85
CHAPTER 5. PERIPHERAL HARDWARE FUNCTIONS
(a) Serial operating mode register (CSIM)
When the 3-wire serial I/O mode is used, CSIM is set as shown below (see 5.5.3 (1) “Serial operating mode
register” for full details of CSIM).
CSIM is manipulated by 8-bit memory manipulation instructions. Bit manipulation of bits 7, 6 and 5 is also
possible.
Reset input clears the CSIM register to 00H.
The shaded area indicates bits used in the 3-wire serial I/O mode.
Address 7 6 5 4 3 2 1 0 Symbol
FE0H CSIE C0I WUP 0 CSIM3 0 CSIM1 0 CSIM
Serial Clock Selection Bit (W)
Serial Interface Operating Mode Selection Bit (W)
Wake-up Function Specification Bit (w)
Match Signal from Address Comparator (R)
Serial Interface Operation Enable/Disable Specification Bit (W)
Remarks (R) Read only
(W) Write only
Serial clock selection bit (W)
Serial Clock
CSIM1 SCK Pin Mode
3-Wire Serial I/O Mode SBI Mode
0 Input clock to SCK pin from off chip Input
1fXX/24 (262 kHz) Output
Remarks Figuer in ( ) apply to fXX = 4.19 MHz operation
Serial interface operating mode selection bit (W)
0SI/P03 (Input)
SO/P02
(CMOS Output)
3-wire serial I/O
mode
SIO 7 to 0 XA
(MSB-fist transfer)
Operating Mode Shift Register Bit Order SO Pin Function Si Pin Function
Wake-up function specification bit (W)
WUP 0 IRQCSI set at end of every serial transfer.
CSIM3