Electronics America Single-Chip Microcontrollers User's Manual

CHAPTER 12 SERIAL INTERFACE 1A0

226 User’s Manual U15331EJ4V1UD

Symbol <7> 6 <5> <4> 3 2 1 0 Address After reset R/W

CSIM1A0 CSIE10 DIR10 ATE0 LSCK10 0 0 SCL101 SCL100 FF78H 00H R/W

Specification of operation enable/disable

CSIE10

Shift register operation Serial counter Port

Note

0 Operation stopped Cleared Port function

1 Operation enabled Count operation enabled Serial function + port function

DIR10 Specification of first bit of serial transfer data

0 MSB

1 LSB

ATE0 Selection of operation mode

0 3-wire serial mode

1 3-wire serial mode with automatic transmit/receive function

LSCK10 Chip enable control of SCK10 pin

0 SCK10 is used as port (P23) when CSIE10 = 0.

SCK10 is used for clock output when CSIE10 = 1.

1 SCK10 is fixed to high-level output when CSIE10 = 0.

SCK10 is used for clock output when CSIE10 = 1.

SCL101 SCL100 Selection of serial clock

0 0 External clock input to SCK10 pin

0 1 fX/2

(1.25 MHz)

1 0 fX/2

(625 kHz)

1 1 fX/2

(313 kHz)

Note When CSIE10 = 0 (SIO1A0 operation stop status), the SCK10/P23, SO10/P24, and SI10/P25 pins can

freely be used as port pins. Also, when CSIE10 is used for transmission only, the SI10/P25 pin can be

used as P25 (CMOS I/O) (set bit 7 (RE0) of ADTC0 to 0).

Remarks 1. f

X: Main system clock oscillation frequency

2. The parenthesized values apply to operation at f

X = 5.0 MHz.