CHAPTER 16 ASYNCHRONOUS SERIAL INTERFACE/3-WIRE SERIAL I/O
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User’s Manual U12697EJ3V0UM
16.4.2 Control registers
• Serial operation mode registers 1 and 2 (CSIM1, CSIM 2)
CSIM1 and CSIM2 are used to set the serial clock, operation mode, and operation enable/disable during the
3-wire serial I/O mode.
CSIM1 and SCIM2 can be set by a 1-bit or 8-bit memory manipulation instruction.
RESET input sets CSIM1 and CSIM2 to 00H.
Figure 16-12. Format of Serial Operation Mode Registers 1 and 2 (CSIM1, CSIM2)
Address: 0FF91H, 0FF92H After reset: 00H R/W
Symbol
7
6
5
4
3
2
1
0
CSIMn
CSIEn
0
0
0
0
MODEn
SCLn1
SCLn0
CSIEn
SIOn operation enable/disable setting
Shift register operation
Serial counter
Port
0
Operation disabled
Clear
Port function
Note
1
Operation enabled
Counter operation
Serial fu port
enabled
function
MODEn
Transfer operation mode flag
Operation mode
Transfer start trigger
SOn output
0
Transmit/receive mode
SIOn write
Normal output
1
Receive only mode
SIOn read
Fix to low level
SCLn1
SCLn0
Clock selection
0
0
External clock to SCKn
0
1
8-bit timer counter 2 (TM2) output (TO2)
1
0
f
XX
/8 (1.56 MHz)
1
1
f
XX
/16 (781 kHz)
Notes 1.
When CSIEn = 0 (SIOn operation stop status), pins connected to SIn, SOn and SCKn can be used as
ports.
2.
Set the external clock and TO2 to f
XX
/8 or below when selecting the external clock (SCKn) and TM2
output (TO2) for the clock.
Remarks 1.
n = 1, 2
2.
Figures in parentheses apply to operation at f
XX
= 12.5 MHz.
