
1
1
f
X
/2
5
(262 kHz)
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