NEC mPD780852 Series, Preliminary User'S Manual

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CHAPTER 14 SERIAL INTERFACE SIO2
Preliminary User’s Manual U14581EJ3V0UM00
14.3 Serial Interface Control Registers
The following three types of registers are used to control the serial interface SIO2.
• Serial operation mode register 2 (CSIM2)
• Serial receive data buffer status register (SRBS2)
• Port mode register 0 (PM0)
(1) Serial operation mode register 2 (CSIM2)
This register is used to set the SIO2 interface’s serial clock, operation mode, and operation enable/disable.
CSIM2 is set with a 1-bit or 8-bit memory manipulation instruction.
RESET input clears CSIM2 to 00H.
Figure 14-2. Serial Operation Mode Register 2 (CSIM2) Format
Address: FF98H After Reset: 00H R/W
Symbol 7 6 5 4 3 2 1 0
CSIM2 CSIE2 0 0 CLPH CLPO MODE2 SCL21 SCL20
CSIE2 SIO2 Operation Enable/Disable Specification
Shift Register Operation Serial Counter Port
0 Operation disabled Clear Port function
1 Operation enabled Counter operation enabled Serial fu port function
CLPH SO2 Output Timing Selection
0 Transfer starts at the first active edge of SCK2.
1 Transfer starts when SCK2 is written.
CLPO Serial Clock Active Level Selection
0 SCK2 is high while serial transfer is stopped.
1 SCK2 is low while serial transfer is stopped.
MODE2 SIO2 Operation Mode Setting
Operation Mode Transfer Start Trigger SO2/P04 Pin
0 Transmit/receive mode Writing to SIO2 SO output
1 Receive-only mode Reading from SIO2 Port function
SCL21 SCL20 Serial Transfer Operation Clock Selection
Operation Clock (Transfer Frequency) Master/Slave
0 0 External clock input to SCK2 Slave mode
0 1 f
X
/2
9
Master mode
1 0 f
X
/2
10
Master mode
1 1 f
X
/2
11
Master mode