CHAPTER 10 SERIAL INTERFACE FUNCTION
User’s Manual U13850EJ4V0UM
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10.5.2 CSI4 control registers
CSI4 uses the following type of registers for control functions.
•
Variable-length serial control register 4 (CSIM4)
•
Variable-length serial setting register 4 (CSIB4)
•
Baud rate generator source clock selection register 4 (BRGCN4)
•
Baud rate generator output clock selection register 4 (BRGCK4)
(1) Variable-length serial control register 4 (CSIM4)
This register is used to enable or disable serial interface channel 4’s serial clock, operation modes, and specific
operations.
CSIM4 can be set by an 8-/1-bit memory manipulation instruction.
RESET input clears CSIM4 to 00H.
Figure 10-50. Variable-Length Serial Control Register 4 (CSIM4)
After reset:
00H
R/W
Address: FFFFF2E2H
<7>
6
5
4
3
2
1
0
CSIM4
CSIE4
0
0
0
0
MODE4
0
SCL4
SIO4 operation enable/disable specification
CSIE4
Shift register operation
Serial counter
Port
0
Operation disabled
Clear
Port function
Note 1
1
Operation enabled
Count operation enabled
Serial fu port function
Note 2
Transfer operation mode flag
MODE4
Operation mode
Transfer start trigger
SO4 output
0
Transmit/receive mode
SIO4 write
Normal output
1
Receive-only mode
SIO4 read
Port function
SCL4
Clock selection
0
External clock input (SCK4)
1
BRG (Baud rate generator)
Notes 1.
When CSIE4 = 0 (SIO4 operation disabled status), the port function is available for the SI4, SO4, and
SCK4 pins.
2.
When CSIE4 = 1 (SIO4 operation enable status), the port function is available only for the SI4 pin
when using the transmit function only and to SO4 pin when using the receive function.